Software Configuration Guide, Cisco IOS Release 15.2(2)E (Catalyst 2960, 2960-S, 2960-SF and 2960-Plus Switches)
Configuring QoS
Downloads: This chapterpdf (PDF - 2.6MB) The complete bookPDF (PDF - 13.4MB) | The complete bookePub (ePub - 3.33MB) | Feedback

Configuring QoS

Contents

Configuring QoS

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http:/​/​www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for QoS

Before configuring standard QoS, you must have a thorough understanding of these items:

  • The types of applications used and the traffic patterns on your network.
  • Traffic characteristics and needs of your network. For example, is the traffic on your network bursty? Do you need to reserve bandwidth for voice and video streams?
  • Bandwidth requirements and speed of the network.
  • Location of congestion points in the network.

QoS ACL Guidelines

Follow these guidelines when configuring QoS with access control lists (ACLs):

  • It is not possible to match IP fragments against configured IP extended ACLs to enforce QoS. IP fragments are sent as best-effort. IP fragments are denoted by fields in the IP header.
  • Only one ACL per class map and only one match class-map configuration command per class map are supported. The ACL can have multiple ACEs, which match fields against the contents of the packet.
  • A trust statement in a policy map requires multiple hardware entries per ACL line. If an input service policy map contains a trust statement in an ACL, the access list might be too large to fit into the available QoS hardware memory, and an error can occur when you apply the policy map to a port. Whenever possible, you should minimize the number of lines is a QoS ACL.

Policing Guidelines

  • The port ASIC device, which controls more than one physical port, supports 256 policers (255 user-configurable policers plus 1 policer reserved for system internal use). The maximum number of user-configurable policers supported per port is 63. Policers are allocated on demand by the software and are constrained by the hardware and ASIC boundaries. You cannot reserve policers per port; there is no guarantee that a port will be assigned to any policer.
  • Only one policer is applied to a packet on an ingress port. Only the average rate and committed burst parameters are configurable.
  • On a port configured for QoS, all traffic received through the port is classified, policed, and marked according to the policy map attached to the port. On a trunk port configured for QoS, traffic in all VLANs received through the port is classified, policed, and marked according to the policy map attached to the port.
  • If you have EtherChannel ports configured on your switch, you must configure QoS classification, policing, mapping, and queueing on the individual physical ports that comprise the EtherChannel. You must decide whether the QoS configuration should match on all ports in the EtherChannel.
  • If you need to modify a policy map of an existing QoS policy, first remove the policy map from all interfaces, and then modify or copy the policy map. After you finish the modification, apply the modified policy map to the interfaces. If you do not first remove the policy map from all interfaces, high CPU usage can occur, which, in turn, can cause the console to pause for a very long time.

General QoS Guidelines

These are the general QoS guidelines:

  • You configure QoS only on physical ports; there is no support for it at the VLAN level.
  • Control traffic (such as spanning-tree bridge protocol data units [BPDUs] and routing update packets) received by the switch are subject to all ingress QoS processing.
  • You are likely to lose data when you change queue settings; therefore, try to make changes when traffic is at a minimum.

Restrictions for QoS

The following are the restrictions for QoS:

  • To use these features, the switch must be running the LAN Base image: stacking, DSCP, auto-QoS, trusted boundary, policing, marking, mapping tables, and weighted tail drop.
  • Ingress queueing is not supported.
  • You can configure QoS only on physical ports. VLAN-based QoS is not supported. You configure the QoS settings, such as classification, queueing, and scheduling, and apply the policy map to a port. When configuring QoS on a physical port, you apply a nonhierarchical policy map to a port.
  • If the switch is running the LAN Lite image, you can configure ACLs, but you cannot attach them to physical interfaces. You can attach them to VLAN interfaces to filter traffic to the CPU.
  • The switch must be running the LAN Base image to use the following QoS features:
    • Policy maps
    • Policing and marking
    • Mapping tables
    • WTD

Information About QoS

QoS Implementation

Typically, networks operate on a best-effort delivery basis, which means that all traffic has equal priority and an equal chance of being delivered in a timely manner. When congestion occurs, all traffic has an equal chance of being dropped.

When you configure the QoS feature, you can select specific network traffic, prioritize it according to its relative importance, and use congestion-management and congestion-avoidance techniques to provide preferential treatment. Implementing QoS in your network makes network performance more predictable and bandwidth utilization more effective.

The QoS implementation is based on the Differentiated Services (Diff-Serv) architecture, a standard from the Internet Engineering Task Force (IETF). This architecture specifies that each packet is classified upon entry into the network.

The classification is carried in the IP packet header, using 6 bits from the deprecated IP type of service (ToS) field to carry the classification (class) information. Classification can also be carried in the Layer 2 frame.

Figure 1. QoS Classification Layers in Frames and Packets. The special bits in the Layer 2 frame or a Layer 3 packet are shown in the following figure:

Layer 2 Frame Prioritization Bits

Layer 2 Inter-Switch Link (ISL) frame headers have a 1-byte User field that carries an IEEE 802.1p class of service (CoS) value in the three least-significant bits. On ports configured as Layer 2 ISL trunks, all traffic is in ISL frames.

Layer 2 802.1Q frame headers have a 2-byte Tag Control Information field that carries the CoS value in the three most-significant bits, which are called the User Priority bits. On ports configured as Layer 2 802.1Q trunks, all traffic is in 802.1Q frames except for traffic in the native VLAN.

Other frame types cannot carry Layer 2 CoS values.

Layer 2 CoS values range from 0 for low priority to 7 for high priority.

Layer 3 Packet Prioritization Bits

Layer 3 IP packets can carry either an IP precedence value or a Differentiated Services Code Point (DSCP) value. QoS supports the use of either value because DSCP values are backward-compatible with IP precedence values.

IP precedence values range from 0 to 7. DSCP values range from 0 to 63.

End-to-End QoS Solution Using Classification

All switches and routers that access the Internet rely on the class information to provide the same forwarding treatment to packets with the same class information and different treatment to packets with different class information. The class information in the packet can be assigned by end hosts or by switches or routers along the way, based on a configured policy, detailed examination of the packet, or both. Detailed examination of the packet is expected to occur closer to the edge of the network, so that the core switches and routers are not overloaded with this task.

Switches and routers along the path can use the class information to limit the amount of resources allocated per traffic class. The behavior of an individual device when handling traffic in the Diff-Serv architecture is called per-hop behavior. If all devices along a path provide a consistent per-hop behavior, you can construct an end-to-end QoS solution.

Implementing QoS in your network can be a simple task or complex task and depends on the QoS features offered by your internetworking devices, the traffic types and patterns in your network, and the granularity of control that you need over incoming and outgoing traffic.

QoS Basic Model

To implement QoS, the switch must distinguish packets or flows from one another (classify), assign a label to indicate the given quality of service as the packets move through the switch, make the packets comply with the configured resource usage limits (police and mark), and provide different treatment (queue and schedule) in all situations where resource contention exists. The switch also needs to ensure that traffic sent from it meets a specific traffic profile (shape).

Figure 2. QoS Basic Model

Actions at Ingress Port

Actions at the ingress port include classifying traffic, policing, marking, queueing, and scheduling:

  • Classifying a distinct path for a packet by associating it with a QoS label. The switch maps the CoS or DSCP in the packet to a QoS label to distinguish one kind of traffic from another. The QoS label that is generated identifies all future QoS actions to be performed on this packet.
  • Policing determines whether a packet is in or out of profile by comparing the rate of the incoming traffic to the configured policer. The policer limits the bandwidth consumed by a flow of traffic. The result is passed to the marker.
  • Marking evaluates the policer and configuration information for the action to be taken when a packet is out of profile and determines what to do with the packet (pass through a packet without modification, marking down the QoS label in the packet, or dropping the packet).
  • Queueing evaluates the QoS label and the corresponding DSCP or CoS value to select into which of the two ingress queues to place a packet. Queueing is enhanced with the weighted tail-drop (WTD) algorithm, a congestion-avoidance mechanism. If the threshold is exceeded, the packet is dropped.
  • Scheduling services the queues based on their configured shaped round robin (SRR) weights. One of the ingress queues is the priority queue, and SRR services it for its configured share before servicing the other queue.

Note


Queueing and scheduling are only supported at egress and not at ingress on the switch.


Actions at Egress Port

Actions at the egress port include queueing and scheduling:

  • Queueing evaluates the QoS packet label and the corresponding DSCP or CoS value before selecting which of the four egress queues to use. Because congestion can occur when multiple ingress ports simultaneously send data to an egress port, WTD differentiates traffic classes and subjects the packets to different thresholds based on the QoS label. If the threshold is exceeded, the packet is dropped.
  • Scheduling services the four egress queues based on their configured SRR shared or shaped weights. One of the queues (queue 1) can be the expedited queue, which is serviced until empty before the other queues are serviced.

Classification Overview

Classification is the process of distinguishing one kind of traffic from another by examining the fields in the packet. Classification is enabled only if QoS is globally enabled on the switch. By default, QoS is globally disabled, so no classification occurs.

During classification, the switch performs a lookup and assigns a QoS label to the packet. The QoS label identifies all QoS actions to be performed on the packet and from which queue the packet is sent.

The QoS label is based on the DSCP or the CoS value in the packet and decides the queueing and scheduling actions to perform on the packet. The label is mapped according to the trust setting and the packet type as shown in Classification Flowchart.

You specify which fields in the frame or packet that you want to use to classify incoming traffic.

Non-IP Traffic Classification

The following table describes the non-IP traffic classification options for your QoS configuration.

Table 1 Non- IP Traffic Classifications

Non-IP Traffic Classification

Description

Trust the CoS value

Trust the CoS value in the incoming frame (configure the port to trust CoS), and then use the configurable CoS-to-DSCP map to generate a DSCP value for the packet.

Layer 2 ISL frame headers carry the CoS value in the 3 least-significant bits of the 1-byte User field.

Layer 2 802.1Q frame headers carry the CoS value in the 3 most-significant bits of the Tag Control Information field. CoS values range from 0 for low priority to 7 for high priority.

Trust the DSCP or trust IP precedence value

Trust the DSCP or trust IP precedence value in the incoming frame. These configurations are meaningless for non-IP traffic. If you configure a port with either of these options and non-IP traffic is received, the switch assigns a CoS value and generates an internal DSCP value from the CoS-to-DSCP map. The switch uses the internal DSCP value to generate a CoS value representing the priority of the traffic.

Perform classification based on configured Layer 2 MAC ACL

Perform the classification based on a configured Layer 2 MAC access control list (ACL), which can examine the MAC source address, the MAC destination address, and other fields. If no ACL is configured, the packet is assigned 0 as the DSCP and CoS values, which means best-effort traffic. Otherwise, the policy-map action specifies a DSCP or CoS value to assign to the incoming frame.

After classification, the packet is sent to the policing, marking, and the ingress queueing and scheduling stages.

After classification, the packet is sent to the policing and marking stages.

IP Traffic Classification

The following table describes the IP traffic classification options for your QoS configuration.

Table 2 IP Traffic Classifications

IP Traffic Classification

Description

Trust the DSCP value

Trust the DSCP value in the incoming packet (configure the port to trust DSCP), and assign the same DSCP value to the packet. The IETF defines the 6 most-significant bits of the 1-byte ToS field as the DSCP. The priority represented by a particular DSCP value is configurable. DSCP values range from 0 to 63.

You can also classify IP traffic based on IPv6 DSCP.

For ports that are on the boundary between two QoS administrative domains, you can modify the DSCP to another value by using the configurable DSCP-to-DSCP-mutation map.

Trust the IP precedence value

Trust the IP precedence value in the incoming packet (configure the port to trust IP precedence), and generate a DSCP value for the packet by using the configurable IP-precedence-to-DSCP map. The IP Version 4 specification defines the 3 most-significant bits of the 1-byte ToS field as the IP precedence. IP precedence values range from 0 for low priority to 7 for high priority.

You can also classify IP traffic based on IPv6 precedence.

Trust the CoS value

Trust the CoS value (if present) in the incoming packet, and generate a DSCP value for the packet by using the CoS-to-DSCP map. If the CoS value is not present, use the default port CoS value.

IP standard or an extended ACL

Perform the classification based on a configured IP standard or an extended ACL, which examines various fields in the IP header. If no ACL is configured, the packet is assigned 0 as the DSCP and CoS values, which means best-effort traffic. Otherwise, the policy-map action specifies a DSCP or CoS value to assign to the incoming frame.

Override configured CoS

Override the configured CoS of incoming packets, and apply the default port CoS value to them. For IPv6 packets, the DSCP value is rewritten by using the CoS-to-DSCP map and by using the default CoS of the port. You can do this for both IPv4 and IPv6 traffic.

After classification, the packet is sent to the policing, marking, and the ingress queueing and scheduling stages.

After classification, the packet is sent to the policing and marking stages.

Classification Flowchart

Figure 3. Classification Flowchart

Access Control Lists

You can use IP standard, IP extended, or Layer 2 MAC ACLs to define a group of packets with the same characteristics (class). You can also classify IP traffic based on IPv6 ACLs.

In the QoS context, the permit and deny actions in the access control entries (ACEs) have different meanings from security ACLs:

  • If a match with a permit action is encountered (first-match principle), the specified QoS-related action is taken.
  • If a match with a deny action is encountered, the ACL being processed is skipped, and the next ACL is processed.
  • If no match with a permit action is encountered and all the ACEs have been examined, no QoS processing occurs on the packet, and the switch offers best-effort service to the packet.
  • If multiple ACLs are configured on a port, the lookup stops after the packet matches the first ACL with a permit action, and QoS processing begins.

    Note


    When creating an access list, note that by default the end of the access list contains an implicit deny statement for everything if it did not find a match before reaching the end.


After a traffic class has been defined with the ACL, you can attach a policy to it. A policy might contain multiple classes with actions specified for each one of them. A policy might include commands to classify the class as a particular aggregate (for example, assign a DSCP) or rate-limit the class. This policy is then attached to a particular port on which it becomes effective.

You implement IP ACLs to classify IP traffic by using the access-list global configuration command; you implement Layer 2 MAC ACLs to classify non-IP traffic by using the mac access-list extended global configuration command.

Classification Based on Class Maps and Policy Maps

To use policy maps, the switch must be running the LAN Base image.

A class map is a mechanism that you use to name a specific traffic flow (or class) and to isolate it from all other traffic. The class map defines the criteria used to match against a specific traffic flow to further classify it. The criteria can include matching the access group defined by the ACL or matching a specific list of DSCP or IP precedence values. If you have more than one type of traffic that you want to classify, you can create another class map and use a different name. After a packet is matched against the class-map criteria, you further classify it through the use of a policy map.

A policy map specifies which traffic class to act on. Actions can include trusting the CoS, DSCP, or IP precedence values in the traffic class; setting a specific DSCP or IP precedence value in the traffic class; or specifying the traffic bandwidth limitations and the action to take when the traffic is out of profile. Before a policy map can be effective, you must attach it to a port.

You create a class map by using the class-map global configuration command or the class policy-map configuration command. You should use the class-map command when the map is shared among many ports. When you enter the class-map command, the switch enters the class-map configuration mode. In this mode, you define the match criterion for the traffic by using the match class-map configuration command.

You can configure a default class by using the class class-default policy-map configuration command. Unclassified traffic (traffic specified in the other traffic classes configured on the policy-map) is treated as default traffic.

You create and name a policy map by using the policy-map global configuration command. When you enter this command, the switch enters the policy-map configuration mode. In this mode, you specify the actions to take on a specific traffic class by using the class, trust, or set policy-map configuration and policy-map class configuration commands.

The policy map can contain the police and police aggregate policy-map class configuration commands, which define the policer, the bandwidth limitations of the traffic, and the action to take if the limits are exceeded.

To enable the policy map, you attach it to a port by using the service-policy interface configuration command.

Policing and Marking Overview

After a packet is classified and has a DSCP-based or CoS-based QoS label assigned to it, the policing and marking process can begin.

Policing involves creating a policer that specifies the bandwidth limits for the traffic. Packets that exceed the limits are out of profile or nonconforming. Each policer decides on a packet-by-packet basis whether the packet is in or out of profile and specifies the actions on the packet. These actions, carried out by the marker, include passing through the packet without modification, dropping the packet, or modifying (marking down) the assigned DSCP of the packet and allowing the packet to pass through. The configurable policed-DSCP map provides the packet with a new DSCP-based QoS label. Marked-down packets use the same queues as the original QoS label to prevent packets in a flow from getting out of order.


Note


All traffic, regardless of whether it is bridged or routed, is subjected to a policer, if one is configured. As a result, bridged packets might be dropped or might have their DSCP or CoS fields modified when they are policed and marked.


You can configure policing on a physical port. After you configure the policy map and policing actions, attach the policy to a port by using the service-policy interface configuration command.

Physical Port Policing

In policy maps on physical ports, you can create the following types of policers:

  • Individual—QoS applies the bandwidth limits specified in the policer separately to each matched traffic class. You configure this type of policer within a policy map by using the police policy-map class configuration command.
  • Aggregate—QoS applies the bandwidth limits specified in an aggregate policer cumulatively to all matched traffic flows. You configure this type of policer by specifying the aggregate policer name within a policy map by using the police aggregate policy-map class configuration command. You specify the bandwidth limits of the policer by using the mls qos aggregate-policer global configuration command. In this way, the aggregate policer is shared by multiple classes of traffic within a policy map.

Policing uses a token-bucket algorithm. As each frame is received by the switch, a token is added to the bucket. The bucket has a hole in it and leaks at a rate that you specify as the average traffic rate in bits per second. Each time a token is added to the bucket, the switch verifies that there is enough room in the bucket. If there is not enough room, the packet is marked as nonconforming, and the specified policer action is taken (dropped or marked down).

How quickly the bucket fills is a function of the bucket depth (burst-byte), the rate at which the tokens are removed (rate-bps), and the duration of the burst above the average rate. The size of the bucket imposes an upper limit on the burst length and limits the number of frames that can be transmitted back-to-back. If the burst is short, the bucket does not overflow, and no action is taken against the traffic flow. However, if a burst is long and at a higher rate, the bucket overflows, and the policing actions are taken against the frames in that burst.

You configure the bucket depth (the maximum burst that is tolerated before the bucket overflows) by using the burst-byte option of the police policy-map class configuration command or the mls qos aggregate-policer global configuration command. You configure how fast (the average rate) that the tokens are removed from the bucket by using the rate-bps option of the police policy-map class configuration command or the mls qos aggregate-policer global configuration command.

Figure 4. Policing and Marking Flowchart on Physical Ports.

Mapping Tables Overview

During QoS processing, the switch represents the priority of all traffic (including non-IP traffic) with a QoS label based on the DSCP or CoS value from the classification stage.

The following table describes QoS processing and mapping tables.

Table 3 QoS Processing and Mapping Tables

QoS Processing Stage

Mapping Table Usage

Classification

During the classification stage, QoS uses configurable mapping tables to derive a corresponding DSCP or CoS value from a received CoS, DSCP, or IP precedence value. These maps include the CoS-to-DSCP map and the IP-precedence-to-DSCP map.

You configure these maps by using the mls qos map cos-dscp and the mls qos map ip-prec-dscp global configuration commands.

On an ingress port configured in the DSCP-trusted state, if the DSCP values are different between the QoS domains, you can apply the configurable DSCP-to-DSCP-mutation map to the port that is on the boundary between the two QoS domains.

You configure this map by using the mls qos map dscp-mutation global configuration command.

Policing

During policing stage, QoS can assign another DSCP value to an IP or a non-IP packet (if the packet is out of profile and the policer specifies a marked-down value). This configurable map is called the policed-DSCP map.

You configure this map by using the mls qos map policed-dscp global configuration command.

Pre-scheduling

Before the traffic reaches the scheduling stage, QoS stores the packet in an ingress and an egress queue according to the QoS label. The QoS label is based on the DSCP or the CoS value in the packet and selects the queue through the DSCP input and output queue threshold maps or through the CoS input and output queue threshold maps. In addition to an ingress or an egress queue, the QOS label also identifies the WTD threshold value.

You configure these maps by using the mls qos srr-queue {input output} dscp-map and the mls qos srr-queue {input output} cos-map global configuration commands.

The CoS-to-DSCP, DSCP-to-CoS, and the IP-precedence-to-DSCP maps have default values that might or might not be appropriate for your network.

The default DSCP-to-DSCP-mutation map and the default policed-DSCP map are null maps; they map an incoming DSCP value to the same DSCP value. The DSCP-to-DSCP-mutation map is the only map you apply to a specific port. All other maps apply to the entire switch.

Queueing and Scheduling Overview

The switch has queues at specific points to help prevent congestion.

Figure 5. Ingress and Egress Queue Location on Switch

Weighted Tail Drop

Both the ingress and egress queues use an enhanced version of the tail-drop congestion-avoidance mechanism called weighted tail drop (WTD). WTD is implemented on queues to manage the queue lengths and to provide drop precedences for different traffic classifications.

As a frame is enqueued to a particular queue, WTD uses the frame’s assigned QoS label to subject it to different thresholds. If the threshold is exceeded for that QoS label (the space available in the destination queue is less than the size of the frame), the switch drops the frame.

Each queue has three threshold values. The QoS label determines which of the three threshold values is subjected to the frame. Of the three thresholds, two are configurable (explicit) and one is not (implicit).

Figure 6. WTD and Queue Operation. The following figure shows an example of WTD operating on a queue whose size is 1000 frames. Three drop percentages are configured: 40 percent (400 frames), 60 percent (600 frames), and 100 percent (1000 frames). These percentages indicate that up to 400 frames can be queued at the 40-percent threshold, up to 600 frames at the 60-percent threshold, and up to 1000 frames at the 100-percent threshold.

In the example, CoS values 6 and 7 have a greater importance than the other CoS values, and they are assigned to the 100-percent drop threshold (queue-full state). CoS values 4 and 5 are assigned to the 60-percent threshold, and CoS values 0 to 3 are assigned to the 40-percent threshold.

Suppose the queue is already filled with 600 frames, and a new frame arrives. It contains CoS values 4 and 5 and is subjected to the 60-percent threshold. If this frame is added to the queue, the threshold will be exceeded, so the switch drops it.

SRR Shaping and Sharing

Both the ingress and egress queues are serviced by shaped round robin (SRR), which controls the rate at which packets are sent. On the ingress queues, SRR sends packets to the stack or internal ring. On the egress queues, SRR sends packets to the egress port.

You can configure SRR on egress queues for sharing or for shaping. However, for ingress queues, sharing is the default mode, and it is the only mode supported.

In shaped mode, the egress queues are guaranteed a percentage of the bandwidth, and they are rate-limited to that amount. Shaped traffic does not use more than the allocated bandwidth even if the link is idle. Shaping provides a more even flow of traffic over time and reduces the peaks and valleys of bursty traffic. With shaping, the absolute value of each weight is used to compute the bandwidth available for the queues.

In shared mode, the queues share the bandwidth among them according to the configured weights. The bandwidth is guaranteed at this level but not limited to it. For example, if a queue is empty and no longer requires a share of the link, the remaining queues can expand into the unused bandwidth and share it among them. With sharing, the ratio of the weights controls the frequency of dequeuing; the absolute values are meaningless. Shaping and sharing is configured per interface. Each interface can be uniquely configured.

Queueing and Scheduling on Egress Queues

The following figure shows queueing and scheduling flowcharts for egress ports on the switch.

Figure 7. Queueing and Scheduling Flowchart for Egress Ports on the Switch


Note


If the expedite queue is enabled, SRR services it until it is empty before servicing the other three queues.


Egress Expedite Queue

Each port supports four egress queues, one of which (queue 1) can be the egress expedite queue. These queues are assigned to a queue-set. All traffic exiting the switch flows through one of these four queues and is subjected to a threshold based on the QoS label assigned to the packet.


Note


If the expedite queue is enabled, SRR services it until it is empty before servicing the other three queues.


Egress Queue Buffer Allocation

The following figure shows the egress queue buffer.

Figure 8. Egress Queue Buffer Allocation. The buffer space is divided between the common pool and the reserved pool. The switch uses a buffer allocation scheme to reserve a minimum amount of buffers for each egress queue, to prevent any queue or port from consuming all the buffers and depriving other queues, and to control whether to grant buffer space to a requesting queue. The switch detects whether the target queue has not consumed more buffers than its reserved amount (under-limit), whether it has consumed all of its maximum buffers (over limit), and whether the common pool is empty (no free buffers) or not empty (free buffers). If the queue is not over-limit, the switch can allocate buffer space from the reserved pool or from the common pool (if it is not empty). If there are no free buffers in the common pool or if the queue is over-limit, the switch drops the frame.

Buffer and Memory Allocation

You guarantee the availability of buffers, set drop thresholds, and configure the maximum memory allocation for a queue-set by using the mls qos queue-set output qset-id threshold queue-id drop-threshold1 drop-threshold2 reserved-threshold maximum-threshold global configuration command. Each threshold value is a percentage of the queue’s allocated memory, which you specify by using the mls qos queue-set output qset-id buffers allocation1 ... allocation4 global configuration command. The sum of all the allocated buffers represents the reserved pool, and the remaining buffers are part of the common pool.

Through buffer allocation, you can ensure that high-priority traffic is buffered. For example, if the buffer space is 400, you can allocate 70 percent of it to queue 1 and 10 percent to queues 2 through 4. Queue 1 then has 280 buffers allocated to it, and queues 2 through 4 each have 40 buffers allocated to them.

You can guarantee that the allocated buffers are reserved for a specific queue in a queue-set. For example, if there are 100 buffers for a queue, you can reserve 50 percent (50 buffers). The switch returns the remaining 50 buffers to the common pool. You also can enable a queue in the full condition to obtain more buffers than are reserved for it by setting a maximum threshold. The switch can allocate the needed buffers from the common pool if the common pool is not empty.

Queues and WTD Thresholds

You can assign each packet that flows through the switch to a queue and to a threshold.

Specifically, you map DSCP or CoS values to an egress queue and map DSCP or CoS values to a threshold ID. You use the mls qos srr-queue output dscp-map queue queue-id {dscp1...dscp8 | threshold threshold-id dscp1...dscp8} or the mls qos srr-queue output cos-map queue queue-id {cos1...cos8 | threshold threshold-id cos1...cos8} global configuration command. You can display the DSCP output queue threshold map and the CoS output queue threshold map by using the show mls qos maps privileged EXEC command.

The queues use WTD to support distinct drop percentages for different traffic classes. Each queue has three drop thresholds: two configurable (explicit) WTD thresholds and one nonconfigurable (implicit) threshold preset to the queue-full state. You assign the two WTD threshold percentages for threshold ID 1 and ID 2. The drop threshold for threshold ID 3 is preset to the queue-full state, and you cannot modify it. You map a port to queue-set by using the queue-set qset-id interface configuration command. Modify the queue-set configuration to change the WTD threshold percentages.

Shaped or Shared Mode

SRR services each queue-set in shared or shaped mode. You map a port to a queue-set by using the queue-set qset-id interface configuration command. You assign shared or shaped weights to the port by using the srr-queue bandwidth share weight1 weight2 weight3 weight4 or the srr-queue bandwidth shape weight1 weight2 weight3 weight4 interface configuration command.

The buffer allocation together with the SRR weight ratios control how much data can be buffered and sent before packets are dropped. The weight ratio is the ratio of the frequency in which the SRR scheduler sends packets from each queue.

All four queues participate in the SRR unless the expedite queue is enabled, in which case the first bandwidth weight is ignored and is not used in the ratio calculation. The expedite queue is a priority queue, and it is serviced until empty before the other queues are serviced. You enable the expedite queue by using the priority-queue out interface configuration command.

You can combine the commands described in this section to prioritize traffic by placing packets with particular DSCPs or CoSs into certain queues, by allocating a large queue size or by servicing the queue more frequently, and by adjusting queue thresholds so that packets with lower priorities are dropped.


Note


The egress queue default settings are suitable for most situations. You should change them only when you have a thorough understanding of the egress queues and if these settings do not meet your QoS solution.


Packet Modification

A packet is classified, policed, and queued to provide QoS. The following packet modifications can occur during the process to provide QoS:

  • For IP and non-IP packets, classification involves assigning a QoS label to a packet based on the DSCP or CoS of the received packet. However, the packet is not modified at this stage; only an indication of the assigned DSCP or CoS value is carried along.
  • During policing, IP and non-IP packets can have another DSCP assigned to them (if they are out of profile and the policer specifies a markdown DSCP). Once again, the DSCP in the packet is not modified, but an indication of the marked-down value is carried along. For IP packets, the packet modification occurs at a later stage; for non-IP packets the DSCP is converted to CoS and used for queueing and scheduling decisions.
  • Depending on the QoS label assigned to a frame and the mutation chosen, the DSCP and CoS values of the frame are rewritten. If you do not configure a table map and if you configure the port to trust the DSCP of the incoming frame, the DSCP value in the frame is not changed, but the CoS is rewritten according to the DSCP-to-CoS map. If you configure the port to trust the CoS of the incoming frame and it is an IP packet, the CoS value in the frame is not changed, but the DSCP might be changed according to the CoS-to-DSCP map. The input mutation causes the DSCP to be rewritten depending on the new value of DSCP chosen. The set action in a policy map also causes the DSCP to be rewritten.

Standard QoS Default Configuration

Standard QoS is disabled by default.

There is no concept of trusted or untrusted ports because the packets are not modified. The CoS, DSCP, and IP precedence values in the packet are not changed.

Traffic is switched in pass-through mode. The packets are switched without any rewrites and classified as best effort without any policing.

When QoS is enabled using the mls qos global configuration command and all other QoS settings are at their defaults, traffic is classified as best effort (the DSCP and CoS value is set to 0) without any policing. No policy maps are configured. The default port trust state on all ports is untrusted.

Related Tasks

Default Ingress Queue Configuration

The following tables describe the default ingress queue configurations.

The following table shows the default ingress queue configuration when QoS is enabled. For the bandwidth allocation feature, bandwidth is equally shared between the queues. SRR sends packets in shared mode only. Queue 2 is the priority queue. SRR services the priority queue for its configured share before servicing the other queue.

Table 4 Default Ingress Queue Configuration

Feature

Queue 1

Queue 2

Buffer allocation

90 percent

10 percent

Bandwidth allocation

4

4

Priority queue bandwidth

0

10

WTD drop threshold 1

100 percent

100 percent

WTD drop threshold 2

100 percent

100 percent

The following table shows the default CoS input queue threshold map when QoS is enabled.

Table 5 Default CoS Input Queue Threshold Map

CoS Value

Queue ID–Threshold ID

0–4

1–1

5

2–1

6, 7

1–1

The following table shows the default DSCP input queue threshold map when QoS is enabled.

Table 6 Default DSCP Input Queue Threshold Map

DSCP Value

Queue ID–Threshold ID

0–39

1–1

40–47

2–1

48–63

1–1

Default Egress Queue Configuration

The following table shows the default egress queue configuration for each queue-set when QoS is enabled. All ports are mapped to queue-set 1. The port bandwidth limit is set to 100 percent and rate unlimited. For the SRR shaped weights (absolute) feature, a shaped weight of zero indicates that the queue is operating in shared mode. For the SRR shared weights feature, one quarter of the bandwidth is allocated to each queue.

Table 7 Default Egress Queue Configuration

Feature

Queue 1

Queue 2

Queue 3

Queue 4

Buffer allocation

25 percent

25 percent

25 percent

25 percent

WTD drop threshold 1

100 percent

200 percent

100 percent

100 percent

WTD drop threshold 2

100 percent

200 percent

100 percent

100 percent

Reserved threshold

50 percent

100 percent

50 percent

50 percent

Maximum threshold

400 percent

400 percent

400 percent

400 percent

SRR shaped weights (absolute)

25

0

0

0

SRR shared weights

25

25

25

25


Note


The maximum user configurable values for WTD drop threshold 1, WTD drop threshold 2, reserved threshold, and maximum threshold are each 3200 percent.


The following table shows the default CoS output queue threshold map when QoS is enabled.

Table 8 Default CoS Output Queue Threshold Map

CoS Value

Queue ID–Threshold ID

0, 1

2–1

2, 3

3–1

4

4–1

5

1–1

6, 7

4–1

The following table shows the default DSCP output queue threshold map when QoS is enabled.

Table 9 Default DSCP Output Queue Threshold Map

DSCP Value

Queue ID–Threshold ID

0–15

2–1

16–31

3–1

32–39

4–1

40–47

1–1

48–63

4–1

Default Mapping Table Configuration

The default DSCP-to-DSCP-mutation map is a null map, which maps an incoming DSCP value to the same DSCP value.

The default policed-DSCP map is a null map, which maps an incoming DSCP value to the same DSCP value (no markdown).

DSCP Maps

Default CoS-to-DSCP Map

You use the CoS-to-DSCP map to map CoS values in incoming packets to a DSCP value that QoS uses internally to represent the priority of the traffic. The following table shows the default CoS-to-DSCP map. If these values are not appropriate for your network, you need to modify them.

Table 10 Default CoS-to-DSCP Map

CoS Value

DSCP Value

0

0

1

8

2

16

3

24

4

32

5

40

6

48

7

56

Default IP-Precedence-to-DSCP Map

You use the IP-precedence-to-DSCP map to map IP precedence values in incoming packets to a DSCP value that QoS uses internally to represent the priority of the traffic. The following table shows the default IP-precedence-to-DSCP map. If these values are not appropriate for your network, you need to modify them.

Table 11 Default IP-Precedence-to-DSCP Map

IP Precedence Value

DSCP Value

0

0

1

8

2

16

3

24

4

32

5

40

6

48

7

56

Default DSCP-to-CoS Map

You use the DSCP-to-CoS map to generate a CoS value, which is used to select one of the four egress queues. The following table shows the default DSCP-to-CoS map. If these values are not appropriate for your network, you need to modify them.

Table 12 Default DSCP-to-CoS Map

DSCP Value

CoS Value

0–7

0

8–15

1

16–23

2

24–31

3

32–39

4

40–47

5

48–55

6

56–63

7

How to Configure QoS

Enabling QoS Globally

By default, QoS is disabled on the switch.

The following procedure to enable QoS globally is required.

SUMMARY STEPS

    1.    configure terminal

    2.    mls qos

    3.    end

    4.    show mls qos

    5.    copy running-config startup-config


DETAILED STEPS
     Command or ActionPurpose
    Step 1configure terminal


    Example:
    
    Switch# configure terminal
    
    
     

    Enters global configuration mode.

     
    Step 2mls qos


    Example:
    
    Switch(config)# mls qos
    
    
     

    Enables QoS globally.

    QoS operates with the default settings described in the related topic sections below.

    Note   

    To disable QoS, use the no mls qos global configuration command.

     
    Step 3end


    Example:
    
    Switch(config)# end
    
    
     

    Returns to privileged EXEC mode.

     
    Step 4show mls qos


    Example:
    
    Switch# show mls qos
    
    
     

    Verifies the QoS configuration.

     
    Step 5copy running-config startup-config


    Example:
    
    Switch# copy running-config 
    startup-config
    
    
     

    (Optional) Saves your entries in the configuration file.

     

    Configuring Classification Using Port Trust States

    These sections describe how to classify incoming traffic by using port trust states.


    Note


    Depending on your network configuration, you must perform one or more of these tasks in this module or one or more of the tasks in the “QoS Policy Configuration” section on page 37-47.


    Configuring the Trust State on Ports Within the QoS Domain

    Packets entering a QoS domain are classified at the edge of the QoS domain. When the packets are classified at the edge, the switch port within the QoS domain can be configured to one of the trusted states because there is no need to classify the packets at every switch within the QoS domain.

    Figure 9. Port Trusted States on Ports Within the QoS Domain

    SUMMARY STEPS

      1.    configure terminal

      2.    interface interface-id

      3.    mls qos trust [cos | dscp | ip-precedence]

      4.    end

      5.    show mls qos interface

      6.    copy running-config startup-config


    DETAILED STEPS
       Command or ActionPurpose
      Step 1configure terminal


      Example:
      
      Switch# configure terminal
      
      
       

      Enters global configuration mode.

       
      Step 2interface interface-id


      Example:
      
      Switch(config)# interface 
      gigabitethernet 1/0/2
      
      
       

      Specifies the port to be trusted, and enters interface configuration mode. Valid interfaces are physical ports.

       
      Step 3mls qos trust [cos | dscp | ip-precedence]


      Example:
      
      Switch(config-if)# mls qos trust cos
      
      
       

      Configures the port trust state.

      By default, the port is not trusted. If no keyword is specified, the default is dscp.

      The keywords have these meanings:

      • cos—Classifies an ingress packet by using the packet CoS value. For an untagged packet, the port default CoS value is used. The default port CoS value is 0.
      • dscp—Classifies an ingress packet by using the packet DSCP value. For a non-IP packet, the packet CoS value is used if the packet is tagged; for an untagged packet, the default port CoS is used. Internally, the switch maps the CoS value to a DSCP value by using the CoS-to-DSCP map.
      • ip-precedence—Classifies an ingress packet by using the packet IP-precedence value. For a non-IP packet, the packet CoS value is used if the packet is tagged; for an untagged packet, the default port CoS is used. Internally, the switch maps the CoS value to a DSCP value by using the CoS-to-DSCP map.

      To return a port to its untrusted state, use the no mls qos trust interface configuration command.

       
      Step 4end


      Example:
      
      Switch(config-if)# end
      
      
       

      Returns to privileged EXEC mode.

       
      Step 5show mls qos interface


      Example:
      
      Switch# show mls qos interface
      
      
       

      Verifies your entries.

       
      Step 6copy running-config startup-config


      Example:
      
      Switch# copy running-config 
      startup-config
      
      
       

      (Optional) Saves your entries in the configuration file.

       

      Configuring the CoS Value for an Interface

      QoS assigns the CoS value specified with the mls qos cos interface configuration command to untagged frames received on trusted and untrusted ports.

      Beginning in privileged EXEC mode, follow these steps to define the default CoS value of a port or to assign the default CoS to all incoming packets on the port.

      SUMMARY STEPS

        1.    configure terminal

        2.    interface interface-id

        3.    mls qos cos {default-cos | override}

        4.    end

        5.    show mls qos interface

        6.    copy running-config startup-config


      DETAILED STEPS
         Command or ActionPurpose
        Step 1configure terminal


        Example:
        
        Switch# configure terminal
        
        
         

        Enters the global configuration mode.

         
        Step 2interface interface-id


        Example:
        
        Switch(config)# interface 
        gigabitethernet 1/1/1
        
        
         

        Specifies the port to be configured, and enters interface configuration mode.

        Valid interfaces include physical ports.

         
        Step 3mls qos cos {default-cos | override}


        Example:
        
        Switch(config-if)# mls qos 
        override
        
        
         

        Configures the default CoS value for the port.

        • For default-cos, specify a default CoS value to be assigned to a port. If the packet is untagged, the default CoS value becomes the packet CoS value. The CoS range is 0 to 7. The default is 0.
        • Use the override keyword to override the previously configured trust state of the incoming packet and to apply the default port CoS value to the port on all incoming packets. By default, CoS override is disabled. Use the override keyword when all incoming packets on specified ports deserve higher or lower priority than packets entering from other ports. Even if a port was previously set to trust DSCP, CoS, or IP precedence, this command overrides the previously configured trust state, and all the incoming CoS values are assigned the default CoS value configured with this command. If an incoming packet is tagged, the CoS value of the packet is modified with the default CoS of the port at the ingress port.
        Note   

        To return to the default setting, use the no mls qos cos {default-cos | override} interface configuration command.

         
        Step 4end


        Example:
        
        Switch(config-if)# end
        
        
         

        Returns to privileged EXEC mode.

         
        Step 5show mls qos interface


        Example:
        
        Switch# show mls qos interface
        
        
         

        Verifies your entries.

         
        Step 6copy running-config startup-config


        Example:
        
        Switch# copy running-config 
        startup-config
        
        
         

        (Optional) Saves your entries in the configuration file.

         

        Configuring a Trusted Boundary to Ensure Port Security

        In a typical network, you connect a Cisco IP Phone to a switch port and cascade devices that generate data packets from the back of the telephone. The Cisco IP Phone guarantees the voice quality through a shared data link by marking the CoS level of the voice packets as high priority (CoS = 5) and by marking the data packets as low priority (CoS = 0). Traffic sent from the telephone to the switch is typically marked with a tag that uses the 802.1Q header. The header contains the VLAN information and the class of service (CoS) 3-bit field, which is the priority of the packet.

        For most Cisco IP Phone configurations, the traffic sent from the telephone to the switch should be trusted to ensure that voice traffic is properly prioritized over other types of traffic in the network. By using the mls qos trust cos interface configuration command, you configure the switch port to which the telephone is connected to trust the CoS labels of all traffic received on that port. Use the mls qos trust dscp interface configuration command to configure a routed port to which the telephone is connected to trust the DSCP labels of all traffic received on that port.

        With the trusted setting, you also can use the trusted boundary feature to prevent misuse of a high-priority queue if a user bypasses the telephone and connects the PC directly to the switch. Without trusted boundary, the CoS labels generated by the PC are trusted by the switch (because of the trusted CoS setting). By contrast, trusted boundary uses CDP to detect the presence of a Cisco IP Phone (such as the Cisco IP Phone 7910, 7935, 7940, and 7960) on a switch port. If the telephone is not detected, the trusted boundary feature disables the trusted setting on the switch port and prevents misuse of a high-priority queue. Note that the trusted boundary feature is not effective if the PC and Cisco IP Phone are connected to a hub that is connected to the switch.

        In some situations, you can prevent a PC connected to the Cisco IP Phone from taking advantage of a high-priority data queue. You can use the switchport priority extend cos interface configuration command to configure the telephone through the switch CLI to override the priority of the traffic received from the PC.

        SUMMARY STEPS

          1.    configure terminal

          2.    cdp run

          3.    interface interface-id

          4.    cdp enable

          5.    Use one of the following:

          • mls qos trust cos
          • mls qos trust dscp

          6.    mls qos trust device cisco-phone

          7.    end

          8.    show mls qos interface

          9.    copy running-config startup-config


        DETAILED STEPS
           Command or ActionPurpose
          Step 1configure terminal


          Example:
          
          Switch# configure terminal
          
          
           

          Enters the global configuration mode.

           
          Step 2cdp run


          Example:
          
          Switch(config)# cdp run
          
          
           

          Enables CDP globally. By default, CDP is enabled.

           
          Step 3interface interface-id


          Example:
          
          Switch(config)# interface 
          gigabitethernet 2/1/1
          
          
           

          Specifies the port connected to the Cisco IP Phone, and enters interface configuration mode.

          Valid interfaces include physical ports.

           
          Step 4cdp enable


          Example:
          
          Switch(config-if)# cdp enable
          
          
           

          Enables CDP on the port. By default, CDP is enabled.

           
          Step 5Use one of the following:
          • mls qos trust cos
          • mls qos trust dscp


          Example:
          
          Switch(config-if)# mls qos trust cos
          
          
           

          Configures the switch port to trust the CoS value in traffic received from the Cisco IP Phone.

          or

          Configures the routed port to trust the DSCP value in traffic received from the Cisco IP Phone.

          By default, the port is not trusted.

           
          Step 6mls qos trust device cisco-phone


          Example:
          
          Switch(config-if)# mls qos trust 
          device cisco-phone
          
          
           

          Specifies that the Cisco IP Phone is a trusted device.

          You cannot enable both trusted boundary and auto-QoS (auto qos voip interface configuration command) at the same time; they are mutually exclusive.

          Note   

          To disable the trusted boundary feature, use the no mls qos trust device interface configuration command.

           
          Step 7end


          Example:
          
          Switch(config-if)# end
          
          
           

          Returns to privileged EXEC mode.

           
          Step 8show mls qos interface


          Example:
          
          Switch# show mls qos interface
          
          
           

          Verifies your entries.

           
          Step 9copy running-config startup-config


          Example:
          
          Switch# copy running-config 
          startup-config
          
          
           

          (Optional) Saves your entries in the configuration file.

           

          Enabling DSCP Transparency Mode

          The switch supports the DSCP transparency feature. It affects only the DSCP field of a packet at egress. By default, DSCP transparency is disabled. The switch modifies the DSCP field in an incoming packet, and the DSCP field in the outgoing packet is based on the quality of service (QoS) configuration, including the port trust setting, policing and marking, and the DSCP-to-DSCP mutation map.

          If DSCP transparency is enabled by using the no mls qos rewrite ip dscp command, the switch does not modify the DSCP field in the incoming packet, and the DSCP field in the outgoing packet is the same as that in the incoming packet.

          Regardless of the DSCP transparency configuration, the switch modifies the internal DSCP value of the packet, which the switch uses to generate a class of service (CoS) value that represents the priority of the traffic. The switch also uses the internal DSCP value to select an egress queue and threshold.

          SUMMARY STEPS

            1.    configure terminal

            2.    mls qos

            3.    no mls qos rewrite ip dscp

            4.    end

            5.    show mls qos interface [interface-id]

            6.    copy running-config startup-config


          DETAILED STEPS
             Command or ActionPurpose
            Step 1configure terminal


            Example:
            
            Switch# configure terminal
            
            
             

            Enters global configuration mode.

             
            Step 2mls qos


            Example:
            
            Switch(config)# mls qos
            
            
             

            Enables QoS globally.

             
            Step 3no mls qos rewrite ip dscp


            Example:
            
            Switch(config)# no mls qos rewrite ip dscp
            
            
             

            Enables DSCP transparency. The switch is configured to not modify the DSCP field of the IP packet.

             
            Step 4end


            Example:
            
            Switch(config)# end
            
            
             

            Returns to privileged EXEC mode.

             
            Step 5show mls qos interface [interface-id]


            Example:
            
            Switch# show mls qos interface gigabitethernet 2/1/1
            
            
             

            Verifies your entries.

             
            Step 6copy running-config startup-config


            Example:
            
            Switch# copy running-config startup-config
            
            
             

            (Optional) Saves your entries in the configuration file.

             

            DSCP Transparency Mode

            To configure the switch to modify the DSCP value based on the trust setting or on an ACL by disabling DSCP transparency, use the mls qos rewrite ip dscp global configuration command.

            If you disable QoS by using the no mls qos global configuration command, the CoS and DSCP values are not changed (the default QoS setting).

            If you enter the no mls qos rewrite ip dscp global configuration command to enable DSCP transparency and then enter the mls qos trust [cos | dscp] interface configuration command, DSCP transparency is still enabled.

            Configuring the DSCP Trust State on a Port Bordering Another QoS Domain

            If you are administering two separate QoS domains between which you want to implement QoS features for IP traffic, you can configure the switch ports bordering the domains to a DSCP-trusted state. The receiving port accepts the DSCP-trusted value and avoids the classification stage of QoS. If the two domains use different DSCP values, you can configure the DSCP-to-DSCP-mutation map to translate a set of DSCP values to match the definition in the other domain.

            Figure 10. DSCP-Trusted State on a Port Bordering Another QoS Domain

            Beginning in privileged EXEC mode, follow these steps to configure the DSCP-trusted state on a port and modify the DSCP-to-DSCP-mutation map. To ensure a consistent mapping strategy across both QoS domains, you must perform this procedure on the ports in both domains.

            SUMMARY STEPS

              1.    configure terminal

              2.    mls qos map dscp-mutation dscp-mutation-name in-dscp to out-dscp

              3.    interface interface-id

              4.    mls qos trust dscp

              5.    mls qos dscp-mutation dscp-mutation-name

              6.    end

              7.    show mls qos maps dscp-mutation

              8.    copy running-config startup-config


            DETAILED STEPS
               Command or ActionPurpose
              Step 1configure terminal


              Example:
              
              Switch# configure terminal
              
              
               

              Enters the global configuration mode.

               
              Step 2mls qos map dscp-mutation dscp-mutation-name in-dscp to out-dscp


              Example:
              
              Switch(config)# mls qos map 
              dscp-mutation 
              gigabitethernet1/0/2-mutation 
              10 11 12 13 to 30
              
              
               

              Modifies the DSCP-to-DSCP-mutation map.

              The default DSCP-to-DSCP-mutation map is a null map, which maps an incoming DSCP value to the same DSCP value.

              • For dscp-mutation-name, enter the mutation map name. You can create more than one map by specifying a new name.
              • For in-dscp, enter up to eight DSCP values separated by spaces. Then enter the to keyword.
              • For out-dscp, enter a single DSCP value.

              The DSCP range is 0 to 63.

               
              Step 3interface interface-id


              Example:
              
              Switch(config)# interface 
              gigabitethernet1/0/2
              
              
               

              Specifies the port to be trusted, and enter interface configuration mode.

              Valid interfaces include physical ports.

               
              Step 4mls qos trust dscp


              Example:
              
              Switch(config-if)# mls qos trust dscp
              
              
               

              Configures the ingress port as a DSCP-trusted port. By default, the port is not trusted.

              Note   

              To return a port to its non-trusted state, use the no mls qos trust interface configuration command.

               
              Step 5mls qos dscp-mutation dscp-mutation-name


              Example:
              
              Switch(config-if)# mls qos dscp-mutation 
              gigabitethernet1/0/2-mutation
              
              
               

              Applies the map to the specified ingress DSCP-trusted port.

              For dscp-mutation-name, specify the mutation map name created in Step 2.

              You can configure multiple DSCP-to-DSCP-mutation maps on an ingress port.

              Note   

              To return to the default DSCP-to-DSCP-mutation map values, use the no mls qos map dscp-mutation dscp-mutation-name global configuration command.

               
              Step 6end


              Example:
              
              Switch(config-if)# end
              
              
               

              Returns to privileged EXEC mode.

               
              Step 7show mls qos maps dscp-mutation


              Example:
              
              Switch# show mls qos maps 
              dscp-mutation
              
              
               

              Verifies your entries.

               
              Step 8copy running-config startup-config


              Example:
              
              Switch# copy-running-config 
              startup-config
              
              
               

              (Optional) Saves your entries in the configuration file.

              Note   

              To return a port to its non-trusted state, use the no mls qos trust interface configuration command. To return to the default DSCP-to-DSCP-mutation map values, use the no mls qos map dscp-mutation dscp-mutation-name global configuration command.

               

              Configuring a QoS Policy

              Configuring a QoS policy typically requires the following tasks:

              • Classifying traffic into classes
              • Configuring policies applied to those traffic classes
              • Attaching policies to ports

              These sections describe how to classify, police, and mark traffic. Depending on your network configuration, you must perform one or more of the modules in this section.

              Classifying Traffic by Using ACLs

              You can classify IP traffic by using IPv4 standard ACLS, IPv4 extended ACLs, or IPv6 ACLs.

              You can classify non-IP traffic by using Layer 2 MAC ACLs.

              Creating an IP Standard ACL for IPv4 Traffic

              Before You Begin

              Before you perform this task, determine which access lists you will be using for your QoS configuration.

              SUMMARY STEPS

                1.    configure terminal

                2.    access-list access-list-number {deny | permit} source [source-wildcard]

                3.    end

                4.    show access-lists

                5.    copy running-config startup-config


              DETAILED STEPS
                 Command or ActionPurpose
                Step 1configure terminal


                Example:
                
                Switch# configure terminal
                
                
                 

                Enters global configuration mode.

                 
                Step 2access-list access-list-number {deny | permit} source [source-wildcard]


                Example:
                
                Switch(config)# access-list 1 
                permit 192.2.255.0 1.1.1.255
                
                
                 

                Creates an IP standard ACL, repeating the command as many times as necessary.

                • For access-list-number, enter the access list number. The range is 1 to 99 and 1300 to 1999.
                • Use the permit keyword to permit a certain type of traffic if the conditions are matched. Use the deny keyword to deny a certain type of traffic if conditions are matched.
                • For source, enter the network or host from which the packet is being sent. You can use the any keyword as an abbreviation for 0.0.0.0 255.255.255.255.
                • (Optional) For source-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.

                When you create an access list, remember that by default the end of the access list contains an implicit deny statement for everything if it did not find a match before reaching the end.

                Note   

                To delete an access list, use the no access-list access-list-number global configuration command.

                 
                Step 3end


                Example:
                
                Switch(config)# end
                
                
                 

                Returns to privileged EXEC mode.

                 
                Step 4show access-lists


                Example:
                Switch# show access-lists
                
                
                 

                Verifies your entries.

                 
                Step 5copy running-config startup-config


                Example:
                
                Switch# copy-running-config 
                startup-config
                
                
                 

                (Optional) Saves your entries in the configuration file.

                 

                Creating an IP Extended ACL for IPv4 Traffic

                Before You Begin

                Before you perform this task, determine which access lists you will be using for your QoS configuration.

                SUMMARY STEPS

                  1.    configure terminal

                  2.    access-list access-list-number {deny | permit} protocol source source-wildcard destination destination-wildcard

                  3.    end

                  4.    show access-lists

                  5.    copy running-config startup-config


                DETAILED STEPS
                   Command or ActionPurpose
                  Step 1configure terminal


                  Example:
                  
                  Switch# configure terminal
                  
                  
                   

                  Enters global configuration mode.

                   
                  Step 2access-list access-list-number {deny | permit} protocol source source-wildcard destination destination-wildcard


                  Example:
                  
                  Switch(config)# access-list 100 permit ip any any dscp 32
                  
                  
                   

                  Creates an IP extended ACL, repeating the command as many times as necessary.

                  • For access-list-number, enter the access list number. The range is 100 to 199 and 2000 to 2699.
                  • Use the permit keyword to permit a certain type of traffic if the conditions are matched. Use the deny keyword to deny a certain type of traffic if conditions are matched.
                  • For protocol, enter the name or number of an IP protocol. Use the question mark (?) to see a list of available protocol keywords.
                  • For source, enter the network or host from which the packet is being sent. You specify this by using dotted decimal notation, by using the any keyword as an abbreviation for source 0.0.0.0 source-wildcard 255.255.255.255, or by using the host keyword for source 0.0.0.0.
                  • For source-wildcard, enter the wildcard bits by placing ones in the bit positions that you want to ignore. You specify the wildcard by using dotted decimal notation, by using the any keyword as an abbreviation for source 0.0.0.0 source-wildcard 255.255.255.255, or by using the host keyword for source 0.0.0.0.
                  • For destination, enter the network or host to which the packet is being sent. You have the same options for specifying the destination and destination-wildcard as those described by source and source-wildcard.

                  When creating an access list, remember that, by default, the end of the access list contains an implicit deny statement for everything if it did not find a match before reaching the end.

                  Note   

                  To delete an access list, use the no access-list access-list-number global configuration command.

                   
                  Step 3end


                  Example:
                  
                  Switch(config)# end
                  
                  
                   

                  Returns to privileged EXEC mode.

                   
                  Step 4show access-lists


                  Example:
                  Switch# show access-lists
                  
                  
                   

                  Verifies your entries.

                   
                  Step 5copy running-config startup-config


                  Example:
                  Switch# copy-running-config 
                  startup-config
                  
                  
                   

                  (Optional) Saves your entries in the configuration file.

                   

                  Creating an IPv6 ACL for IPv6 Traffic

                  Before You Begin

                  Before you perform this task, determine which access lists you will be using for your QoS configuration.

                  SUMMARY STEPS

                    1.    configure terminal

                    2.    ipv6 access-list access-list-name

                    3.    {deny | permit} protocol {source-ipv6-prefix/prefix-length | any | host source-ipv6-address} 
[operator [port-number]] {destination-ipv6-prefix/ prefix-length | any | host destination-ipv6-address} [operator [port-number]] [dscp value] [fragments] [log] [log-input] [routing] [sequence value] [time-range name]

                    4.    end

                    5.    show ipv6 access-list

                    6.    copy running-config startup-config


                  DETAILED STEPS
                     Command or ActionPurpose
                    Step 1configure terminal


                    Example:
                    
                    Switch# configure terminal
                    
                    
                     

                    Enters global configuration mode.

                     
                    Step 2ipv6 access-list access-list-name


                    Example:
                    
                    Switch(config)# ipv6 
                    access-list ipv6_Name_ACL
                    
                    
                     

                    Creates an IPv6 ACL and enters IPv6 access-list configuration mode.

                    Accesses list names cannot contain a space or quotation mark or begin with a numeric.

                    Note   

                    To delete an access list, use the no ipv6 access-list access-list-number global configuration command.

                     
                    Step 3{deny | permit} protocol {source-ipv6-prefix/prefix-length | any | host source-ipv6-address} 
[operator [port-number]] {destination-ipv6-prefix/ prefix-length | any | host destination-ipv6-address} [operator [port-number]] [dscp value] [fragments] [log] [log-input] [routing] [sequence value] [time-range name]

                    Example:
                    
                    Switch(config-ipv6-acl)# 
                    permit ip host 10::1 host 
                    11::2 host
                    
                    
                     

                    Enters deny or permit to specify whether to deny or permit the packet if conditions are matched. These are the conditions:

                    For protocol, enter the name or number of an Internet protocol: ahp, esp, icmp, ipv6, pcp, stcp, tcp, or udp, or an integer in the range 0 to 255 representing an IPv6 protocol number.

                    • The source-ipv6-prefix/prefix-length or destination-ipv6-prefix/ prefix-length is the source or destination IPv6 network or class of networks for which to set deny or permit conditions, specified in hexadecimal and using 16-bit values between colons (see RFC 2373).
                    • Enter any as an abbreviation for the IPv6 prefix ::/0.
                    • For host source-ipv6-address or destination-ipv6-address, enter the source or destination IPv6 host address for which to set deny or permit conditions, specified in hexadecimal using 16-bit values between colons.
                    • (Optional) For operator, specify an operand that compares the source or destination ports of the specified protocol. Operands are lt (less than), gt (greater than), eq (equal), neq (not equal), and range. If the operator follows the source-ipv6-prefix/prefix-length argument, it must match the source port. If the operator follows the destination-ipv6- prefix/prefix-length argument, it must match the destination port.
                    • (Optional) The port-number is a decimal number from 0 to 65535 or the name of a TCP or UDP port. You can use TCP port names only when filtering TCP. You can use UDP port names only when filtering UDP.
                    • (Optional) Enter dscp value to match a differentiated services code point value against the traffic class value in the Traffic Class field of each IPv6 packet header. The acceptable range is from 0 to 63.
                    • (Optional) Enter fragments to check noninitial fragments. This keyword is visible only if the protocol is IPv6.
                    • (Optional) Enter log to cause a logging message to be sent to the console about the packet that matches the entry. Enter log-input to include the input interface in the log entry. Logging is supported only for router ACLs.
                    • (Optional) Enter routing to specify that IPv6 packets be routed.
                    • (Optional) Enter sequence value to specify the sequence number for the access list statement. The acceptable range is from 1 to 4294967295.
                    • (Optional) Enter time-range name to specify the time range that applies to the deny or permit statement.
                     
                    Step 4end


                    Example:
                    
                    Switch(config-ipv6-acl)# end
                    
                    
                     

                    Returns to privileged EXEC mode.

                     
                    Step 5show ipv6 access-list


                    Example:
                    
                    Switch# show ipv6 
                    access-list
                    
                    
                     

                    Verifies the access list configuration.

                     
                    Step 6copy running-config startup-config


                    Example:
                    
                    Switch# copy-running-config 
                    startup-config
                    
                    
                     

                    (Optional) Saves your entries in the configuration file.

                     

                    Creating a Layer 2 MAC ACL for Non-IP Traffic

                    Before You Begin

                    Before you perform this task, determine that Layer 2 MAC access lists are required for your QoS configuration.

                    SUMMARY STEPS

                      1.    configure terminal

                      2.    mac access-list extended name

                      3.    {permit | deny} {host src-MAC-addr mask | any | host dst-MAC-addr | dst-MAC-addr mask} [type mask]

                      4.    end

                      5.    show access-lists [access-list-number | access-list-name]

                      6.    copy running-config startup-config


                    DETAILED STEPS
                       Command or ActionPurpose
                      Step 1configure terminal


                      Example:
                      
                      Switch# configure terminal
                      
                      
                       

                      Enters global configuration mode.

                       
                      Step 2mac access-list extended name


                      Example:
                      
                      Switch(config)# mac access-list 
                      extended maclist1
                      
                      
                       

                      Creates a Layer 2 MAC ACL by specifying the name of the list.

                      After entering this command, the mode changes to extended MAC ACL configuration.

                      Note   

                      To delete an access list, use the no mac access-list extended access-list-name global configuration command.

                       
                      Step 3{permit | deny} {host src-MAC-addr mask | any | host dst-MAC-addr | dst-MAC-addr mask} [type mask]

                      Example:
                      
                      Switch(config-ext-mac1) # permit 0001.0000.0001 
                      0.0.0 0002.0000.0001 0.0.0
                      
                      
                      
                      Switch(config-ext-mac1) # permit 0001.0000.0002 
                      0.0.0 0002.0000.0002 0.0.0 xns-idp
                      
                       

                      Specifies the type of traffic to permit or deny if the conditions are matched, entering the command as many times as necessary.

                      • For src-MAC-addr, enter the MAC address of the host from which the packet is being sent. You specify this by using the hexadecimal format (H.H.H), by using the any keyword as an abbreviation for source 0.0.0, source-wildcard ffff.ffff.ffff, or by using the host keyword for source 0.0.0.
                      • For mask, enter the wildcard bits by placing ones in the bit positions that you want to ignore.
                      • For dst-MAC-addr, enter the MAC address of the host to which the packet is being sent. You specify this by using the hexadecimal format (H.H.H), by using the any keyword as an abbreviation for source 0.0.0, source-wildcard ffff.ffff.ffff, or by using the host keyword for source 0.0.0.
                      • (Optional) For type mask, specify the Ethertype number of a packet with Ethernet II or SNAP encapsulation to identify the protocol of the packet. For type, the range is from 0 to 65535, typically specified in hexadecimal. For mask, enter the don’t care bits applied to the Ethertype before testing for a match.

                      When creating an access list, remember that, by default, the end of the access list contains an implicit deny statement for everything if it did not find a match before reaching the end.

                       
                      Step 4end


                      Example:
                      
                      Switch(config-ext-mac1)# end
                      
                      
                       

                      Returns to privileged EXEC mode.

                       
                      Step 5show access-lists [access-list-number | access-list-name]


                      Example:
                      
                      Switch# show access-lists
                      
                      
                       

                      Verifies your entries.

                       
                      Step 6copy running-config startup-config


                      Example:
                      
                      Switch# copy-running-config 
                      startup-config
                      
                      
                       

                      (Optional) Saves your entries in the configuration file.

                       

                      Classifying Traffic by Using Class Maps

                      You use the class-map global configuration command to name and to isolate a specific traffic flow (or class) from all other traffic. The class map defines the criteria to use to match against a specific traffic flow to further classify it. Match statements can include criteria such as an ACL, IP precedence values, or DSCP values. The match criterion is defined with one match statement entered within the class-map configuration mode.


                      Note


                      You can also create class maps during policy map creation by using the class policy-map configuration command.


                      SUMMARY STEPS

                        1.    configure terminal

                        2.    Use one of the following:

                        • access-list access-list-number {deny | permit} source [source-wildcard]
                        • access-list access-list-number {deny | permit} protocol source [source-wildcard] destination [destination-wildcard]
                        • ipv6 access-list access-list-name {deny | permit} protocol {source-ipv6-prefix/prefix-length | any | host source-ipv6-address} 
[operator [port-number]] {destination-ipv6-prefix/ prefix-length | any | host destination-ipv6-address} [operator [port-number]] [dscp value] [fragments] [log] [log-input] [routing] [sequence value] [time-range name]
                        • mac access-list extended name {permit | deny} {host src-MAC-addr mask | any | host dst-MAC-addr | dst-MAC-addr mask} [type mask]

                        3.    class-map [match-all | match-any] class-map-name

                        4.    match {access-group acl-index-or-name | ip dscp dscp-list | ip precedence ip-precedence-list}

                        5.    end

                        6.    show class-map

                        7.    copy running-config startup-config


                      DETAILED STEPS
                         Command or ActionPurpose
                        Step 1configure terminal


                        Example:
                        
                        Switch# configure terminal
                        
                        
                         

                        Enters the global configuration mode.

                         
                        Step 2Use one of the following:
                        • access-list access-list-number {deny | permit} source [source-wildcard]
                        • access-list access-list-number {deny | permit} protocol source [source-wildcard] destination [destination-wildcard]
                        • ipv6 access-list access-list-name {deny | permit} protocol {source-ipv6-prefix/prefix-length | any | host source-ipv6-address} 
[operator [port-number]] {destination-ipv6-prefix/ prefix-length | any | host destination-ipv6-address} [operator [port-number]] [dscp value] [fragments] [log] [log-input] [routing] [sequence value] [time-range name]
                        • mac access-list extended name {permit | deny} {host src-MAC-addr mask | any | host dst-MAC-addr | dst-MAC-addr mask} [type mask]


                        Example:
                        
                        Switch(config)# access-list 103 permit ip any 
                        any dscp 10
                        
                        
                         

                        Creates an IP standard or extended ACL, an IPv6 ACL for IP traffic, or a Layer 2 MAC ACL for non-IP traffic, repeating the command as many times as necessary.

                        When creating an access list, remember that, by default, the end of the access list contains an implicit deny statement for everything if it did not find a match before reaching the end.

                         
                        Step 3class-map [match-all | match-any] class-map-name


                        Example:
                        
                        Switch(config)# class-map class1
                        
                        
                         

                        Creates a class map, and enters class-map configuration mode.

                        By default, no class maps are defined.

                        • (Optional) Use the match-all keyword to perform a logical-AND of all matching statements under this class map. All match criteria in the class map must be matched.
                        • (Optional) Use the match-any keyword to perform a logical-OR of all matching statements under this class map. One or more match criteria must be matched.
                        • For class-map-name, specify the name of the class map.

                        If neither the match-all or match-any keyword is specified, the default is match-all.

                        Note   

                        To delete an existing class map, use the no class-map [match-all | match-any] class-map-name global configuration command.

                         
                        Step 4match {access-group acl-index-or-name | ip dscp dscp-list | ip precedence ip-precedence-list}


                        Example:
                        
                        Switch(config-cmap)# match ip dscp 10 11 12
                        
                        
                         

                        Defines the match criterion to classify traffic.

                        By default, no match criterion is defined.

                        Only one match criterion per class map is supported, and only one ACL per class map is supported.

                        • For access-group acl-index-or-name, specify the number or name of the ACL created in Step 2.
                        • To filter IPv6 traffic with the match access-group command, create an IPv6 ACL, as described in Step 2.
                        • For ip dscp dscp-list, enter a list of up to eight IP DSCP values to match against incoming packets. Separate each value with a space. The range is 0 to 63.
                        • For ip precedence ip-precedence-list, enter a list of up to eight IP-precedence values to match against incoming packets. Separate each value with a space. The range is 0 to 7.
                        Note   

                        To remove a match criterion, use the no match {access-group acl-index-or-name | ip dscp | ip precedence} class-map configuration command.

                         
                        Step 5end


                        Example:
                        
                        Switch(config-cmap)# end
                        
                        
                         

                        Returns to privileged EXEC mode.

                         
                        Step 6show class-map


                        Example:
                        
                        Switch# show class-map
                        
                        
                         

                        Verifies your entries.

                         
                        Step 7copy running-config startup-config


                        Example:
                        
                        Switch# copy-running-config startup-config
                        
                        
                         

                        (Optional) Saves your entries in the configuration file.

                         

                        Classifying Traffic by Using Class Maps and Filtering IPv6 Traffic


                        Note


                        IPv6 QoS is not supported on switches running the LAN base feature set.


                        To apply the primary match criteria to only IPv4 traffic, use the match protocol command with the ip keyword. To apply the primary match criteria to only IPv6 traffic, use the match protocol command with the ipv6 keyword.

                        SUMMARY STEPS

                          1.    configure terminal

                          2.    class-map {match-all} class-map-name

                          3.    match protocol [ip | ipv6]

                          4.    match {ip dscp dscp-list | ip precedence ip-precedence-list}

                          5.    end

                          6.    show class-map

                          7.    copy running-config startup-config


                        DETAILED STEPS
                           Command or ActionPurpose
                          Step 1configure terminal


                          Example:
                          
                          Switch# configure terminal
                          
                          
                           

                          Enters the global configuration mode.

                           
                          Step 2class-map {match-all} class-map-name


                          Example:
                          
                          Switch(config)# class-map cm-1
                          
                          
                           

                          Creates a class map, and enters class-map configuration mode.

                          By default, no class maps are defined.

                          When you use the match protocol command, only the match-all keyword is supported.

                          • For class-map-name, specify the name of the class map.

                          If neither the match-all or match-any keyword is specified, the default is match-all.

                          Note   

                          To delete an existing class map, use the no class-map [match-all | match-any] class-map-name global configuration command.

                           
                          Step 3match protocol [ip | ipv6]


                          Example:
                          
                          Switch(config-cmap)#  match protocol ip
                          
                          
                           

                          (Optional) Specifies the IP protocol to which the class map applies:

                          • Use the argument ip to specify IPv4 traffic and ipv6 to specify IPv6 traffic.
                          • When you use the match protocol command, only the match-all keyword is supported for the class-map command.
                           
                          Step 4match {ip dscp dscp-list | ip precedence ip-precedence-list}


                          Example:
                          
                          Switch(config-cmap)# match ip dscp 10
                          
                          
                           

                          Defines the match criterion to classify traffic.

                          By default, no match criterion is defined.

                          • For ip dscp dscp-list, enter a list of up to eight IP DSCP values to match against incoming packets. Separate each value with a space. The range is 0 to 63.
                          • For ip precedence ip-precedence-list, enter a list of up to eight IP-precedence values to match against incoming packets. Separate each value with a space. The range is 0 to 7.
                          Note   

                          To remove a match criterion, use the no match {access-group acl-index-or-name | ip dscp | ip precedence} class-map configuration command.

                           
                          Step 5end


                          Example:
                          
                          Switch(config-cmap)# end
                          
                          
                           

                          Returns to privileged EXEC mode.

                           
                          Step 6show class-map


                          Example:
                          
                          Switch# show class-map
                          
                          
                           

                          Verifies your entries.

                           
                          Step 7copy running-config startup-config


                          Example:
                          
                          Switch# copy-running-config startup-config
                          
                          
                           

                          (Optional) Saves your entries in the configuration file.

                           

                          Classifying, Policing, and Marking Traffic on Physical Ports by Using Policy Maps

                          You can configure a policy map on a physical port that specifies which traffic class to act on. Actions can include trusting the CoS, DSCP, or IP precedence values in the traffic class; setting a specific DSCP or IP precedence value in the traffic class; and specifying the traffic bandwidth limitations for each matched traffic class (policer) and the action to take when the traffic is out of profile (marking).

                          A policy map also has these characteristics:

                          • A policy map can contain multiple class statements, each with different match criteria and policers.
                          • A policy map can contain a predefined default traffic class explicitly placed at the end of the map.
                          • A separate policy-map class can exist for each type of traffic received through a port.

                          Follow these guidelines when configuring policy maps on physical ports:

                          • You can attach only one policy map per ingress port.
                          • If you configure the IP-precedence-to-DSCP map by using the mls qos map ip-prec-dscp dscp1...dscp8 global configuration command, the settings only affect packets on ingress interfaces that are configured to trust the IP precedence value. In a policy map, if you set the packet IP precedence value to a new value by using the set ip precedence new-precedence policy-map class configuration command, the egress DSCP value is not affected by the IP-precedence-to-DSCP map. If you want the egress DSCP value to be different than the ingress value, use the set dscp new-dscp policy-map class configuration command.
                          • If you enter or have used the set ip dscp command, the switch changes this command to set dscp in its configuration.
                          • You can use the set ip precedence or the set precedence policy-map class configuration command to change the packet IP precedence value. This setting appears as set ip precedence in the switch configuration.
                          • A policy-map and a port trust state can both run on a physical interface. The policy-map is applied before the port trust state.
                          • When you configure a default traffic class by using the class class-default policy-map configuration command, unclassified traffic (traffic that does not meet the match criteria specified in the traffic classes) is treated as the default traffic class (class-default).
                          SUMMARY STEPS

                            1.    configure terminal

                            2.    class-map [match-all | match-any] class-map-name

                            3.    policy-map policy-map-name

                            4.    class [class-map-name | class-default]

                            5.    trust [cos | dscp | ip-precedence]

                            6.    set {dscp new-dscp | ip precedence new-precedence}

                            7.    police rate-bps burst-byte [exceed-action {drop | policed-dscp-transmit}]

                            8.    exit

                            9.    exit

                            10.    interface interface-id

                            11.    service-policy input policy-map-name

                            12.    end

                            13.    show policy-map [policy-map-name [class class-map-name]]

                            14.    copy running-config startup-config


                          DETAILED STEPS
                             Command or ActionPurpose
                            Step 1configure terminal


                            Example:
                            
                            Switch# configure terminal
                            
                            
                             

                            Enters the global configuration mode.

                             
                            Step 2class-map [match-all | match-any] class-map-name


                            Example:
                            
                            Switch(config)# class-map ipclass1
                            
                            
                             

                            Creates a class map, and enters class-map configuration mode.

                            By default, no class maps are defined.

                            • (Optional) Use the match-all keyword to perform a logical-AND of all matching statements under this class map. All match criteria in the class map must be matched.
                            • (Optional) Use the match-any keyword to perform a logical-OR of all matching statements under this class map. One or more match criteria must be matched.
                            • For class-map-name, specify the name of the class map.

                            If neither the match-all or match-any keyword is specified, the default is match-all.

                             
                            Step 3policy-map policy-map-name


                            Example:
                            
                            Switch(config-cmap)# policy-map flowit
                            
                            
                             

                            Creates a policy map by entering the policy map name, and enters policy-map configuration mode.

                            By default, no policy maps are defined.

                            The default behavior of a policy map is to set the DSCP to 0 if the packet is an IP packet and to set the CoS to 0 if the packet is tagged. No policing is performed.

                            Note   

                            To delete an existing policy map, use the no policy-map policy-map-name global configuration command.

                             
                            Step 4class [class-map-name | class-default]


                            Example:
                            
                            Switch(config-pmap)# class ipclass1
                            
                            
                             

                            Defines a traffic classification, and enters policy-map class configuration mode.

                            By default, no policy map class-maps are defined.

                            If a traffic class has already been defined by using the class-map global configuration command, specify its name for class-map-name in this command.

                            A class-default traffic class is pre-defined and can be added to any policy. It is always placed at the end of a policy map. With an implied match any included in the class-default class, all packets that have not already matched the other traffic classes will match class-default.

                            Note   

                            To delete an existing class map, use the no class class-map-name policy-map configuration command.

                             
                            Step 5trust [cos | dscp | ip-precedence]


                            Example:
                            
                            Switch(config-pmap-c)# trust dscp
                            
                            
                             

                            Configures the trust state, which QoS uses to generate a CoS-based or DSCP-based QoS label.

                            This command is mutually exclusive with the set command within the same policy map. If you enter the trust command, go to Step 6.

                            By default, the port is not trusted. If no keyword is specified when the command is entered, the default is dscp.

                            The keywords have these meanings:

                            • cos—QoS derives the DSCP value by using the received or default port CoS value and the CoS-to-DSCP map.
                            • dscp—QoS derives the DSCP value by using the DSCP value from the ingress packet. For non-IP packets that are tagged, QoS derives the DSCP value by using the received CoS value; for non-IP packets that are untagged, QoS derives the DSCP value by using the default port CoS value. In either case, the DSCP value is derived from the CoS-to-DSCP map.
                            • ip-precedence—QoS derives the DSCP value by using the IP precedence value from the ingress packet and the IP-precedence-to-DSCP map. For non-IP packets that are tagged, QoS derives the DSCP value by using the received CoS value; for non-IP packets that are untagged, QoS derives the DSCP value by using the default port CoS value. In either case, the DSCP value is derived from the CoS-to-DSCP map.
                            Note    To return to the untrusted state, use the no trust policy-map configuration command
                             
                            Step 6set {dscp new-dscp | ip precedence new-precedence}


                            Example:
                            
                            Switch(config-pmap-c)# set dscp 45
                            
                            
                             

                            Classifies IP traffic by setting a new value in the packet.

                            • For dscp new-dscp, enter a new DSCP value to be assigned to the classified traffic. The range is 0 to 63.
                            • For ip precedence new-precedence, enter a new IP-precedence value to be assigned to the classified traffic. The range is 0 to 7.
                            Note   

                            To remove an assigned DSCP or IP precedence value, use the no set {dscp new-dscp | ip precedence new-precedence} policy-map configuration command.

                             
                            Step 7police rate-bps burst-byte [exceed-action {drop | policed-dscp-transmit}]


                            Example:
                            
                            Switch(config-pmap-c)# police 100000 
                            80000 drop
                            
                            
                             

                            Defines a policer for the classified traffic.

                            By default, no policer is defined.

                            • For rate-bps, specify average traffic rate in bits per second (b/s). The range is 8000 to 10000000000.
                            • For burst-byte, specify the normal burst size in bytes. The range is 8000 to 1000000.
                            • (Optional) Specifies the action to take when the rates are exceeded. Use the exceed-action drop keywords to drop the packet. Use the exceed-action policed-dscp-transmit keywords to mark down the DSCP value (by using the policed-DSCP map) and to send the packet.
                            Note   

                            To remove an existing policer, use the no police rate-bps burst-byte [exceed-action {drop | policed-dscp-transmit}] policy-map configuration command.

                             
                            Step 8exit


                            Example:
                            
                            Switch(config-pmap-c)# exit
                            
                            
                             

                            Returns to policy map configuration mode.

                             
                            Step 9exit


                            Example:
                            
                            Switch(config-pmap)# exit
                            
                            
                             

                            Returns to global configuration mode.

                             
                            Step 10interface interface-id


                            Example:
                            
                            Switch(config)# interface 
                            gigabitethernet 2/0/1
                            
                            
                             

                            Specifies the port to attach to the policy map, and enters interface configuration mode.

                            Valid interfaces include physical ports.

                             
                            Step 11service-policy input policy-map-name


                            Example:
                            
                            Switch(config-if)# service-policy 
                            input flowit
                            
                            
                             

                            Specifies the policy-map name, and applies it to an ingress port.

                            Only one policy map per ingress port is supported.

                            Note   

                            To remove the policy map and port association, use the no service-policy input policy-map-name interface configuration command.

                             
                            Step 12end


                            Example:
                            
                            Switch(config-if)# end
                            
                            
                             

                            Returns to privileged EXEC mode.

                             
                            Step 13show policy-map [policy-map-name [class class-map-name]]


                            Example:
                            
                            Switch# show policy-map
                            
                            
                             

                            Verifies your entries.

                             
                            Step 14copy running-config startup-config


                            Example:
                            
                            Switch# copy-running-config 
                            startup-config
                            
                            
                             

                            (Optional) Saves your entries in the configuration file.

                             

                            Classifying, Policing, and Marking Traffic by Using Aggregate Policers

                            By using an aggregate policer, you can create a policer that is shared by multiple traffic classes within the same policy map. However, you cannot use the aggregate policer across different policy maps or ports.

                            You can configure aggregate policers only in nonhierarchical policy maps on physical ports.

                            SUMMARY STEPS

                              1.    configure terminal

                              2.    mls qos aggregate-policer aggregate-policer-name rate-bps burst-byte exceed-action {drop | policed-dscp-transmit}

                              3.    class-map [match-all | match-any] class-map-name

                              4.    policy-map policy-map-name

                              5.    class [class-map-name | class-default]

                              6.    police aggregate aggregate-policer-name

                              7.    exit

                              8.    interface interface-id

                              9.    service-policy input policy-map-name

                              10.    end

                              11.    show mls qos aggregate-policer [aggregate-policer-name]

                              12.    copy running-config startup-config


                            DETAILED STEPS
                               Command or ActionPurpose
                              Step 1configure terminal


                              Example:
                              
                              Switch# configure terminal
                              
                              
                               

                              Enters the global configuration mode.

                               
                              Step 2mls qos aggregate-policer aggregate-policer-name rate-bps burst-byte exceed-action {drop | policed-dscp-transmit}


                              Example:
                              
                              Switch(config)# mls qos aggregate-police 
                              transmit1 48000 8000 exceed-action policed-dscp-transmit
                              
                              
                               

                              Defines the policer parameters that can be applied to multiple traffic classes within the same policy map.

                              By default, no aggregate policer is defined.

                              • For aggregate-policer-name, specify the name of the aggregate policer.
                              • For rate-bps, specify average traffic rate in bits per second (b/s). The range is 8000 to 10000000000.
                              • For burst-byte, specify the normal burst size in bytes. The range is 8000 to 1000000.
                              • Specifies the action to take when the rates are exceeded. Use the exceed-action drop keywords to drop the packet. Use the exceed-action policed-dscp-transmit keywords to mark down the DSCP value (by using the policed-DSCP map) and to send the packet.
                               
                              Step 3class-map [match-all | match-any] class-map-name


                              Example:
                              
                              Switch(config)# class-map ipclass1
                              
                              
                               

                              Creates a class map to classify traffic as necessary.

                               
                              Step 4policy-map policy-map-name


                              Example:
                              
                              Switch(config-cmap)# policy-map aggflow1
                              
                              
                               

                              Creates a policy map by entering the policy map name, and enters policy-map configuration mode.

                               
                              Step 5class [class-map-name | class-default]


                              Example:
                              
                              Switch(config-cmap-p)# class ipclass1
                              
                              
                               

                              Defines a traffic classification, and enters policy-map class configuration mode.

                               
                              Step 6police aggregate aggregate-policer-name


                              Example:
                              
                              Switch(configure-cmap-p)# police aggregate transmit1
                              
                              
                               

                              Applies an aggregate policer to multiple classes in the same policy map.

                              For aggregate-policer-name, enter the name specified in Step 2.

                              To remove the specified aggregate policer from a policy map, use the no police aggregate aggregate-policer-name policy map configuration command. To delete an aggregate policer and its parameters, use the no mls qos aggregate-policer aggregate-policer-name global configuration command.

                               
                              Step 7exit


                              Example:
                              
                              Switch(configure-cmap-p)# exit
                              
                              
                               

                              Returns to global configuration mode.

                               
                              Step 8interface interface-id


                              Example:
                              
                              Switch(config)# interface gigabitethernet 2/0/1
                              
                              
                               

                              Specifies the port to attach to the policy map, and enters interface configuration mode.

                              Valid interfaces include physical ports.

                               
                              Step 9service-policy input policy-map-name


                              Example:
                              
                              Switch(config-if)# service-policy input aggflow1
                              
                              
                               

                              Specifies the policy-map name, and applies it to an ingress port.

                              Only one policy map per ingress port is supported.

                               
                              Step 10end


                              Example:
                              
                              Switch(configure-if)# end
                              
                              
                               

                              Returns to privileged EXEC mode.

                               
                              Step 11show mls qos aggregate-policer [aggregate-policer-name]


                              Example:
                              
                              Switch# show mls qos aggregate-policer transmit1
                              
                              
                               

                              Verifies your entries.

                               
                              Step 12copy running-config startup-config


                              Example:
                              
                              Switch# copy-running-config startup-config
                              
                              
                               

                              (Optional) Saves your entries in the configuration file.

                               
                              Related Concepts

                              Configuring DSCP Maps

                              Configuring the CoS-to-DSCP Map

                              You use the CoS-to-DSCP map to map CoS values in incoming packets to a DSCP value that QoS uses internally to represent the priority of the traffic.

                              Beginning in privileged EXEC mode, follow these steps to modify the CoS-to-DSCP map. This procedure is optional.

                              SUMMARY STEPS

                                1.    configure terminal

                                2.    mls qos map cos-dscp dscp1...dscp8

                                3.    end

                                4.    show mls qos maps cos-dscp

                                5.    copy running-config startup-config


                              DETAILED STEPS
                                 Command or ActionPurpose
                                Step 1configure terminal


                                Example:
                                
                                Switch# configure terminal
                                
                                
                                 

                                Enters the global configuration mode.

                                 
                                Step 2mls qos map cos-dscp dscp1...dscp8


                                Example:
                                
                                Switch(config)# mls qos map 
                                cos-dscp 10 15 20 25 30 35 40 45
                                
                                
                                 

                                Modifies the CoS-to-DSCP map.

                                For dscp1...dscp8, enter eight DSCP values that correspond to CoS values 0 to 7. Separate each DSCP value with a space.

                                The DSCP range is 0 to 63.

                                Note   

                                To return to the default map, use the no mls qos cos-dscp global configuration command.

                                 
                                Step 3end


                                Example:
                                
                                Switch(config)# end
                                
                                
                                 

                                Returns to privileged EXEC mode.

                                 
                                Step 4show mls qos maps cos-dscp


                                Example:
                                
                                Switch# show mls qos maps cos-dscp
                                
                                
                                 

                                Verifies your entries.

                                 
                                Step 5copy running-config startup-config


                                Example:
                                
                                Switch# copy-running-config 
                                startup-config
                                
                                
                                 

                                (Optional) Saves your entries in the configuration file.

                                 
                                Related Concepts

                                Configuring the IP-Precedence-to-DSCP Map

                                You use the IP-precedence-to-DSCP map to map IP precedence values in incoming packets to a DSCP value that QoS uses internally to represent the priority of the traffic.

                                Beginning in privileged EXEC mode, follow these steps to modify the IP-precedence-to-DSCP map. This procedure is optional.

                                SUMMARY STEPS

                                  1.    configure terminal

                                  2.    mls qos map ip-prec-dscp dscp1...dscp8

                                  3.    end

                                  4.    show mls qos maps ip-prec-dscp

                                  5.    copy running-config startup-config


                                DETAILED STEPS
                                   Command or ActionPurpose
                                  Step 1configure terminal


                                  Example:
                                  
                                  Switch# configure terminal
                                  
                                  
                                   

                                  Enters global configuration mode.

                                   
                                  Step 2mls qos map ip-prec-dscp dscp1...dscp8


                                  Example:
                                  
                                  Switch(config)# mls qos map 
                                  ip-prec-dscp 10 15 20 25 30 35 40 
                                  45
                                  
                                  
                                   

                                  Modifies the IP-precedence-to-DSCP map.

                                  For dscp1...dscp8, enter eight DSCP values that correspond to the IP precedence values 0 to 7. Separate each DSCP value with a space.

                                  The DSCP range is 0 to 63.

                                  Note   

                                  To return to the default map, use the no mls qos ip-prec-dscp global configuration command.

                                   
                                  Step 3end


                                  Example:
                                  
                                  Switch(config)# end
                                  
                                  
                                   

                                  Returns to privileged EXEC mode.

                                   
                                  Step 4show mls qos maps ip-prec-dscp


                                  Example:
                                  Switch# show mls qos maps ip-prec-dscp
                                  
                                  
                                   

                                  Verifies your entries.

                                   
                                  Step 5copy running-config startup-config


                                  Example:
                                  
                                  Switch# copy-running-config 
                                  startup-config
                                  
                                  
                                   

                                  (Optional) Saves your entries in the configuration file.

                                   
                                  Related Concepts

                                  Configuring the Policed-DSCP Map

                                  You use the policed-DSCP map to mark down a DSCP value to a new value as the result of a policing and marking action.

                                  The default policed-DSCP map is a null map, which maps an incoming DSCP value to the same DSCP value.

                                  Beginning in privileged EXEC mode, follow these steps to modify the policed-DSCP map. This procedure is optional.

                                  SUMMARY STEPS

                                    1.    configure terminal

                                    2.    mls qos map policed-dscp dscp-list to mark-down-dscp

                                    3.    end

                                    4.    show mls qos maps policed-dscp

                                    5.    copy running-config startup-config


                                  DETAILED STEPS
                                     Command or ActionPurpose
                                    Step 1configure terminal


                                    Example:
                                    
                                    Switch# configure terminal
                                    
                                    
                                     

                                    Enters global configuration mode.

                                     
                                    Step 2mls qos map policed-dscp dscp-list to mark-down-dscp


                                    Example:
                                    
                                    Switch(config)# mls qos map 
                                    policed-dscp 50 51 52 53 54 55 56 
                                    57 to 0
                                    
                                    
                                     

                                    Modifies the policed-DSCP map.

                                    • For dscp-list, enter up to eight DSCP values separated by spaces. Then enter the to keyword.
                                    • For mark-down-dscp, enter the corresponding policed (marked down) DSCP value.
                                    Note   

                                    To return to the default map, use the no mls qos policed-dscp global configuration command.

                                     
                                    Step 3end


                                    Example:
                                    
                                    Switch(config)# end
                                    
                                    
                                     

                                    Returns to privileged EXEC mode.

                                     
                                    Step 4show mls qos maps policed-dscp


                                    Example:
                                    
                                    Switch(config)# show mls qos maps 
                                    policed-dscp
                                    
                                    
                                     

                                    Verifies your entries.

                                     
                                    Step 5copy running-config startup-config


                                    Example:
                                    
                                    Switch# 
                                    
                                    
                                     

                                    (Optional) Saves your entries in the configuration file.

                                     
                                    Related Concepts

                                    Configuring the DSCP-to-CoS Map

                                    You use the DSCP-to-CoS map to generate a CoS value, which is used to select one of the four egress queues.

                                    Beginning in privileged EXEC mode, follow these steps to modify the DSCP-to-CoS map. This procedure is optional.

                                    SUMMARY STEPS

                                      1.    configure terminal

                                      2.    mls qos map dscp-cos dscp-list to cos

                                      3.    end

                                      4.    show mls qos maps dscp-to-cos

                                      5.    copy running-config startup-config


                                    DETAILED STEPS
                                       Command or ActionPurpose
                                      Step 1configure terminal


                                      Example:
                                      
                                      Switch# configure terminal
                                      
                                      
                                       

                                      Enters the global configuration mode.

                                       
                                      Step 2mls qos map dscp-cos dscp-list to cos


                                      Example:
                                      
                                      Switch# mls qos map dscp-cos 0 8 
                                      16 24 32 40 48 50 to 0
                                      
                                      
                                       

                                      Modifies the DSCP-to-CoS map.

                                      • For dscp-list, enter up to eight DSCP values separated by spaces. Then enter the to keyword.
                                      • For cos, enter the CoS value to which the DSCP values correspond.

                                      The DSCP range is 0 to 63; the CoS range is 0 to 7.

                                      Note   

                                      To return to the default map, use the no mls qos dscp-cos global configuration command.

                                       
                                      Step 3end


                                      Example:
                                      
                                      Switch(config)# end
                                      
                                      
                                       

                                      Returns to privileged EXEC mode.

                                       
                                      Step 4show mls qos maps dscp-to-cos


                                      Example:
                                      
                                      Switch# show mls qos maps 
                                      dscp-to-cos
                                      
                                      
                                       

                                      Verifies your entries.

                                       
                                      Step 5copy running-config startup-config


                                      Example:
                                      
                                      Switch# copy-running-config 
                                      startup-config
                                      
                                      
                                       

                                      (Optional) Saves your entries in the configuration file.

                                       
                                      Related Concepts

                                      Configuring the DSCP-to-DSCP-Mutation Map

                                      If two QoS domains have different DSCP definitions, use the DSCP-to-DSCP-mutation map to translate one set of DSCP values to match the definition of another domain. You apply the DSCP-to-DSCP-mutation map to the receiving port (ingress mutation) at the boundary of a QoS administrative domain.

                                      With ingress mutation, the new DSCP value overwrites the one in the packet, and QoS applies the new value to the packet. The switch sends the packet out the port with the new DSCP value.

                                      You can configure multiple DSCP-to-DSCP-mutation maps on an ingress port. The default DSCP-to-DSCP-mutation map is a null map, which maps an incoming DSCP value to the same DSCP value.

                                      Beginning in privileged EXEC mode, follow these steps to modify the DSCP-to-DSCP-mutation map. This procedure is optional.

                                      SUMMARY STEPS

                                        1.    configure terminal

                                        2.    mls qos map dscp-mutation dscp-mutation-name in-dscp to out-dscp

                                        3.    interface interface-id

                                        4.    mls qos trust dscp

                                        5.    mls qos dscp-mutation dscp-mutation-name

                                        6.    end

                                        7.    show mls qos maps dscp-mutation

                                        8.    copy running-config startup-config


                                      DETAILED STEPS
                                         Command or ActionPurpose
                                        Step 1configure terminal


                                        Example:
                                        
                                        Switch# configure terminal
                                        
                                        
                                         

                                        Enters the global configuration mode.

                                         
                                        Step 2mls qos map dscp-mutation dscp-mutation-name in-dscp to out-dscp


                                        Example:
                                        
                                        Switch(config)# mls qos map dscp-mutation 
                                        mutation1 1 2 3 4 5 6 7 to 0
                                        
                                        
                                         

                                        Modifies the DSCP-to-DSCP-mutation map.

                                        • For dscp-mutation-name, enter the mutation map name. You can create more than one map by specifying a new name.
                                        • For in-dscp, enter up to eight DSCP values separated by spaces. Then enter the to keyword.
                                        • For out-dscp, enter a single DSCP value.

                                        The DSCP range is 0 to 63.

                                        Note   

                                        To return to the default map, use the no mls qos dscp-mutation dscp-mutation-name global configuration command.

                                         
                                        Step 3interface interface-id


                                        Example:
                                        
                                        Switch(config)# interface gigabitethernet1/0/1
                                        
                                        
                                         

                                        Specifies the port to which to attach the map, and enters interface configuration mode.

                                        Valid interfaces include physical ports.

                                         
                                        Step 4mls qos trust dscp


                                        Example:
                                        
                                        Switch(config-if)# mls qos trust dscp
                                        
                                        
                                         

                                        Configures the ingress port as a DSCP-trusted port. By default, the port is not trusted.

                                         
                                        Step 5mls qos dscp-mutation dscp-mutation-name


                                        Example:
                                        
                                        Switch(config-if)# mls qos dscp-mutation mutation1
                                        
                                        
                                         

                                        Applies the map to the specified ingress DSCP-trusted port.

                                        For dscp-mutation-name, enter the mutation map name specified in Step 2.

                                         
                                        Step 6end


                                        Example:
                                        
                                        Switch(config-if)# end
                                        
                                        
                                         

                                        Returns to privileged EXEC mode.

                                         
                                        Step 7show mls qos maps dscp-mutation


                                        Example:
                                        
                                        Switch# show mls qos maps dscp-mutation
                                        
                                        
                                         

                                        Verifies your entries.

                                         
                                        Step 8copy running-config startup-config


                                        Example:
                                        
                                        Switch# copy-running-config startup-config
                                        
                                        
                                         

                                        (Optional) Saves your entries in the configuration file.

                                         
                                        Related Concepts

                                        Configuring Egress Queue Characteristics

                                        Depending on the complexity of your network and your QoS solution, you might need to perform all of the tasks in the following modules. You need to make decisions about these characteristics:

                                        • Which packets are mapped by DSCP or CoS value to each queue and threshold ID?
                                        • What drop percentage thresholds apply to the queue-set (four egress queues per port), and how much reserved and maximum memory is needed for the traffic type?
                                        • How much of the fixed buffer space is allocated to the queue-set?
                                        • Does the bandwidth of the port need to be rate limited?
                                        • How often should the egress queues be serviced and which technique (shaped, shared, or both) should be used?

                                        Configuration Guidelines

                                        Follow these guidelines when the expedite queue is enabled or the egress queues are serviced based on their SRR weights:

                                        • If the egress expedite queue is enabled, it overrides the SRR shaped and shared weights for queue 1.
                                        • If the egress expedite queue is disabled and the SRR shaped and shared weights are configured, the shaped mode overrides the shared mode for queue 1, and SRR services this queue in shaped mode.
                                        • If the egress expedite queue is disabled and the SRR shaped weights are not configured, SRR services this queue in shared mode.

                                        Allocating Buffer Space to and Setting WTD Thresholds for an Egress Queue-Set

                                        You can guarantee the availability of buffers, set WTD thresholds, and configure the maximum allocation for a queue-set by using the mls qos queue-set output qset-id threshold queue-id drop-threshold1 drop-threshold2 reserved-threshold maximum-threshold global configuration command.

                                        Each threshold value is a percentage of the queue’s allocated buffers, which you specify by using the mls qos queue-set output qset-id buffers allocation1 ... allocation4 global configuration command. The queues use WTD to support distinct drop percentages for different traffic classes.


                                        Note


                                        The egress queue default settings are suitable for most situations. You should change them only when you have a thorough understanding of the egress queues and if these settings do not meet your QoS solution.


                                        Beginning in privileged EXEC mode, follow these steps to configure the memory allocation and to drop thresholds for a queue-set. This procedure is optional.

                                        SUMMARY STEPS

                                          1.    configure terminal

                                          2.    mls qos srr-queue output queues 8

                                          3.    mls qos queue-set output qset-id buffers allocation1 ... allocation8

                                          4.    mls qos queue-set output qset-id threshold queue-id drop-threshold1 drop-threshold2 reserved-threshold maximum-threshold

                                          5.    interface interface-id

                                          6.    queue-set qset-id

                                          7.    end

                                          8.    show mls qos interface [interface-id] buffers

                                          9.    copy running-config startup-config


                                        DETAILED STEPS
                                           Command or ActionPurpose
                                          Step 1configure terminal


                                          Example:
                                          
                                          Switch# configure terminal
                                          
                                          
                                           

                                          Enters the global configuration mode.

                                           
                                          Step 2mls qos srr-queue output queues 8


                                          Example:
                                          Switch(config)# mls qos srr-queue output queues 8
                                          
                                          
                                           

                                          (Optional) The switch supports 4 egress queues by default, although you can enable a total of 8 egress queues. Use the optional mls qos srr-queue output queues 8 command to enable the additional 4 egress queues.

                                          Once 8 queue support is enabled, you can then proceed to configure the additional 4 queues. Any existing egress queue configuration commands are then modified to support the additional queue parameters.

                                          Note   

                                          The option to enable 8 queues is only available on a standalone switch.

                                           

                                          Step 3mls qos queue-set output qset-id buffers allocation1 ... allocation8


                                          Example:
                                          
                                          Switch(config)# mls qos queue-set output 2 buffers 40 20 20 20 10 10 10 10
                                          
                                          
                                           

                                          Allocates buffers to a queue set.

                                          By default, all allocation values are equally mapped among the four queues (25, 25, 25, 25). Each queue has 1/4 of the buffer space. When eight egress queues are configured, then by default 30 percent of the total buffer space is allocated to queue 2 and 10 percent (each) to queues 1,3,4,5,6,7, and 8.

                                          If you enabled 8 egress queues as described in Step 2 above, then the following applies:

                                          • For qset-id, enter the ID of the queue set. The range is 1 to 2. Each port belongs to a queue set, which defines all the characteristics of the four egress queues per port.
                                          • For allocation1 ... allocation8, specify eight percentages, one for each queue in the queue set. For allocation1, allocation3, and allocation4 to allocation8, the range is 0 to 99. For allocation2, the range is 1 to 100 (including the CPU buffer).

                                          Allocate buffers according to the importance of the traffic; for example, give a large percentage of the buffer to the queue with the highest-priority traffic.

                                          Note   

                                          To return to the default setting, use the no mls qos queue-set output qset-id buffers global configuration command.

                                           
                                          Step 4mls qos queue-set output qset-id threshold queue-id drop-threshold1 drop-threshold2 reserved-threshold maximum-threshold


                                          Example:
                                          
                                          Switch(config)# mls qos queue-set output 2 threshold 2 40 60 100 200
                                          
                                          
                                           

                                          Configures the WTD thresholds, guarantee the availability of buffers, and configure the maximum memory allocation for the queue-set (four egress queues per port).

                                          By default, the WTD thresholds for queues 1, 3, and 4 are set to 100 percent. The thresholds for queue 2 are set to 200 percent. The reserved thresholds for queues 1, 2, 3, and 4 are set to 50 percent. The maximum thresholds for all queues are set to 400 percent by default.

                                          If you enabled 8 egress queues as described in Step 2 above, then the following applies:

                                          • For qset-id, enter the ID of the queue-set specified in Step 2. The range is 1 to 2.
                                          • For queue-id, enter the specific queue in the queue set on which the command is performed. The queue-id range is 1-4 by default and 1-8 when 8 queues are enabled.
                                          • For drop-threshold1 drop-threshold2, specify the two WTD thresholds expressed as a percentage of the queue’s allocated memory. The range is 1 to 3200 percent.
                                          • For reserved-threshold, enter the amount of memory to be guaranteed (reserved) for the queue expressed as a percentage of the allocated memory. The range is 1 to 100 percent.
                                          • For maximum-threshold, enable a queue in the full condition to obtain more buffers than are reserved for it. This is the maximum memory the queue can have before the packets are dropped if the common pool is not empty. The range is 1 to 3200 percent.
                                          Note   

                                          To return to the default WTD threshold percentages, use the no mls qos queue-set output qset-id threshold [queue-id] global configuration command.

                                           
                                          Step 5interface interface-id


                                          Example:
                                          
                                          Switch(config)# interface gigabitethernet1/0/1
                                          
                                          
                                           

                                          Specifies the port of the outbound traffic, and enter interface configuration mode.

                                           
                                          Step 6queue-set qset-id


                                          Example:
                                          
                                          Switch(config-id)# queue-set 2
                                          
                                          
                                           

                                          Maps the port to a queue-set.

                                          For qset-id, enter the ID of the queue-set specified in Step 2. The range is 1 to 2. The default is 1.

                                           
                                          Step 7end


                                          Example:
                                          
                                          Switch(config-id)# end
                                          
                                          
                                           

                                          Returns to privileged EXEC mode.

                                           
                                          Step 8show mls qos interface [interface-id] buffers


                                          Example:
                                          
                                          Switch# show mls qos interface buffers
                                          
                                          
                                           

                                          Verifies your entries.

                                           
                                          Step 9copy running-config startup-config


                                          Example:
                                          
                                          Switch# copy-running-config startup-config
                                          
                                          
                                           

                                          (Optional) Saves your entries in the configuration file.

                                          To return to the default setting, use the no mls qos queue-set output qset-id buffers global configuration command. To return to the default WTD threshold percentages, use the no mls qos queue-set output qset-id threshold [queue-id] global configuration command.

                                           

                                          Mapping DSCP or CoS Values to an Egress Queue and to a Threshold ID

                                          You can prioritize traffic by placing packets with particular DSCPs or costs of service into certain queues and adjusting the queue thresholds so that packets with lower priorities are dropped.


                                          Note


                                          The egress queue default settings are suitable for most situations. You should change them only when you have a thorough understanding of egress queues and if these settings do not meet your QoS solution.


                                          Beginning in privileged EXEC mode, follow these steps to map DSCP or CoS values to an egress queue and to a threshold ID. This procedure is optional.

                                          SUMMARY STEPS

                                            1.    configure terminal

                                            2.    Use one of the following:

                                            • mls qos srr-queue output dscp-map queue queue-id threshold threshold-id dscp1...dscp8
                                            • mls qos srr-queue output cos-map queue queue-id threshold threshold-id cos1...cos8

                                            3.    end

                                            4.    show mls qos maps

                                            5.    copy running-config startup-config


                                          DETAILED STEPS
                                             Command or ActionPurpose
                                            Step 1configure terminal


                                            Example:
                                            
                                            Switch# configure terminal
                                            
                                            
                                             

                                            Enters global configuration mode.

                                             
                                            Step 2Use one of the following:
                                            • mls qos srr-queue output dscp-map queue queue-id threshold threshold-id dscp1...dscp8
                                            • mls qos srr-queue output cos-map queue queue-id threshold threshold-id cos1...cos8


                                            Example:
                                            
                                            Switch(config)# mls qos srr-queue output 
                                            dscp-map queue 1 threshold 2 10 11
                                            
                                            
                                             

                                            Maps DSCP or CoS values to an egress queue and to a threshold ID.

                                            By default, DSCP values 0–15 are mapped to queue 2 and threshold 1. DSCP values 16–31 are mapped to queue 3 and threshold 1. DSCP values 32–39 and 48–63 are mapped to queue 4 and threshold 1. DSCP values 40–47 are mapped to queue 1 and threshold 1.

                                            By default, CoS values 0 and 1 are mapped to queue 2 and threshold 1. CoS values 2 and 3 are mapped to queue 3 and threshold 1. CoS values 4, 6, and 7 are mapped to queue 4 and threshold 1. CoS value 5 is mapped to queue 1 and threshold 1.

                                            • For queue-id, the range is 1 to 4.
                                            • For threshold-id, the range is 1 to 3. The drop-threshold percentage for threshold 3 is predefined. It is set to the queue-full state.
                                            • For dscp1...dscp8, enter up to eight values, and separate each value with a space. The range is 0 to 63.
                                            • For cos1...cos8, enter up to eight values, and separate each value with a space. The range is 0 to 7.
                                            Note   

                                            To return to the default DSCP output queue threshold map or the default CoS output queue threshold map, use the no mls qos srr-queue output dscp-map or the no mls qos srr-queue output cos-map global configuration command.

                                             
                                            Step 3end


                                            Example:
                                            
                                            Switch(config)# end
                                            
                                            
                                             

                                            Returns to privileged EXEC mode.

                                             
                                            Step 4show mls qos maps


                                            Example:
                                            
                                            Switch# show mls qos maps
                                            
                                            
                                             

                                            Verifies your entries.

                                            The DSCP output queue threshold map appears as a matrix. The d1 column specifies the most-significant digit of the DSCP number; the d2 row specifies the least-significant digit in the DSCP number. The intersection of the d1 and the d2 values provides the queue ID and threshold ID; for example, queue 2 and threshold 1 (02-01).

                                            The CoS output queue threshold map shows the CoS value in the top row and the corresponding queue ID and threshold ID in the second row; for example, queue 2 and threshold 2 (2-2).

                                             
                                            Step 5copy running-config startup-config


                                            Example:
                                            
                                            Switch# copy-running-config 
                                            startup-config
                                            
                                            
                                             

                                            (Optional) Saves your entries in the configuration file.

                                            To return to the default DSCP output queue threshold map or the default CoS output queue threshold map, use the no mls qos srr-queue output dscp-map or the no mls qos srr-queue output cos-map global configuration command.

                                             
                                            Related Concepts

                                            Configuring SRR Shaped Weights on Egress Queues

                                            You can specify how much of the available bandwidth is allocated to each queue. The ratio of the weights is the ratio of frequency in which the SRR scheduler sends packets from each queue.

                                            You can configure the egress queues for shaped or shared weights, or both. Use shaping to smooth bursty traffic or to provide a smoother output over time.

                                            Beginning in privileged EXEC mode, follow these steps to assign the shaped weights and to enable bandwidth shaping on the four egress queues mapped to a port. This procedure is optional.

                                            SUMMARY STEPS

                                              1.    configure terminal

                                              2.    interface interface-id

                                              3.    srr-queue bandwidth shape weight1 weight2 weight3 weight4

                                              4.    end

                                              5.    show mls qos interface interface-id queueing

                                              6.    copy running-config startup-config


                                            DETAILED STEPS
                                               Command or ActionPurpose
                                              Step 1configure terminal


                                              Example:
                                              
                                              Switch# configure terminal
                                              
                                              
                                               

                                              Enters the global configuration mode.

                                               
                                              Step 2interface interface-id


                                              Example:
                                              
                                              Switch(config)# interface 
                                              gigabitethernet2/0/1
                                              
                                              
                                               

                                              Specifies the port of the outbound traffic, and enters interface configuration mode.

                                               
                                              Step 3srr-queue bandwidth shape weight1 weight2 weight3 weight4


                                              Example:
                                              
                                              Switch(config-if)# srr-queue 
                                              bandwidth shape 8 0 0 0
                                              
                                              
                                               

                                              Assigns SRR weights to the egress queues. By default, weight1 is set to 25; weight2, weight3, and weight4 are set to 0, and these queues are in shared mode.

                                              For weight1 weight2 weight3 weight4, enter the weights to control the percentage of the port that is shaped. The inverse ratio (1/weight) controls the shaping bandwidth for this queue. Separate each value with a space. The range is 0 to 65535.

                                              If you configure a weight of 0, the corresponding queue operates in shared mode. The weight specified with the srr-queue bandwidth shape command is ignored, and the weights specified with the srr-queue bandwidth share interface configuration command for a queue come into effect. When configuring queues in the same queue-set for both shaping and sharing, make sure that you configure the lowest number queue for shaping.

                                              The shaped mode overrides the shared mode.

                                              To return to the default setting, use the no srr-queue bandwidth shape interface configuration command.

                                               
                                              Step 4end


                                              Example:
                                              
                                              Switch(config-if)# end
                                              
                                              
                                               

                                              Returns to privileged EXEC mode.

                                               
                                              Step 5show mls qos interface interface-id queueing


                                              Example:
                                              
                                              Switch# show mls qos interface 
                                              interface-id queuing
                                              
                                              
                                               

                                              Verifies your entries.

                                               
                                              Step 6copy running-config startup-config


                                              Example:
                                              
                                              Switch# copy running-config 
                                              startup-config
                                              
                                              
                                               

                                              (Optional) Saves your entries in the configuration file.

                                              To return to the default setting, use the no srr-queue bandwidth shape interface configuration command.

                                               

                                              Configuring SRR Shared Weights on Egress Queues

                                              In shared mode, the queues share the bandwidth among them according to the configured weights. The bandwidth is guaranteed at this level but not limited to it. For example, if a queue empties and does not require a share of the link, the remaining queues can expand into the unused bandwidth and share it among them. With sharing, the ratio of the weights controls the frequency of dequeuing; the absolute values are meaningless.


                                              Note


                                              The egress queue default settings are suitable for most situations. You should change them only when you have a thorough understanding of the egress queues and if these settings do not meet your QoS solution.


                                              Beginning in privileged EXEC mode, follow these steps to assign the shared weights and to enable bandwidth sharing on the four egress queues mapped to a port. This procedure is optional.

                                              SUMMARY STEPS

                                                1.    configure terminal

                                                2.    interface interface-id

                                                3.    srr-queue bandwidth share weight1 weight2 weight3 weight4

                                                4.    end

                                                5.    show mls qos interface interface-id queueing

                                                6.    copy running-config startup-config


                                              DETAILED STEPS
                                                 Command or ActionPurpose
                                                Step 1configure terminal


                                                Example:
                                                
                                                Switch# configure terminal
                                                
                                                
                                                 

                                                Enters global configuration mode.

                                                 
                                                Step 2interface interface-id


                                                Example:
                                                
                                                Switch(config)# interface 
                                                gigabitethernet2/0/1
                                                
                                                
                                                 

                                                Specifies the port of the outbound traffic, and enters interface configuration mode.

                                                 
                                                Step 3srr-queue bandwidth share weight1 weight2 weight3 weight4


                                                Example:
                                                
                                                Switch(config-id)# srr-queue 
                                                bandwidth share 1 2 3 4
                                                
                                                
                                                 

                                                Assigns SRR weights to the egress queues. By default, all four weights are 25 (1/4 of the bandwidth is allocated to each queue).

                                                For weight1 weight2 weight3 weight4, enter the weights to control the ratio of the frequency in which the SRR scheduler sends packets. Separate each value with a space. The range is 1 to 255.

                                                To return to the default setting, use the no srr-queue bandwidth share interface configuration command.

                                                 
                                                Step 4end


                                                Example:
                                                
                                                Switch(config-id)# end
                                                
                                                
                                                 

                                                Returns to privileged EXEC mode.

                                                 
                                                Step 5show mls qos interface interface-id queueing


                                                Example:
                                                
                                                Switch# show mls qos interface 
                                                interface_id queuing
                                                
                                                
                                                 

                                                Verifies your entries.

                                                 
                                                Step 6copy running-config startup-config


                                                Example:
                                                
                                                Switch# copy-running-config 
                                                startup-config
                                                
                                                
                                                 

                                                (Optional) Saves your entries in the configuration file.

                                                To return to the default setting, use the no srr-queue bandwidth share interface configuration command.

                                                 

                                                Configuring the Egress Expedite Queue

                                                You can ensure that certain packets have priority over all others by queuing them in the egress expedite queue. SRR services this queue until it is empty before servicing the other queues.

                                                Beginning in privileged EXEC mode, follow these steps to enable the egress expedite queue. This procedure is optional.

                                                SUMMARY STEPS

                                                  1.    configure terminal

                                                  2.    mls qos

                                                  3.    interface interface-id

                                                  4.    priority-queue out

                                                  5.    end

                                                  6.    show running-config

                                                  7.    copy running-config startup-config


                                                DETAILED STEPS
                                                   Command or ActionPurpose
                                                  Step 1configure terminal


                                                  Example:
                                                  
                                                  Switch# configure terminal
                                                  
                                                  
                                                   

                                                  Enters global configuration mode.

                                                   
                                                  Step 2mls qos


                                                  Example:
                                                  
                                                  Switch(config)# mls qos
                                                  
                                                  
                                                   

                                                  Enables QoS on a switch.

                                                   
                                                  Step 3interface interface-id


                                                  Example:
                                                  
                                                  Switch(config)# interface 
                                                  gigabitethernet1/0/1
                                                  
                                                  
                                                   

                                                  Specifies the egress port, and enters interface configuration mode.

                                                   
                                                  Step 4priority-queue out


                                                  Example:
                                                  
                                                  Switch(config-if)# priority-queue out
                                                  
                                                  
                                                   

                                                  Enables the egress expedite queue, which is disabled by default.

                                                  When you configure this command, the SRR weight and queue size ratios are affected because there is one fewer queue participating in SRR. This means that weight1 in the srr-queue bandwidth shape or the srr-queue bandwidth share command is ignored (not used in the ratio calculation).

                                                  Note   

                                                  To disable the egress expedite queue, use the no priority-queue out interface configuration command.

                                                   
                                                  Step 5end


                                                  Example:
                                                  
                                                  Switch(config-if)# end
                                                  
                                                  
                                                   

                                                  Returns to privileged EXEC mode.

                                                   
                                                  Step 6show running-config


                                                  Example:
                                                  
                                                  Switch# show running-config
                                                  
                                                  
                                                   

                                                  Verifies your entries.

                                                   
                                                  Step 7copy running-config startup-config


                                                  Example:
                                                  
                                                  Switch# copy running-config 
                                                  startup-config
                                                  
                                                  
                                                   

                                                  (Optional) Saves your entries in the configuration file.

                                                  To disable the egress expedite queue, use the no priority-queue out interface configuration command.

                                                   
                                                  Related Concepts

                                                  Limiting the Bandwidth on an Egress Interface

                                                  You can limit the bandwidth on an egress port. For example, if a customer pays only for a small percentage of a high-speed link, you can limit the bandwidth to that amount.


                                                  Note


                                                  The egress queue default settings are suitable for most situations. You should change them only when you have a thorough understanding of the egress queues and if these settings do not meet your QoS solution.


                                                  Beginning in privileged EXEC mode, follow these steps to limit the bandwidth on an egress port. This procedure is optional.

                                                  SUMMARY STEPS

                                                    1.    configure terminal

                                                    2.    interface interface-id

                                                    3.    srr-queue bandwidth limit weight1

                                                    4.    end

                                                    5.    show mls qos interface [interface-id] queueing

                                                    6.    copy running-config startup-config


                                                  DETAILED STEPS
                                                     Command or ActionPurpose
                                                    Step 1configure terminal


                                                    Example:
                                                    
                                                    Switch# configure terminal
                                                    
                                                    
                                                     

                                                    Enters global configuration mode.

                                                     
                                                    Step 2interface interface-id


                                                    Example:
                                                    
                                                    Switch(config)# interface 
                                                    gigabitethernet2/0/1
                                                    
                                                    
                                                     

                                                    Specifies the port to be rate-limited, and enters interface configuration mode.

                                                     
                                                    Step 3srr-queue bandwidth limit weight1


                                                    Example:
                                                    
                                                    Switch(config-if)# srr-queue 
                                                    bandwidth limit 80
                                                    
                                                    
                                                     

                                                    Specifies the percentage of the port speed to which the port should be limited. The range is 10 to 90.

                                                    By default, the port is not rate-limited and is set to 100 percent.

                                                    Note    To return to the default setting, use the no srr-queue bandwidth limit interface configuration command.
                                                     
                                                    Step 4end


                                                    Example:
                                                    
                                                    Switch(config-if)# end
                                                    
                                                    
                                                     

                                                    Returns to privileged EXEC mode.

                                                     
                                                    Step 5show mls qos interface [interface-id] queueing


                                                    Example:
                                                    
                                                    Switch# show mls qos interface 
                                                    interface_id queueing
                                                    
                                                    
                                                     

                                                    Verifies your entries.

                                                     
                                                    Step 6copy running-config startup-config


                                                    Example:
                                                    
                                                    Switch# copy-running-config 
                                                    startup-config
                                                    
                                                    
                                                     

                                                    (Optional) Saves your entries in the configuration file.

                                                    To return to the default setting, use the no srr-queue bandwidth limit interface configuration command.

                                                     

                                                    Monitoring Standard QoS

                                                    Table 13 Commands for Monitoring Standard QoS on the Switch

                                                    Command

                                                    Description

                                                    show class-map [class-map-name]

                                                    Displays QoS class maps, which define the match criteria to classify traffic.

                                                    show mls qos

                                                    Displays global QoS configuration information.

                                                    show mls qos aggregate-policer [aggregate-policer-name]

                                                    Displays the aggregate policer configuration.

                                                    show mls qos input-queue

                                                    Displays QoS settings for the ingress queues.

                                                    show mls qos interface [interface-id] [buffers | policers | queueing | statistics]

                                                    Displays QoS information at the port level, including the buffer allocation, which ports have configured policers, the queueing strategy, and the ingress and egress statistics.

                                                    show mls qos maps [cos-dscp | cos-input-q |cos-output-q | dscp-cos | dscp-input-q |dscp-mutation dscp-mutation-name | dscp-output-q | ip-prec-dscp | policed-dscp]

                                                    Displays QoS mapping information.

                                                    show mls qos queue-set [qset-id]

                                                    Displays QoS settings for the egress queues.

                                                    show policy-map [policy-map-name [class class-map-name]]

                                                    Displays QoS policy maps, which define classification criteria for incoming traffic.

                                                    Do not use the show policy-map interface privileged EXEC command to display classification information for incoming traffic. The control-plane and interface keywords are not supported, and the statistics shown in the display should be ignored.

                                                    show running-config | include rewrite

                                                    Displays the DSCP transparency setting.

                                                    Configuration Examples for QoS

                                                    Example: Configuring Port to the DSCP-Trusted State and Modifying the DSCP-to-DSCP-Mutation Map

                                                    This example shows how to configure a port to the DSCP-trusted state and to modify the DSCP-to-DSCP-mutation map (named gi1/0/2-mutation) so that incoming DSCP values 10 to 13 are mapped to DSCP 30:

                                                    
                                                    Switch(config)# mls qos map dscp-mutation gigabitethernet1/0/2-mutation 
                                                    10 11 12 13 to 30 
                                                    Switch(config)# interface gigabitethernet1/0/2
                                                    Switch(config-if)# mls qos trust dscp
                                                    Switch(config-if)# mls qos dscp-mutation gigabitethernet1/0/2-mutation
                                                    Switch(config-if)# end
                                                    
                                                    
                                                    Related Concepts

                                                    Examples: Classifying Traffic by Using ACLs

                                                    This example shows how to allow access for only those hosts on the three specified networks. The wildcard bits apply to the host portions of the network addresses. Any host with a source address that does not match the access list statements is rejected.

                                                    
                                                    Switch(config)# access-list 1 permit 192.5.255.0 0.0.0.255
                                                    Switch(config)# access-list 1 permit 128.88.0.0 0.0.255.255
                                                    Switch(config)# access-list 1 permit 36.0.0.0 0.0.0.255
                                                    ! (Note: all other access implicitly denied)
                                                    
                                                    

                                                    This example shows how to create an ACL that permits IP traffic from any source to any destination that has the DSCP value set to 32:

                                                    
                                                    Switch(config)# access-list 100 permit ip any any dscp 32
                                                    
                                                    

                                                    This example shows how to create an ACL that permits IP traffic from a source host at 10.1.1.1 to a destination host at 10.1.1.2 with a precedence value of 5:

                                                    
                                                    Switch(config)# access-list 100 permit ip host 10.1.1.1 host 10.1.1.2 precedence 5
                                                    
                                                    

                                                    This example shows how to create an ACL that permits PIM traffic from any source to a destination group address of 224.0.0.2 with a DSCP set to 32:

                                                    
                                                    Switch(config)# access-list 102 permit pim any 224.0.0.2 dscp 32
                                                    
                                                    

                                                    This example shows how to create an ACL that permits IPv6 traffic from any source to any destination that has the DSCP value set to 32:

                                                    
                                                    Switch(config)# ipv6 access-list 100 permit ip any any dscp 32
                                                    
                                                    

                                                    This example shows how to create an ACL that permits IPv6 traffic from a source host at 10.1.1.1 to a destination host at 10.1.1.2 with a precedence value of 5:

                                                    
                                                    Switch(config)# ipv6 access-list ipv6_Name_ACL permit ip host 10::1 host 10.1.1.2 
                                                    precedence 5
                                                    
                                                    

                                                    This example shows how to create a Layer 2 MAC ACL with two permit statements. The first statement allows traffic from the host with MAC address 0001.0000.0001 to the host with MAC address 0002.0000.0001. The second statement allows only Ethertype XNS-IDP traffic from the host with MAC address 0001.0000.0002 to the host with MAC address 0002.0000.0002.

                                                    
                                                    Switch(config)# mac access-list extended maclist1
                                                    Switch(config-ext-macl)# permit 0001.0000.0001 0.0.0 0002.0000.0001 0.0.0
                                                    Switch(config-ext-macl)# permit 0001.0000.0002 0.0.0 0002.0000.0002 0.0.0 xns-idp
                                                    ! (Note: all other access implicitly denied)
                                                    
                                                    
                                                    Related References

                                                    Examples: Classifying Traffic by Using Class Maps

                                                    This example shows how to configure the class map called class1. The class1 has one match criterion, which is access list 103. It permits traffic from any host to any destination that matches a DSCP value of 10.

                                                    
                                                    Switch(config)# access-list 103 permit ip any any dscp 10
                                                    Switch(config)# class-map class1
                                                    Switch(config-cmap)# match access-group 103
                                                    Switch(config-cmap)# end
                                                    Switch#
                                                    
                                                    

                                                    This example shows how to create a class map called class2, which matches incoming traffic with DSCP values of 10, 11, and 12.

                                                    
                                                    Switch(config)# class-map class2
                                                    Switch(config-cmap)# match ip dscp 10 11 12
                                                    Switch(config-cmap)# end
                                                    Switch#
                                                    
                                                    

                                                    This example shows how to create a class map called class3, which matches incoming traffic with IP-precedence values of 5, 6, and 7:

                                                    
                                                    Switch(config)# class-map class3
                                                    Switch(config-cmap)# match ip precedence 5 6 7 
                                                    Switch(config-cmap)# end
                                                    Switch#
                                                    
                                                    

                                                    This example shows how to configure a class map to match IP DSCP and IPv6:

                                                    
                                                    Switch(config)# Class-map cm-1
                                                    Switch(config-cmap)# match ip dscp 10
                                                    Switch(config-cmap)# match protocol ipv6
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# Class-map cm-2
                                                    Switch(config-cmap)# match ip dscp 20
                                                    Switch(config-cmap)# match protocol ip
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# Policy-map pm1
                                                    Switch(config-pmap)# class cm-1
                                                    Switch(config-pmap-c)# set dscp 4
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# class cm-2
                                                    Switch(config-pmap-c)# set dscp 6
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# exit
                                                    Switch(config)# interface G1/0/1
                                                    Switch(config-if)# service-policy input pm1
                                                    
                                                    

                                                    This example shows how to configure a class map that applies to both IPv4 and IPv6 traffic:

                                                    
                                                    Switch(config)# ip access-list 101 permit ip any any
                                                    Switch(config)# ipv6 access-list ipv6-any permit ip any any
                                                    Switch(config)# Class-map cm-1
                                                    Switch(config-cmap)# match access-group 101
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# class-map cm-2
                                                    Switch(config-cmap)# match access-group name ipv6-any
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# Policy-map pm1
                                                    Switch(config-pmap)# class cm-1
                                                    Switch(config-pmap-c)# set dscp 4
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# class cm-2
                                                    Switch(config-pmap-c)# set dscp 6
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# exit
                                                    Switch(config)# interface G0/1
                                                    Switch(config-if)# switch mode access
                                                    Switch(config-if)# service-policy input pm1
                                                    
                                                    

                                                    Examples: Classifying, Policing, and Marking Traffic on Physical Ports Using Policy Maps

                                                    This example shows how to create a policy map and attach it to an ingress port. In the configuration, the IP standard ACL permits traffic from network 10.1.0.0. For traffic matching this classification, the DSCP value in the incoming packet is trusted. If the matched traffic exceeds an average traffic rate of 48000 b/s and a normal burst size of 8000 bytes, its DSCP is marked down (based on the policed-DSCP map) and sent:

                                                    
                                                    Switch(config)# access-list 1 permit 10.1.0.0 0.0.255.255
                                                    Switch(config)# class-map ipclass1
                                                    Switch(config-cmap)# match access-group 1
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# policy-map flow1t
                                                    Switch(config-pmap)# class ipclass1
                                                    Switch(config-pmap-c)# trust dscp
                                                    Switch(config-pmap-c)# police 1000000 8000 exceed-action policed-dscp-transmit
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# exit
                                                    Switch(config)# interface gigabitethernet2/0/1
                                                    Switch(config-if)# service-policy input flow1t
                                                    
                                                    

                                                    This example shows how to create a Layer 2 MAC ACL with two permit statements and attach it to an ingress port. The first permit statement allows traffic from the host with MAC address 0001.0000.0001 destined for the host with MAC address 0002.0000.0001. The second permit statement allows only Ethertype XNS-IDP traffic from the host with MAC address 0001.0000.0002 destined for the host with MAC address 0002.0000.0002.

                                                    
                                                    Switch(config)# mac access-list extended maclist1
                                                    Switch(config-ext-mac)# permit 0001.0000.0001 0.0.0 0002.0000.0001 0.0.0
                                                    Switch(config-ext-mac)# permit 0001.0000.0002 0.0.0 0002.0000.0002 0.0.0 xns-idp
                                                    Switch(config-ext-mac)# exit
                                                    Switch(config)# mac access-list extended maclist2
                                                    Switch(config-ext-mac)# permit 0001.0000.0003 0.0.0 0002.0000.0003 0.0.0
                                                    Switch(config-ext-mac)# permit 0001.0000.0004 0.0.0 0002.0000.0004 0.0.0 aarp
                                                    Switch(config-ext-mac)# exit
                                                    Switch(config)# class-map macclass1
                                                    Switch(config-cmap)# match access-group maclist1
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# policy-map macpolicy1
                                                    Switch(config-pmap)# class macclass1
                                                    Switch(config-pmap-c)# set dscp 63
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# class macclass2 maclist2
                                                    Switch(config-pmap-c)# set dscp 45
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# exit
                                                    Switch(config)# interface gigabitethernet1/0/1
                                                    Switch(config-if)# mls qos trust cos
                                                    Switch(config-if)# service-policy input macpolicy1
                                                    
                                                    

                                                    This example shows how to create a class map that applies to both IPv4 and IPv6 traffic with the default class applied to unclassified traffic:

                                                    
                                                    Switch(config)# ip access-list 101 permit ip any any
                                                    Switch(config)# ipv6 access-list ipv6-any permit ip any any
                                                    Switch(config)# class-map cm-1
                                                    Switch(config-cmap)# match access-group 101
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# class-map cm-2
                                                    Switch(config-cmap)# match access-group name ipv6-any
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# policy-map pm1
                                                    Switch(config-pmap)# class cm-1
                                                    Switch(config-pmap-c)# set dscp 4
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# class cm-2
                                                    Switch(config-pmap-c)# set dscp 6
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# class class-default
                                                    Switch(config-pmap-c)# set dscp 10
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# exit
                                                    Switch(config)# interface G0/1
                                                    Switch(config-if)# switch mode access
                                                    Switch(config-if)# service-policy input pm1
                                                    
                                                    

                                                    Examples: Classifying, Policing, and Marking Traffic by Using Aggregate Policers

                                                    This example shows how to create an aggregate policer and attach it to multiple classes within a policy map. In the configuration, the IP ACLs permit traffic from network 10.1.0.0 and from host 11.3.1.1. For traffic coming from network 10.1.0.0, the DSCP in the incoming packets is trusted. For traffic coming from host 11.3.1.1, the DSCP in the packet is changed to 56. The traffic rate from the 10.1.0.0 network and from host 11.3.1.1 is policed. If the traffic exceeds an average rate of 48000 b/s and a normal burst size of 8000 bytes, its DSCP is marked down (based on the policed-DSCP map) and sent. The policy map is attached to an ingress port.

                                                    
                                                    Switch(config)# access-list 1 permit 10.1.0.0 0.0.255.255
                                                    Switch(config)# access-list 2 permit 11.3.1.1
                                                    Switch(config)# mls qos aggregate-police transmit1 48000 8000 exceed-action 
                                                    policed-dscp-transmit
                                                    Switch(config)# class-map ipclass1
                                                    Switch(config-cmap)# match access-group 1
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# class-map ipclass2
                                                    Switch(config-cmap)# match access-group 2
                                                    Switch(config-cmap)# exit
                                                    Switch(config)# policy-map aggflow1
                                                    Switch(config-pmap)# class ipclass1
                                                    Switch(config-pmap-c)# trust dscp
                                                    Switch(config-pmap-c)# police aggregate transmit1
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# class ipclass2
                                                    Switch(config-pmap-c)# set dscp 56
                                                    Switch(config-pmap-c)# police aggregate transmit1
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# class class-default
                                                    Switch(config-pmap-c)# set dscp 10
                                                    Switch(config-pmap-c)# exit
                                                    Switch(config-pmap)# exit
                                                    Switch(config)# interface gigabitethernet2/0/1
                                                    Switch(config-if)# service-policy input aggflow1
                                                    Switch(config-if)# exit
                                                    
                                                    
                                                    Related Concepts

                                                    Examples: Configuring DSCP Maps

                                                    This example shows how to modify and display the CoS-to-DSCP map:

                                                    
                                                    Switch(config)# mls qos map cos-dscp 10 15 20 25 30 35 40 45
                                                    Switch(config)# end
                                                    Switch# show mls qos maps cos-dscp
                                                    
                                                    Cos-dscp map:
                                                            cos:   0  1  2  3  4  5  6  7
                                                         --------------------------------
                                                           dscp:   10 15 20 25 30 35 40 45
                                                    
                                                    

                                                    This example shows how to modify and display the IP-precedence-to-DSCP map:

                                                    
                                                    Switch(config)# mls qos map ip-prec-dscp 10 15 20 25 30 35 40 45
                                                    Switch(config)# end
                                                    Switch# show mls qos maps ip-prec-dscp
                                                    
                                                    IpPrecedence-dscp map:
                                                         ipprec:   0  1  2  3  4  5  6  7
                                                         --------------------------------
                                                           dscp:   10 15 20 25 30 35 40 45
                                                    
                                                    

                                                    This example shows how to map DSCP 50 to 57 to a marked-down DSCP value of 0:

                                                    
                                                    Switch(config)# mls qos map policed-dscp 50 51 52 53 54 55 56 57 to 0
                                                    Switch(config)# end
                                                    Switch# show mls qos maps policed-dscp
                                                    Policed-dscp map:
                                                         d1 :  d2 0  1  2  3  4  5  6  7  8  9
                                                         ---------------------------------------
                                                          0 :    00 01 02 03 04 05 06 07 08 09
                                                          1 :    10 11 12 13 14 15 16 17 18 19
                                                          2 :    20 21 22 23 24 25 26 27 28 29
                                                          3 :    30 31 32 33 34 35 36 37 38 39
                                                          4 :    40 41 42 43 44 45 46 47 48 49
                                                          5 :    00 00 00 00 00 00 00 00 58 59
                                                          6 :    60 61 62 63
                                                    
                                                    

                                                    Note


                                                    In this policed-DSCP map, the marked-down DSCP values are shown in the body of the matrix. The d1 column specifies the most-significant digit of the original DSCP; the d2 row specifies the least-significant digit of the original DSCP. The intersection of the d1 and d2 values provides the marked-down value. For example, an original DSCP value of 53 corresponds to a marked-down DSCP value of 0.


                                                    This example shows how to map DSCP values 0, 8, 16, 24, 32, 40, 48, and 50 to CoS value 0 and to display the map:

                                                    
                                                    Switch(config)# mls qos map dscp-cos 0 8 16 24 32 40 48 50 to 0
                                                    Switch(config)# end
                                                    Switch# show mls qos maps dscp-cos
                                                    Dscp-cos map:
                                                         d1 :  d2 0  1  2  3  4  5  6  7  8  9
                                                         ---------------------------------------
                                                          0 :    00 00 00 00 00 00 00 00 00 01
                                                          1 :    01 01 01 01 01 01 00 02 02 02
                                                          2 :    02 02 02 02 00 03 03 03 03 03
                                                          3 :    03 03 00 04 04 04 04 04 04 04
                                                          4 :    00 05 05 05 05 05 05 05 00 06
                                                          5 :    00 06 06 06 06 06 07 07 07 07
                                                          6 :    07 07 07 07
                                                    
                                                    

                                                    Note


                                                    In the above DSCP-to-CoS map, the CoS values are shown in the body of the matrix. The d1 column specifies the most-significant digit of the DSCP; the d2 row specifies the least-significant digit of the DSCP. The intersection of the d1 and d2 values provides the CoS value. For example, in the DSCP-to-CoS map, a DSCP value of 08 corresponds to a CoS value of 0.


                                                    This example shows how to define the DSCP-to-DSCP-mutation map. All the entries that are not explicitly configured are not modified (remains as specified in the null map):

                                                    
                                                    Switch(config)# mls qos map dscp-mutation mutation1 1 2 3 4 5 6 7 to 0
                                                    Switch(config)# mls qos map dscp-mutation mutation1 8 9 10 11 12 13 to 10
                                                    Switch(config)# mls qos map dscp-mutation mutation1 20 21 22 to 20
                                                    Switch(config)# mls qos map dscp-mutation mutation1 30 31 32 33 34 to 30
                                                    Switch(config)# interface gigabitethernet1/0/1
                                                    Switch(config-if)# mls qos trust dscp
                                                    Switch(config-if)# mls qos dscp-mutation mutation1
                                                    Switch(config-if)# end
                                                    Switch# show mls qos maps dscp-mutation mutation1
                                                    Dscp-dscp mutation map:
                                                       mutation1:
                                                         d1 :  d2 0  1  2  3  4  5  6  7  8  9
                                                         ---------------------------------------
                                                          0 :    00 00 00 00 00 00 00 00 10 10
                                                          1 :    10 10 10 10 14 15 16 17 18 19
                                                          2 :    20 20 20 23 24 25 26 27 28 29
                                                          3 :    30 30 30 30 30 35 36 37 38 39
                                                          4 :    40 41 42 43 44 45 46 47 48 49
                                                          5 :    50 51 52 53 54 55 56 57 58 59
                                                          6 :    60 61 62 63
                                                    
                                                    

                                                    Note


                                                    In the above DSCP-to-DSCP-mutation map, the mutated values are shown in the body of the matrix. The d1 column specifies the most-significant digit of the original DSCP; the d2 row specifies the least-significant digit of the original DSCP. The intersection of the d1 and d2 values provides the mutated value. For example, a DSCP value of 12 corresponds to a mutated value of 10.


                                                    Related Concepts

                                                    Examples: Configuring Egress Queue Characteristics

                                                    This example shows how to map a port to queue-set 2. It allocates 40 percent of the buffer space to egress queue 1 and 20 percent to egress queues 2, 3, and 4. It configures the drop thresholds for queue 2 to 40 and 60 percent of the allocated memory, guarantees (reserves) 100 percent of the allocated memory, and configures 200 percent as the maximum memory that this queue can have before packets are dropped:

                                                    
                                                    Switch(config)# mls qos queue-set output 2 buffers 40 20 20 20
                                                    Switch(config)# mls qos queue-set output 2 threshold 2 40 60 100 200
                                                    Switch(config)# interface gigabitethernet1/0/1
                                                    Switch(config-if)# queue-set 2
                                                    
                                                    

                                                    This example shows how to map DSCP values 10 and 11 to egress queue 1 and to threshold 2:

                                                    
                                                    Switch(config)# mls qos srr-queue output dscp-map queue 1 threshold 2 10 11
                                                    
                                                    

                                                    This example shows how to configure bandwidth shaping on queue 1. Because the weight ratios for queues 2, 3, and 4 are set to 0, these queues operate in shared mode. The bandwidth weight for queue 1 is 1/8, which is 12.5 percent:

                                                    
                                                    Switch(config)# interface gigabitethernet2/0/1
                                                    Switch(config-if)# srr-queue bandwidth shape 8 0 0 0
                                                    
                                                    

                                                    This example shows how to configure the weight ratio of the SRR scheduler running on an egress port. Four queues are used, and the bandwidth ratio allocated for each queue in shared mode is 1/(1+2+3+4), 2/(1+2+3+4), 3/(1+2+3+4), and 4/(1+2+3+4), which is 10 percent, 20 percent, 30 percent, and 40 percent for queues 1, 2, 3, and 4. This means that queue 4 has four times the bandwidth of queue 1, twice the bandwidth of queue 2, and one-and-a-third times the bandwidth of queue 3.

                                                    
                                                    Switch(config)# interface gigabitethernet2/0/1
                                                    Switch(config-if)# srr-queue bandwidth share 1 2 3 4
                                                    
                                                    

                                                    This example shows how to enable the egress expedite queue when the SRR weights are configured. The egress expedite queue overrides the configured SRR weights.

                                                    
                                                    Switch(config)# interface gigabitethernet1/0/1
                                                    Switch(config-if)# srr-queue bandwidth shape 25 0 0 0
                                                    Switch(config-if)# srr-queue bandwidth share 30 20 25 25
                                                    Switch(config-if)# priority-queue out
                                                    Switch(config-if)# end
                                                    
                                                    

                                                    This example shows how to limit the bandwidth on a port to 80 percent:

                                                    
                                                    Switch(config)# interface gigabitethernet2/0/1
                                                    Switch(config-if)# srr-queue bandwidth limit 80
                                                    
                                                    

                                                    When you configure this command to 80 percent, the port is idle 20 percent of the time. The line rate drops to 80 percent of the connected speed, which is 800 Mb/s. These values are not exact because the hardware adjusts the line rate in increments of six.

                                                    Where to Go Next

                                                    Review the auto-QoS documentation to see if you can use these automated capabilities for your QoS configuration.

                                                    Additional References

                                                    Related Documents

                                                    Related Topic Document Title

                                                    For complete syntax and usage information for the commands used in this book.

                                                    Catalyst 2960-X Switch Quality of Service Command Reference

                                                    Standards and RFCs

                                                    Standard/RFC Title

                                                    MIBs

                                                    MIB MIBs Link

                                                    All supported MIBs for this release.

                                                    To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

                                                    http:/​/​www.cisco.com/​go/​mibs

                                                    Technical Assistance

                                                    Description Link

                                                    The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

                                                    To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

                                                    Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

                                                    http:/​/​www.cisco.com/​support

                                                    Feature History and Information for QoS

                                                    Release Modification

                                                    This feature was introduced.