Cisco ME3400 Ethernet Access Switch Software Configuration Guide, Rel 12.2(60)EZ
Configuring QoS
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Configuring QoS

Table Of Contents

Configuring QoS

Understanding QoS

Modular QoS CLI

Input and Output Policies

Input Policy Maps

Output Policy Maps

Classification

Class Maps

The match Command

Classification Based on Layer 2 CoS

Classification Based on IP Precedence

Classification Based on IP DSCP

Classification Comparisons

Classification Based on QoS ACLs

Classification Based on QoS Groups

Classification Based on VLAN IDs

Table Maps

Policing

Individual Policing

Aggregate Policing

Unconditional Priority Policing

Marking

QoS Treatment for Performance-Monitoring Protocols

Cisco IP-SLAs

Two-Way Active Measurement Protocol

QoS Treatment for IP-SLA and TWAMP Probes

Marking

Queuing

QoS Marking for CPU-Generated Traffic

QoS Queuing for CPU-Generated Traffic

Configuration Guidelines

Congestion Management and Scheduling

Traffic Shaping

Class-Based Weighted Fair Queuing

Priority Queuing

Congestion Avoidance and Queuing

Configuring QoS

Default QoS Configuration

QoS Configuration Guidelines

Using ACLs to Classify Traffic

Creating IP Standard ACLs

Creating IP Extended ACLs

Creating Layer 2 MAC ACLs

Using Class Maps to Define a Traffic Class

Configuring Table Maps

Attaching a Traffic Policy to an Interface

Configuring Input Policy Maps

Configuring Input Policy Maps with Individual Policing

Configuring Input Policy Maps with Aggregate Policing

Configuring Input Policy Maps with Marking

Configuring Per-Port Per-VLAN QoS with Hierarchical Input Policy Maps

Configuring Output Policy Maps

Configuring Output Policy Maps with Class-Based-Weighted-Queuing

Configuring Output Policy Maps with Class-Based Shaping

Configuring Output Policy Maps with Port Shaping

Configuring Output Policy Maps with Class-Based Priority Queuing

Configuring Output Policy Maps with Weighted Tail Drop

Configuring QoS Marking and Queuing for CPU-Generated Traffic

Configuration Examples QoS Marking and Queuing for CPU-Generated Traffic

Displaying QoS Information

QoS Statistics

Configuration Examples for Policy Maps

QoS Configuration for Customer A

QoS Configuration for Customer B

Modifying Output Policies and Adding or Deleting Classification Criteria

Modifying Output Policies and Changing Queuing or Scheduling Parameters

Modifying Output Policies and Adding or Deleting Configured Actions

Modifying Output Policies and Adding or Deleting a Class


Configuring QoS


This chapter describes how to configure quality of service (QoS) by using the modular QoS command-line interface (CLI), or MQC, commands on the Cisco ME 3400 Ethernet Access switch. With QoS, you can provide preferential treatment to certain types of traffic at the expense of others. When QoS is not configured, the switch offers best-effort service to each packet, regardless of the packet contents or size. It sends the packets without any assurance of reliability, delay bounds, or throughput. MQC provides a comprehensive hierarchical configuration framework for prioritizing or limiting specific streams of traffic.

The switch supports QoS for both IPv4 and IPv6 traffic when a dual IPv4 and IPv6 SDM template is configured. For more information about configuring IPv6 QoS, see Chapter 40 "Configuring IPv6 QoS."

For more information about Cisco IOS MQC commands, see the "Cisco IOS Quality of Service Solutions Command Reference" at this site:

http://www.cisco.com/en/US/docs/ios/qos/configuration/guide/12_4/qos_12_4_book.html

For complete syntax and usage information for the platform-specific commands used in this chapter, see the command reference for this release.

Understanding QoS

QoS Treatment for Performance-Monitoring Protocols

Configuring QoS

Displaying QoS Information

Configuration Examples for Policy Maps

Understanding QoS

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 traffic-management techniques to provide preferential treatment. Implementing QoS in your network makes network performance more predictable and bandwidth utilization more effective.

Figure 34-1 shows the MQC model.

Figure 34-1 Modular QoS CLI Model

Basic QoS includes these actions.

Packet classification organizes traffic by whether the traffic matches a specific criteria. When a packet is received, the switch identifies all key packet fields: class of service (CoS), Differentiated Services Code Point (DSCP), or IP precedence. The switch classifies the packet based on this content or based on an access-control list lookup. For more information, see the "Classification" section.

Packet policing determines whether a packet is in or out of profile by comparing the rate of the incoming traffic to the configured policer. You can control the traffic flow for packets that conform to or exceed the configured policer. For more information, see the "Policing" section.

Packet prioritization or marking evaluates the classification and policer information to determine the action to take. All packets that belong to a classification can be remarked. When you configure a policer, packets that meet or exceed the permitted bandwidth requirements (bits per second) can be conditionally passed through, dropped, or reclassified. For more information, see the "Marking" section.

Congestion management uses queuing and scheduling algorithms to queue and sort traffic that is leaving a port. The switch supports these scheduling and traffic-limiting features: class-based weighted fair queuing (CBWFQ), class-based traffic shaping, port shaping, and class-based priority queuing. You can provide guaranteed bandwidth to a particular class of traffic while still servicing other traffic queues. For more information, see the "Congestion Management and Scheduling" section.

Queuing on the switch is enhanced with the weighted tail-drop (WTD) algorithm, a congestion-avoidance mechanism. WTD differentiates traffic classes and regulates the queue size (in number of packets) based on the classification. For more information, see the "Congestion Avoidance and Queuing" section.

This section includes information about these topics:

Modular QoS CLI

Input and Output Policies

Classification

Table Maps

Policing

Marking

Congestion Management and Scheduling

Congestion Avoidance and Queuing

Modular QoS CLI

Modular QoS CLI (MQC) allows you to create traffic policies and attach these policies to interfaces. A traffic policy contains a traffic class and one or more QoS features. You use a traffic class to classify traffic, and the QoS features in the traffic policy determine how to treat the classified traffic.

Modular QoS CLI configuration includes these steps:


Step 1 Define a traffic class.

Use the class-map [match-all | match-any] class-map-name global configuration command to define a traffic class and to enter class-map configuration mode. A traffic class contains three elements: a name, an instruction on how to evaluate the configured match commands (if more than one match command is configured in the class map), and a series of match commands

You name the traffic class in the class-map command line to enter class-map configuration mode.

You can optionally include keywords to evaluate these match commands by entering class-map match-any or class-map match-all. If you specify match-any, the traffic being evaluated must match one of the specified criteria. If you specify match-all, the traffic being evaluated must match all of the specified criteria. A match-all class map can contain only one match statement, but a match-any class map can contain multiple match statements.


Note If you do not enter match-all or match-any, the default is to match all.


You use the match class-map configuration commands to specify criteria for classifying packets. If a packet matches the specified criteria, that packet is considered a member of the class and is forwarded according to the QoS specifications set in the traffic policy. Packets that fail to meet any of the matching criteria are classified as members of the default traffic class.

Step 2 Create a traffic policy to associate the traffic class with one or more QoS features.

You use the policy-map policy-map-name global configuration command to create a traffic policy and to enter policy-map configuration mode. A traffic policy defines the QoS features to associate with the specified traffic class. A traffic policy contains three elements: a name, a traffic class (specified with the class policy-map configuration command), and the QoS policies configured in the class.

You name the traffic policy in the policy-map command line to enter policy-map configuration mode.

In policy-map configuration mode, enter the name of the traffic class used to classify traffic to the specified policy, and enter policy-map class configuration mode.

In policy-map class configuration mode, you can enter the QoS features to apply to the classified traffic. These include using the set, police, or police aggregate commands for input policy maps or the bandwidth, priority, queue-limit or shape average commands for output policy maps.


Note A packet can match only one traffic class within a traffic policy. If a packet matches more than one traffic class in the traffic policy, the first traffic class defined in the policy is used. To configure more than one match criterion for packets, you can associate multiple traffic classes with a single traffic policy.


Step 3 Attach the traffic policy to an interface.

You use the service-policy interface configuration command to attach the policy map to an interface for packets entering or leaving the interface. Specify whether the traffic policy characteristics are applied to incoming or outgoing packets. For example, entering the service-policy output class1 interface configuration command attaches all the characteristics of the traffic policy named class1 to the specified interface. All packets leaving the specified interface are evaluated according to the criteria specified in the traffic policy named class1.


Note If you enter the no policy-map configuration command or the no policy-map policy-map-name global configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. The policy map is then detached and deleted. For example:
Warning: Detaching Policy test1 from Interface GigabitEthernet0/1



Input and Output Policies

Policy maps are either input policy maps or output policy maps, attached to packets as they enter or leave the switch by service policies applied to interfaces. Input policy maps perform policing and marking on received traffic. Policed packets can be dropped or reduced in priority (marked down) if they exceed the maximum permitted rates. Output policy maps perform scheduling and queuing on traffic as it leaves the switch.

Input policies and output policies have the same basic structure; the difference is in the characteristics that they regulate. Figure 34-2 shows the relationship of input and output policies.

You can configure a maximum of 256 policy maps.

The number of configurable policer profiles on the ME-3400 is 254

You can apply one input policy map and one output policy map to an interface.

When CPU protection is enabled (the default), you can configure 45 ingress policers per port. If you disable CPU protection by entering the no policer cpu uni all global configuration command and reloading the switch, you can configure a maximum of 63 policers per port (62 on every fourth port) for user-defined classes and one for class-default. You can enter the show policer cpu uni-eni {drop | rate} privileged EXEC command to see if CPU protection is enabled.

Figure 34-2 Input and Output Policy Relationship

Input Policy Maps

Input policy map classification criteria include matching a CoS, a DSCP, or an IP precedence value or matching an access control list (ACL) or VLAN ID (for per-port, per-VLAN QoS). Input policy maps can have any of these actions:

Setting or marking a CoS, a DSCP, an IP precedence, or QoS group value

Individual policing

Aggregate policing

Only input policies provide matching on access groups or VLAN IDs, and only output policies provide matching on QoS groups. You can assign a QoS group number in an input policy and match it in the output policy. The class class-default is used in a policy map for any traffic that does not explicitly match any other class in the policy map. Input policy maps do not support queuing and scheduling keywords, such as bandwidth, queue-limit, priority, and shape average.

An input policy map can have a maximum of 64 classes plus class-default. You can configure a maximum of 64 classes in an input policy.

Output Policy Maps

Output policy map classification criteria include matching a CoS, a DSCP, an IP precedence, or a QoS group value.

Output policy maps can have any of these actions:

Queuing (queue-limit)

Scheduling (bandwidth, priority, and shape average)

Output policy maps do not support matching of access groups. You can use QoS groups as an alternative by matching the appropriate access group in the input policy map and setting a QoS group. In the output policy map, you can then match the QoS group. See the "Classification Based on QoS Groups" section for more information.

Output policies do not support marking or policing (except in the case of priority with policing). There is no egress packet marking on the switch (no set command in an output policy).

The class class-default is used in a policy map for any traffic that does not explicitly match any other class in the policy map. There can be a maximum of four classes in the output policy map (including class-default) because egress ports have a maximum of four queues.

An output policy map attached to an egress port can match only the packets that are already matched by an input policy map attached to the ingress port for the packets. You can attach an output policy map to any or all ports on the switch. The switch supports configuration and attachment of a unique output policy map for each port. However, these output policy maps can contain only three unique configurations of queue limits. These three unique queue-limit configurations can be included in as many output policy maps as there are ports on the switch. There are no limitations on the configurations of bandwidth, priority, or shaping.

You can configure the output policy classification criteria for CPU-generated traffic by using the cpu traffic qos [cos value | dscp value | precedence value | qos-group value] global configuration command.

Classification

Classification distinguishes one kind of traffic from another by examining the fields in the packet header. When a packet is received, the switch examines the header and identifies all key packet fields. A packet can be classified based on an ACL, on the DSCP, the CoS, or the IP precedence value in the packet, or by the VLAN ID. Figure 34-3 has examples of classification information carried in a Layer 2 or a Layer 3 IP packet header, using six bits from the deprecated IP type of service (ToS) field to carry the classification information.

On ports configured as Layer 2 IEEE 802.1Q trunks, all traffic is in 802.1Q frames except for traffic in the native VLAN. Layer 2 802.1Q frame headers have a 2-byte Tag Control Information field that carries the CoS value, called the User Priority bits, in the three most-significant bits, and the VLAN ID value in the 12 least-significant bits. Other frame types cannot carry Layer 2 CoS values.

Layer 2 CoS values range from 0 to 7.

Layer 3 IP packets can carry either an IP precedence value or a 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.

Output remarking is based on the Layer 2 or Layer 3 marking type, marking value and packet type.

Figure 34-3 QoS Classification Layers in Frames and Packets

These sections contain additional information about classification:

"Class Maps" section

"The match Command" section

"Classification Based on Layer 2 CoS" section

"Classification Based on IP Precedence" section

"Classification Based on IP DSCP" section

"Classification Comparisons" section

"Classification Based on QoS ACLs" section

"Classification Based on QoS Groups" section

"Classification Based on VLAN IDs" section

Class Maps

As explained previously, you use an MQC class map to name a specific traffic flow (or class) and to isolate it from all other traffic. A class map defines the criteria used to match against a specific traffic flow to classify it further. 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. When you enter the class-map command with a class-map name, 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. After a packet is matched against the class-map criteria, it is acted on by the associated action specified in a policy map.

You can match more than one criterion for classification. You can also create a class map that requires that all matching criteria in the class map is in the packet header by using the class map match-all class-map name global configuration command to enter class map configuration mode.


Note You can configure only one match entry in a match-all class map.


You can use the class map match-any class-map name global configuration command to define a classification with any of the listed criteria.


Note If you do not enter match-all or match-any, the default is to match all. A match-all class map cannot have more than one classification criterion (match statement). A class map with no match condition has a default of match all.


The match Command

To configure the type of content used to classify packets, you use the match class-map configuration command to specify the classification criteria. If a packet matches the configured criteria, it belongs to a specific class and is forwarded according to the specified policy. For example, you can use the match class-map command with CoS, IP DSCP, and IP precedence values. These values are referred to as markings on a packet. You can also match an access group, a QoS group, or a VLAN ID or ID range for per-port, per-VLAN QoS.

For an input policy map, you cannot configure an IP classification (match ip dscp, match ip precedence, match ip acl) and a non-IP classification (match cos or match mac acl) in the same policy map or class map.

When an input policy map with only Layer 2 classification is attached to a routed port or a switch port containing a routed switch virtual interface (SVI), the service policy acts only on switching eligible traffic and not on routing eligible traffic.

On an 802.1Q tunnel port, you can use only an input policy map with Layer 2 classification based on MAC ACLs to classify traffic. Input policy maps with Layer 3 classification, match Layer 2 CoS classification, or per-port, per-VLAN policies are not supported on tunnel ports.

In an output policy map, no two class maps can have the same classification criteria, that is, the same match qualifiers and values.

This example shows how to create a class map example to define a class that matches any of the listed criteria. In this example, if a packet is received with the DSCP equal to 32 or a 40, the packet is identified (classified) by the class map.

Switch(config)# class-map match-any example
Switch(config-cmap)# match ip dscp 32
Switch(config-cmap)# match ip dscp 40
Switch(config-cmap)# exit

Classification Based on Layer 2 CoS

You can use the match command to classify Layer 2 traffic based on the CoS value, which ranges from 0 to 7.


Note A match cos command is supported only on Layer 2 802.1Q trunk ports.


This example shows how to create a class map to match a CoS value of 5:

Switch(config)# class-map premium
Switch(config-cmap)# match cos 5
Switch(config-cmap)# exit

Classification Based on IP Precedence

You can classify IPv4 traffic based on the packet IP precedence values, which range from 0 to 7.

This example shows how to create a class map to match an IP precedence value of 4:

Switch(config)# class-map sample
Switch(config-cmap)# match ip precedence 4
Switch(config-cmap)# exit

Classification Based on IP DSCP

When you classify IPv4 traffic based on IP DSCP value, and enter the match ip dscp class-map configuration command, you have several classification options:

Entering a specific DSCP value (0 to 63).

Using the Default service, which corresponds to an IP precedence and DSCP value of 0. The default per-hop behavior (PHB) is usually best-effort service.

Using Assured Forwarding (AF) by entering the binary representation of the DSCP value. AF sets the relative probability that a specific class of packets is forwarded when congestion occurs and the traffic does not exceed the maximum permitted rate. AF per-hop behavior provides delivery of IP packets in four different AF classes: AF11-13 (the highest), AF21-23, AF31-33, and AF41-43 (the lowest). Each AF class could be allocated a specific amount of buffer space and drop probabilities, specified by the binary form of the DSCP number. When congestion occurs, the drop precedence of a packet determines the relative importance of the packet within the class. An AF41 provides the best probability of a packet being forwarded from one end of the network to the other.

Entering Class Selector (CS) service values of 1 to 7, corresponding to IP precedence bits in the ToS field of the packet.

Using Expedited Forwarding (EF) to specify a low-latency path, which corresponds to a DSCP value of 46. EF services use priority queuing to preempt lower priority traffic classes.

This display shows the available classification options:

Switch(config-cmap)# match ip dscp ?
  <0-63>   Differentiated services codepoint value
  af11     Match packets with AF11 dscp (001010)
  af12     Match packets with AF12 dscp (001100)
  af13     Match packets with AF13 dscp (001110)
  af21     Match packets with AF21 dscp (010010)
  af22     Match packets with AF22 dscp (010100)
  af23     Match packets with AF23 dscp (010110)
  af31     Match packets with AF31 dscp (011010)
  af32     Match packets with AF32 dscp (011100)
  af33     Match packets with AF33 dscp (011110)
  af41     Match packets with AF41 dscp (100010)
  af42     Match packets with AF42 dscp (100100)
  af43     Match packets with AF43 dscp (100110)
  cs1      Match packets with CS1(precedence 1) dscp (001000)
  cs2      Match packets with CS2(precedence 2) dscp (010000)
  cs3      Match packets with CS3(precedence 3) dscp (011000)
  cs4      Match packets with CS4(precedence 4) dscp (100000)
  cs5      Match packets with CS5(precedence 5) dscp (101000)
  cs6      Match packets with CS6(precedence 6) dscp (110000)
  cs7      Match packets with CS7(precedence 7) dscp (111000)
  default  Match packets with default dscp (000000)
  ef       Match packets with EF dscp (101110)
 
   

For more information on DSCP prioritization, see RFC-2597 (AF per-hop behavior), RFC-2598 (EF), or RFC-2475 (DSCP).

Classification Comparisons

Table 34-1 shows suggested IP DSCP, IP precedence, and CoS values for typical traffic types.

Table 34-1 Typical Traffic Classifications 

Traffic Type
DSCP per-hop
DSCP (decimal)
IP Precedence
CoS

Voice-bearer—traffic in a priority queue or the queue with the highest service weight and lowest drop priority.

EF

46

5

5

Voice control—signaling traffic, related to call setup, from a voice gateway or a voice application server.

AF31

26

3

3

Video conferencing—in most networks, video conferencing over IP has similar loss, delay, and delay variation requirements as voice over IP traffic.

AF41

34

4

4

Streaming video—relatively high bandwidth applications with a high tolerance for loss, delay, and delay variation. Usually considered more important than regular background applications such as e-mail and web browsing.

AF13

14

1

1

Mission critical date (gold data)—delay-sensitive applications critical to the operation of an enterprise.

Level 1
Level 2
Level 3


AF21
AF22
AF23


18
20
22


2
2
2


2
2
2

Less critical data (silver data)—noncritical, but relatively important data.

Level 1
Level 2
Level 3


AF11
AF12
AF13


10
12
14


1
1
1


1
1
1

Best-effort data (bronze data)—other traffic, including all noninteractive traffic, regardless of importance.

Default

0

0

0

Less than best-effort data—noncritical, bandwidth-intensive data traffic given the least preference. This traffic is the first type to be dropped.

Level 1
Level 2
Level 3

 



2
4
6



0
0
0



0
0
0


Classification Based on QoS ACLs

Packets can also be classified in input policy maps based on an ACL lookup. The ACL classification is communicated to an output policy by assigning a QoS group or number in the input policy map. To classify based on ACL lookup, you first create an IP or MAC ACL. Configure a class map and use the match access-group {acl-number | acl name} class-map configuration command, and attach the class map to a policy map.


Note You cannot configure match access-group for an output policy map.


You can use IP standard, IP extended, or Layer 2 MAC ACLs to define a group of packets with the same characteristics (a class). You use the access-list global configuration command to configure IP ACLS to classify IP traffic based on Layer 3 and Layer 4 parameters. You use the mac access-list extended global configuration command to configure Layer 2 MAC ACLs to classify IP and non-IP traffic based on Layer 2 parameters.


Note You cannot 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.


You can use only ACLs with a permit action in a match access-group command. ACLs with a deny action are never matched in a QoS policy.


Note Only one access-group is supported per class for an input policy map.


Classification Based on QoS Groups

A QoS group is an internal label that the switch uses to identify packets as members of a specific class. The label is not part of the packet header and is restricted to the switch that sets the label. QoS groups provide a way to tag a packet for subsequent QoS action without explicitly marking (changing) the packet. You can then communicate an ACL match from an input policy map to an output policy map.

A QoS group is identified at ingress and used at egress; it is assigned in an input policy to identify packets in an output policy. See Figure 34-3. The QoS groups help aggregate different classes of input traffic for a specific action in an output policy.

Figure 34-4 QoS Groups

You can use QoS groups to aggregate multiple input streams across input classes and policy maps for the same QoS treatment on the egress port. Assign the same QoS group number in the input policy map to all streams that require the same egress treatment, and match to the QoS group number in the output policy map to specify the required queuing and scheduling actions.

You can also use QoS groups to identify traffic entering a particular interface if the traffic must be treated differently at the output based on the input interface.

You can use QoS groups to configure per-port, per-VLAN QoS output policies on the egress interface for bridged traffic on the VLAN. Assign a QoS group number to a VLAN on the ingress interface by configuring a per-port, per-VLAN input policy. Then use the same QoS-group number for classification at the egress. Because the VLAN of bridged traffic does not change during forwarding through the switch, the QoS-group number assigned to the ingress VLAN can be used on the egress interface to identify the same VLAN.

You can use the cpu traffic qos [cos value | dscp value | precedence value | qos-group value] global configuration command to configure a QoS group number for CPU-generated traffic.

Independently you can assign QoS-group numbers at the ingress to any combination of interfaces, VLANs, traffic flows, and aggregated traffic. To assign QoS-group numbers, configure a QoS group marking in an input policy map, along with any other marking or policing actions required in the input policy map for the same service class. This configuration allows the input marking and policing functions to be decoupled from the egress classification function if necessary because only the QoS group must be used for egress classification.

To communicate an ACL classification to an output policy, you assign a QoS number to specify packets at ingress. This example identifies specific packets as part of QoS group 1 for later processing in an output policy:

Switch(config)# policy-map in-gold-policy
Switch(config-pmap)# class in-class1
Switch(config-pmap-c)# set qos-group 1
Switch(config-cmap-c)# exit
Switch(config-cmap)# exit
 
   

You use the set qos-group command only in an input policy. The assigned QoS group identification is then used in an output policy with no mark or change to the packet. You use the match qos-group in the output policy.


Note You cannot configure match qos-group for an input policy map.


This example creates an output policy to match the QoS group created in the input policy map in-gold-policy. Traffic internally tagged as qos-group 1 is identified and processed by the output policy.

Switch(config)# class-map out-class1
Switch(config-cmap)# match qos-group 1
Switch(config-cmap)# exit
 
   

The switch supports a maximum of 100 QoS groups.

Classification Based on VLAN IDs

With classification based on VLAN IDs, you can apply QoS policies to frames carried on a user-specified VLAN for a given interface. You can use hierarchical policy maps for per-VLAN classification on trunk ports if the switch is running the metro IP access or metro access image. Per-VLAN classification is not required on access ports because access ports carry traffic for a single VLAN. If you try to attach an input per-port, per VLAN hierarchical policy to a port that is not a trunk port, the configuration is rejected.

The switch supports two policy levels: a parent level and a child level. With the QoS parent-child structure, you can reference a child policy in a parent policy to provide additional control of a specific traffic type. For per-port, per-VLAN QoS, the parent-level class map specifies only the VLAN match criteria, and the child-level class maps provide more detailed classification for frames matching the parent-level class map. You can configure multiple service classes at the parent level to match different combinations of VLANs, and you can apply independent QoS policies to each parent service class using any child policy map.


Note A per-port, per-VLAN parent-level class map supports only a child-policy association; it does not allow any actions to be configured. In earlier releases, for a parent-level class map, you could not configure a child-policy association for the class class-default. Starting with Cisco IOS Release 12.2(53)SE, you can enter class class-default in the parent policy map to classify all VLANs not identified by parent VLAN classes.


Per-port, per-VLAN QoS has these limitations:

You can apply a per-port, per-VLAN hierarchical policy map only to trunk ports.

You can configure classification based on VLAN ID only in the parent level of a per-port, per-VLAN hierarchical policy map.

When the child policy map attached to a VLAN or set of VLANs contains only Layer 3 classification (match ip dscp, match ip precedence, match IP ACL), you must be careful to ensure that these VLANs are not carried on any port other than the one on which this per-port, per-VLAN policy is attached. Not following this restriction could result in improper QoS behavior for ingress traffic on these VLANs.

We also recommend that you restrict VLAN membership on the trunk ports to which the per-port, per-VLAN is applied by using the switchport trunk allowed vlan interface configuration command. Overlapping VLAN membership between trunk ports that have per-port, per-VLAN policies with Layer 3 classification could also result in unexpected QoS behavior.

In this example, the class maps in the child-level policy map specify matching criteria for voice, data, and video traffic, and the child policy map sets the action for input policing each type of traffic. The parent-level policy map specifies the VLANs to which the child policy maps are applied on the specified port.

Switch(config)# class-map match-any dscp-1 data
Switch(config-cmap)# match ip dscp 1
Switch(config-cmap)# exit
Switch(config)# class-map match-any dscp-23 video
Switch(config-cmap)# match ip dscp 23
Switch(config-cmap)# exit
Switch(config)# class-map match-any dscp-63 voice
Switch(config-cmap)# match ip dscp-63
Switch(config-cmap)# exit
Switch(config)# class-map match-any customer-1-vlan
Switch(config-cmap)# match vlan 100
Switch(config-cmap)# match vlan 200
Switch(config-cmap)# match vlan 300
Switch(config-cmap)# exit

Note You can also enter the match criteria as match vlan 100 200 300 with the same result.


Switch(config)# policy-map child policy-1
Switch(config-pmap)# class dscp-63 voice
Switch(config-pmap-c)# police cir 10000000 bc 50000
Switch(config-pmap-c)# conform-action set-cos-transmit 5
Switch(config-pmap-c)# exceed-action drop
Switch(config-pmap-c)# exit
Switch(config-pmap)# class dscp-1 data
Switch(config-pmap-c)# set cos 0
Switch(config-pmap-c)# exit
Switch(config-pmap)# class dscp-23 video
Switch(config-pmap-c)# set cos 4
Switch(config-pmap-c)# set ip precedence 4
Switch(config-pmap-c)# exit
 
   
Switch(config)# policy-map parent-customer-1
Switch(config-pmap)# class customer-1-vlan
Switch(config-pmap-c)# service-policy ingress-policy-1
Switch(config-pmap-c)# exit
 
   
Switch(config)# interface fastethernet0/1
Switch(config-if)# switchport mode trunk
Switch(config-if)# service-policy input customer-1-ingress
Switch(config-pmap-c)# exit
 
   

Note Each per-port, per-VLAN parent policy class, except class-default, can have a child policy association.


See the "Configuring Per-Port Per-VLAN QoS with Hierarchical Input Policy Maps" section for configuration information, including configuration guidelines and limitations.

Table Maps

You can use table maps to manage many traffic flows with a single command. You can specify table maps in set commands and use them as mark-down mapping for the policers. You can also use table maps to map an incoming QoS marking to a replacement marking without having to configure many explicit matches and sets. Table maps are used only in input policy maps.

Table maps can be used to:

Correlate specific CoS, DSCP, or IP precedence values to specific CoS, DSCP, or IP precedence values

Mark down a CoS, DSCP, or IP precedence value

Assign defaults for unmapped values

A table map includes one of these default actions:

default default-value—applies a specific default value (0 to 63) for all unmapped values

default copy—maps all unmapped values to the equivalent value in another qualifier

default ignore—makes no changes for unmapped values

This example creates a table to map specific CoS values to DSCP values. The default command maps all unmapped CoS values to a DSCP value of 63.

Switch(config)# table-map cos-dscp-tablemap
Switch(config-tablemap)# map from 5 to 46
Switch(config-tablemap)# map from 6 to 56
Switch(config-tablemap)# map from 7 to 57
Switch(config-tablemap)# default 63
Switch(config-tablemap)# exit
 
   

The switch supports a maximum of 256 unique table maps. You can enter up to 64 different map from-to entries in a table map. These table maps are supported on the switch:

DSCP to CoS

DSCP to precedence

DSCP to DSCP

CoS to DSCP

CoS to precedence

CoS to CoS

Precedence to CoS

Precedence to DSCP

Precedence to precedence

Table maps modify only one parameter (CoS, IP precedence, or DSCP, whichever is configured) and are only effective when configured with a set command in a policy map or with a conform-action or exceed-action command in a police function.

Table maps are not supported in output policy maps. For more information, set the "Configuring Table Maps" section.

Policing

After a packet is classified, you can use policing as shown in Figure 34-5 to regulate the class of traffic. The policing function limits the amount of bandwidth available to a specific traffic flow or prevents a traffic type from using excessive bandwidth and system resources. A policer identifies a packet as in or out of profile by comparing the rate of the inbound traffic to the configuration profile of the policer and traffic class. Packets that exceed the permitted average rate or burst rate are out of profile or nonconforming. These packets are dropped or modified (marked for further processing), depending on the policer configuration.

Policing is used primarily on receiving interfaces. You can attach a policy map with a policer only in an input service policy. The only policing allowed in an output policy map is in priority classes. See the "Unconditional Priority Policing" section.

Figure 34-5 Policing of Classified Packets

These sections describe the types of policing supported on the switch:

Individual Policing

Aggregate Policing

Unconditional Priority Policing

Individual Policing

Individual policing applies only to input policy maps. In policy-map configuration mode, you enter the class command followed by class-map name, and enter policy-map class configuration mode.

You use the police policy-map class configuration command to define the policer, the committed rate limitations of the traffic, committed burst size limitations of the traffic, and the action to take for a class of traffic that is below the limits (conform-action) and above the limits (exceed-action). If you do not specify burst size (bc), the system calculates an appropriate burst size value. The calculated value is appropriate for most applications. For more information, see the "Attaching a Traffic Policy to an Interface" section.

To make the policy map effective, you attach it to a physical port by using the service-policy input interface configuration command. Policing is done only on received traffic, so you can only attach a policer to an input service policy.

This example is of basic policing for all traffic received with a CoS of 4. The first value following the police command limits the average traffic rate to 10, 000,000 bits per second (bps); the second value represents the additional burst size (10 KB). The policy is assigned to Fast Ethernet port 1.

Switch(config)# class-map video-class
Switch(config-cmap)# match cos 4
Switch(config-cmap)# exit
Switch(config)# policy-map video-policy
Switch(config-pmap)# class video-class
Switch(config-pmap-c)# police 10000000 10000
Switch(config-pmap-c-police)# exit
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input video-policy
Switch(config-if)# exit
 
   

You can use the conform-action and exceed-action policy-map class configuration commands or the conform-action and exceed-action policy-map class police configuration commands to specify the action to be taken when the packet conforms to or exceeds the specified traffic rate.

Conform actions are to send the packet without modifications, to set a new CoS, DSCP, or IP precedence value, or to set a QoS group value for classification at the egress. Exceed actions are to drop the packet, to send the packet without modification, to set a new CoS, DSCP, or IP precedence to a value, or to set a QoS group value for classification at the egress.

You can configure each marking action by using explicit values, table maps, or a combination of both. Table maps list specific traffic attributes and map (or convert) them to other attributes.

You can configure multiple conform and exceed actions simultaneously for each service class.

After you create a table map, you configure a policy-map policer to use the table map.


Note When you use a table map in an input policy map, the protocol type for the from-action in the table map must be the same as the protocol type of the associated classification. For example, if a class map represents IP classification, the from-type action in the table map must be either dscp or precedence. If the class map represents a non-IP classification, the from-type action in the table map must be cos.


To configure multiple actions in a class, you can enter multiple conform or exceed action entries in policy-map class police configuration mode, as in this example:

Switch(config)# policy-map map1
Switch(config-pmap)# class class1
Switch(config-pmap-c)# police 100000 500000
Switch(config-pmap-c-police)# conform-action set-cos-transmit 4
Switch(config-pmap-c-police)# conform-action set-dscp-transmit dscp table 
conform-dscp-to-dscp-mutation
Switch(config-pmap-c-police)# conform-action set-qos-transmit 10
Switch(config-pmap-c-police)# exceed-action set-cos-transmit 2
Switch(config-pmap-c-police)# exceed-action set-dscp-transmit dscp table 
exceed-dscp-to-dscp-mutation
Switch(config-pmap-c-police)# exceed-action set-qos-transmit 20
Switch(config-pmap-c-police)# exit
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit

Aggregate Policing

Aggregate policing applies only to input policy maps. An aggregate policer differs from an individual policer because it is shared by multiple traffic classes within a policy map.

You can use the policer aggregate global configuration command to set a policer for all traffic received or sent on a physical interface. When you configure an aggregate policer, you can configure specific burst sizes and conform and exceed actions. If you do not specify burst size (bc), the system calculates an appropriate burst size value. The calculated value is appropriate for most applications.

You can configure multiple conform and exceed actions simultaneously for each service class. Conform actions are to send the packet without modifications, to set a QoS group value for classification at the egress, or to set a new CoS, DSCP, or IP precedence value. Exceed actions are to drop the packet, to send the packet without modification, to set a QoS group for classification at the egress, or to set a new CoS, DSCP, or IP precedence to a value. You can configure each marking conform or exceed action by using explicit values, using table maps, or using a combination of both. Table maps list specific traffic attributes and map (or convert) them to other attributes.

Aggregate policing is not supported across VLANs in per-port, per-VLAN policy maps.

After you create a table map, you configure a policy-map policer to use the table map.


Note When you use a table map in an input policy map, the protocol type for the from-action in the table map must be the same as the protocol type of the associated classification. For example, if a class map represents IP classification, the from-type action in the table map must be either dscp or precedence. If the class map represents a non-IP classification, the from-type action in the table map must be cos.


You can configure multiple conform and exceed actions simultaneously for an aggregate policer as parameters in the policer aggregate global configuration command, but enter the actions in a particular order. See the configuration guideline in the "Configuring Input Policy Maps with Aggregate Policing" section.

After you configure the aggregate policer, you create a policy map and an associated class map, associate the policy map with the aggregate policer, and apply the service policy to a port.


Note Only one policy map can use any specific aggregate policer. Aggregate policing cannot be used to aggregate traffic streams across multiple interfaces. It can be used only to aggregate traffic streams across multiple classes in a policy map attached to an interface and aggregate streams across VLANs on a port in a per-port, per-VLAN policy map.


After you configure the policy map and policing actions, attach the policy to an ingress port by using the service-policy interface configuration command.

The class maps in this example refer to access lists.

Switch(config)# policer aggregate agg1 cir 23000 bc 10000 conform-action set-dscp-transmit 
46 exceed-action drop
Switch(config)# class-map testclass
Switch(config-cmap)# match access-group 1
Switch(config-cmap)# exit
Switch(config)# class-map videoclass
Switch(config-cmap)# match access-group 2
Switch(config-cmap)# exit
Switch(config)# policy-map testexample
Switch(config-pmap)# class testclass
Switch(config-pmap-c)# police aggregate agg1 
Switch(config-pmap-c)# exit
Switch(config-pmap)# class video-class
Switch(config-pmap-c)# police aggregate agg1 
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input testexample
Switch(config-if)# exit
 
   

For configuration information, see the "Configuring Input Policy Maps with Aggregate Policing" section.

Unconditional Priority Policing

Priority policing applies only to output policy maps. You can use the priority policy-map class configuration command in an output policy map to designate a low-latency path, or class-based priority queuing, for a specific traffic class. With strict priority queuing, the packets in the priority queue are scheduled and sent until the queue is empty, at the expense of other queues. Excessive use of high-priority queuing can create congestion for lower priority traffic.

To eliminate this congestion, you can use the priority with police feature (priority policing) to reduce the bandwidth used by the priority queue and allocate traffic rates on other queues. Priority with police is the only form of policing supported in output policy maps.

See also the "Configuring Output Policy Maps with Class-Based Priority Queuing" section.


Note You cannot configure a policer committed burst size for an unconditional priority policer. Any configured burst size is ignored.


This example shows how to use the priority with police commands to configure out-class1 as the priority queue, with traffic going to the queue limited to 20,000,000 bps so that the priority queue never uses more than that limit. Traffic above that rate is dropped, which allows other traffic queues to receive some port bandwidth, in this case a minimum bandwidth guarantee of 500,000 and 200,000 kbps. The class class-default queue gets the remaining port bandwidth.

Switch(config)# policy-map policy1
Switch(config-pmap)# class out-class1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police 200000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class2
Switch(config-pmap-c)# bandwidth 500000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class3
Switch(config-pmap-c)# bandwidth 200000
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# service-policy output policy1
Switch(config-if)# exit

Marking

You can use packet marking in input policy maps to set or modify the attributes for traffic belonging to a specific class. After network traffic is organized into classes, you use marking to identify certain traffic types for unique handling. For example, you can change the CoS value in a class or set IP DSCP or IP precedence values for a specific type of traffic. These new values are then used to determine how the traffic is treated. You can also use marking to assign traffic to a QoS group within the switch.

Traffic marking is typically performed on a specific traffic type at the ingress port. The marking action can cause the CoS, DSCP, or precedence bits to be rewritten or left unchanged, depending on the configuration. The priority of a packet can be increased or decreased in accordance with the policy used in the QoS domain so that other QoS functions can use the marking information to judge the relative and absolute importance of the packet. The marking function can use information from the policing function or directly from the classification function.

You can specify and mark traffic by using the set commands in a policy map for all supported QoS markings (CoS, IP DSCP, IP precedence, and QoS groups). A set command unconditionally marks the packets that match a specific class. You then attach the policy map to an interface as an input policy map.

You can also mark traffic by using the set command with table maps.Table maps list specific traffic attributes and maps (or converts) them to another attribute. A table map establishes a to-from relationship for the attribute and defines the change.

You can simultaneously configure actions to modify DSCP, precedence, and COS markings in the packet for the same service along with QoS group marking actions. You can use the QoS group number defined in the marking action for egress classification.


Note When you use a table map in an input policy map, the protocol type of the from-type action in the table map must be the same as the protocol type of the associated classification. For example, if a class map represents an IP classification, the from-type action in the table map must be either dscp or precedence. If the class map represents a non-IP classification, the from-type action in the table map must be cos.


After you create a table map, you configure a policy map to use the table map. See the "Congestion Management and Scheduling" section. Figure 34-6 shows the steps for marking traffic.

Figure 34-6 Marking of Classified Traffic

This example uses a policy map to remark a packet. The first marking (the set command) applies to the QoS default class map that matches all traffic not matched by class AF31-AF33 and sets all traffic to an IP DSCP value of 1. The second marking sets the traffic in classes AF31 to AF33 to an IP DSCP of 3.

Switch(config)# policy-map Example
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# set ip dscp 1
Switch(config-pmap-c)# exit
Switch(config-pmap)# class AF31-AF33
Switch(config-pmap-c)# set ip dscp 3
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input Example 
Switch(config-if)# exit

QoS Treatment for Performance-Monitoring Protocols

Cisco IP-SLAs

Two-Way Active Measurement Protocol

QoS Treatment for IP-SLA and TWAMP Probes

QoS Marking for CPU-Generated Traffic

QoS Queuing for CPU-Generated Traffic

Configuration Guidelines

Cisco IP-SLAs

For information about Cisco IP service level agreements (IP-SLAs), see Understanding Cisco IOS IP SLAs.

Two-Way Active Measurement Protocol

For information about the Two-Way Active Measurement Protocol (TWAMP), see Understanding TWAMP and Configuring TWAMP.

QoS Treatment for IP-SLA and TWAMP Probes

The QoS treatment for IP-SLA and TWAMP probes must exactly reflect the effects that occur to the normal data traffic crossing the device.

The generating device does not change the probe markings. It queues these probes based on the configured queueing policies for normal traffic.

Marking

By default, the class of service (CoS) marking of CFM traffic (including IP SLAs using CFM probes) is not changed. This feature cannot change this behavior.

By default, IP traffic marking (including IP SLA and TWAMP probes) is not changed. This feature can change this behavior.

Queuing

The CFM traffic (including IP SLAs using CFM probes) is queued according to its CoS value and the output policy map configured on the egress port, similar to normal traffic. This feature cannot change this behavior.

IP traffic (including IP SLA and TWAMP probes) is queued according to the markings specified in the cpu traffic qos global configuration command and the output policy map on the egress port. If this command is not configured, all IP traffic is statically mapped to a queue on the egress port.

QoS Marking for CPU-Generated Traffic

You can use QoS marking to set or modify the attributes of traffic from the CPU. The QoS marking action can cause the CoS, DSCP, or IP precedence bits in the packet to be rewritten or left unchanged. QoS uses packet markings to identify certain traffic types and how to treat them on the local switch and the network.

You can also use marking to assign traffic to a QoS group within the switch. This QoS group is an internal label that does not modify the packet, but it can be used to identify the traffic type when configuring egress queuing on the network port.

You can specify and mark traffic CPU-generated traffic by using these global configuration commands:

cpu traffic qos cos {cos_value | cos [table-map table-map-name] | dscp [table-map table-map-name] | precedence [table-map table-map-name]}

cpu traffic qos dscp {dscp_value | cos [table-map table-map-name] | dscp [table-map table-map-name] | precedence [table-map table-map-name]}

cpu traffic qos precedence {precedence_value | cos [table-map table-map-name] | dscp [table-map table-map-name] | precedence [table-map table-map-name]}

cpu traffic qos qos-group value

You can mark CoS, IP-DSCP, IP precedence, and QoS group by configuring an explicit value or by using the table-map keyword. Table maps list specific traffic attributes and map (or convert) them to another attribute. A table map establishes a to-from relationship for the attribute and defines the change:

Marking CoS by using the CoS, or the IP-DSCP, or the IP precedence of IP CPU-packets

Marking CoS by using the CoS of non-IP CPU-packets.

Marking IP DSCP by using the CoS, or the IP-DSCP, or the IP precedence of the CPU-packet

Marking IP precedence by using the CoS, or the IP-DSCP, or the IP precedence of the CPU-packet

You can configure either IP-DSCP or IP precedence marking.

You can also simultaneously configure marking actions to modify CoS, IP-DSCP or IP precedence, and QoS group.

The cpu traffic qos command specifies the traffic to which it applies: all CPU traffic, only CPU IP traffic, or only CPU non-IP traffic. All other traffic retains its QoS markings. This feature does not affect CFM traffic (including Layer 2 IP SLA probes using CFM).


Note You can mark CoS, IP-DSCP, and IP precedence of CPU-generated traffic by using table maps.


QoS Queuing for CPU-Generated Traffic

You can use the QoS markings established for the CPU-generated traffic by the cpu traffic qos global configuration command as packet identifiers in the class-map of an output policy-map to map CPU traffic to class-queues in the output policy-map on the egress port. You can then use output policy-maps on the egress port to configure queuing and scheduling for traffic leaving the switch from that port.

If you want to map all CPU-generated traffic to a single class in the output policy-maps without changing the CoS, IP DSCP, or IP-precedence packet markings, you can use QoS groups for marking CPU-generated traffic.

If you want to map all CPU-generated IP traffic to classes in the output policy maps based on IP-DSCP or IP precedence without changing those packet markings, you can use a table map:

Configure IP-DSCP or IP precedence marking by using DSCP or precedence as the map from value without a table map.

Configure IP-DSCP or IP-precedence marking by using DSCP or precedence as the map from value with a table map, using only the default and copy keywords.

If you want to map all CPU-generated traffic to classes in the output policy maps based on the CoS without changing the CoS packet markings, you can use the table map:

Configure CoS marking by using CoS as the map from value without a table map.

Configure CoS marking using CoS as the map from value with a table map, using only the default and copy keywords.

For details about table maps, see the "Table Maps" section.

Using the cpu traffic qos global configuration command with table mapping, you can configure multiple marking and queuing policies to work together or independently. You can queue native VLAN traffic based on the CoS markings configured using the cpu traffic qos global configuration command.

The cpu traffic qos command specifies the traffic to which it applies: all CPU traffic, only CPU-IP traffic, or only CPU non-IP traffic. All other traffic is statically mapped to a CPU-default queue on the egress port. All CFM traffic (including Layer 2 IP SLA probes using CFM) is mapped to classes in the output policy map and queued based on their CoS value.


Note You can queue based on the CoS, IP-DSCP, and IP precedence of CPU-generated traffic.


Configuration Guidelines

This feature must be configured globally for a switch; it cannot be configured per-port or per-protocol.

Enter each cpu traffic qos marking action on a separate line.

The cpu traffic qos cos global configuration command configures CoS marking for CPU-generated traffic by using either a specific CoS value or a table map, but not both. A new configuration overwrites the existing configuration.

The cpu traffic qos dscp global configuration command configures IP-DSCP marking for CPU-generated IP traffic by using either a specific DSCP value or a table map, but not both. A new configuration overwrites the existing configuration.

The cpu traffic qos precedence global configuration command configures IP-precedence marking for CPU-generated IP traffic by using either a specific precedence value or a table map, but not both. A new configuration overwrites the existing configuration.

The cpu traffic qos dscp and cpu traffic qos precedence global configuration commands are mutually exclusive. A new configuration overwrites the existing configuration.

When the cpu traffic qos dscp global configuration command is configured with table maps, you can configure only one map from value at a time—DSCP, precedence, or CoS. A new configuration overwrites the existing configuration. Packets that are marked by this command can be classified and queued by an output policy map based on the marked DSCP or precedence value.

When the cpu traffic qos precedence global configuration command is configured with table maps, you can configure only one map from value at a time—DSCP, precedence, or CoS. A new configuration overwrites the existing configuration. Packets that are marked by this command can be classified and queued by an output policy map based on the marked precedence or DSCP value.

You cannot configure a map from value of both DSCP and precedence. A new configuration overwrites the existing configuration.

When the cpu traffic qos cos global configuration command is configured with table maps, you can configure two map from values at a time—CoS and either DSCP or precedence.

If the cpu traffic qos cos global configuration command is configured with only a map from value of DSCP or precedence:

The CoS value of IP packets is mapped by using the DSCP (or precedence) value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

The CoS value of non-IP packets remains unchanged.

If the cpu traffic qos cos global configuration command is configured with a map from value of CoS:

The CoS value of IP packets is mapped by using the CoS value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

The CoS value of non-IP packets is mapped by using the CoS value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

If the cpu traffic qos cos global configuration command is configured with a map from value of DSCP or precedence and CoS:

The CoS value of IP packets is mapped by using the DSCP or precedence value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

The CoS value of non-IP packets is mapped by using the CoS value in the packet and the configured table map. Packets can be classified and queued by an output policy map based on the marked CoS value.

The cpu traffic qos qos-group global configuration command can be used to configure QoS group marking for CPU-generated traffic only for a specific QoS group. The table-map option is not available.

Congestion Management and Scheduling

Cisco Modular QoS CLI (MQC) provides several related mechanisms to control outgoing traffic flow. They are implemented in output policy maps to control output traffic queues. The scheduling stage holds packets until the appropriate time to send them to one of the four traffic queues. Queuing assigns a packet to a particular queue based on the packet class, and is enhanced by the WTD algorithm for congestion avoidance. You can use different scheduling mechanisms to provide a guaranteed bandwidth to a particular class of traffic while also serving other traffic in a fair way. You can limit the maximum bandwidth that a particular class of traffic consumes and ensure that delay-sensitive traffic in a low-latency queue is sent before traffic in other queues.

The switch supports these scheduling mechanisms:

Traffic shaping

You use the shape average policy map class configuration command to specify that a class of traffic has a maximum permitted average rate. You specify the maximum rate in bits per second.

Class-based-weighted-fair-queuing (CBWFQ)

You can use the bandwidth policy-map class configuration command to control the bandwidth allocated to a specific class. Minimum bandwidth can be specified as a bit rate or a percentage of total bandwidth or of remaining bandwidth.

Priority queuing or class-based priority queuing

You use the priority policy-map class configuration command to specify the priority of a type of traffic over other types of traffic. You can specify strict priority for the high-priority traffic and allocate any excess bandwidth to other traffic queues, or specify priority with unconditional policing of high-priority traffic and allocate the known remaining bandwidth among the other traffic queues.

To configure strict priority, use only the priority policy-map class configuration command to configure the priority queue. Use the bandwidth remaining percent policy-map class configuration command for the other traffic classes to allocate the excess bandwidth in the desired ratios.

To configure priority with unconditional policing, configure the priority queue by using the priority policy-map class configuration command and the police policy-map class configuration command to rate-limit the priority queue unconditionally. In this case, you can configure the other traffic classes with bandwidth or shape average, depending on requirements.

These sections contain additional information about scheduling:

Traffic Shaping

Class-Based Weighted Fair Queuing

Priority Queuing

Traffic Shaping

Traffic shaping is a traffic-control mechanism similar to traffic policing. While traffic policing is used in input policy maps, traffic shaping occurs as traffic leaves an interface. The switch can apply class-based shaping to classes of traffic leaving an interface and port shaping to all traffic leaving an interface. Configuring a queue for traffic shaping sets the maximum bandwidth or peak information rate (PIR) of the queue.


Note You cannot configure traffic shaping (shape average) and CBWFQ (bandwidth) or priority queuing (priority) for the same class in an output policy map. You cannot configure traffic shaping for a traffic class when strict priority (priority without police) is configured for another class within the output policy-map.


Class-Based Shaping

Class-based shaping uses the shape average policy-map class configuration command to limit the rate of data transmission as the number of bits per second to be used for the committed information rate for a class of traffic. The switch supports separate queues for three classes of traffic. The fourth queue is always the default queue for class class-default, unclassified traffic.


Note In the Cisco ME switch, configuring traffic shaping also automatically sets the minimum bandwidth guarantee or committed information rate (CIR) of the queue to the same value as the PIR.


This example shows how to configure traffic shaping for outgoing traffic on a Fast Ethernet port so that outclass1, outclass2, and outclass3 get a maximum of 50, 20, and 10 Mbps, respectively, of the available port bandwidth. The class class-default at a minimum gets the remaining bandwidth.

Switch(config)# policy-map out-policy
Switch(config-pmap)# class classout1
Switch(config-pmap-c)# shape average 50000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class classout2
Switch(config-pmap-c)# shape average 20000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class classout3
Switch(config-pmap-c)# shape average 10000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet 0/1
Switch(config-if)# service-policy output out-policy
Switch(config-if)# exit

Port Shaping

To configure port shaping (a transmit port shaper), create a policy map that contains only a default class, and use the shape average command to specify the maximum bandwidth for a port.

This example shows how to configure a policy map that shapes a port to 90 Mbps, allocated according to the out-policy policy map configured in the previous example. The service-policy policy map class command is used to create a child policy to the parent:

Switch(config)# policy-map out-policy-parent
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# shape average 90000000
Switch(config-pmap-c)# service-policy out-policy
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output out-policy-parent
Switch(config-if)# exit

Parent-Child Hierarchy

The switch also supports parent policy levels and child policy levels for traffic shaping. The QoS parent-child structure is used for specific purposes where a child policy is referenced in a parent policy to provide additional control of a specific traffic type.

The first policy level, the parent level, is used for port shaping, and you can specific only one class of type class-default within the policy. This example shows a parent-level policy map:

Switch(config)# policy-map parent
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# shape average 50000000
Switch(config-pmap-c)# exit
 
   

The second policy level, the child level, is used to control a specific traffic stream or class, as in this example:

Switch(config)# policy-map child
Switch(config-pmap)# class class1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# exit

Note The total of the minimum bandwidth guarantees (CIR) for each queue of the child policy cannot exceed the total port-shape rate.


This example shows a parent-child configuration:

Switch(config)# policy-map parent
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# shape average 50000000
Switch(config-pmap-c)# service-policy child
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output parent
Switch(config-if)# exit

Class-Based Weighted Fair Queuing

You can configure class-based weighted fair queuing (CBWFQ) to set the relative precedence of a queue by allocating a portion of the total bandwidth that is available for the port. You use the bandwidth policy-map class configuration command to set the output bandwidth for a class of traffic as a rate (kilobits per second), a percentage of total bandwidth, or a percentage of remaining bandwidth.


Note When you configure bandwidth in a policy map, configure all rates in the same format, either a configured rate or a percentage. The total of the minimum bandwidth guarantees (CIR) for each queue of the policy cannot exceed the total speed of the parent.


When you use the bandwidth policy-map class configuration command to configure a class of traffic as an absolute rate (kilobits per second) or a percentage of total bandwidth, you represent the minimum bandwidth guarantee (CIR) for that traffic class. This means that the traffic class gets at least the bandwidth that is indicated by the command, but is not limited to that bandwidth. Any excess bandwidth on the port is allocated to each class in the same ratio in which the CIR rates are configured.


Note You cannot configure bandwidth as an absolute rate or a percentage of total bandwidth when strict priority (priority without police) is configured for another class in the output policy.


When you use the bandwidth policy-map class configuration command to configure a class of traffic as a percentage of remaining bandwidth, you represent the portion of the excess bandwidth of the port that is allocated to the class. The class is allocated bandwidth only if there is excess bandwidth on the port, and if there is no minimum bandwidth guarantee for this traffic class.


Note You can configure bandwidth as percentage of remaining bandwidth only when strict priority (priority without police) is configured for another class in the output policy map.


For more information, see the "Configuring Output Policy Maps with Class-Based-Weighted-Queuing" section.


Note You cannot configure bandwidth and traffic shaping (shape average) or priority queuing (priority) for the same class in an output policy map.


This example shows how to set the precedence of output queues by setting bandwidth in kilobits per second. The classes outclass1, outclass2, and outclass3 and class-default get a minimum of 40000, 20000, 10000, and 10,000 kbps. Any excess bandwidth is divided among the classes in the same proportion as the CIR rated.

Switch(config)# policy-map out-policy
Switch(config-pmap)# class outclass1
Switch(config-pmap-c)# bandwidth 40000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass2
Switch(config-pmap-c)# bandwidth 20000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass3
Switch(config-pmap-c)# bandwidth 10000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# bandwidth 10000
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet 0/1
Switch(config-if)# service-policy output out-policy
Switch(config-if)# exit
 
   

Note When you configure CIR bandwidth for a class as an absolute rate or percentage of the total bandwidth, any excess bandwidth remaining after servicing the CIR of all the classes in the policy map is divided among the classes in the same proportion as the CIR rates. If the CIR rate of a class is configured as 0, that class is also not eligible for any excess bandwidth and as a result receives no bandwidth.


This example shows how to allocate the excess bandwidth among queues by configuring bandwidth for a traffic class as a percentage of remaining bandwidth. The class outclass1 is given priority queue treatment. The other classes are configured to get percentages of the excess bandwidth if any remains after servicing the priority queue: outclass2 is configured to get 50 percent, outclass3 to get 20 percent, and the class class-default to get the remaining 30 percent.

Switch(config)# policy-map out-policy
Switch(config-pmap)# class outclass1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass2
Switch(config-pmap-c)# bandwidth remaining percent 50
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass3
Switch(config-pmap-c)# bandwidth remaining percent 20
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet 0/1
Switch(config-if)# service-policy output out-policy
Switch(config-if)# exit

Priority Queuing

You can use the priority policy-map class configuration command to ensure that a particular class of traffic is given preferential treatment. With strict priority queuing, the priority queue is constantly serviced. All packets in the queue are scheduled and sent until the queue is empty. Priority queuing allows traffic for the associated class to be sent before packets in other queues are sent.


Note Exercise care when using the priority command. Excessive use of strict priority queuing might cause congestion in other queues.


The switch supports strict priority queuing or priority used with the police policy-map command.

Strict priority queuing (priority without police) assigns a traffic class to a low-latency queue to ensure that packets in this class have the lowest possible latency. When this queuing is configured, the priority queue is continually serviced until it is empty, possibly at the expense of packets in other queues.


Note You cannot configure priority without policing for a traffic class when traffic shaping or CBWFQ are configured for another class in the same output policy map.


You can use priority with the police policy-map command, or unconditional priority policing, to reduce the bandwidth used by the priority queue. This policing is the only form that is supported in output policy maps. Using this combination of commands configures a maximum rate on the priority queue, and you can use the bandwidth and shape average policy-map commands for other classes to allocate traffic rates on other queues.


Note When priority is configured in an output policy map without the police command, you can only configure the other queues for sharing by using the bandwidth remaining percent policy-map command to allocate excess bandwidth.


Priority queuing has these restrictions:

You can associate the priority command with a single unique class for all attached output polices on the switch.

You cannot configure priority and any other scheduling action (shape average or bandwidth) in the same class.

You cannot configure priority queuing for the class-default of an output policy map.

For more information, see the "Configuring Output Policy Maps with Class-Based Priority Queuing" section.

This example shows how to configure the class out-class1 as a strict priority queue so that all packets in that class are sent before any other class of traffic. Other traffic queues are configured so that out-class-2 gets 50 percent of the remaining bandwidth and out-class3 gets 20 percent of the remaining bandwidth. The class class-default receives the remaining 30 percent with no guarantees.

Switch(config)# policy-map policy1
Switch(config-pmap)# class out-class1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class2
Switch(config-pmap-c)# bandwidth remaining percent 50
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class3
Switch(config-pmap-c)# bandwidth remaining percent 20
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet 0/1
Switch(config-if)# service-policy output policy1
Switch(config-if)# exit
 
   

This example shows how to use the priority with police commands to configure out-class1 as the priority queue, with traffic going to the queue limited to 20,000,000 bps so that the priority queue does not use more than that amount. Traffic above that rate is dropped. The other traffic queues are configured to use 50 and 20 percent of the bandwidth that is left, as in the previous example.

Switch(config)# policy-map policy1
Switch(config-pmap)# class out-class1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police 200000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class2
Switch(config-pmap-c)# bandwidth percent 50
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class3
Switch(config-pmap-c)# bandwidth percent 20
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
 
   
Switch(config)# interface gigabitethernet 0/1
Switch(config-if)# service-policy output policy1
Switch(config-if)# exit

Congestion Avoidance and Queuing

Congestion avoidance uses algorithms such as tail drop to control the number of packets entering the queuing and scheduling stage to avoid congestion and network bottlenecks. The switch uses weighted tail drop (WTD) to manage the queue sizes and provide a drop precedence for traffic classifications. You set the queue size limits depending on the markings of the packets in the queue. Each packet that travels through the switch can be assigned to a specific queue and threshold. For example, specific DSCP or CoS values can be mapped to a specific egress queue and threshold.

WTD is implemented on traffic queues to manage the queue size and to provide drop precedences for different traffic classifications. As a frame enters a particular queue, WTD uses the packet classification to subject it to different thresholds. If the total destination queue size is greater than the threshold of any reclassified traffic, the next frame of that traffic is dropped.

Figure 34-7 shows an example of WTD operating on a queue of 1000 frames. Three drop percentages are configured: 40 percent (400 frames), 60 percent (600 frames), and 100 percent (1000 frames). These percentages mean that traffic reclassified to the 40-percent threshold is dropped when the queue depth exceeds 400 frames, traffic reclassified to 60 percent is dropped when the queue depth exceeds 600 frames, and traffic 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.

Figure 34-7 WTD and Queue Operation

In this 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.

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

WTD is configured by using the queue-limit policy-map class command. The command adjusts the queue size (buffer size) associated with a particular class of traffic. You specify the threshold as the number of packets, where each packet is a fixed unit of 256 bytes or as a percentage value. You can specify different queue sizes in absolute (number of packets) or percentage terms for different classes of traffic (CoS, DSCP, precedence, or QoS group) in the same queue. Setting a queue limit establishes a drop threshold for the associated traffic when congestion occurs.

You cannot configure the queue size in absolute and percentage terms in the same policy.


Note You cannot configure queue size by using the queue-limit policy map class command without first configuring a scheduling action (bandwidth, shape average, or priority). The only exception is when you configure queue-limit for the class-default of an output policy map.


The switch supports up to three unique queue-limit configurations across all output policy maps. Within an output policy map, only four queues (classes) are allowed, including the class default. Each queue has three thresholds defined. Only three unique threshold value configurations are allowed on the switch. However, multiple policy maps can share the same queue-limits. When two policy maps a share queue-limit configuration, all threshold values must be the same for all the classes in both policy maps.

For more information, see the "Configuring Output Policy Maps with Class-Based-Weighted-Queuing" section.

This example configures class A to match DSCP values and a policy map, PM1. The DSCP values of 30 and 50 are mapped to unique thresholds (32 and 64, respectively). The DSCP values of 40 and 60 are mapped to the maximum threshold of 112 packets.

Switch(config)# class-map match-any classA
Switch(config-cmap)# match ip dscp 30 40 50 60
Switch(config-cmap)# exit
Switch(config)# policy-map PM1
Switch(config-pmap)# class classA
Switch(config-pmap-c)# bandwidth percent 50
Switch(config-pmap-c)# queue-limit 112
Switch(config-pmap-c)# queue-limit dscp 30 32
Switch(config-pmap-c)# queue-limit dscp 50 64
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet 0/1
Switch(config-if)# service-policy output PM1
Switch(config-if)# exit
 
   

You can use these same queue-limit values in multiple output policy maps on the switch. However, changing one of the queue-limit values in a class creates a new, unique queue-limit configuration. You can attach only three unique queue-limit configurations in output policy maps to interfaces at any one time. If you attempt to attach an output policy map with a fourth unique queue-limit configuration, you see this error message:

QoS: Configuration failed. Maximum number of allowable unique queue-limit 
configurations exceeded.

Note When you configure a queue limit for a class in an output policy map, all other output policy maps must use the same qualifier type and qualifier value format. Only the queue-limit threshold values can be different. For example, when you configure class A queue limit thresholds for dscp 30 and dscp 50 in policy map PM1, and you configure class A queue limits in policy map PM2, use dscp 30 and dscp 50 as qualifiers. You cannot use dscp 20 and dscp 40. The threshold values can be different, but different threshold values creates a new queue-limit configuration.


By default, the total amount of buffer space is divided equally among all ports and all queues per port, which is adequate for many applications. You can decrease the queue size for latency-sensitive traffic or increase the queue size for bursty traffic.


Note When you use the queue-limit command to configure queue thresholds for a class, the WTD thresholds must be less than or equal to the queue maximum threshold. A queue size configured with no qualifier must be larger than any queue sizes configured with qualifiers.


When you configure queue limit, the range for the number of packets is from 16 to 4272, in multiples of 16, where each packet is a fixed unit of 256 bytes.


Note For optimal performance, we strongly recommend that you configure the queue-limit to 272 or less.


Queue bandwidth and queue size (queue limit) are configured separately and are not interdependent. Consider the type of traffic being sent when you configure bandwidth and queue-limit:

A large buffer (queue limit) can better accommodate bursty traffic without packet loss, but at the cost of increased latency.

A small buffer reduces latency but is more appropriate for steady traffic flows than for bursty traffic.

Small buffers are typically used to optimize priority queuing. For traffic that is priority queued, the buffer size usually accommodates only a few packets; large buffer sizes that increase latency are not necessary. For high-priority latency-sensitive packets, configure a relatively large bandwidth and relatively small queue size.


Note These restrictions apply to WTD qualifiers:

You cannot configure more than two threshold values for WTD qualifiers (cos, dscp, precedence, qos-group) by using the queue-limit command. However, there is no limit to the number of qualifiers that you can map to these thresholds. You can configure a third threshold value to set the maximum queue by using the queue-limit command with no qualifiers.

A WTD qualifier in the queue-limit command must be the same as at least one match qualifier in the associated class map.


This example shows how to configure bandwidth and queue limit so that out-class1, out-class2, out-class3, and class-default get a minimum of 40, 20, 10 and 10 percent of the traffic bandwidth, respectively. The corresponding queue-sizes are set to 48, 32, 16 and 272 (256-byte) packets:

Switch(config)# policy-map out-policy
Switch(config-pmap)# class outclass1
Switch(config-pmap-c)# bandwidth percent 40
Switch(config-pmap-c)# queue-limit 48
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass2
Switch(config-pmap-c)# bandwidth percent 20
Switch(config-pmap-c)# queue-limit 32
Switch(config-pmap-c)# exit
Switch(config-pmap)# class outclass3
Switch(config-pmap-c)# bandwidth percent 10
Switch(config-pmap-c)# queue-limit 16
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# bandwidth percent 10
Switch(config-pmap-c)# queue-limit 272
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet 0/1
Switch(config-if)# service-policy output out-policy
Switch(config-if)# exit
 
   

You can configure and attach as many output policy maps as there are switch ports, but only three unique queue-limit configurations are allowed. When another output policy map uses the same queue-limit and class configurations, even if the bandwidth percentages are different, it is considered to be the same queue-limit configuration.

Configuring QoS

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

The types of applications used and the traffic patterns on your network.

Traffic characteristics and needs of your network. Is the traffic 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.

These sections describe how to classify, police, and mark incoming traffic, and schedule and queue outgoing traffic. Depending on your network configuration, you must perform one or more of these tasks.

Default QoS Configuration

QoS Configuration Guidelines

Using ACLs to Classify Traffic

Using Class Maps to Define a Traffic Class

Configuring Table Maps

Attaching a Traffic Policy to an Interface

Configuring Input Policy Maps

Configuring Output Policy Maps

Configuring QoS Marking and Queuing for CPU-Generated Traffic

Default QoS Configuration

There are no policy maps, class maps, table maps, or policers configured. At the egress port, all traffic goes through a single default queue that is given the full operational port bandwidth. The default size of the default queue is 160 (256-byte) packets.

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 without any rewrites and classified as best effort without any policing.

QoS Configuration Guidelines

You can configure QoS only on physical ports.

On a port configured for QoS, all traffic received through the port is classified, policed, and marked according to the input 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 a per-port, per-VLAN policy map is attached, traffic on the trunk port is classified, policed, and marked for the VLANs specified in the parent-level policy, according to the child policy map associated with each VLAN.

If you have EtherChannel ports configured on your switch, configure QoS classification, policing, mapping, and queuing on the individual physical ports that comprise the EtherChannel. Decide whether the QoS configuration must match on all ports in the EtherChannel.

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.

When you try to attach a new policy to an interface and the number of policer instances is more than 255, you receive an error message, and the configuration fails.

On all ME 3400 switches, you can specify 256 unique VLAN classification criteria within a per-port, per-VLAN policy-map, across all ports on the switch. Any policy attachment or change that causes this limit to be exceeded fails with a VLAN label resources exceeded error message.

ME 3400 and ME 3400E 24TS, 2CS, and 12 CS models supported ingress QoS classification for 254 unique VLAN IDs on the switch. Starting with Cisco IOS Release 12.2(53)SE, on the 24TS and 2CS switches, you can configure ingress QoS classification for 256 or more VLAN IDs (255 unique VLAN IDs plus the class-default, which can classify on all remaining VLAN-IDs). On the 12CS switches, you can configure ingress QoS classification for 1024 or more VLAN-IDs on the switch (255 unique VLAN IDs plus class default, which can classify on all the rest of the VLAN-IDs, on each set of four ports).

On all ME 3400 switches, you can attach per-port and per-port, per-VLAN policy-maps across all ports on the switch until QoS ACE classification resource limitations are reached. Any policy attachment or change that causes this limit to be exceeded fails with a TCAM resources exceeded error message.

When CPU protection is enabled, you can configure only 45 policers per port. Disabling CPU protection allows you to configure up to 64 policers per port. You can enter the show policer cpu uni-eni {drop | rate} privileged EXEC command to see if CPU protection is enabled.

Note these limitations when you disable CPU protection:

When CPU protection is disabled, you can configure a maximum of 63 policers per port (62 on every fourth port) for user-defined classes, and one for class-default for all ME 3400 switches. Any policy attachment or change that causes this limit to be exceeded fails with a policer resources exceeded error message.

When CPU protection is disabled, you can configure a maximum of 255 policers on the switch for the ME3400-24TS platform. Any policy attachment or change that causes this limit to be exceeded fails with a policer resources exceeded error message.

If you disable CPU protection and attach a policy map with more than 45 policers, and then enable CPU protection again, and reload, 19 policers per port are again required for CPU protection. During reload, the policers 46 and above reaches the policer resources exceeded error condition and no policers are attached to those classes.

See the configuration sections for specific QoS features for more configuration guidelines related to each feature.

Using ACLs to Classify Traffic

You can classify IP traffic by using IP standard or IP extended ACLs. You can classify IP and non-IP traffic by using Layer 2 MAC ACLs. For more information about configuring ACLs, see Chapter 32 "Configuring Network Security with ACLs."

Follow these guidelines when configuring QoS ACLs:

You cannot 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.

The switch supports only one access group per class in an input policy map.

You cannot configure match-access group in an output policy map.

In past releases, multifield classification using Layer-3 IP ACLs and DSCP classification simultaneously for every packet was not fully supported. You could configure either Layer-3 IP ACL classification or DSCP classification for every packet. Also multifield classification using Layer-2 MAC ACLs and COS classification simultaneously for every packet was not fully supported. You could configure either Layer-2 MAC-ACL classification or COS classification for every packet.

In Cisco IOS Release 12.2(53)SE and later, you can simultaneously configure multifield classification with Layer-3 IP ACLs and DSCP classification for every packet by using the IP access group to identify the required DSCP value to be classified along with other IP-header fields. You can also simultaneously configure multifield classification with Layer-2 MAC ACLs and COS classification for every packet by using the MAC access group to identify the COS value to be classified along with other MAC-header fields.

These sections describe how to create QoS ACLs:

"Creating IP Standard ACLs" section

"Creating IP Extended ACLs" section

"Creating Layer 2 MAC ACLs" section

Creating IP Standard ACLs

Beginning in privileged EXEC mode, follow these steps to create an IP standard ACL for IP traffic:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

access-list access-list-number permit source [source-wildcard]

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

For access-list-number, enter the access list number. The range is 1-99 and 1300-1999.

Always use the permit keyword for ACLs used as match criteria in QoS policies. QoS policies do not match ACLs that use the deny keyword.

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.

or

ip access-list standard name

Define a standard IPv4 access list using a name, and enter access-list configuration mode. The name can be a number from 1 to 99.

In access-list configuration mode, enter permit source [source-wildcard]

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show access-lists

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

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

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.

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

Creating IP Extended ACLs

Beginning in privileged EXEC mode, follow these steps to create an IP extended ACL for IP traffic:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

access-list access-list-number permit protocol {source source-wildcard destination destination-wildcard} [precedence precedence] [tos tos] [dscp dscp]

Note If you enter a dscp value, you cannot enter tos or precedence. You can enter both a tos and a precedence value with no dscp.

Create an IP extended ACL. Repeat the step as many times as necessary.

For access-list-number, enter the access list number. The range is 100-199 and 2000-2699.

Always use the permit keyword for ACLs used as match criteria in QoS policies. QoS policies do not match deny ACLs.

For protocol, enter the name or number of an IP protocol. Use the question mark (?) to see a list of available protocols. To match any Internet Protocol (including ICMP, TCP, and UDP), enter ip.

The source is the number of the network or host sending the packet.

The source-wildcard applies wildcard bits to the source.

The destination is the network or host number receiving the packet.

The destination-wildcard applies wildcard bits to the destination.

You can specify source, destination, and wildcards as:

The 32-bit quantity in dotted-decimal format.

The keyword any for 0.0.0.0 255.255.255.255 (any host).

The keyword host for a single host 0.0.0.0.

Other keywords are optional and have these meanings:

precedence—Enter to match packets with a precedence level specified as a number from 0 to 7 or by name: routine (0), priority (1), immediate (2), flash (3), flash-override (4), critical (5), internet (6), network (7).

tos—Enter to match by type of service level, specified by a number from 0 to 15 or a name: normal (0), max-reliability (2), max-throughput (4), min-delay (8).

dscp—Enter to match packets with the DSCP value specified by a number from 0 to 63, or use the question mark (?) to see a list of available values.

or

ip access-list extended name

Define an extended IPv4 access list using a name, and enter access-list configuration mode. The name can be a number from 100 to 199.

In access-list configuration mode, enter permit protocol {source source-wildcard destination destination-wildcard} [precedence precedence] [tos tos] [dscp dscp] as defined in Step 2.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show access-lists

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

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

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

Creating Layer 2 MAC ACLs

Beginning in privileged EXEC mode, follow these steps to create a Layer 2 MAC ACL for non-IP traffic:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

mac access-list extended name

Create a Layer 2 MAC ACL by specifying the name of the list and enter extended MAC ACL configuration mode.

Step 3 

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

Always use the permit keyword for ACLs used as match criteria in QoS policies.

For src-MAC-addr, enter the MAC address of the host from which the packet is being sent. You can specify in hexadecimal format (H.H.H), use the any keyword for source 0.0.0, source-wildcard ffff.ffff.ffff, or use 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 can specify in hexadecimal format (H.H.H), use the any keyword for source 0.0.0, source-wildcard ffff.ffff.ffff, or use 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.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

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

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

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

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
Switch(config-ext-macl)# exit

Using Class Maps to Define a Traffic Class

You use the class-map global configuration command to name and to isolate a specific traffic flow (or class) from all other traffic. A class map defines the criteria to use to match against a specific traffic flow to classify it further. Match statements can include criteria such as an ACL, CoS value, DSCP value, IP precedence values, or QoS group values, or VLAN IDs. You define match criterion with one or more match statements entered in the class-map configuration mode.

Follow these guidelines when configuring class maps:

A match-all class map cannot have more than one classification criterion (one match statement), but a match-any class map can contain multiple match statements.

The match cos and match vlan commands are supported only on Layer 2 802.1Q trunk ports.

You use a class map with the match vlan command in the parent policy in input hierarchical policy maps for per-port, per-VLAN QoS on trunk ports. A policy is considered a parent policy map when it has one or more of its classes associated with a child policy map. Each class within a parent policy map is called a parent class. You can configure only the match vlan command in parent classes. You cannot configure the match vlan command in classes within the child policy map.

For an input policy map, you cannot configure an IP classification (match ip dscp, match ip precedence, match ip acl) and a non-IP classification (match cos or match mac acl) in the same policy map or class map. For a per-port, per-VLAN hierarchical policy map, this rule applies to the child policy map.

You cannot configure match qos-group for an input policy map.

In an output policy map, no two class maps can have the same classification criteria; that is, the same match qualifiers and values.

The maximum number of class maps on the switch is 1024.

Beginning in privileged EXEC mode, follow these steps to create a class map and to define the match criterion to classify traffic:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

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

Create a class map, and enter 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 no matching statements are specified, the default is match-all.

Note A match-all class map cannot have more than one classification criterion (match statement).

Step 3 

match {access-group acl-index-or-name | cos cos-list | ip dscp dscp-list | ip precedence ip-precedence-list | qos-group value | vlan vlan-list}

Define the match criterion to classify traffic. By default, no match criterion is defined.

Only one match type 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 an ACL. Matching access groups is supported only in input policy maps.

For cos cos-list, enter a list of up to four CoS values in a single line to match against incoming packets. Separate each value with a space. You can enter multiple cos-list lines to match more than four CoS values. The range is 0-7.

For ip dscp dscp-list, enter a list of up to eight IPv4 DSCP values to match against incoming packets. Separate each value with a space. You can enter multiple dscp-list lines to match more than eight DSCP values. The numerical range is 0-63. You can also configure DSCP values in other forms. See the "Classification Based on IP DSCP" section.

For ip precedence ip-precedence-list, enter a list of up to four IPv4 precedence values to match against incoming packets. Separate each value with a space. You can enter multiple ip-precedence-list lines to match more than four precedence values. The range is 0-7.

For vlan vlan-list, specify a VLAN ID or a range of VLANs to be used in a parent policy map for per-port, per-VLAN QoS on a trunk port. The VLAN ID range is 1-4094.

For qos-group value, specify the QoS group number. The range is 0-99. Matching of QoS groups is supported only in output policy maps.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show class-map

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no form of the appropriate command to delete an existing class map or remove a match criterion.

This example shows how to create access list 103 and 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 any any dscp 10
Switch(config)# class-map class1
Switch(config-cmap)# match access-group 103
Switch(config-cmap)# exit
 
   

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 match-any class2
Switch(config-cmap)# match ip dscp 10 11 12
Switch(config-cmap)# exit
 
   

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 match-any class3
Switch(config-cmap)# match ip precedence 5 6 7 
Switch(config-cmap)# exit
 
   

This example shows how to create a parent class-map called parent-class, which matches incoming traffic with VLAN IDs in the range from 30 to 40.

Switch(config)# class-map match-any parent-class
Switch(config-cmap)# match vlan 30-40
Switch(config-cmap)# exit

Configuring Table Maps

You can configure table maps to manage a lot of traffic flows with a single command. You use table maps to correlate specific DSCP, IP precedence, and CoS values to each other, to mark down a DSCP, IP precedence, or CoS value, or to assign default values. You can specify table maps in set commands and use them as mark-down mapping for the policers.

These table maps are supported on the switch:

DSCP to CoS, precedence, or DSCP

CoS to DSCP, precedence, or CoS

Precedence to CoS, DSCP, or precedence

Note these guidelines when configuring table maps:

The switch supports a maximum of 256 unique table maps.

The maximum number of map statements within a table map is 64.

Table maps cannot be used in output policy maps.

Beginning in privileged EXEC mode, follow these steps to create a table map:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

table-map table-map-name

Create a table map by entering a table-map name and entering table-map configuration mode.

Step 3 

map from from-value to to-value

Enter the mapping values to be included in the table. For example, if the table map is a DSCP-to-CoS table map, the from-value would be the DSCP value and the to_value would be the CoS value. Both ranges are from 0 to 63.

Enter this command multiple times to include all the values that you want to map.

Step 4 

default {default-value | copy | ignore}

Set the default behavior for a value not found in the table map.

Enter a default-value to specify a certain value. For example, in a DSCP-to-CoS table map, this value would be a specific CoS value to apply to all unmapped DSCP values. The range is from 0 to 63.

Enter copy to map unmapped values to an equivalent value. In a DSCP-to-CoS table map, this command maps all unmapped DSCP values to the equivalent CoS value.

Enter ignore to leave unmapped values unchanged. In a DSCP-to-CoS table map, the switch does not change the CoS value of unmapped DSCP values.

Step 5 

end

Return to privileged EXEC mode.

Step 6 

show table-map [table-map-name]

Verify your entries.

Step 7 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To delete a table map, use the no table-map table-map-name global configuration command.

This example shows how to create a DSCP-to-CoS table map. A complete table would typically include additional map statements for the higher DSCP values. The default of 4 in this table means that unmapped DSCP values are assigned a CoS value of 4.

Switch(config)# table-map dscp-to-cos
Switch(config-tablemap)# map from 1 to 1
Switch(config-tablemap)# map from 2 to 1
Switch(config-tablemap)# map from 3 to 1
Switch(config-tablemap)# map from 4 to 2
Switch(config-tablemap)# map from 5 to 2
Switch(config-tablemap)# map from 6 to 3
Switch(config-tablemap)# default 4
Switch(config-tablemap)# end
Switch# show table-map dscp-to-cos

Attaching a Traffic Policy to an Interface

You use the service-policy interface configuration command to attach a traffic policy to an interface and to specify the direction in which the policy is applied: either an input policy map for incoming traffic or an output policy map for outgoing traffic. Input and output policy maps support different QoS features. See the "Configuring Input Policy Maps" section and the "Configuring Output Policy Maps" section for restrictions on input and output policy maps.

You can attach a service policy only to a physical port. You can attach only one input policy map and one output policy map per port.


Note If you enter the no policy-map configuration command or the no policy-map policy-map-name global configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. The policy map is then detached and deleted. For example:
Warning: Detaching Policy test1 from Interface GigabitEthernet0/1


Beginning in privileged EXEC mode, follow these steps to attach a policy map to a port:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Specify the port to attach to the policy map, and enter interface configuration mode. Valid interfaces are physical ports.

Step 3 

service-policy {input | output} policy-map-name

Specify the policy-map name and whether it is an input policy map or an output policy map.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show policy-map interface [interface-id]

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

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

Configuring Input Policy Maps

Policy maps specify which traffic class to act on and what actions to take. All traffic that fails to meet matching criteria of a traffic class belongs to the default class. Input policy maps regulate traffic entering the switch. In an input policy, you can match CoS, DSCP, IP precedence, ACLs, or VLAN IDs and configure individual policing, aggregate policing, or marking to a CoS, DSCP, IP precedence, or QoS group value.

Follow these guidelines when configuring input policy maps:

You can attach only one input policy map per port.

The maximum number of policy maps configured on the switch is 256.

The maximum number of classes in each input policy map is 64 plus class-default.

The number of input policy maps that can be attached in a switch is limited by the availability of hardware resources. If you attempt to attach an input policy map that causes any hardware resource limitation to be exceeded, the configuration fails.

After you have attached a single-level policy map to an interface by using the service-policy input interface configuration command, you can modify the policy without detaching it from the interface. You can add or delete classification criteria, add or delete classes, add or delete actions, or change the parameters of the configured actions (policers, rates, mapping, marking, and so on). You can also change criteria for the child policy of a hierarchical policy map, as in a per-port per-VLAN hierarchical policy map.

For the parent policy of a hierarchical policy map, you cannot add or delete a class at the parent level if the policy map is attached to an interface. Detach the policy from the interface, modify the policy, and then reattach it to the interface.

You can configure a maximum 2-level hierarchical policy map as an input policy map only with VLAN-based classification at the parent level and no VLAN-based classification at the child level.

When an input policy map with only Layer 2 classification is attached to a routed port or a switch port containing a routed SVI, the service policy acts only on switching eligible traffic and not on routing eligible traffic.

On an 802.1Q tunnel port, you can use only an input policy map with Layer 2 classification based on MAC ACLs to classify traffic. Input policy maps with Layer 3 classification or with Layer 2 classification based on CoS or VLAN ID are not supported on tunnel ports.

Input policy maps support policing and marking, not scheduling or queuing. You cannot configure bandwidth, priority, queue-limit, or shape average in input policy maps.

These sections describe how to configure different types of input policy maps:

Configuring Input Policy Maps with Individual Policing

Configuring Input Policy Maps with Aggregate Policing

Configuring Input Policy Maps with Marking

Configuring Per-Port Per-VLAN QoS with Hierarchical Input Policy Maps

Configuring Input Policy Maps with Individual Policing

You use the police policy-map class configuration command to configure individual policers to define the committed rate limitations, committed burst size limitations of the traffic, and the action to take for a class of traffic.

Follow these guidelines when configuring individual policers:

Policing is supported only on input policy maps.

The switch supports a maximum of 229 policers. (228 user-configurable policers and 1 policer reserved for internal use).

When CPU protection is enabled (the default), you can configure 45 ingress policers per port. If you disable CPU protection by entering the no policer cpu uni all global configuration command and reloading the switch, you can configure a maximum of 63 policers per port (62 on every fourth port) for user-defined classes and one for class-default. You can enter the show policer cpu uni-eni {drop | rate} privileged EXEC command to see if CPU protection is enabled.

When you use a table map for police exceed-action in an input policy map, the protocol type of the map from type of action must be the same as the protocol type of the associated classification. For example, if the associated class map represents an IP classification, the map from type of action that references the table map must be dscp or precedence. If the associated class map represents a non-IP classification, the map from type of action that references the table map must be cos.

Beginning in privileged EXEC mode, follow these steps to create an input policy map with individual policing:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode. By default, no class maps are defined.

Step 3 

class {class-map-name | class-default}

Enter a class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

If you enter a class-map name, you must have already created the class map by using the class-map global configuration command.

Step 4 

police {rate-bps | cir cir-bps} [burst-bytes | bc burst-bytes]

Define a policer for the class of traffic.

By default, no policer is defined.

For rate-bps, specify average traffic rate in bits per second (bps). The range is 8000-1000000000.

For cir cir-bps, specify a committed information rate (CIR) in bits per second (bps). The range is 8000-1000000000.

For burst-bytes (optional), specify the normal burst size in bytes. The range is 8000-1000000.

For bc burst-bytes (optional), specify the conformed burst (bc) or the number of acceptable burst bytes. The range is 8000-1000000.

Step 5 

conform-action cos {cos_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}
or
conform-action [ip] dscp {dscp_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}
or
conform-action [ip] precedence {precedence_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}
or
conform-action qos-group value
or
transmit

(Optional) Enter the action to be taken on packets that conform to the CIR.

For cos cos_value, enter a new CoS value to be assigned to the classified traffic. The range is 0-7.

For [ip] dscp dscp_value, enter a new DSCP value to be assigned to the classified traffic. The range is 0-63.

For [ip] precedence precedence_value, enter a new IP-precedence value to be assigned to the classified traffic. The range is 0-7.

Or you can configure a CoS, DSCP, or IP precedence table and optionally enter the table name. If you do not enter table table-map name, the table map default behavior is copy. See the "Configuring Table Maps" section.

For qos-group value, identify a QoS group to be used at egress to identify specific packets. The range is from 0 to 99.

Note You can enter a single conform-action as part of the command string following the police command. You can also press Enter after the police command to enter policy-map class police configuration mode, where you can enter multiple actions. In policy-map class police configuration mode, enter an action to take.

Step 6 

exceed-action cos {cos_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}
or
exceed-action [ip] dscp {dscp_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}
or
exceed-action [ip] precedence {precedence_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}
or
exceed-action qos-group value

(Optional) Enter the action to be taken for packets that do not conform to the CIR.

For cos cos_value, enter a new CoS value to be assigned to the classified traffic. The range is 0-7.

For [ip] dscp dscp_value, enter a new DSCP value to be assigned to the classified traffic. The range is 0-63.

For [ip] precedence precedence_value, enter a new IP-precedence value to be assigned to the classified traffic. The range is 0-7.

Or you can configure a CoS, DSCP, or IP precedence table and optionally enter the table name. If you do not enter table table-map name, the table map default behavior is copy. See the "Configuring Table Maps" section.

For qos-group value, identify a QoS group to be used at egress to identify specific packets. The range is from 0 to 99.

Note You can enter a single exceed-action as part of the command string following the police command. Or you can press Enter after the police command to enter policy-map class police configuration mode, where you can enter multiple actions. In policy-map class police configuration mode, enter an action to take.

Note If you explicitly configure exceed-action drop as keywords in the command, enter policy-map class police configuration mode and enter the no exceed-action drop command to remove the previously configured exceed action before you can enter the new exceed-action.

Step 7 

exit

Return to policy-map configuration mode.

Step 8 

exit

Return to global configuration mode.

Step 9 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 10 

service-policy input policy-map-name

Attach the policy map (created in Step 2) to the ingress interface.

Step 11 

end

Return to privileged EXEC mode.

Step 12 

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

Verify your entries.

Step 13 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

If you enter the no policy-map configuration command or the no policy-map policy-map-name global configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. The policy map is then detached and deleted. For example:
Warning: Detaching Policy test1 from Interface GigabitEthernet0/1

After you have created an input policy map, you attach it to an interface in the input direction. See the "Attaching a Traffic Policy to an Interface" section.

Use the no form of the appropriate command to delete an existing policy map, class map, or policer.

This example shows how to create a traffic classification with a CoS value of 4, create a policy map, and attach it to an ingress port. The average traffic rate is limited to 10,000,000 b/s with a burst size of 10,000 bytes:

Switch(config)# class-map video-class
Switch(config-cmap)# match cos 4
Switch(config-cmap)# exit
Switch(config)# policy-map video-policy
Switch(config-pmap)# class video-class
Switch(config-pmap-c)# police 10000000 10000
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input video-policy
Switch(config-if)# exit
 
   

This example shows how to create policy map with a conform action of set dscp and a default exceed action.

Switch(config)# class-map in-class-1
Switch(config-cmap)# match ip dscp 14
Switch(config-cmap)# exit
Switch(config)# policy-map in-policy
Switch(config-pmap)# class in-class-1
Switch(config-pmap-c)# police 230000 8000 conform-action set-dscp-transmit 33 
exceed-action drop
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input in-policy
Switch(config-if)# exit
 
   

This example shows how to use policy-map class police configuration mode to set multiple conform actions and an exceed action. The policy map sets a committed information rate of 23,000 bits per second (bps) and a conform burst size of 10,000 bytes. The policy map includes multiple conform actions (for DSCP and for Layer 2 CoS) and an exceed action.

Switch(config)# class-map cos-set-1
Switch(config-cmap)# match cos 3
Switch(config-cmap)# exit
Switch(config)# policy-map map1
Switch(config-pmap)# class cos-set-1
Switch(config-pmap-c)# police cir 23000 bc 10000
Switch(config-pmap-c-police)# conform-action set-dscp-transmit 48
Switch(config-pmap-c-police)# conform-action set-cos-transmit 5
Switch(config-pmap-c-police)# exceed-action drop
Switch(config-pmap-c-police)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input map1
Switch(config-if)# exit
 
   

This example shows how to use policy-map class police configuration mode to set exceed action mark-down using table-maps. The policy map sets a committed information rate of 23,000 bps and a conform burst-size of 10,000 bytes. The policy map includes the default conform action (transmit) and the exceed action to mark the Layer 2 CoS value based on the table map and to mark IP DSCP to af41.

Switch(config)# policy-map in-policy
Switch(config-pmap)# class in-class-1
Switch(config-pmap-c)# police cir 23000 bc 10000 
Switch(config-pmap-c-police)# exceed-action set-cos-transmit cos table 
police-cos-markdn-tablemap
Switch(config-pmap-c-police)# exceed-action set-dscp-transmit af41
Switch(config-pmap-c-police)# exit
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input in-policy
Switch(config-if)# exit

Configuring Input Policy Maps with Aggregate Policing

You use the policer aggregate global configuration command to configure an aggregate policer. Multiple traffic classes within the same policy map are shared by an aggregate policer. You define the aggregate policer, create a policy map, associate a class map with the policy map, associate the policy map with the aggregate policer, and apply the service policy to a port.

Follow these guidelines when configuring aggregate policers:

Aggregate policing is supported only on input policy maps.

The switch supports a maximum of 229 policers associated with ports (228 user-configurable policers and 1 policer reserved for internal use).

When CPU protection is enabled (the default), you can configure 45 ingress policers per port. If you disable CPU protection by entering the no policer cpu uni all global configuration command and reloading the switch, you can configure a maximum of 63 policers per port (62 on every fourth port) for user-defined classes and one for class-default. You can enter the show policer cpu uni-eni {drop | rate} privileged EXEC command to see if CPU protection is enabled.

The maximum number of configured aggregate policers is 256.

Only one policy map can use any specific aggregate policer. Aggregate policing cannot be used to aggregate streams across multiple interfaces. You can use aggregate policing only to aggregate streams across multiple classes in a policy map attached to an interface and to aggregate traffic streams across VLANs on a port in a per-port, per-VLAN policy map.

When you use a table map for police exceed-action in an input policy map, the protocol type of the map from type of action must be the same as the protocol type of the associated classification. For example, if the associated class map represents an IP classification, the map from type of action that references the table map must be either dscp or precedence. If the associated class map represents a non-IP classification, the map from type of action that references the table map must be cos.

You can configure multiple conform and exceed actions simultaneously for an aggregate policer as parameters in the policer aggregate global configuration command, but you must enter the actions in this order:

conform-action must be followed by transmit or by set actions in this order:

set-qos-transmit

set-dscp-transmit or set-prec-transmit

set-cos-transmit

exceed-action must be followed by drop or transmit or by set actions in this order:

set-qos-transmit

set-dscp-transmit or set-prec-transmit

set-cos-transmit

Beginning in privileged EXEC mode, follow these steps to create an aggregate policer:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policer aggregate aggregate-policer-name {rate-bps | cir cir-bps} [bc burst- value] [conform-action [set-cos-transmit {cos_value | [cos | dscp | precedence] [table table-map name]} | set-dscp-transmit {dscp_value | [cos | dscp | precedence] [table table-map name]} | set-prec-transmit {precedence_value | [cos | dscp | precedence] [table table-map name]} | set-qos-transmit qos-group_value | transmit] [exceed action [drop | set-cos-transmit {cos_value | [cos | dscp | precedence] [table table-map name]} | set-dscp-transmit {dscp_value | [cos | dscp | precedence] [table table-map name]} | set-prec-transmit {precedence_value | [cos | dscp | precedence] [table table-map name]} | set-qos-transmit qos-group_value | transmit]]

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

For aggregate-policer-name, specify the name of the aggregate policer.

For rate-bps, specify average traffic rate in bits per second (bps). The range is 8000-1000000000.

For cir cir-bps, specify the committed information rate in bits per second. The range is 8000-1000000000 bps.

(Optional) For bc burst-value, specify conform burst and the number of acceptable burst bytes. The range is 8000-1000000 bytes.

(Optional) For conform-action, specify the action to take on packets that conform to the CIR. The default is to send the packet.

(Optional) For exceed-action, specify the action to take on packets that exceed the CIR. The default is to drop the packet.

See the command reference for this release or the "Configuring Input Policy Maps with Individual Policing" section for definitions of the available keywords.

Step 3 

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 4 

class {class-map-name | class-default}

Enter a class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

If you enter a class-map name, you must have already created the class map by using the class-map global configuration command.

Step 5 

police aggregate aggregate-policer-name

Apply an aggregate policer to multiple classes in the same policy map. For aggregate-policer-name, enter the name specified in Step 2.

Step 6 

exit

Return to policy-map configuration mode.

Step 7 

exit

Return to global configuration mode.

Step 8 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 9 

service-policy input policy-map-name

Attach the policy map (created in Step 3) to the ingress interface.

Step 10 

end

Return to privileged EXEC mode.

Step 11 

end

Return to privileged EXEC mode.

Step 12 

show policer aggregate [aggregate-policer-name]

Verify your entries.

Step 13 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an aggregate policer, you attach it to an ingress port. See the "Attaching a Traffic Policy to an Interface" section.

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

This example shows how to create an aggregate policer and attach it to multiple classes within a policy map. The policy map is attached to an ingress port.

Switch(config)# policer aggregate example 10900000 80000 conform-action transmit 
exceed-action drop
Switch(config)# class-map testclass1
Switch(config-cmap)# match access-group 1
Switch(config-cmap)# exit
Switch(config)# class-map testclass2
Switch(config-cmap)# match access-group 2
Switch(config-cmap)# exit
Switch(config)# policy-map testexample
Switch(config-pmap)# class testclass
Switch(config-pmap-c)# police aggregate example 
Switch(config-pmap-c)# exit
Switch(config-pmap)# class testclass2
Switch(config-pmap-c)# police aggregate example 
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input testexample
Switch(config-if)# exit
 
   

Configuring Input Policy Maps with Marking

You use the set policy-map class configuration command to set or modify the attributes for traffic belonging to a specific class. Follow these guidelines when configuring marking in policy maps:

You can configure a maximum of 100 QoS groups on the switch.

When you use a table map for marking in an input policy map, the protocol type of the map from type of action must be the same as the protocol type of the associated classification. For example, if the associated class map represents an IP classification, the map from type of action that references the table map must be either dscp or precedence. If the associated class map represents a non-IP classification, the map from type of action that references the table map must be cos.

Beginning in privileged EXEC mode, follow these steps to create an input policy map that marks traffic:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3 

class {class-map-name | class-default}

Enter a class-map name, or class-default to match all unclassified packets, and enter policy-map class configuration mode.

If you enter a class-map name, you must have already created the class map by using the class-map global configuration command.

Step 4 

set qos-group value
and/or
set cos {cos_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}
and/or
set [ip] dscp {dscp_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}
and/or

and/or
set [ip] precedence {precedence_value | cos [table table-map-name] | dscp [table table-map-name] | precedence [table table-map-name]}

Mark traffic by setting a new value in the packet, specifying a table map, or specifying a QoS group.

For qos-group value, identify a QoS group to be used at egress to identify specific packets. The range is from 0 to 99.

For cos cos_value, enter a new CoS value to be assigned to the classified traffic. The range is 0-7.

For [ip] dscp new-dscp, enter a new DSCP value to be assigned to the classified traffic. The range is 0-63.

For [ip] precedence new-precedence, enter a new IP-precedence value to be assigned to the classified traffic. The range is 0-7.

You can also configure a CoS, DSCP, or IP precedence table and optionally enter the table name. If you do not enter table table-map name, the table map default behavior is copy. See the "Configuring Table Maps" section.

Step 5 

exit

Return to policy-map configuration mode.

Step 6 

exit

Return to global configuration mode.

Step 7 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 8 

service-policy input policy-map-name

Attach the policy map (created in Step 2) to the ingress interface.

Step 9 

end

Return to privileged EXEC mode.

Step 10 

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

Verify your entries.

Step 11 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no form of the appropriate command to delete a policy map or table map or remove an assigned CoS, DSCP, precedence, or QoS-group value.

This example uses a policy map to remark a packet. The first marking (the set command) applies to the QoS default class map that matches all traffic not matched by class AF31-AF33 and sets all traffic to an IP DSCP value of 1. The second marking sets the traffic in classes AF31 to AF33 to an IP DSCP of 3.

Switch(config)# policy-map Example
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# set ip dscp 1
Switch(config-pmap-c)# exit
Switch(config-pmap)# class AF31-AF33
Switch(config-pmap-c)# set ip dscp 3
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy input Example 
Switch(config-if)# exit

Configuring Per-Port Per-VLAN QoS with Hierarchical Input Policy Maps

Per-port, per-VLAN QoS allows classification based on VLAN IDs for applying QoS for frames received on a given interface and VLAN. This classification is achieved by using a hierarchical policy map, with a parent policy and a child policy.

Note these guidelines and limitations when configuring per-port, per-VLAN QoS:

The feature is supported only by using a two-level hierarchical input policy map, where the parent level defines the VLAN-based classification, and the child level defines the QoS policy to be applied to the corresponding VLAN or VLANs.

You can configure multiple service classes at the parent level to match different combinations of VLANs, and you can apply independent QoS policies to each parent-service class using any child policy map

A policy is considered a parent policy map when it has one or more of its classes associated with a child policy map. Each class within a parent policy-map is called a parent-class. In parent classes, you can configure only the match vlan class-map configuration command. You cannot configure the match vlan command in classes within the child policy map.

You cannot configure a mixture of Layer 2 and Layer 3 class maps in a child policy map. When you attempt to associate such a child policy map with a parent policy, the configuration is rejected. However, you can associate Layer 2 child policies and Layer 3 child policies with different parent-level class maps.

Per-port, per-VLAN QoS is supported only on 802.1Q trunk ports.

When the child policy-map attached to a VLAN or set of VLANs contains only Layer 3 classification (match ip dscp, match ip precedence, match IP ACLs), take care to ensure that these VLANs are not carried on any other port besides the one on which the per-port, per-vlan policy is attached. Not following this rule could result in improper QoS behavior for traffic ingressing the switch on these VLANs.

We also recommend that you restrict VLAN membership on the trunk ports to which the per-port, per-VLAN is applied by using the switchport trunk allowed vlan interface configuration command. Overlapping VLAN membership between trunk ports that have per-port, per-VLAN policies with Layer 3 classification could also result in unexpected QoS behavior.

In past releases in a per-port, per-VLAN hierarchical input policy-map, you could not associate a child policy with the class class-default of the parent policy map. You could only classify on known VLANs received on a port. In Cisco IOS Release 12.2(53)SE and later, you can enter class class-default in the parent policy map of a per-port, per-VLAN hierarchical input policy map to classify all VLANs not identified by specified parent VLAN classes. You can then associate a child-policy to this parent class class-default by using the service-policy child-policy-map name policy-map class configuration command to specify child classes and actions to apply to this traffic.

These same limitations from past releases about combinations of child-policies with a particular VLAN-ID in per-port, per-VLAN policies across the switch also apply to the class-default in per-port, per-VLAN policies.

You cannot combine Layer 2 child policies classifying on S-COS, C-COS, or Layer 2 (MAC) ACLs and Layer 3 child policies classifying on DSCP, IP precedence, or Layer 3 (IP) ACLs.

You cannot combine a class default only child policy and a Layer 3 child policy classifying on DSCP, IP precedence, or Layer 3 (IP) ACLs.

Configuring per-port, per-VLAN QoS includes these tasks:

Creating Child-Policy Class Maps

Creating Parent-Policy Class Maps

Creating Child Policy Maps

Creating a Parent Policy Map

Attaching a Parent Policy Map to an Interface

Creating Child-Policy Class Maps

Beginning in privileged EXEC mode, follow these steps to create one or more child-policy class maps:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

class-map [match-all | match-any] child-class-map-name

Create a class map, and enter 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 no matching statements are specified, the default is match-all.

Note A match-all class map cannot have more than one classification criterion (match statement).

Step 3 

match {access-group acl-index-or-name | cos cos-list | ip dscp dscp-list | ip precedence ip-precedence-list | qos-group value | vlan vlan-list}

Define the match criterion to classify traffic. By default, no match criterion is defined.

Only one match type 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 an ACL. Matching access groups is supported only in input policy maps.

For cos cos-list, enter a list of up to four CoS values in a single line to match against incoming packets. Separate each value with a space. You can enter multiple cos-list lines to match more than four CoS values. The range is 0-7.

For ip dscp dscp-list, enter a list of up to eight IPv4 DSCP values to match against incoming packets. Separate each value with a space. You can enter multiple dscp-list lines to match more than eight DSCP values. The numerical range is 0-63. You can also configure DSCP values in other forms. See the "Classification Based on IP DSCP" section.

For ip precedence ip-precedence-list, enter a list of up to four IPv4 precedence values to match against incoming packets. Separate each value with a space. You can enter multiple ip-precedence-list lines to match more than four precedence values. The range is 0-7.

For qos-group value, specify the QoS group number. The range is 0 to99. Matching of QoS groups is supported only in output policy maps.

For vlan vlan-list, specify a VLAN ID or a range of VLANs to be used in a parent policy map for per-port, per-VLAN QoS on a trunk port. The VLAN ID range is 1-4094.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show class-map

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Creating Parent-Policy Class Maps

Beginning in privileged EXEC mode, follow these steps to create one or more parent-policy class maps:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

class-map match-any parent-class-map-name

Create a match-any class map for the parent policy, and enter class-map configuration mode.

Note You can enter match-all or not enter either match-any or match-all (to default to match-all) if you are going to match only one VLAN ID.

Step 3 

match vlan vlan-id

Define the VLAN or VLANs on which to classify traffic.

For vlan-id, specify a VLAN ID, a series of VLAN IDs separated by a space, or a range of VLANs separated by a hyphen to be used in a parent policy map for per-port, per-VLAN QoS on a trunk port. The VLAN ID range is 1-4094.

You can also enter the match vlan command multiple times to match multiple VLANs.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show class-map

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Creating Child Policy Maps

Beginning in privileged EXEC mode, follow these steps to create one or more child policy maps:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policy-map child-policy-map-name

Create a child policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3 

class {child-class-map-name | class-default}

Enter a child class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

Step 4 

Use the police policy-map class configuration command to configure policers and the action to take for a class of traffic, or use the set policy-map class configuration command to mark traffic belonging to the class.

Step 5 

end

Return to privileged EXEC mode.

Step 6 

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

Verify your entries.

Step 7 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Creating a Parent Policy Map

Beginning in privileged EXEC mode, follow these steps to create a parent policy map and attach it to an interface:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policy-map parent-policy-map-name

Create a parent policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3 

class {parent-class-map-name | class-default}

Enter the parent class-map name, and enter policy-map class configuration mode.

Step 4 

service policy child-policy-map-name

Associate the child policy map with the parent policy map

Step 5 

end

Return to privileged EXEC mode.

Step 6 

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

Verify your entries.

Step 7 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Attaching a Parent Policy Map to an Interface

Beginning in privileged EXEC mode, follow these steps to create and attach the parent policy map to an interface:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 3 

switchport mode trunk

Configure the port as a trunk port.

Step 4 

switchport trunk allowed vlan vlan-list

(Recommended) Restrict VLAN membership for trunk ports to avoid overlapping VLAN membership if the per-port, per-VLAN policy includes Layer 3 classification.

Step 5 

service-policy input parent- policy-map-name

Attach the parent policy map (created in the previous section) to the ingress interface.

Step 6 

end

Return to privileged EXEC mode.

Step 7 

show policy-map interface [interface-id]

Verify your entries.

Step 8 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

This example shows using multiple parent classes to classify matching criteria for voice and video on customer VLANs.

Switch(config)# class-map match-any video
Switch(config-cmap)# match ip dscp af41
Switch(config-cmap)# exit
Switch(config)# class-map match-any voice
Switch(config-cmap)# match ip dscp ef
Switch(config-cmap)# exit
 
   
Switch(config)# class-map match-any customer1-vlan
Switch(config-cmap)# match vlan 100-105
Switch(config-cmap)# exit
Switch(config)# class-map match-any customer2-vlan
Switch(config-cmap)# match vlan 110-120
Switch(config-cmap)# exit
 
   
Switch(config)# policy-map child-policy-1
Switch(config-pmap)# class voice
Switch(config-pmap-c)# police cir 10000000 bc 50000
Switch(config-pmap-c-police)# conform-action set-cos-transmit 5
Switch(config-pmap-c-police)# exceed-action drop
Switch(config-pmap-c-police)# exit
Switch(config-pmap-c)# exit
Switch(config-pmap)# class video
Switch(config-pmap-c)# set cos 4
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# set cos 0
Switch(config-pmap-c)# exit
 
   
Switch(config)# policy-map child-policy-2
Switch(config-pmap)# class voice
Switch(config-pmap-c)# police cir 5000000
Switch(config-pmap-c-police)# conform-action set-cos-transmit 5
Switch(config-pmap-c-police)# exceed-action drop
Switch(config-pmap-c-police)# exit
Switch(config-pmap-c)# exit
Switch(config-pmap)# class video
Switch(config-pmap-c)# police cir 40000000
Switch(config-pmap-c-police)# conform-action set-cos-transmit 4
Switch(config-pmap-c-police)# exceed-action set-cos-transmit 1
Switch(config-pmap-c-police)# exit
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# set cos 0
Switch(config-pmap-c)# exit
 
   
Switch(config)# policy-map uni-parent
Switch(config-pmap)# class customer1-vlan
Switch(config-pmap-c)# service-policy child-policy-1
Switch(config-pmap-c)# exit
Switch(config-pmap)# class customer2-vlan
Switch(config-pmap-c)# service-policy child-policy-2
Switch(config-pmap-c)# exit
 
   
Switch(config)# interface fastethernet0/1
Switch(config-if)# switchport mode trunk
Switch(config-if)# switchport trunk allowed vlan 100-105, 110-120
Switch(config-if)# service-policy input uni-parent
Switch(config-pmap-c)# exit
 
   

In this example, the child policy map child-policy-1 is associated with the class customer1-vlan and child policy-2 uses the class class-default to associate it with all other traffic.

Switch(config)# policy-map uni-parent
Switch(config-pmap)# class customer1-vlan
Switch(config-pmap-c)# service-policy child-policy-1
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# service-policy child-policy-2
Switch(config-pmap-c)# exit

Configuring Output Policy Maps

You use output policy maps to manage congestion avoidance, queuing, and scheduling of packets leaving the switch. The switch has four egress queues, and you use output policy maps to control the queue traffic. You configure shaping, queue-limit, and bandwidth on these queues. You can use high priority (class-based priority queuing). Policing is not supported on output policy maps, except when configuring priority with police for class-based priority queuing. Output policy map classification criteria are matching a CoS, DSCP, or IP precedence value or a QoS group.

Follow these guidelines when configuring output policy maps on physical ports:

You can configure and attach as many output policy maps as there are ports on the switch. Multiple output policy maps can use the same queue-limit configuration. However, these policy maps can have only three unique queue-limit configurations.

Output policy maps can have a maximum of four classes, including the class class-default.

All output policy maps must have the same number of defined class-maps defined, either 1, 2, or 3.

All output policy maps must use the same set of classes, although the actions for each class can differ for each output policy map.

In a child policy map, the class-default supports all output policy map actions except priority and police. Action restrictions for class-default are the same as for other classes except that a queue limit configuration for class-default does not require a scheduling action.

To classify based on criteria at the output, the criteria must be established at the input. You can establish criteria at the input through classification only when you configure only policing and not marking, or through explicit marking when you configure any marking (policing with conform or exceed marking or unconditional set marking).

You cannot configure class-based priority queuing under the class class-default in an output policy map

In an output policy map, unless priority queuing is configured, the class default receives a minimum bandwidth guarantee equal to the unconfigured bandwidth on the port.

After you have attached an output policy map to an interface by using the service-policy interface configuration command, you can change only the parameters of the configured actions (rates, percentages, and so on) or add or delete classification criteria of the class map while the policy map is attached to the interface. To add or delete a class or action, detach the policy map from all interfaces, modify it, and then reattach it to interfaces.


Note If you anticipate that you need three classes in a policy map, define three classes when you create the policy map, even if you are not ready to use all three at that time. You cannot add a class to a policy map after it has been attached to an interface.


When at least one output policy map is attached to an active port, other active ports without output policy maps attached might incorrectly schedule and incorrectly order traffic that uses the same classes as the attached output policy maps. We recommend attaching output policy maps to all ports that are in use. We also recommend putting any unused ports in the shutdown state by entering the shutdown interface configuration command. For example, if you attach an output policy map that shapes DSCP 23 traffic to a port, DSCP traffic that is sent out of any other port without a policy map attached could be incorrectly scheduled or ordered incorrectly with respect to other traffic sent out of the same port.

We strongly recommended that you disable port speed autonegotiation when you attach an output policy map to a port to prevent the port from autonegotiating to a rate that would make the output policy map invalid. You can configure a static port speed by using the speed interface configuration command. If an output policy-map is configured on a port that is set for autonegotiation and the speed autonegotiates to a value that invalidates the policy, the port is put in the error-disabled state.

You can attach only one output policy map per port.

The maximum number of policy maps configured on the switch is 256.

These sections describe how to configure different types of output policy maps:

Configuring Output Policy Maps with Class-Based-Weighted-Queuing

Configuring Output Policy Maps with Class-Based Shaping

Configuring Output Policy Maps with Port Shaping

Configuring Output Policy Maps with Class-Based Priority Queuing

Configuring Output Policy Maps with Weighted Tail Drop

Configuring Output Policy Maps with Class-Based-Weighted-Queuing

You use the bandwidth policy-map class configuration command to configure class-based weighted fair queuing (CBWFQ). CBWFQ sets the relative precedence of a queue by allocating a portion of the total bandwidth that is available for the port.

Follow these guidelines when configuring CBWFQ:

When configuring bandwidth in a policy map, all rate configurations must be in the same format, either a configured rate or a percentage.

The total rate of the minimum bandwidth guarantees for each queue of the policy cannot exceed the total speed for the interface.

You cannot configure CBWFQ (bandwidth) and traffic (shape average) or priority queuing (priority) for the same class in an output policy map.

You cannot configure bandwidth as an absolute rate or a percentage of total bandwidth when strict priority (priority without police) is configured for another class map.

You can configure bandwidth as a percentage of remaining bandwidth only when strict priority (priority without police) is configured for another class in the output policy map.

When you configure CIR bandwidth for a class as an absolute rate or a percentage of total bandwidth, any excess bandwidth that remains after servicing the CIR of all classes in the policy map is divided among the classes the same proportion as the CIR rates. If you configure the CIR rate of a class to be 0, that class is not eligible for any excess bandwidth and receives no bandwidth.

Beginning in privileged EXEC mode, follow these steps to use CBWFQ to control bandwidth allocated to a traffic class by specifying a minimum bandwidth as a bit rate or a percentage:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3 

class {class-map-name | class-default}

Enter a child class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

Step 4 

bandwidth {rate | percent value | remaining percent value}

Set output bandwidth limits for the policy-map class.

Enter a rate to set bandwidth in kilobits per second. The range is from 64 to 1000000.

Enter percent value to set bandwidth as a percentage of the total bandwidth. The range is 1-100 percent.

Enter remaining percent value to set bandwidth as a percentage of the remaining bandwidth. The range is 1-100 percent. This keyword is valid only when strict priority (priority without police) is configured for another class in the output policy map.

Specify the same units in each bandwidth configuration in an output policy (absolute rates or percentages). The total guaranteed bandwidth cannot exceed the total available rate.

Step 5 

exit

Return to policy-map configuration mode.

Step 6 

exit

Return to global configuration mode.

Step 7 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 8 

service-policy output policy-map-name

Attach the policy map (created in Step 2) to the egress interface.

Step 9 

end

Return to privileged EXEC mode.

Step 10 

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

Verify your entries.

Step 11 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the "Attaching a Traffic Policy to an Interface" section.

Use the no form of the appropriate command to delete an existing policy map, class map, or bandwidth configuration.


Note If you enter the no policy-map configuration command or the no policy-map policy-map-name global configuration command to delete a policy map that is attached to an interface, a warning message appears that lists any interfaces from which the policy map is being detached. The policy map is then detached and deleted. For example:
Warning: Detaching Policy test1 from Interface GigabitEthernet0/1


This example shows how to set the precedence of a queue by allocating 25 percent of the total available bandwidth to the traffic class defined by the class map:

Switch(config)# policy-map gold_policy
Switch(config-pmap)# class out_class-1
Switch(config-pmap-c)# bandwidth percent 25
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# service-policy output gold_policy
Switch(config-if)# exit

Configuring Output Policy Maps with Class-Based Shaping

You use the shape average policy-map class configuration command to configure traffic shaping. Class-based shaping is a control mechanism that is applied to classes of traffic leaving an interface and uses the shape average command to limit the rate of data transmission used for the committed information rate (CIR) for the class.

Follow these guidelines when configuring class-based shaping:

Configuring a queue for traffic shaping sets the maximum bandwidth or peak information rate (PIR) of the queue. In the Cisco ME switch, configuring traffic shaping automatically also sets the minimum bandwidth guarantee or CIR of the queue to the same value as the PIR.

You cannot configure CBWFQ (bandwidth) or priority queuing (priority) and traffic (shape average) for the same class in an output policy map.

You cannot configure traffic shaping for a traffic class when strict priority (priority without police) is configured for another class within the output policy-map.

Beginning in privileged EXEC mode, follow these steps to use class-based shaping to configure the maximum permitted average rate for a class of traffic:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3 

class {class-map-name | class-default}

Enter a child class-map name or class-default to match all unclassified packets, and enter policy-map class configuration mode.

Step 4 

shape average target bps

Specify the average class-based shaping rate.

For target bps, specify the average bit rate in bits per second. The range is from 64000 to 1000000000.

Step 5 

exit

Return to policy-map configuration mode.

Step 6 

exit

Return to global configuration mode.

Step 7 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 8 

service-policy output policy-map-name

Attach the policy map (created in Step 2) to the egress interface.

Step 9 

end

Return to privileged EXEC mode.

Step 10 

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

Verify your entries.

Step 11 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the "Attaching a Traffic Policy to an Interface" section.

Use the no form of the appropriate command to delete an existing policy map or class map or to delete a class-based shaping configuration.

This example shows how to configure traffic shaping for outgoing traffic on a Fast Ethernet port so that outclass1, outclass2, and outclass3 get a maximum of 50, 20, and 10 Mb/s of the available port bandwidth. The class class-default gets the remaining bandwidth.

Switch(config)# policy-map out-policy
Switch(config-pmap)# class classout1
Switch(config-pmap-c)# shape average 50000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class classout2
Switch(config-pmap-c)# shape average 20000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class classout3
Switch(config-pmap-c)# shape average 10000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output out-policy
Switch(config-if)# exit

Configuring Output Policy Maps with Port Shaping

Port shaping is applied to all traffic leaving an interface. It uses a policy map with only class default when the maximum bandwidth for the port is specified by using the shape average command. A child policy can be attached to the class-default in a hierarchical policy map format to specify class-based actions for the queues on the shaped port.

The total of the minimum bandwidth guarantees (CIR) for each queue of the child policy cannot exceed the total port shape rate.

Beginning in privileged EXEC mode, follow these steps to use port shaping to configure the maximum permitted average rate for a class of traffic:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policy-map policy-map-name

Create a hierarchical policy map by entering the hierarchical policy map name, and enter policy-map configuration mode for the parent policy.

Step 3 

class class-default

Enter a policy-map class configuration mode for the default class.

Step 4 

shape average target bps

Specify the average class-based shaping rate.

For target bps, specify the average bit rate in bits per second. The range is from 4000000 to 1000000000.

Step 5 

service-policy policy-map-name

Specify the child policy-map to be used in the hierarchical policy map if required.

Step 6 

exit

Return to policy-map configuration mode.

Step 7 

exit

Return to global configuration mode.

Step 8 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 9 

service-policy output policy-map-name

Attach the parent policy map (created in Step 2) to the egress interface.

Step 10 

end

Return to privileged EXEC mode.

Step 11 

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

Verify your entries.

Step 12 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created the hierarchical output policy map, you attach it to an egress port. See the "Attaching a Traffic Policy to an Interface" section.

Use the no form of the appropriate command to delete an existing hierarchical policy map, to delete a port shaping configuration, or to remove the policy map from the hierarchical policy map.

This example shows how to configure port shaping by configuring a hierarchical policy map that shapes a port to 90 Mbps, allocated according to the out-policy policy map configured in the previous example.

Switch(config)# policy-map out-policy-parent
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# shape average 90000000
Switch(config-pmap-c)# service-policy out-policy
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output out-policy-parent
Switch(config-if)# exit

Configuring Output Policy Maps with Class-Based Priority Queuing

You can use the priority policy-map class configuration command to ensure that a particular class of traffic is given preferential treatment. With strict priority queuing, the priority queue is constantly serviced; all packets in the queue are scheduled and sent until the queue is empty. Excessive use of the priority queues can possibly delay packets in other queues and create unnecessary congestion.

You can configure strict priority queuing (priority without police), or you can configure an unconditional priority policer (priority with police). Follow these guidelines when configuring priority queuing:

You can associate the priority command with a single unique class for all attached output policies on the switch.

When you configure a traffic class as a priority queue, you can configure only police and queue-limit as other queuing actions for the same class. You cannot configure bandwidth or shape average with priority queues in the same class.

You cannot associate the priority command with the class-default of the output policy map.

Configuring Priority Without Police

Follow these guidelines when configuring strict priority queuing (priority without police):

You cannot configure priority queuing without policing for a traffic class when class-based shaping (shape average) or CBWFQ (bandwidth) is configured for another class within the output policy-map.

When you configure priority queuing without policing for a traffic class, you can only configure the other queues for sharing by using the bandwidth remaining percent policy-map class configuration command to allocate excess bandwidth. This command does not guarantee the allocated bandwidth, but does ensure the rate of distribution.

Beginning in privileged EXEC mode, follow these steps to configure a strict priority queue:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

class-map class-map-name

Create classes for three egress queues. Enter match conditions classification for each class.

Step 3 

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 4 

class class-map-name

Enter the name of the priority class (created by using the class-map global configuration command), and enter policy-map class configuration mode for the priority class.

Step 5 

priority

Set the strict scheduling priority for this class.

Note Only one unique class map on the switch can be associated with a priority command. You cannot configure priority along with any other queuing action (bandwidth or shape average).

Step 6 

exit

Exit policy-map class configuration mode for the priority class.

Step 7 

class class-map-name

Enter the name of a nonpriority class, and enter policy-map class configuration mode for that class.

Step 8 

bandwidth remaining percent value

Set output bandwidth limits for the policy-map class as a percentage of the remaining bandwidth. The range is 1-100 percent.

Step 9 

exit

Exit policy-map class configuration mode for the class

Step 10 

exit

Return to global configuration mode.

Step 11 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 12 

service-policy output policy-map-name

Attach the policy map (created in Step 3) to the egress interface.

Step 13 

end

Return to privileged EXEC mode.

Step 14 

show policy-map

Verify your entries.

Step 15 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the "Attaching a Traffic Policy to an Interface" section.

Use the no form of the appropriate command to delete an existing policy map or class map or to cancel strict priority queuing for the priority class or the bandwidth setting for the other classes.

This example shows how to configure the class out-class1 as a strict priority queue so that all packets in that class are sent before any other class of traffic. Other traffic queues are configured so that out-class-2 gets 50 percent of the remaining bandwidth and out-class3 gets 20 percent of the remaining bandwidth. The class class-default receives the remaining 30 percent with no guarantees.

Switch(config)# policy-map policy1
Switch(config-pmap)# class out-class1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class2
Switch(config-pmap-c)# bandwidth remaining percent 50
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class3
Switch(config-pmap-c)# bandwidth remaining percent 20
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# service-policy output policy1
Switch(config-if)# exit

Configuring Priority With Police

You can use the priority with police feature and configure an unconditional priority policer to limit the bandwidth used by the priority queue and allocate bandwidth or shape other queues. Follow these guidelines when configuring priority with police:

You cannot configure a policer committed burst size for an unconditional priority policer even though the keyword is visible in the CLI help. Any configured burst size is ignored when you try to attach the output service policy.

The allowed police rate range is 64000-1000000000 bps, even though the range that appears in the CLI help is 8000-1000000000. You cannot attach an output service policy with an out-of-range rate.

You cannot configure priority with policing for a traffic class when bandwidth remaining percent is configured for another class in the same output policy map.

Beginning in privileged EXEC mode, follow these steps to configure priority with police:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

class-map class-map-name

Create classes for three egress queues. Enter match conditions classification for each class.

Step 3 

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 4 

class class-map-name

Enter the name of the priority class (created by using the class-map global configuration command), and enter policy-map class configuration mode for the priority class.

Step 5 

priority

Configure this class as the priority class.

Note Only one unique class map on the switch can be associated with a priority command.

Step 6 

police {rate-bps | cir cir-bps}

Define a policer for the priority class of traffic.

For rate-bps, specify average traffic rate in bits per second (bps). The range is 64000-1000000000.

Note When you use the police command with the priority command in an output policy, the police rate range and the CIR range are 64000-1000000000 bps, even though the range that appears in the CLI help is 8000-1000000000. You cannot attach an output service policy with an out-of-range rate.

For cir cir-bps, specify a committed information rate (CIR) in bits per second (bps). The range is 64000-1000000000.

Note Although visible in the command-line help string, the burst-size option is not supported in output policy maps. You cannot attach an output service policy map that has a configured burst size.

Step 7 

conform-action [transmit]

(Optional) Enter the action to be taken on packets that conform to the CIR. If no action is entered, the default action is to send the packet.

Note You can enter a single conform-action as part of the command string following the police command. You can also enter a carriage return after the police command and enter policy-map class police configuration mode to enter the conform-action. When the police command is configured with priority in an output policy map, only the default conform-action of transmit is supported. Although visible in the command-line help string, the other police conform actions are not supported in output policy maps.

Step 8 

exceed-action [drop]

(Optional) Enter the action to be taken for packets that do not conform to the CIR. If no action is entered, the default action is to drop the packet.

Note You can enter a single exceed-action as part of the command string following the police command. You can also enter a carriage return after the police command and enter policy-map class police configuration mode to enter the exceed-action. When the police command is configured with priority in an output policy map, only the default exceed-action of drop is supported. Although visible in the command-line help string, the other police exceed actions are not supported in output policy maps.

Step 9 

exit

Exit policy-map class configuration mode for the priority class.

Step 10 

class class-map-name

Enter the name of the first nonpriority class, and enter policy-map class configuration mode for that class.

Step 11 

bandwidth {rate | percent value}

or

shape average target bps

Set output bandwidth limits for the policy-map class in kilobits per second (the range is 64-1000000) or a percentage of the total bandwidth (the range is 1-100 percent). Or, specify the average class-based shaping rate in bits per second (the range is 64000-1000000000).

Step 12 

exit

Return to policy-map configuration mode.

Step 13 

exit

Return to global configuration mode.

Step 14 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 15 

service-policy output policy-map-name

Attach the policy map (created in Step 3) to the egress interface.

Step 16 

end

Return to privileged EXEC mode.

Step 17 

show policy-map

Verify your entries.

Step 18 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the "Attaching a Traffic Policy to an Interface" section.

Use the no form of the appropriate command to delete an existing policy map or class map or to cancel the priority queuing or policing for the priority class or the bandwidth setting for the other classes.

This example shows how to use the priority with police commands to configure out-class1 as the priority queue, with traffic going to the queue limited to 20,000,000 bps so that the priority queue never uses more than the limit. Traffic above that rate is dropped. The other traffic queues are configured as in the previous example.

Switch(config)# policy-map policy1
Switch(config-pmap)# class out-class1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police 200000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class2
Switch(config-pmap-c)# bandwidth percent 50
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class3
Switch(config-pmap-c)# bandwidth percent 20
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# service-policy output policy1
Switch(config-if)# exit

Configuring Output Policy Maps with Weighted Tail Drop

Weighted tail drop (WTD) adjusts the queue size (buffer size) associated with a traffic class. You configure WTD by using the queue-limit policy-map class configuration command.

Follow these guidelines when configuring WTD:

Configuring WTD with the queue-limit command is supported only when you first configure a scheduling action, such as bandwidth, shape average, or priority. The exception is when you are configuring queue-limit in the class-default.

You can configure and attach as many output policy maps as there are ports. Multiple output policy maps can use the same queue-limit configuration. However, these policy maps can have only three unique queue-limit configurations.

You can use the queue-limit command to configure the queue-limit for CPU-generated traffic.

When you use the queue-limit command to configure queue thresholds for a class, the WTD thresholds must be less than or equal to the queue maximum threshold. A queue size configured with no qualifier must be larger than any queue sizes configured with qualifiers.

You cannot configure more than two unique threshold values for the WTD qualifiers (cos, dscp, precedence, or qos-group) in the queue-limit command. However, there is no limit to the number of qualifiers that you can map to those thresholds. You can configure a third unique threshold value to set the maximum queue, using the queue-limit command with no qualifiers.

A WTD qualifier in the queue-limit command must be the same as at least one match qualifier in the associated class map.

In an output policy map, when you configure a queue-limit for a unique class, all other output policy maps must use the same format of qualifier type and qualifier value. Only queue-limit threshold values can be different. For example, when you configure class A queue-limit thresholds for dscp 30 and dscp 50 in policy-map1, and you configure class A queue-limits in policy-map 2, use dscp 30 and dscp 50 as qualifiers. You cannot use dscp 20 and dscp 40. The threshold values can be different, but different threshold values would create a new unique queue-limit configuration.

Beginning in privileged EXEC mode, follow these steps to use WTD to adjust the queue size for a traffic class:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

policy-map policy-map-name

Create a policy map by entering the policy map name, and enter policy-map configuration mode.

Step 3 

class {class-map-name | class-default}

Enter a child class-map name, or class-default to match all unclassified packets, and enter policy-map class configuration mode.

If you enter a class-map name, perform Step 4 to configure a scheduling action (bandwidth, shape average, or priority) before you go to Step 5 to configure queue-limit.

If you enter class-default, you can skip Step 4.

Step 4 

bandwidth {rate | percent value | remaining percent value}
or
shape average target bps
or
priority

Configure a scheduling action for the traffic class. For more information, see these topics:

"Configuring Output Policy Maps with Class-Based-Weighted-Queuing" section

"Configuring Output Policy Maps with Class-Based Shaping" section

"Configuring Output Policy Maps with Port Shaping" section

"Configuring Output Policy Maps with Class-Based Priority Queuing" section.

Step 5 

queue-limit [cos value | dscp value | precedence value | qos-group value] number-of-packets [packets]

Specify the queue size for the traffic class.

(Optional) For cos value, specify a CoS value. The range is from 0 to 7.

(Optional) For dscp value, specify a DSCP value. The range is from 0 to 63.

(Optional) For precedence value, specify an IP precedence value. The range is from 0 to 7.

(Optional) For qos-group value, enter a QoS group value. The range is from 0 to 99.

For number-of-packets, set the minimum threshold for WTD. The range is from 16 to 544, in multiples of 16, where each packet is a fixed unit of 256 bytes.

Note For optimal performance, we strongly recommend that you configure the queue-limit to 272 or less.

The value is specified in packets by default, but the packets keyword is optional.

Note Multiple output policy maps can use the same queue-limit configuration. However these policy maps can have only three unique queue-limit configurations.

Step 6 

exit

Return to policy-map configuration mode.

Step 7 

exit

Return to global configuration mode.

Step 8 

interface interface-id

Enter interface configuration mode for the interface to which you want to attach the policy.

Step 9 

service-policy output policy-map-name

Attach the policy map (created in Step 2) to the egress interface.

Note If you try to attach an output policy map that contains a fourth queue-limit configuration, you see an error message, and the attachment is not allowed.

Step 10 

end

Return to privileged EXEC mode.

Step 11 

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

Verify your entries.

Step 12 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you have created an output policy map, you attach it to an egress port. See the "Configuring Output Policy Maps" section.

Use the no form of the appropriate command to delete an existing policy map or class map or to delete a WTD configuration.

This example shows a policy map with a specified bandwidth and queue size. Traffic that is not DSCP 30 or 10 is assigned a queue limit of 112 packets. Traffic with a DSCP value of 30 is assigned a queue-limit of 48 packets, and traffic with a DSCP value of 10 is assigned a queue limit of 32 packets. All traffic not belonging to the class traffic is classified into class-default, which is configured with 10 percent of the total available bandwidth and a large queue size of 256 packets.

Switch(config)# policy-map gold-policy
Switch(config-pmap)# class traffic
Switch(config-pmap-c)# bandwidth percent 50
Switch(config-pmap-c)# queue-limit 112
Switch(config-pmap-c)# queue-limit dscp 30 48
Switch(config-pmap-c)# queue-limit dscp 10 32
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# bandwidth percent 10
Switch(config-pmap-c)# queue-limit 256
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# service-policy output gold-policy
Switch(config-if)# exit

Configuring QoS Marking and Queuing for CPU-Generated Traffic

Beginning in privileged EXEC mode, follow these steps to configure marking and queuing of CPU-generated traffic. This procedure is optional.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

Configure global table maps

Refer to the "Configuring Table Maps" section.

Step 3 

cpu traffic qos cos {cos-value | cos [table-map table-map-name] | dscp [table-map table-map-name] | prec [table-map table-map-name]}

Mark traffic by setting a new CoS value or by specifying a table map.

For cos-value, enter a new CoS value. The range is 0-7.

You can also mark CoS based on the CoS, DSCP, or IP-precedence value. You can optionally use a table map to configure CoS. If you do not enter table-map table-map-name, the table map default behavior is copy. See the "Table Maps" section.

When you complete this step, go to Step 7.

Step 4 

cpu traffic qos dscp {dscp_value | cos [table-map table-map-name] | dscp [table-map table-map-name] | prec [table-map table-map-name]}

Mark traffic by setting a new DsCP value or by specifying a table map.

For dscp new-dscp, enter a new DSCP value for the classified traffic. The range is 0-63.

You can also configure a table map to mark DSCP based on the CoS, DSCP, or IP-precedence value. You can optionally enter the table name. If you do not enter table-map table-map-map name, the table map default behavior is copy. See the "Table Maps" section.

For additional DSCP classification options, see the "Classification Based on IP DSCP" section.

When you complete this step, go to Step 7.

Step 5 

cpu traffic qos precedence {precedence_value | cos [table-map table-map-name] | dscp [table-map table-map-name] | prec [table-map table-map-name]}

Mark traffic by setting a new precedence value or by specifying a table map.

For precedence new-precedence, enter a new IP-precedence value as a number from 0 to 7 or by name: routine (0), priority (1), immediate (2), flash (3), flash-override (4), critical (5), internet (6), network (7).

You can also configure a table map to mark precedence based on the CoS, DSCP, or IP-precedence value. You can optionally enter the table name. If you do not enter table-map table-map-map name, the table map default behavior is copy. See the "Table Maps" section.

When you complete this step, go to Step 7.

Step 6 

cpu traffic qos qos-group qos-group-value

Mark traffic by using a QoS group.

For qos-group-value, identify a QoS group to use at egress. The range is 0-9.

When you complete this step, go to Step 7.

Step 7 

end

Return to privileged EXEC mode.

Step 8 

Configure output policy maps to map QoS markings like COS, IP DSCP, IP precedence, and QoS group to class queues, configure queuing and scheduling

Refer to the "Configuring Output Policy Maps" section.

Step 9 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Step 10 

show running-config

Display the configured class maps, policy maps, table maps, and CPU traffic QoS settings.

Step 11 

show cpu traffic qos

Display the QoS marking values for CPU-generated traffic.

Step 12 

show table-map [table-map-name]

Display information for all table maps or the specified table map.

Step 13 

show policy-map [policy-map-name | interface [interface-id] [output] [class class-name]]

Display QoS policy map information for the specified policy map name, interface, input or output policy maps, or policy-map class.

To disable any command, use the no form of the command.

Configuration Examples QoS Marking and Queuing for CPU-Generated Traffic

Example 1

This example shows how to configure egress queuing based on the DSCP value of CPU-generated IP packets.

All CPU-generated IP traffic queues on the egress port, based on its IP DSCP value, and the configured output policy map output-policy.

All IP SLA or TWAMP probes with the DSCP value ef to simulate voice traffic are assigned to the voice class.

All IP SLA or TWAMP probes with the DSCP values af41, af42, and af43 to simulate video traffic are assigned to the video class.

All IP control protocol traffic with the DSCP values 48 and 56 are assigned to the network-internetwork-control class.

The rest of the IP traffic is assigned to the default class.

All CPU-generated non-IP traffic is statically mapped to a fixed queue on the egress port.

All CFM traffic is queued to the default class because there is no class based on CoS.

 
   
Switch(config)# cpu traffic qos dscp dscp

Class:

Switch(config)# class-map match-any video
Switch(config-cmap)# match ip dscp af41 af42 af43
Switch(config-cmap)# exit
 
   
Switch(config)# class-map match-any voice
Switch(config-cmap)# match ip dscp ef
Switch(config-cmap)# exit
 
   
Switch(config)# class-map match-any network-internetwork-control
Switch(config-cmap)# match ip dscp 48 56
Switch(config-cmap)# exit

Policy:

Switch(config)# policy-map output-policy
Switch(config-pmap)# class voice
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police cir 10000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class video
Switch(config-pmap-c)# bandwidth percent 40
Switch(config-pmap-c)# exit
Switch(config-pmap)# class network-internetwork-control
Switch(config-pmap-c)# bandwidth percent 10
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# bandwidth percent 30
Switch(config-pmap-c)# exit

Interface

Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output output-policy
Switch(config-pmap-c)# exit
 
   

Example 2

This example shows how to mark the CoS of CPU-generated IP traffic (including IP-SLA and TWAMP) based on the DSCP value in the packet and to configure egress queuing based on the CoS value.

All CPU-generated IP traffic queues on the egress port, based on the IP DSCP value and the configured output policy map called output-policy.

All IP SLA or TWAMP probes with the DSCP value ef to simulate voice traffic are assigned to the voice class.

All IP SLA or TWAMP probes with the DSCP values af41, af42, and af43 to simulate video traffic are assigned to the video class.

All IP control protocol traffic with the DSCP values 48 and 56 are assigned to the network-internetwork-control class.

The rest of the IP traffic is assigned to the default class.

All CPU-generated non-IP traffic with CoS 5 is assigned to the voice class.

All CPU-generated non-IP traffic with CoS 3 is assigned to the video class.

All CPU-generated non-IP traffic with CoS 6 and 7 is assigned to the network-internetwork-control class.

All CFM traffic with CoS 5 is assigned to the voice class.

All CFM traffic with CoS 3 is assigned to the video class.

All CFM traffic with CoS 6 and 7 is assigned to the network-internetwork-control class.

Table Map:

Switch(config)# table-map dscp-to-cos
Switch(config-tablemap)# map from 46 to 5
Switch(config-tablemap)# map from 48 to 6
Switch(config-tablemap)# map from 56 to 7
Switch(config-tablemap)# map from af41 to 3
Switch(config-tablemap)# map from af42 to 3
Switch(config-tablemap)# map from af43 to 3
Switch(config-tablemap)# default 0
Switch(config-tablemap)# end

CPU QoS:

Switch(config)# cpu traffic qos cos dscp table-map dscp-to-cos
Switch(config)# cpu traffic qos cos cos 

Class:

Switch(config)# class-map match-any video
Switch(config-cmap)# match cos 3
Switch(config-cmap)# exit
 
   
Switch(config)# class-map match-any voice
Switch(config-cmap)# match cos 5
Switch(config-cmap)# exit
 
   
Switch(config)# class-map match-any network-internetwork-control
Switch(config-cmap)# match cos 6 7
Switch(config-cmap)# exit

Policy:

Switch(config)# policy-map output-policy
Switch(config-pmap)# class voice
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police cir 10000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class video
Switch(config-pmap-c)# bandwidth percent 40
Switch(config-pmap-c)# exit
Switch(config-pmap)# class network-internetwork-control
Switch(config-pmap-c)# bandwidth percent 10
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# bandwidth percent 30
Switch(config-pmap-c)# exit

Interface

Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output output-policy
Switch(config-pmap-c)# exit
 
   

Example 3

This example shows how to:

Mark the DSCP value of CPU-generated IP traffic (including IP-SLA and TWAMP) based on the DSCP value in the packet.

Mark the CoS of CPU-generated IP traffic (including IP-SLA and TWAMP) based on the DSCP value in the packet.

Mark the CoS of CPU-generated non-IP traffic based on the CoS value in the packet.

Mark all CPU-generated traffic with the QoS group.

Configure egress queuing based on the QoS group.

The example has these results:

All CPU-generated IP traffic with DSCP values 46, 48, and 56 retains the existing markings.

For all other CPU-generated IP packets, the DSCP value is reset to 0.

All CPU-generated IP traffic with DSCP values 46, 48, and 56 is mapped to the corresponding CoS values of 5, 6, and 7 respectively.

For all other CPU-generated IP packets, the CoS value resets to 0.

All CPU-generated non-IP traffic with the CoS values of 5, 6, and 7 retain the existing markings.

For all other CPU-generated non-IP packets, the CoS value resets to 0.

All CPU-generated traffic goes through a single class called cpu-traffic. The user-voice classes user-voice and user-video are reserved for user traffic. As a result, CPU traffic and user traffic are separated into different queues on the egress port.

Table Map

Switch(config)# table-map dscp-to-cos
Switch(config-tablemap)# map from 46 to 5
Switch(config-tablemap)# map from 48 to 6
Switch(config-tablemap)# map from 56 to 7
Switch(config-tablemap)# default 0
Switch(config-tablemap)# end
 
   
Switch(config)# table-map dscp-to-dscp
Switch(config-tablemap)# map from 46 to 46
Switch(config-tablemap)# map from 48 to 48
Switch(config-tablemap)# map from 56 to 56
Switch(config-tablemap)# default 0
Switch(config-tablemap)# end
 
   
Switch(config)# table-map cos-to-cos
Switch(config-tablemap)# map from 5 to 5
Switch(config-tablemap)# map from 6 to 6
Switch(config-tablemap)# map from 7 to 7
Switch(config-tablemap)# default 0
Switch(config-tablemap)# end

CPU QoS:

Switch(config)# cpu traffic qos dscp dscp table-map dscp-to-dscp
Switch(config)# cpu traffic qos cos dscp table dscp-to-cos
Switch(config)# cpu traffic qos cos cos table cos-to-cos
Switch(config)# cpu traffic qos qos-group 50

Class:

Switch(config)# class-map match-any cpu-traffic
Switch(config-cmap)# match qos-group 50
Switch(config-cmap)# exit
 
   
Switch(config)# class-map match-any user-video
Switch(config-cmap)# match cos 3
Switch(config-cmap)# exit
 
   
Switch(config)# class-map match-any user-voice
Switch(config-cmap)# match cos 5
Switch(config-cmap)# exit
 
   
Policy:
Switch(config)# policy-map output-policy
Switch(config-pmap)# class user-voice
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police cir 10000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class user-video
Switch(config-pmap-c)# bandwidth percent 40
Switch(config-pmap-c)# exit
Switch(config-pmap)# class cpu-traffic
Switch(config-pmap-c)# bandwidth percent 10
Switch(config-pmap-c)# exit
Switch(config-pmap)# class class-default
Switch(config-pmap-c)# bandwidth percent 30
Switch(config-pmap-c)# exit
 
Interface: 
Switch(config)# interface fastethernet0/1
Switch(config-if)# service-policy output output-policy
Switch(config-pmap-c)# exit
 
   

Displaying QoS Information

To display QoS information, use one or more of the privileged EXEC commands in Table 34-2. For explanations about available keywords, see the command reference for this release.

Table 34-2 Commands for Displaying Standard QoS Information 

Command
Purpose

show class-map [class-map-name]

Display QoS class-map information for all class maps or the specified class map.

show policer aggregate [aggregate-policer-name]

Display information about all aggregate policers or the specified aggregate policer.

show policy-map [policy-map-name | interface [interface-id] [input | output] [class class-name]]

Display QoS policy map information for the specified policy map name, interface, input or output policy maps, or policy-map class.

show cpu traffic qos

Display the QoS marking values for CPU-generated traffic.

show running-config

Display the configured class maps, policy maps, table maps, and aggregate policers.

show table-map [table-map-name]

Display information for all configured table maps or the specified table map.


QoS Statistics

There are several ways to display QoS input and output policy-map statistics.

For input policy maps, you can use the show policy-map interface [interface-id] privileged EXEC command to display per-class per-policer conform and exceed statistics. Policer conform statistics are the number of packets that conform to the configured policer profile; policer exceed statistics are the number of packets that exceed the configured policer profile. The switch does not support per-class classification statistics, but you can determine these statistics by configuring policing at line rate for the class. In this case, no packets exceed the configured policer profile, and the policer conform statistics would equal the class classification statistics.

Another way to view input QoS statistics is in the output of the show platform qos statistics interface [interface-id] privileged EXEC command. The per-port frame statistics are sorted by the DSCP and CoS values of the incoming frames on the port. These statistics do not provide any information about the MQC input policy map configured on the interface.

For output policy maps, you can use the show policy-map interface [interface-id] command to display per-class classification statistics that show the total number of packets that match the specified class. This count includes the total number of packets that are sent and dropped for that class. You can use the same command to view the per-class tail drop statistics.

Configuration Examples for Policy Maps

This section includes configuration examples for configuring QoS policies on the Cisco ME switch, including configuration limitations and restrictions. The sections are broken into different configurations actions that a customer might do. Each section provides the exact sequence of steps that you must follow for successful configuration or modification.

QoS Configuration for Customer A

QoS Configuration for Customer B

Modifying Output Policies and Adding or Deleting Classification Criteria

Modifying Output Policies and Changing Queuing or Scheduling Parameters

Modifying Output Policies and Adding or Deleting Configured Actions

Modifying Output Policies and Adding or Deleting a Class

QoS Configuration for Customer A

This section provides examples of the initial configuration and activation of QoS policies for a customer switch. Input and output QoS service policies are configured based on the requirements and attached to relevant ports.

In the initial configuration for Customer A, Fast Ethernet ports 1 through 24 are user network interfaces (UNIs) and are disabled by default. Gigabit Ethernet ports 1 and 2 are network node interfaces (NNIs) and are enabled by default.

This overall sequence is for initial configuration:

Configure classes and policies.

Shut down all active ports.

Attach policies to ports to be activated.

Take the ports out of the shut-down state.

Leave unused ports shut down.

Note these restrictions for configuring output policies:

You can define up to three classes in the output policy map.

The defined classes must be the same as other output policy maps.

The number of defined classes in each output policy map must be same.

Assign an action to each class since there can be no empty class.

Each class configuration must be based on the classification/marking done in the input policy-map.

This example configures classes for input service policies and defines three classes of service: gold, silver, and bronze. Because a match-all classification (the default) can have only single classification criterion, the match-any classification is used so that you can add classification criteria in the future.

Switch# config terminal
Switch(config)# class-map match-any gold-in
Switch(config-cmap)# match ip dscp af11
Switch(config-cmap)# exit
Switch(config)# class-map match-any silver-in
Switch(config-cmap)# match ip dscp af21
Switch(config-cmap)# exit
Switch(config)# class-map match-any bronze-in
Switch(config-cmap)# match ip dscp af31
Switch(config-cmap)# exit
 
   

This example shows how to configure an input policy map that marks the gold class and polices the silver class to 50 Mb/s and the bronze class to 20 Mb/s.

Switch(config)# policy-map input-all
Switch(config-pmap)# class gold-in
Switch(config-pmap-c)# set ip dscp af43
Switch(config-pmap-c)# exit
Switch(config-pmap)# class silver-in
Switch(config-pmap-c)# police 50000000
Switch(config-pmap)# class bronze-in
Switch(config-pmap-c)# police 20000000
Switch(config-pmap-c)# exit
 
   

This example configures classes for output service policies with three classes of service: gold, silver, and bronze. The gold class is configured to match the marked value in the input service policy. Because a match-all classification (the default) can have only single classification criterion, the match-any classification is used so that you can add classification criteria in the future.

Switch# config terminal
Switch(config)# class-map match-any gold-out
Switch(config-cmap)# match ip dscp af43
Switch(config-cmap)# exit
Switch(config)# class-map match-any silver-out
Switch(config-cmap)# match ip dscp af21
Switch(config-cmap)# exit
Switch(config)# class-map match-any bronze-out
Switch(config-cmap)# match ip dscp af31
Switch(config-cmap)# exit
 
   

This example configures one output service policy to be applied to both Gigabit Ethernet NNIs, providing priority with rate-limiting to the gold class, class-based shaping for the silver class, and a minimum bandwidth guarantee of 10 percent to the bronze class.

Switch(config)# policy-map output-g1-2
Switch(config-pmap)# class gold-out
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police 50000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class silver-out
Switch(config-pmap-c)# shape average 200000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class bronze-out
Switch(config-pmap-c)# bandwidth percent 10
Switch(config-pmap-c)# exit
 
   

This example configures a second output service policy to be applied to Fast Ethernet UNIs 1 to 8, providing strict priority to the gold class and distributing the remaining bandwidth in the desired proportions over the remaining classes.

Switch(config)# policy-map output1-8
Switch(config-pmap)# class gold-out
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# exit
Switch(config-pmap)# class silver-out
Switch(config-pmap-c)# bandwidth remaining percent 50
Switch(config-pmap-c)# exit
Switch(config-pmap)# class bronze-out
Switch(config-pmap-c)# bandwidth remaining percent 20
Switch(config-pmap-c)# exit
 
   

This example attaches the input and output service policies to the Gigabit Ethernet ports and activates them.

Switch(config)# interface range gigabitethernet0/1-2
Switch(config-if-range)# service-policy input input-all
Switch(config-if-range)# service-policy output output-g1-2
Switch(config-if-range)# no shutdown
Switch(config-if-range)# exit
 
   

This example attaches the input and output service policies to Fast Ethernet ports 1 to 8 and activates them.

Switch(config)# interface range fastethernet0/1 - 8
Switch(config-if-range)# service-policy input input-all
Switch(config-if-range)# service-policy output output1-8
Switch(config-if-range)# no shutdown
Switch(config-if-range)# exit

QoS Configuration for Customer B

This section provides examples for configuring and activating QoS policies on the switch for a new set of customers without affecting the current customers. Input and output QoS service policies are configured based on the requirements and attached to relevant ports. The example uses an existing input policy-map and configures a new output policy map for the new customers.

In the initial configuration for Customer B, Fast Ethernet ports 1 through 8 are UNIs and are active. Fast Ethernet ports 9 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

This overall sequence is for initial configuration:

Define any new required output policies.

Attach input and output policies to ports to be activated.

Take the ports out of the shut-down state.

Note these restrictions when configuring output policies:

You can define up to three classes in the output policy map.

The defined classes must be the same as other output policy maps.

The number of defined classes in each output policy map must be same.

Assign an action to each class; that is, there can be no empty class.

Each class configuration must be based on the classification/marking done in the input policy-map.

This example configures a third output service policy to be attached to Fast Ethernet UNIs 9 through 12, providing a minimum guaranteed bandwidth of 50 Mb/s to the gold class, 20 Mb/s to the silver class, and 10 Mb/s to the bronze class:

Switch(config)# policy-map output9-12
Switch(config-pmap)# class gold-out
Switch(config-pmap-c)# bandwidth 50000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class silver-out
Switch(config-pmap-c)# bandwidth 20000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class bronze-out
Switch(config-pmap-c)# bandwidth 10000
Switch(config-pmap-c)# exit
 
   

This example attaches the output policy for Fast Ethernet ports 9 through 12 and activates the ports:

Switch# config terminal
Switch(config)# interface range fastethernet0/9-12
Switch(config-if-range)# service-policy input input-all
Switch(config-if-range)# service-policy output output9-12
Switch(config-if-range)# no shutdown
Switch(config-if-range)# exit

Modifying Output Policies and Adding or Deleting Classification Criteria

This section provides examples of updating an existing set of output policy maps to add or delete classification criteria. The modification might be required due to a change in the service provisioning requirements or a change in the input service policy map. You can make the change without shutting down any port.

In the initial configuration, Fast Ethernet ports 1 through 12 are UNIs and are active. Fast Ethernet ports 13 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

This overall sequence is for initial configuration:

Change the configured class map for an input service policy.

Change the configured class map for an output service policy.

This example modifies classes for an input service policy by adding classification criteria to the silver-in class to match ip dscp cs5. This configuration is required for the output policy-map to match to dscp cs5.

Switch(config)# class-map match-any silver-in
Switch(config-cmap)# match ip dscp af21
Switch(config-cmap)# match ip dscp cs5
Switch(config-cmap)# exit
 
   

This example modifies classes for an output service policy, adding classification criteria to the silver-out class to match ip dscp cs5. This adds dscp cs5 to the silver-out class on all configured and attached output service policies. The dscp cs5 flow now receives the same queuing and scheduling treatment as the silver-out class.

Switch# config terminal
Switch(config)# class-map match-any silver-out
Switch(config-cmap)# match ip dscp af21
Switch(config-cmap)# match ip dscp cs5
Switch(config-cmap)# exit
 
   

Use the same procedure when deleting a match statement associated with a configured class.

Modifying Output Policies and Changing Queuing or Scheduling Parameters

This section provides examples of updating an existing set of output policy maps to modify the parameters of the configured queuing and scheduling actions. The modification in the output policy map might be required due to a change in the service provisioning requirements. You can make the change without shutting down any port.

In the initial configuration, Fast Ethernet ports 1 through 12 are UNIs and are active. Fast Ethernet ports 13 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

The requirement is to change the action parameters.

Note these restrictions when configuring output policies:

You can define up to three classes in the output policy map.

The defined classes must be the same as other output policy maps.

The number of defined classes in each output policy map must be same.

Assign an action to each class; that is, there can be no empty class.

Each class configuration must be based on the classification or marking done in the input policy-map.

This example modifies the third output service policy servicing Fast Ethernet UNIs 8 through 12 by providing minimum guaranteed bandwidth of 40 Mb/s to the gold class (changed from 50 Mb/s), 30 Mb/s to the silver class (changed from 20 Mb/s), and 20 Mb/s to the bronze class (changed from 10 Mbps).

Switch(config)# policy-map output9-12
Switch(config-pmap)# class gold-out
Switch(config-pmap-c)# bandwidth 40000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class silver-out
Switch(config-pmap-c)# bandwidth 30000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class bronze-out
Switch(config-pmap-c)# bandwidth 20000
Switch(config-pmap-c)# exit

Modifying Output Policies and Adding or Deleting Configured Actions

This section provides examples of updating an existing set of output policy maps to add or delete queuing and scheduling actions. The modification in the output policy map might be required due to a change in the service provisioning requirements. You can make the change without shutting down ports that are not configured with the output policy map to be modified. But, shut down the ports that are configured with that output policy map. If you are not using this output policy map, you are not affected.

In the initial configuration, Fast Ethernet ports 1 through 12 are UNIs and are active. Fast Ethernet ports 13 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

This list contains the overall sequence of configuration:

Shut down all active ports carrying the policy to be modified.

Detach the output policy from all ports to which it is attached.

Make modifications to the output policy.

Reattach the output policy to the appropriate ports.

Take the ports out of the shutdown state.

Note these restrictions for configuring output policies:

You can define up to three classes in the output policy map.

The defined classes must be the same as other output policy maps.

The number of defined classes in each output policy map must be same.

Assign an action to each class; that is, there can be no empty class.

Each class configuration must be based on the classification/marking done in the input policy-map.

These steps shut down all ports carrying the output policy, in this case only the Gigabit Ethernet ports.

Switch(config)# interface range gigabitEthernet0/1-2
Switch(config-if-range)# shutdown
Switch(config-if-range)# exit
 
   

These steps detach the output policy to be modified, in this case the one configured on the Gigabit Ethernet ports:

Switch(config)# interface range gigabitEthernet0/1-2
Switch(config-if-range)# no service-policy output output-g1-2
Switch(config-if-range)# exit
 
   

These steps modify the output service policy servicing the Gigabit Ethernet NNIs. Instead of providing a minimum bandwidth guarantee of 10 percent to the bronze class, the policy is modified to provide class-based shaping to 100,000 bps.

Switch(config)# policy-map output-g1-2
Switch(config-pmap)# class bronze-out
Switch(config-pmap-c)# no bandwidth percent 10
Switch(config-pmap-c)# shape average 100000
Switch(config-pmap-c)# exit
 
   

These steps reattach the output policy to the Gigabit Ethernet ports:

Switch(config)# interface range gigabitethernet0/1-2
Switch(config-if-range)# service-policy output output9-12
Switch(config-if-range)# exit
 
   

These steps activate all Gigabit Ethernet ports:

Switch(config)# interface range gigabitethernet0/1-2
Switch(config-if-range)# no shutdown
Switch(config-if-range)# exit

Modifying Output Policies and Adding or Deleting a Class

This section provides examples of updating an existing set of output policy maps to add or delete entire classes. The modification in the output policy map might be required due to a change in the service provisioning requirements or a change in the input service policy. To make this change, shut down all active ports on the switch. For this kind of update to any output policy map, all customers could potentially be affected. To avoid the affects of ports being down, we recommend that you consider possible future upgrades when you configure classes in output service policies.

In the initial configuration, Fast Ethernet ports 1 through 12 are UNIs and are active. Fast Ethernet ports 13 through 24 are UNIs and are shut down. Gigabit Ethernet ports 1 and 2 are NNIs and are enabled by default.

This list is the overall sequence of configuration:

Shut down all active ports.

Detach the output policies from all Fast Ethernet and Gigabit Ethernet ports.

Delete the class.

Reattach the output policies to the Fast Ethernet and Gigabit Ethernet ports.

Take the Fast Ethernet and Gigabit Ethernet ports out of the shutdown state.

These steps shut down all active and applicable Fast Ethernet and Gigabit Ethernet ports:

Switch(config)# interface range gigabitethernet0/1-2, fastethernet0/1-12
Switch(config-if-range)# shutdown
Switch(config-if-range)# exit
 
   

These steps detach all output policies from the affected Fast Ethernet and Gigabit Ethernet ports:

Switch(config)# interface range fastethernet0/1-8
Switch(config-if-range)# no service-policy output output1-8
Switch(config-if-range)# exit
 
   
Switch(config)# interface range fastethernet0/9-12
Switch(config-if-range)# no service-policy output output9-12
Switch(config-if-range)# exit
 
   
 
   
Switch(config)# interface range gigabitethernet0/1-2
Switch(config-if-range)# no service-policy output output-g1-2
Switch(config-if-range)# exit
 
   

These steps delete a class from all output policy maps and input policy maps; the input policy can be left attached or can be detached:

Switch(config)# policy-map output1-8
Switch(config-pmap)# no class bronze-out
Switch(config-pmap-c)# exit
Switch(config)# policy-map output9-12
Switch(config-pmap)# no class bronze-out
Switch(config-pmap-c)# exit
Switch(config)# policy-map output-g1-2
Switch(config-pmap)# no class bronze-out
Switch(config-pmap-c)# exit
Switch(config)# policy-map input-all
Switch(config-pmap)# no class bronze-in
Switch(config-pmap-c)# exit
 
   

These steps reattach all policies to the Fast Ethernet and Gigabit Ethernet ports:

Switch(config)# interface range fastethernet0/1-8
Switch(config-if-range)# service-policy output output1-8
Switch(config-if-range)# exit
 
   
Switch(config)# interface range fastethernet0/9-12
Switch(config-if-range)# service-policy output output9-12
Switch(config-if-range)# exit
 
   
Switch(config)# interface range gigabitethernet0/1-2
Switch(config-if-range)# service-policy output output9-12
Switch(config-if-range)# exit
 
   

These steps activate all applicable Fast Ethernet and Gigabit Ethernet ports:

Switch(config)# interface range gigabitethernet0/1-2, fastethernet0/1-12
Switch(config-if-range)# no shutdown
Switch(config-if-range)# exit
 
   

Use the same procedure when adding a class to an attached output service policy.


Note Problems can occur if you do not follow the previous sequence.


When a policy map is attached to an interface, all traffic that does not explicitly match the configured class maps within the policy map goes through the default queue (class class-default). However, in some cases, traffic that does not explicitly match the output policy-map classes could go through more than one queue. This queuing problem can occur when you do not follow the previous procedure and do not attach an output policy to all active ports.

For example, consider this case where only two ports are configured with an output policy and we want to delete a class in the output policy.

Shut down two ports:

Switch(config)# interface range fastethernet0/1-2
Switch(config-if-range)# shutdown
Switch(config-if-range)# exit
 
   

Detach the output policy from both ports:

Switch(config)# interface range fastEthernet0/1-2
Switch(config-if)# no service-policy output output1-2
Switch(config-if)# exit
 
   

Delete a class in the output policy:

Switch(config)# policy-map output1-2
Switch(config-pmap)# no class bronze-out
Switch(config-pmap-c)# exit
 
   

Attach the output policy to only one port and not to the other:

Switch(config)# interface FastEthernet0/1
Switch(config-if)# service-policy output output1-2
Switch(config-if)# exit
 
   

Enable both ports:

Switch(config)# interface range fastethernet0/1-2
Switch(config-if-range)# no shutdown
Switch(config-if-range)# exit
 
   

When traffic leaves Fast Ethernet port 2, instead of going through a single default-queue, it goes through the same number of queues as there are classes defined in the output policy-map attached to Fast Ethernet port 1. In this case, it would be three. In some cases, packets for a flow out of Fast Ethernet port 2 might be reordered if a flow splits across more than one queue. You can avoid this problem by leaving ports in a shut-down state until you attach an output policy.