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Catalyst 6500 Series Software Configuration Guide, 5.5
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Index
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About This Guide
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Product Overview
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Command-Line Interfaces
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Configuring the Switch IP Address and Default Gateway
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Configuring Ethernet, Fast Ethernet, and Gigabit Ethernet Switching
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Configuring EtherChannel
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Configuring Spanning Tree
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Configuring Spanning-Tree PortFast, UplinkFast, and BackboneFast
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Configuring VTP
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Configuring VLANs
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Configuring Ethernet VLAN Trunks
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Configuring GVRP
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Configuring Dynamic Port VLAN Membership with VMPS
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Checking Port Status and Connectivity
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Administering the Switch
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Controlling Access to the Switch Using Authentication, Authorization, and Accounting
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Configuring Redundant Supervisor Engines
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Modifying the Switch Boot Configuration
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Working With the Flash File System
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Working with System Software Images
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Working with Configuration Files
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Configuring System Message Logging
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Configuring DNS
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Configuring CDP
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Configuring UDLD
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Configuring NTP
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Configuring Broadcast Suppression
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Configuring Layer 3 Protocol Filtering
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Configuring IP Permit List
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Configuring Port Security
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Configuring SNMP
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Configuring RMON
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Configuring SPAN and RSPAN
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Using Switch TopN Reports
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Configuring Multicast Services
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Configuring Quality of Service
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Configuring a Voice-Over-IP Network
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Table Of Contents
Configuring Quality of Service
Ethernet Ingress Port Features
Layer 3 Switching Engine Features
Layer 2 Switching Engine Features
Single-Port ATM OC-12 Switching Module Features
Multilayer Switch Feature Card
Ethernet Ingress Port Marking, Scheduling, Congestion Avoidance, and Classification
Ethernet Ingress Port Scheduling and Congestion Avoidance
Ethernet Ingress Port Classification Features with a Layer 3 Switching Engine
Classification, Marking, and Policing with a Layer 3 Switching Engine
Final Layer 3 Switching Engine CoS and ToS Values
Classification and Marking with a Layer 2 Switching Engine
Ethernet Egress Port Scheduling, Congestion Avoidance, and Marking
Congestion Avoidance on Dual Transmit Queue Ports
Congestion Avoidance on Triple Transmit Queue Ports
Enabling Port-Based or VLAN-Based QoS
Configuring the Trust State of a Port
Configuring the CoS Value for a Port
ACE Name, Marking Rule, Policing, and Filtering Syntax
Reverting to Default Values in Default ACLs
Detaching ACLs from Interfaces
Mapping a CoS Value to a Host Destination MAC Address/VLAN Pair
Deleting a CoS Value to a Host Destination MAC Address/VLAN Pair
Enabling Microflow Policing of Nonrouted Traffic
Disabling Microflow Policing of Nonrouted Traffic
Configuring Receive Queue Tail-Drop Thresholds
Configuring Dual Transmit Queue Tail-Drop Thresholds
Configuring Triple Transmit Queue WRED Drop Thresholds
Allocating Bandwidth Between Transmit Queues
Configuring the Transmit Queue Size Ratio
Mapping CoS Values to Drop Thresholds
Configuring Single-Receive, Dual-Transmit Queue Ports
Clearing Single-Receive, Dual-Transmit Queue Ports
Configuring Dual-Receive, Triple-Transmit Queue Ports
Clearing Dual-Receive, Triple-Transmit Queue Ports
Mapping CoS Values to DSCP Values
Mapping IP Precedence Values to DSCP Values
Mapping DSCP Values to CoS Values
Selecting COPS-DS as the QoS Policy Source
Selecting Locally Configured QoS Policy
Enabling Use of Locally Configured QoS Policy
Removing Roles From Port ASICs
Configuring Policy Decision Point Servers
Deleting PDP Server Configuration
Configuring the COPS-DS Domain Name
Deleting the COPS-DS Domain Name
Configuring the COPS-DS Communications Parameters
Enabling Participation in the DSBM Election
Disabling Participation in the DSBM Election
Configuring Policy Decision Point Servers
Deleting PDP Server Configuration
Configuring RSVP Policy Timeout
Configuring RSVP Use of Local Policy
Configuring Quality of Service
This chapter describes how to configure the quality of service (QoS) feature on the Catalyst 6000 family switches.
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For complete syntax and usage information for the commands used in this chapter, refer to the Catalyst 6000 and 6500 Series Command Reference publication.
This chapter consists of these sections:
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Understanding How QoS Works
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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.
The QoS feature on the Catalyst 6000 family switches selects network traffic, prioritizes it according to its relative importance, and provides priority-indexed treatment through congestion avoidance techniques. Implementing QoS in your network makes network performance more predictable and bandwidth utilization more effective.
There are three ways to configure QoS on the Catalyst 6000 family switches:
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QoS sets Layer 2 and Layer 3 values in network traffic to a configured value or to a value based on received Layer 2 or Layer 3 values. IP traffic retains the Layer 3 value when it leaves the switch.
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These sections describe QoS:
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Definitions
This section defines some QoS terminology.
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Layer 2 Inter-Switch Link (ISL) frame headers have a 1-byte User field that carries an IEEE 802.1p CoS value in the three least significant bits.
Layer 2 802.1Q frame headers have a 2-byte Tag Control Information field that carries the CoS value in the three most significant bits, which are called the User Priority bits.
Other frame types cannot carry CoS values.
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Flowcharts
Figure 35-1 illustrates traffic flow through the QoS features; Figure 35-2 through Figure 35-7 show more details of the traffic flow through QoS features.
Figure 35-1 Traffic Flow Through QoS Features
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Figure 35-2 Ethernet ingress Port Classification, Marking, Scheduling, and Congestion Avoidance
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Figure 35-3 Layer 3 Switching Engine Classification, Marking, and Policing
Figure 35-4 Layer 2 Switching Engine Classification and Marking
Figure 35-5 Multilayer Switch Feature Card Marking
Figure 35-6 Ethernet Egress Port Scheduling, Congestion Avoidance, and Marking
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Figure 35-7 Single-Port ATM OC-12 Switching Module Marking
QoS Feature Set Summary
The QoS feature set on your switch is determined by which switching engine daughter card is installed on the supervisor engine. Enter a show module command for the supervisor engine to determine which switching engine is installed in your switch. The display shows the "Sub-Type" to be one of the following:
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Ethernet Ingress Port Features
With any switching engine, QoS supports classification, marking, scheduling, and congestion avoidance using Layer 2 CoS values at Ethernet ingress ports. Classification, marking, scheduling, and congestion avoidance at Ethernet ingress ports do not use or set Layer 3 IP precedence or DSCP values. With a Layer 3 switching engine, you can configure Ethernet ingress port trust states that can be used by the switching engine to set Layer 3 IP precedence or DSCP values and the Layer 2 CoS value. For more information, see the "Ethernet Ingress Port Marking, Scheduling, Congestion Avoidance, and Classification" section.
Layer 3 Switching Engine Features
With a Layer 3 switching engine, QoS supports classification, marking, and policing using IP, IPX, and MAC access control lists (ACLs). ACLs contain access control entries (ACEs) that specify Layer 2, 3, and 4 classification criteria, a marking rule, and policing rules. Marking sets the Layer 3 IP precedence or DSCP values and the Layer 2 CoS value to either received or configured Layer 2 or Layer 3 values. Policing uses bandwidth limits to either drop or mark nonconforming traffic. For more information, see the "Classification, Marking, and Policing with a Layer 3 Switching Engine" section.
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Layer 2 Switching Engine Features
With a Layer 2 switching engine, QoS supports classification using Layer 2 destination MAC addresses and VLANs and marking using Layer 2 CoS values. Classification and marking with a Layer 2 switching engine do not use or set Layer 3 IP precedence or DSCP values. For more information, see the "Classification and Marking with a Layer 2 Switching Engine" section.
Ethernet Egress Port Features
With any switching engine, QoS supports Ethernet egress port scheduling and congestion avoidance using Layer 2 CoS values. Ethernet egress port marking sets Layer 2 CoS values and, with a Layer 3 switching engine, Layer 3 DSCP values. For more information, see the "Ethernet Egress Port Scheduling, Congestion Avoidance, and Marking" section.
Single-Port ATM OC-12 Switching Module Features
The ingress interface from a single-port ATM OC-12 switching module is untrusted and QoS sets CoS to zero in all traffic received from it. With a Layer 3 switching engine, QoS can mark IP traffic transmitted to a single-port ATM OC-12 switching module with Layer 3 DSCP values.
Multilayer Switch Feature Card
QoS marks IP traffic transmitted to an MSFC with Layer 3 DSCP values. CoS is zero in all traffic sent from an MSFC to egress ports.
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Ethernet Ingress Port Marking, Scheduling, Congestion Avoidance, and Classification
The trust state of an Ethernet port determines how it marks, schedules, and classifies received traffic, and whether or not congestion avoidance is implemented. You can configure the trust state of each port with one of these keywords:
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For more information, see the "Configuring the Trust State of a Port" section.
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Ports configured with the untrusted keyword are called untrusted ports. Ports configured with the trust-ipprec, trust-dscp, or trust-cos keywords are called trusted ports. QoS implements ingress port congestion avoidance only on ports configured with the trust-cos keyword.
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Marking at Untrusted Ports
With either a Layer 2 switching engine or a Layer 3 switching engine, QoS marks all frames received through untrusted ports with the port CoS value (the default is zero). QoS does not implement ingress port congestion avoidance on untrusted ports: the traffic goes directly to the switching engine.
Marking at Trusted Ports
When an ISL frame enters the switch through a trusted port, QoS accepts the three least significant bits in the User field as a CoS value. When an 802.1Q frame enters the switch through a trusted port, QoS accepts the User Priority bits as a CoS value. QoS marks all traffic received in other frame types with the port CoS value.
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Ethernet Ingress Port Scheduling and Congestion Avoidance
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QoS uses CoS-value-based receive queue drop thresholds to avoid congestion in traffic entering the switch through a port configured with the trust-cos keyword (for more information, see the "Configuring the Trust State of a Port" section).
Receive Queues
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Strict-priority queues are serviced in preference to other queues. QoS services traffic in a strict-priority queue before servicing the standard queue. When QoS services the standard queue, after receiving a packet, it checks for traffic in the strict-priority queue. If QoS detects traffic in the strict-priority queue, it suspends its service of the standard queue and completes service of all traffic in the strict-priority queue before returning to the standard queue.
Scheduling
QoS schedules traffic through the receive queues based on CoS values. In the dual-receive-queue default configuration, QoS assigns all traffic with CoS 5 to the strict priority queue; QoS assigns all other traffic to the standard queue. In the single-receive-queue default configuration, QoS assigns all traffic to the standard queue.
Congestion Avoidance
If a port is configured with the trust-cos keyword, QoS implements CoS-value-based receive drop thresholds to avoid congestion in received traffic.
Ports with a single receive queue have this default drop threshold configuration:
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Ports with dual receive queues have this default drop threshold configuration:
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Figure 35-8 illustrates the drop thresholds for a port with a single receive queue. Drop thresholds in other configurations function similarly.
Figure 35-8 Receive Queue Drop Thresholds
Ethernet Ingress Port Classification Features with a Layer 3 Switching Engine
You can use the untrusted, trust-ipprec, trust-dscp, and trust-cos port keywords to classify traffic on a per-port basis for a Layer 3 switching engine to mark.
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For a Layer 3 switching engine to mark traffic in response to per-port classification, the traffic must match an ACE that contains the dscp ACE keyword (see the "Marking Rules" section). Table 35-2 lists the per-port classifications and the marking rules that they invoke.
QoS uses configurable mapping tables to set DSCP, which is a 6-bit value, from CoS and IP precedence, which are 3-bit values (for more information, see the "Internal DSCP Values" section and the "Configuring DSCP Value Maps" section).
Classification, Marking, and Policing with a Layer 3 Switching Engine
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These sections describe classification, marking, and policing with a Layer 3 switching engine:
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Internal DSCP Values
During processing, a Layer 3 switching engine represents the priority of all traffic (including non-IP traffic) with a DSCP value. QoS uses configurable mapping tables to derive DSCP, which is a 6-bit value, from CoS or IP precedence, which are 3-bit values (for more information, see the "Mapping CoS Values to DSCP Values" section and the "Mapping IP Precedence Values to DSCP Values" section).
When traffic leaves a Layer 3 switching engine, QoS uses a configurable mapping table to derive a CoS value from the DSCP value associated with traffic (see the "Mapping DSCP Values to CoS Values" section). For IP traffic, QoS sends the internal DSCP value to Ethernet egress ports to be written into IP packets. QoS sends the CoS value to Ethernet egress ports and ATM modules for use in scheduling and to be written into ISL and 802.1Q frames.
For trust-dscp and trust-ipprec IP traffic, QoS creates a ToS byte from the 6-bit DSCP value (which may equal an IP precedence value) plus the original 2 least-significant bits from the received ToS byte and sends it to the egress port to be written into IP packets.
ACLs
On a Layer 3 switching engine, QoS uses ACLs that contain ACEs. The ACEs specify classification criteria, a marking rule, and policing rules. QoS compares received traffic to the ACEs in ACLs until a match occurs. When the traffic matches the classification criteria in an ACE, QoS marks and polices the packet as specified in the ACE and makes no further comparisons.
A Layer 3 switching engine supports up to 250 ACLs and a combined total (all ACEs in all ACLs) of up to approximately 8,000 ACEs (other features configured on the switch may decrease the space available to store ACEs).
There are three ACL types: IP, IPX, and MAC. QoS compares traffic of each type (IP, IPX, and MAC) only to the corresponding ACL type (see Table 35-3).
QoS supports user-created named ACLs, each containing an ordered list of ACEs, and user-configurable default ACLs, each containing a single ACE.
Named ACLs
You create a named ACL when you enter an ACE with a new ACL name. You add an ACE to an existing ACL when you enter an ACE with the name of the existing ACL.
You can specify the classification criteria for each ACE in a named ACL. The classification criteria can be specific values or wildcards (for more information, see the "Creating or Modifying ACLs" section).
These sections describe the classification criteria that can be specified in a named ACL:
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IP ACE Layer 3 Classification Criteria
You can create IP ACEs that match traffic with specific Layer 3 values by including these Layer 3 parameters (see the "Named IP ACLs" section):
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IP ACE Layer 4 Protocol Classification Criteria
You can create IP ACEs that match specific Layer 4 protocol traffic by including a Layer 4 protocol parameter (see the "IP ACLs for Other Layer 4 Protocols" section). You can specify the protocol numerically (0-255) or with these keywords: ahp (51), eigrp (88), esp (50), gre (47), igrp (9), icmp (1), igmp (2), igrp (9), ip (0), ipinip (4), nos (94), ospf (89), pcp (108), pim (103), tcp (6), or udp (17).
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IP ACE Layer 4 TCP Classification Criteria
You can create Transmission Control Protocol (TCP) ACEs that match traffic for specific TCP ports by including TCP source and/or destination port parameters (for more information, see the "IP ACEs for TCP Traffic" section). You can specify TCP port parameters numerically (0-65535) or with these keywords:
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IP ACE Layer 4 UDP Classification Criteria
You can create User Datagram Protocol (UDP) ACEs that match traffic for specific UDP source and/or destination ports by including UDP port parameters (for more information, see the "IP ACEs for UDP Traffic" section). You can specify UDP port parameters numerically (0-65535) or with these keywords:
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IP ACE Layer 4 ICMP Classification Criteria
You can create Internet Control Management Protocol (ICMP) ACEs that match traffic containing specific ICMP messages by including ICMP types and, optionally, ICMP codes (for more information, see the "IP ACEs for ICMP Traffic" section). You can specify ICMP types and codes numerically (0-255) or with these keywords:
administratively-prohibited
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net-tos-unreachable
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alternate-address1
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net-unreachable
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conversion-error
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network-unknown
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6
dod-host-prohibited
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10
no-room-for-option
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dod-net-prohibited
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9
option-missing
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echo
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packet-too-big
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echo-reply
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parameter-problem
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general-parameter-problem1
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port-unreachable
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3
host-isolated
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8
precedence-unreachable
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15
host-precedence-unreachable
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14
protocol-unreachable
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2
host-redirect
5
1
reassembly-timeout
11
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host-tos-redirect
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3
redirect1
5
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host-tos-unreachable
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12
router-advertisement
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host-unknown
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7
router-solicitation
10
0
host-unreachable
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1
source-quench
4
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information-reply
16
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source-route-failed
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5
information-request
15
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time-exceeded1
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mask-reply
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timestamp-reply
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mask-request
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timestamp-request
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mobile-redirect
32
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traceroute
30
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net-redirect
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ttl-exceeded
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net-tos-redirect
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unreachable1
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1 Matches all code values
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IP ACE Layer 4 IGMP Classification Criteria
You can create IGMP ACEs that match traffic containing specific IGMP messages by including an IGMP type parameter (for more information, see the "IP ACEs for IGMP Traffic" section). You can specify the IGMP type numerically (0-255) or with these keywords: host-query (1), host-report (2), dvmrp (3), pim (4), or trace (5).
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IPX ACE Classification Criteria
You can create IPX ACEs that match specific IPX traffic by including these parameters (for more information, see the "Named IPX ACLs" section):
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MAC ACE Layer 2 Classification Criteria
You can create MAC ACEs that match specific Ethernet traffic by including these Layer 2 parameters (for more information, see the "Named MAC ACLs" section):
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