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Cisco Systems OL-4266-08 manual 42-118

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Chapter 42 Configuring PFC QoS

Common QoS Scenarios

To assign traffic to these queues, you need to configure a mapping of priority values to queues. QoS uses the DSCP-to-CoS map to map the 64 possible outgoing DSCP values to the eight possible 802.1p values, and then uses a CoS-to-queue map to map the CoS values to queues.

When the packet enters the router, QoS is either configured to classify and mark the packet with a configured DSCP value (as in the “Classifying Traffic from PCs and IP Phones in the Access Layer” section on page 42-113) or to trust the packet’s incoming DSCP value (as in the “Accepting the Traffic Priority Value on Interswitch Links” section on page 42-116). These options determine the packet’s priority as it leaves the router.

This example shows how to display the DSCP-to-CoS mapping:

Router#	show	mls qos maps				dscp-cos
Dscp-cos map:										(dscp= d1d2)
d1 : d2 0 1 2 3						4	5	6 7 8 9
-------------------------------------
0	:	00	00	00	00	00	00	00 00	01	01
1	:	01	01	01	01	01	01	02 02	02	02
2	:	02	02	02	02	03	03	03 03	03	03
3	:	03	03	04	04	04	04	04 04	04	04
4	:	05	05	05	05	05	05	05 05	06	06
5	:	06	06	06	06	06	06	07 07	07	07
6	:	07	07	07	07
Router#

The example marked the voice traffic with a DSCP value of 46. You can use the command output to translate DSCP 46 to CoS 5. You can use the command output to translate the other marked DSCP values to CoS values.

You can make changes to this mapping table to suit the needs of your particular network. Only minor changes are typically necessary; this example does not make any changes.

For queueing purposes, the configuration derives a CoS value from the outgoing DSCP value. This CoS value is used for queue assignment even if the outgoing port is an access port (that is, not a trunk port). However, there will be no 802.1q VLAN tag transmitted on the network if the outgoing port is an access port.

Map each derived CoS value to the queue structure. This example shows how to display the default CoS-to-queue mapping, which shows the queue to which each of the eight CoS values is mapped:

Router# show queueing interface gigabitethernet 5/1 begin cos-map

queue thresh cos-map

---------------------------------------

1				1	0
1				2	1
1				3
1				4
1				5
1				6
1				7
1				8
2				1	2
2				2	3	4
2				3
2				4
2				5
2				6
2				7
2				8
3				1	6	7
3				2
3				3
3				4
			Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX


	42-118					OL-4266-08
	42-118					OL-4266-08

Image 118

Cisco Systems OL-4266-08 manual 42-118

Contents

A P T E R 42-1Overview Port Types Supported by PFC QoS42-2 PFC QoS Feature Processing Overview 42-32shows traffic flow and PFC QoS features with a PFC3 42-43shows traffic flow and PFC QoS features with a PFC2 42-5Component Overview Ingress LAN Port PFC QoS Features42-6 Flowchart of Ingress LAN Port PFC QoS Features 42-7Ingress Congestion Avoidance PFC and DFC QoS FeaturesPort Trust These sections describe PFCs and DFCs as they relate to QoSFeature Supported Policy Feature CardsPFC and DFC QoS Feature List and Flowchart Supported Distributed Forwarding Cards42-10 Ingress PFC QoSFinal Internal Dscp Value Internal Dscp ValuesInitial Internal Dscp Value 42-11Port-Based PFC QoS and VLAN-Based PFC QoS PFC QoS Egress Port FeaturesThese sections describe PFC QoS egress port features 42-12Egress CoS Values Flowchart of PFC QoS Egress LAN Port Features42-13 Egress PFC QoS Interfaces Egress Dscp Mutation with a PFC3Egress ToS Byte Egress ACL Support for Remarked DscpMarking on Egress OSM Ports 42-15Ingress Classification and Marking at Trusted Ports Understanding Classification and MarkingClassification and Marking at Untrusted Ingress Ports 42-16Ingress Classification and Marking at Trust Dscp Ports Classification and Marking at Ingress OSM PortsIngress Classification and Marking at Trust CoS LAN Ports 42-1742-18 Overview of Policers PolicersClassification and Marking on the Msfc These sections describe policersAggregate Policers 42-20Microflow Policers 42-21Ingress and Egress Buffers and Layer 2 CoS-Based Queues Understanding Port-Based Queue Types42-22 42-23 Ingress Queue Types 42-24Egress Queue Types 42-25Ingress Egress Queue Drop Module to Queue Type Mappings42-26 42-27 42-28 Feature Default Value PFC QoS Global SettingsFollowing global PFC QoS settings apply = CoS Egress CoS set from final internal Dscp valuesTransmit-Queue Limit s Default Values With PFC QoS EnabledReceive-Queue Limits 42-30Bandwidth Allocation Ratios Default Drop-Threshold Percentages and CoS Value Mappings42-31 1q4t Receive Queues 1q2t Receive Queues42-32 1p1q0t Receive Queues 1p1q4t Receive Queues42-33 1p1q8t Receive Queues 42-341q8t Receive Queues 42-352q8t Receive Queues 42-3611, 13, 15-17, 19, 21, 23 8q4t Receive QueuesStandard receive queue Threshold CoS Lowest priority 27, 29, 31, 33, 39, 41-4542-38 48-63 42-3942-40 2q2t Transmit Queues 8q8t Receive Queues42-41 1p2q2t Transmit Queues 42-421p3q8t Transmit Queues 42-431p7q4t Transmit Queues 42-4442-45 48-63 42-461p7q8t Transmit Queues Tail-drop 100% nonconfigurable42-47 1p3q1t Transmit Queues 42-481p2q1t Transmit Queues Default Values With PFC QoS Disabled42-49 General Guidelines 42-50Wrr-queue bandwidth except Gigabit Ethernet LAN ports PFC3 Guidelines42-51 PFC2 Guidelines 42-52Policy Map Class Command Restrictions Class Map Command RestrictionsPolicy Map Command Restrictions Supported Granularity for CIR and PIR Rate ValuesSupported Granularity for CIR and PIR Token Bucket Sizes 42-54IP Precedence and Dscp Values 42-55Enabling PFC QoS Globally Command Purpose42-56 Default Enables ignore port trust globally on the routerDisables ignore port trust globally on the router Enabling Ignore Port TrustEnabling Queueing-Only Mode Configuring Dscp Transparency42-58 Enabling Microflow Policing of Bridged Traffic 42-59Enabling VLAN-Based PFC QoS on Layer 2 LAN Ports 42-60Creating Named Aggregate Policers Enabling Egress ACL Support for Remarked Dscp42-61 42-62 42-63 These sections describe PFC QoS policy configuration Configuring a PFC QoS Policy42-64 IPv4 Yes 100 to 1300 to 2000 to IPv6 Yes named PFC QoS Policy Configuration OverviewProtocol Numbered ACLs Extended ACLs Named ACLs Yes 800 to Yes 900 to Supported only with PFC2 MAC LayerConfiguring Protocol-Independent MAC ACL Filtering Configuring MAC ACLs42-66 Enabling VLAN-Based MAC QoS Filtering 42-67Configuring MAC ACLs 42-68Configuring ARP ACLs for QoS Filtering 42-69Creating a Class Map Configuring a Class Map42-70 Clears the ACL configuration from the class map Configuring Filtering in a Class MapOptional Configures the class map to filter using an ACL Class Map Filtering Guidelines and RestrictionsVerifying Class Map Configuration 42-72Creating a Policy Map Configuring a Policy MapPolicy Map Class Configuration Guidelines and Restrictions To create a policy map, perform this taskConfiguring Policy Map Class Actions Creating a Policy Map Class and Configuring Filtering42-74 Configuring the Policy Map Class Trust State Configuring Policy Map Class Marking42-75 Configuring a Per-Interface Policer Configuring Policy Map Class PolicingUsing a Named Aggregate Policer 42-7642-77 42-78 Exits policy map class configuration mode Verifying Policy Map ConfigurationTo verify policy map configuration, perform this task Additional classes in the policy mapAttaches a policy map to the interface Attaching a Policy Map to an InterfaceTo attach a policy map to an interface, perform this task Removes the policy map from the interface42-81 Router# show policy-map interface fastethernet 5/36To configure a named Dscp mutation map, perform this task Configuring Egress Dscp Mutation on a PFC3Configuring Named Dscp Mutation Maps 42-82Removes the egress Dscp mutation map from Attaching an Egress Dscp Mutation Map to an InterfaceAttaches an egress Dscp mutation map to the interface 42-8342-84 Configuring Ingress CoS Mutation Maps 42-85Mapping Received CoS Values to Internal Dscp Values Configuring Dscp Value Maps42-86 Configures a Dscp markdown map Configuring Dscp Markdown Values42-87 42-88 Mapping Internal Dscp Values to Egress CoS Values Configures the internal Dscp to egress CoS map42-89 Reverts to the default trust state untrusted Configuring the Trust State of Ethernet LAN and OSM PortsConfigures the trust state of the port 42-90Configuring the Ingress LAN Port CoS Value 42-91Reverts to the default port CoS value Configuring Standard-Queue Drop Threshold PercentagesConfigures the ingress LAN port CoS value 42-92Configuring a Tail-Drop Receive Queue 42-93Configuring a WRED-Drop and Tail-Drop Receive Queue Configuring a WRED-Drop Transmit Queue42-94 Configuring a WRED-Drop and Tail-Drop Transmit Queue 42-95Configuring 1q4t/2q2t Tail-Drop Threshold Percentages 42-96Tail-drop thresholds Configures the receive- and transmit-queue tail-dropReverts to the default receive- and transmit-queue 42-97Mapping QoS Labels to Queues and Drop Thresholds Configuring DSCP-Based Queue Mapping42-98 Enabling DSCP-Based Queue Mapping Configuring Ingress DSCP-Based Queue MappingConfiguring the Port to Trust Dscp 42-99Maps Dscp values to the standard receive queue Reverts to the default mappingMapping Dscp Values to Standard Receive-Queue Thresholds 42-100Queueing interface command 42-101Maps Dscp values to a standard transmit-queue Mapping Dscp Values to Standard Transmit-Queue Thresholds42-102 Mapping Dscp Values to the Transmit Strict-Priority Queue 42-103Maps CoS values to the standard receive queue Configuring CoS-Based Queue MappingMapping CoS Values to Standard Receive-Queue Thresholds 42-104Maps CoS values to a standard transmit-queue threshold Mapping CoS Values to Standard Transmit-Queue Thresholds42-105 Maps CoS values to the receive and transmit Mapping CoS Values to Strict-Priority Queues42-106 Maps CoS values to a tail-drop threshold 42-107Allocating Bandwidth Between Standard Transmit Queues 42-10842-109 Sets the size ratio between the receive queues Setting the Receive-Queue Size RatioReverts to the default size ratio 42-110Configures the strict priority queue size Configuring the Transmit-Queue Size RatioConfigures the queue size ratio between transmit queues 42-111Sample Network Design Overview Access LayerDistribution and Core Interswitch Links 42-11242-113 Identify the SAP Traffic from the PC Dvlan Identify the Voice Signaling Traffic from an IP Phone VvlanIdentify the Voice Traffic from an IP Phone Vvlan 42-11442-115 Set dscp efAccepting the Traffic Priority Value on Interswitch Links 42-116Prioritizing Traffic on Interswitch Links 42-11742-118 CoS from DSCP-to-CoS map Output Queue Voice Strict Priority Voice signaling Queue 2, ThresholdTraffic Type 42-119Class map commands Using Policers to Limit the Amount of Traffic from a PC42-120 To monitor the policing operation, use these commands 42-121PFC QoS Glossary 42-12242-123 42-124