9 Modular QoS CLI Service Policy Overview This module describes the policy part of the Modular QoS CLI (MQC). The module describes all the mechanisms that are currently supported by the MQC. As well, the module describes the class-based approach to the marking, shaping, policing, dropping and/or scheduling of IP packets using the modular QoS CLI. Objectives Upon completion of this module, you will be able to perform the following tasks: n Describe the policy part of the Modular QoS CLI n Configure packet marking with modular CLI n Configure policing and shaping with modular CLI n Configure class-based WFQ with modular CLI n Configure congestion avoidance mechanisms (WRED) with modular CLI n Configure low-latency queuing n Monitor and troubleshoot policy maps 9-2 IP QoS Modular QoS CLI Service Policy Copyright 2001, Cisco Systems, Inc. Service Policy Overview This lesson introduces the part of the MQC that is used to enable QoS mechanisms for classified traffic. Objectives Upon completion of this lesson, you will be able to perform the following tasks: n Describe and configure policy maps. n List all the QoS mechanisms currently available in the MQC. n Monitor and troubleshoot policy maps. Copyright 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy 9-3 © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy-5 Service Policy Service Policy • One aspect of modularity of the MQC is the configuration part • MQC is split into two modules: – Configuration of classification – Configuration of service policies • Classification is configured by using class maps • Service Policy is configured by using policy maps The Cisco IOS Modular QoS CLI (MQC) is the new, unified method of QoS mechanism configuration in Cisco IOS. MQC separates classification and QoS mechanism configuration by separating the configuration tasks into: n Configuration of class-maps, which define the classification of traffic n Configuration of service policies, which define how QoS mechanisms are applied to traffic classes This creates a flexible environment for the modular configuration of many QoS features, and significantly reduces overhead and the possibility of errors because configuration information is not unnecessarily duplicated. 9-4 IP QoS Modular QoS CLI Service Policy Copyright 2001, Cisco Systems, Inc. © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy-6 Modular QoS CLI Modular QoS CLI Classification Service Policy Class 1? Class 2? Class N? CB-WFQ CB-LLQ CB-Policing Service Policy implements per-hop behaviors (PHBs) for all traffic classes Supported mechanisms: • CB-WFQ • CB-LLQ • CB-Policing • CB-Shaping • CB-Marking • Up to 256 classes can be used within one service policy The service policy is used to configure QoS mechanisms, which may be applied to classes. The QoS mechanisms implement local per-hop behaviors (PHBs) for attached traffic classes. The QoS system, which implements PHB configured via the MQC, is the Class-Based Weighted Fair Queuing system, which integrates many QoS features in a single system, configured via a common (MQC) interface. A service policy can have up to 256 classes used within it and attached to an interface. Class-based Weighted Fair Queuing and Class-based Low-latency Queuing are an exception – only 64 classes can be used with one service policy. Copyright 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy 9-5 © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy -7 PHB Mechanisms PHB Mechanisms • MQC Supports the following QoS mechanisms: – Class-based Weighted Fair Queuing (CB-WFQ) to guarantee bandwidth – Class-based Low-latency Queuing (CB-LLQ) to guarantee bandwidth and low-latency – Class-based Policing (CB-Policing) to limit traffic rate by dropping excess traffic – Class-based Shaping (CB-Shaping) to limit traffic rate by delaying excess traffic – Class-based Marking (CB-Marking) to mark packets The MQC configures the CB-WFQ system, which in turn implements the following QoS functions: n Class-based Weighted Fair Queuing, which is used to guarantee bandwidth within the CB-WFQ system n Class-based Low-latency Queuing, which is used to guarantee bandwidth and provide low latency to time-critical traffic n Class-based Policing, which performs rate limiting by traffic policing n Class-based Shaping, which performs rate limiting by traffic shaping n Class-based Marking, which performs packet and frame marking 9-6 IP QoS Modular QoS CLI Service Policy Copyright 2001, Cisco Systems, Inc. © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy -8 Configuring Policy Maps Configuring Policy Maps policy-map name policy-map name Router(config)# • Enter policy-map configuration mode • Policy maps are identified by a case-sensitive name class class-map class class-map Router(config-pmap)# • Enter the per-class policy configuration mode by using the name of a previously configured class-map • Use the name “class-default” to configure the policy for the default class class class-map condition class class-map condition Router(config-pmap)# • Optionally you can define a new class-map by entering the condition after the name of the new class map • Class map will use the match-any strategy Service policies are configured using the policy-map command. Up to 256 classes can be used within one policy-map using the class command with the name of a preconfigured class-map. A non-existent class can also be used within the policy-map configuration mode if the match condition is specified after the name of the class. The running configuration will reflect such a configuration by using the match any strategy and inserting a full class-map configuration. The following table shows starting and resulting configuration modes for the class- map, policy-map and class commands: Starting configuration mode Command Configuration mode Router(config)# class-map Router(config-cmap)# Router(config)# policy-map Router(config-pmap)# Router(config-pmap)# class Router(config-pmap-c)# All traffic that is not classified by any of the class-maps used within the policy map is part of the default class class-default. This class has no QoS guarantees by default. The default class, when used on output, can use one FIFO queue of flow-based WFQ. The default class is part of every policy-map even if not configured. Copyright 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy 9-7 © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy -9 Configuring Policy Maps Configuring Policy Maps description description description description Router(config-pmap)# • It is recommended to use descriptions in large and complex configurations • The description has no operational meaning rename policy-maprename policy-map Router(config-pmap)# • Complex policy-maps can be renamed by using the rename policy-map command • All references to the policy map are also renamed <PHB mechanism> <PHB mechanism> Router(config-pmap-c)# • Per-class service policies are configured within the per-class policy- map configuration mode Policy maps, like class maps, should use descriptions in large QoS implementations where a large number of different policy maps are used. Renaming a policy map would normally require the renaming of all the references to the policy map. Using the rename command simplifies the renaming process by automatically renaming all references. The remainder of this module focuses on the various QoS mechanisms that are configured per-class within the policy-map configuration mode (config-pmap-c). 9-8 IP QoS Modular QoS CLI Service Policy Copyright 2001, Cisco Systems, Inc. © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy-10 Configuring Policy Maps Configuring Policy Maps service-policy {input | output} policy-mapservice-policy {input | output} policy-map Router(config-if)# • Attaches the specified service policy map to the input or output interface • The interface should be in the default queuing mode prior to using this command if it is used on output class-map HTTP match protocol http ! policy-map PM class HTTP bandwidth 2000 class class-default bandwidth 6000 ! class-map HTTP match protocol http ! policy-map PM class HTTP bandwidth 2000 class class-default bandwidth 6000 ! interface Serial0/0 service-policy output PM ! interface Serial0/0 service-policy output PM ! The last configuration step when configuring QoS mechanisms using the Modular QoS CLI, is to attach a policy map to the inbound or outbound packets, using the service-policy command. The router immediately verifies the correctness of parameters used in the policy map. If there is a mistake in the policy-map configuration, the router will display a message explaining what is wrong with the policy map. The sample configuration shows how a policy map is used to separate HTTP from other traffic. HTTP is guaranteed 2Mbps. All other traffic belongs to the default class and is guaranteed 6Mbps. Copyright 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy 9-9 © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy-11 Attaching Policy Maps to ATM PVCs Attaching Policy Maps to ATM PVCs interface atm 5/0/0.1 point-to-point service-policy output PM1 ! interface atm 5/0/0.2 point-to-point pvc 1/40 service-policy output PM2 ! interface atm 5/0/0.1 point-to-point service-policy output PM1 ! interface atm 5/0/0.2 point-to-point pvc 1/40 service-policy output PM2 ! service-policy {input | output} policy-mapservice-policy {input | output} policy-map Router(config-subif)# • Service policies can be attached to an ATM (sub)interface • Using service policies on the main interface and subinterfaces at the same time is not supported in the distributed (VIP-based) version service-policy {input | output} policy-mapservice-policy {input | output} policy-map Router(config-if-atm-vc)# • Service policies can also be attached to an ATM PVC Service policies can be applied to interfaces, subinterfaces or individual ATM virtual circuits. Refer to the “IP QoS – IP over ATM” module for a more detailed description of MQC usage on ATM interfaces. 9-10 IP QoS Modular QoS CLI Service Policy Copyright 2001, Cisco Systems, Inc. © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy-12 Attaching Policy Maps to Frame Relay Interfaces Attaching Policy Maps to Frame Relay Interfaces service-policy {input | output} policy-mapservice-policy {input | output} policy-map Router(config-subif)# • Service policy can be attached to an interface and/or to a subinterface • Service policy attached to a subinterface can not include CB-WFQ or CB-LLQ except in the distributed (VIP-based) version • Using service policies on the main interface and subinterfaces at the same time is not supported in the distributed (VIP-based) version Service policies can also be used on Frame Relay interfaces or subinterfaces. [...]... © 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy 9-1 1 Policy Map Example class-map match-all Test1 class-map match-all Test1 match protocol http protocol match access-group 100 match access-group 100 class-map match-any Test2 class-map match-any Test2 match protocol http match protocol match access-group 101 match access-group 101 ! ! policy-map Test policy-map class Test1 bandwidth... 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy 9-1 7 CB-WFQ Forwarded Packets CB-WFQ Class 1? Tail-drop Queue 1 Class 2? Tail-drop Queue 2 Hardware Queuing System CB-WFQ Scheduler Class-default? Tail-drop Hardware Q Interface Default Queue • Up to 64 classes (class maps) and one default class © 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy-22 CB-WFQ uses up to 64 class... is set to 1024 and the discard threshold is set to 50 policy-map A class A bandwidth 1000 class class-default fair-queue 1024 queue-limit 50 Copyright © 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy 9-2 7 9-2 8 IP QoS Modular QoS CLI Service Policy Copyright © 2001, Cisco Systems, Inc CB-WFQ Example 1 policy-map Policy1 policy-map Policy1 class Class1 class Class1 bandwidth 2000 2000... FastEthernet0/0 ip address 10.1.1.1 255.255.255.0 ip address 10.1.1.1 duplex auto duplex speed 10 speed 10 max-reserved-bandwidth 80 max-reserved-bandwidth 80 service-policy output Policy1 service-policy ip rtp priority 16384 16383 1000 ip rtp priority 16384 16383 1000 ! BWavail = 10000 kbps * 80% - (2000+2000+1000) kbps = 3000 kbps © 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy-32 The sample... FastEthernet0/0 ip address 10.1.1.1 255.255.255.0 ip address 10.1.1.1 duplex auto duplex speed 10 speed 10 max-reserved-bandwidth 80 max-reserved-bandwidth 80 service-policy output Policy1 service-policy ip rtp priority 16384 16383 1000 ip rtp priority 16384 16383 1000 ! BWavail = 10000 kbps * 80% - 1000 kbps = 7000 kbps © 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy-35 Example 3 shows... available bandwidth) 9-2 6 IP QoS Modular QoS CLI Service Policy Copyright © 2001, Cisco Systems, Inc Configuring CB-WFQ Router(config-pmap-c)# queue-limit queue-limit • Set the maximum number of packets this queue can hold • The default maximum is 64 • Sets the discard threshold in the “class-default” if flow-based WFQ is used Router(config-pmap-c)# fair-queue [dynamic-queues] • The “class-default” class... Serial0/0.1 point-to-point frame-relay class Voice frame-relay class ! ! map-class frame-relay Voice map-class frame-relay Voice service-policy output LLQ service-policy ! ! © 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy-13 A Frame Relay map class is needed when attaching a policy map to an individual virtual circuit The sample configuration illustrates how per-VC Low-latency queuing... Systems, Inc IP QoS Modular QoS CLI Service Policy-36 The show interface command confirms the calculation of available bandwidth for Example 3 Copyright © 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy 9-3 3 Monitoring and Troubleshooting CB-WFQ Router# show policy-map interface [intf] • Displays parameters and statistics of CB-WFQ Router#show policy -map interface Router#show policy-map interface... Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy-29 The show interface command confirms the calculation of available bandwidth for Example 2 Copyright © 2001, Cisco Systems, Inc IP QoS Modular QoS CLI Service Policy 9-2 5 Configuring CB-WFQ Router(config-pmap-c)# bandwidth bandwidth • Allocate a fixed amount of bandwidth to a class • Set the value in kbps Router(config-pmap-c)# bandwidth percent... Systems, Inc IP QoS Modular QoS CLI Service Policy-24 CB-WFQ reserves 64 FIFO queues in the WFQ system The default queue limit is 64 (tail-drop) and can be configured with WRED (random drop) 9-2 0 IP QoS Modular QoS CLI Service Policy Copyright © 2001, Cisco Systems, Inc CB-WFQ Scheduling • CB-WFQ guarantees bandwidth according to weights assigned to traffic classes • Weights can be defined by specifying: . 9-4 IP QoS Modular QoS CLI Service Policy Copyright 2001, Cisco Systems, Inc. © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy-6 Modular QoS CLI Modular QoS CLI Classification Service. Inc. IP QoS Modular QoS CLI Service Policy 9-7 © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy -9 Configuring Policy Maps Configuring Policy Maps description description description. Inc. IP QoS Modular QoS CLI Service Policy 9-1 9 © 2001, Cisco Systems, Inc. IP QoS Modular QoS CLI Service Policy-23 CB-WFQ Classification CB-WFQ Classification • Classification uses class-maps •