Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Congestion management controls congestion after it has occurred on a network. Congestion can be managed on Cisco IOS XR software by using packet queueing methods, and by shaping the packet flow through use of traffic regulation mechanisms. Packet queueing methods define packet scheduling or the order in which packets are dequeued to the interface for transmission on the physical wire.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Contents Feature History for Configuring Modular QoS Congestion Management on Cisco IOS XR Software Contents Release Modification Release 2.0 This feature was introduced on the Cisco CRS-1. Release 3.0 No modification. Release 3.2 This feature was first supported on the Cisco XR 12000 Series Router with the exception of the following: Two-rate policer and two-token bucket algorithm.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Information About Configuring QoS Congestion Management on Cisco IOS XR Software • Low-Latency Queueing with Strict Priority Queueing, page QC-32 • Traffic Shaping, page QC-33 • Traffic Shaping Mechanism Regulates Traffic, page QC-33 • Traffic Policing, page QC-34 • Traffic Policing Mechanism Regulates Traffic, page QC-35 • Traffic Shaping Versus Traffic Policing, page QC-37 Congestion Management Overview Cong
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Information About Configuring QoS Congestion Management on Cisco IOS XR Software compensate for the excess data that was served previously. As a result, the average amount of data dequeued per queue is close to the configured value. In addition, MDRR allows for a strict priority queue for delay-sensitive traffic.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Information About Configuring QoS Congestion Management on Cisco IOS XR Software Traffic Shaping Traffic shaping allows you to control the traffic flow exiting an interface to match its transmission to the speed of the remote target interface and ensure that the traffic conforms to policies contracted for it.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Information About Configuring QoS Congestion Management on Cisco IOS XR Software Figure 2 illustrates how a traffic shaping mechanism regulates traffic flow. Figure 2 How a Traffic Shaping Mechanism Regulates Traffic Token bucket Yes Match Outgoing packets transmitted Classify Configured traffic shaping rate Packet classification "Token bucket" shaping criteria applied (e.g.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Information About Configuring QoS Congestion Management on Cisco IOS XR Software Traffic policing is often configured on interfaces at the edge of a network to limit the rate of traffic entering or leaving the network. In the most common traffic policing configurations, traffic that conforms is sent and traffic that exceeds is sent with a decreased priority or is dropped.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Information About Configuring QoS Congestion Management on Cisco IOS XR Software Figure 3 How a Traffic Policing Mechanism Regulates Traffic CIR Bc No B>Tc No Packet of size B Exceed Conform Action Action 127091 Yes The time interval between token updates (Tc) to the token bucket is updated at the CIR value each time a packet arrives at the traffic policer. The Tc token bucket can contain up to the Bc value.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Traffic Shaping Versus Traffic Policing Although traffic shaping and traffic policing can be implemented together on the same network, there are distinct differences between them, as shown in Table 3.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Restrictions The amount of bandwidth configured should be large enough to also accommodate Layer 2 overhead. A policy map can have all class bandwidths specified in kilobits per second or percentages but not a mixture of both in the same class. The bandwidth command is supported only on policies configured on outgoing interfaces. SUMMARY STEPS 1.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Step 4 Command or Action Purpose bandwidth {kbps | percent value} Enters policy map class configuration mode. • Specifies the bandwidth allocated for a class belonging to a policy map. • In this example, class class1 is guaranteed 50 percent of the interface bandwidth.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Step 13 Command or Action Purpose service-policy {input | output} policy-map Attaches a policy map to an input or output interface to be used as the service policy for that interface. • Example: RP/0/RP0/CPU0:router(config-if)# service-policy output policy1 Step 14 The traffic policy evaluates all traffic leaving that interface.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software SUMMARY STEPS 1. configure 2. policy-map policy-name 3. class class-name 4. police cir kbps [exceed-action action] 5. priority 6. exit 7. exit 8. interface type instance 9. service-policy {input | output} policy-map 10. end or commit 11.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Step 7 Command or Action Purpose exit Returns the router to global configuration mode. Example: RP/0/RP0/CPU0:router(config-pmap)# exit Step 8 interface type instance Enters interface configuration mode, and configures an interface.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Shaping performed on incoming interfaces is done at the Layer 3 level and does not include the Layer 2 header in the rate calculation. Restrictions The bandwidth, priority, and shape average commands should not be configured together in the same class. SUMMARY STEPS 1. configure 2. policy-map policy-name 3. class class-name 4.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Step 5 Command or Action Purpose exit Returns the router to policy map configuration mode. Example: RP/0/RP0/CPU0:router(config-pmap-c)# exit Step 6 Returns the router to global configuration mode.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Configuring Traffic Policing Traffic policing allows you to control the maximum rate of traffic sent or received on an interface. SUMMARY STEPS 1. configure 2. policy-map policy-name 3. class class-name 4.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software How to Configure QoS Congestion Management on Cisco IOS XR Software Step 4 Command or Action Purpose police {cir {kbps | percent percent}} [bc conform-burst] [be peak-burst] [conform-action action [exceed-action action] [pir kbps] [violate-action action] Configures traffic policing.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Configuration Examples for Configuring QoS Congestion Management on Cisco IOS XR Software Step 9 Command or Action Purpose end Saves configuration changes.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Configuration Examples for Configuring QoS Congestion Management on Cisco IOS XR Software RP/0/RP0/CPU0:Jun 8 16:55:11.819 : config[65546]: %MGBL-LIBTARCFG-6-COMMIT : Configuration committed by user 'cisco'. Use 'show configuration commit changes 1000006140' to view the changes.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Where to Go Next policy-map p2 class voip police cir percent 20 commit RP/0/RP0/CPU0:Jun 8 16:51:51.679 : config[65546]: %MGBL-LIBTARCFG-6-COMMIT : Configuration committed by user 'cisco'. Use 'show configuration commit changes 1000006135' to view the changes. exit exit interface bundle-poS 1 service-policy input p2 commit RP/0/RP0/CPU0:Jun 8 16:52:02.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Additional References Additional References The following sections provide references related to implementing QoS congestion management on Cisco IOS XR software. Related Documents Related Topic Document Title Packet classification Configuring Modular QoS Packet Classification on Cisco IOS XR, Release 3.2 WRED, RED, and tail drop Configuring QoS Congestion Avoidance on Cisco IOS XR Software, Release 3.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Additional References Technical Assistance Description Link http://www.cisco.com/techsupport The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.
Configuring Modular Quality of Service Congestion Management on Cisco IOS XR Software Additional References Cisco IOS XR Modular Quality of Service Configuration Guide QC-52