1、Traffic Policing and ShapingConfiguring Class-Based ShapingClass-Based Shaping OverviewClass-based shaping is used to rate-limit packets.Class-based shaping delays exceeding packets rather than dropping them.Class-based shaping has no marking capabilities.Class-based shaping is a version of GTS usin

2、g MQC.Traffic Shaping MethodsClass-based shaping has two shaping methods:Shaping to the configured average rateShaping to the peak rateShaping to the Average rate means forwarding packets at the configured average rate with allowed bursting up to Be when there are extra tokens available. This is the

3、 more common method used.Shaping to the Peak rate means forwarding packets at the peak rate of up to Bc + Be of traffic at every Tc. However, traffic sent above the CIR may be dropped during network congestion. Peak rate shaping is mended when: Network has additional bandwidth availableApplication t

4、olerates occasional packet lossConfiguring Class-Based Shapingshape average | peak average-bit-rate Bc Berouter(config-pmap-c)#It is mended that you omit the Bc and Be to let Cisco IOS software select the optimal values for these variables.shape average | peak percent Bc Berouter(config-pmap-c)#Spec

5、ifies the bandwidth percentage. Valid range is a number from 1 to 100.It is mended that you omit the Bc and Be to let Cisco IOS software select the optimal values for these variables.The shape (percent) command cannot be configured for use in nested policy maps on 7500 routers or below.Cisco IOS sof

6、tware calculated values:Bc=Be=8000 bits, Tc=500msPeak Rate = AvgRate * (1+Be/Bc)= 16000 * (1 /8000)= 32000 bpsClass-Based Shaping Example:Average Rate, Peak Rateclass-map Shape match protocol citrix!policy-map ShapeAvg class Shape shape average 16000 !policy-map ShapePeak class Shape shape peak 1600

7、0 !interface Serial0/0 service-policy output ShapeAvg!interface Serial0/1 service-policy output ShapePeakClass-Based Shaping Example:Class-Based Shaping with CBWFQBandwidth statement provides a minimum bandwidth guarantee for the traffic class.Shape statement provides a maximum traffic rate for the

8、traffic class, and exceed traffic is queued.policy-map shape-cbwfq !class cust1 shape average 384000 bandwidth 256 !interface Serial 0/0 service-policy output shape-cbwfqClass-Based Shaping Example: Class-Based Shaping Hierarchical Policy Mapsservice out shape-allMonitoring Class-Based Shapingrouter

9、show policy-map shape-cbwfq Policy Map shape-cbwfq Class cust1 Traffic Shaping Average Rate Traffic Shaping CIR 384000 (bps) Max. Buffers Limit 1000 (Packets) Bandwidth 256 (kbps) Max Threshold 64 (packets)show policy-map policy-map-namerouterDisplays information about the indicated policy map, incl

10、uding the configuration of all classes for a specified service policy map Monitoring Class-Based Shaping (Cont.)router#show policy-map interface s0/0 Serial0/0 Service-policy output: shape-cbwfq Class-map: cust1 (match-all) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match: acces

11、s-group 101 Traffic Shaping Target/Average Byte Sustain Excess Interval Increment Rate Limit bits/int bits/int (ms) (bytes) 384000/384000 1968 7872 7872 207 984 Adapt Queue Packets Bytes Packets Bytes Shaping Active Depth Delayed Delayed Active - 0 0 0 0 0 no Queueing Output Queue: Conversation 266

12、Bandwidth 256 (kbps) Max Threshold 64 (packets) (pkts matched/bytes matched) 0/0 (depth/total drops/no-buffer drops) 0/0/0 Class-map: class-default (match-any) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match: anySummaryClass-based shaping delays exceeding packets rather than dropping them and has no marking capabilities.Class-based shaping can shape to the configured average rate or to the peak rate for packets satisfying the match criteria for a class. Peak Rat