Get Shape.

CB Shaping to the Average, forwards traffic to the average rate (CIR), and can burst to Be is there is extra tokens available, now in the other hand we also have, CB Shaping to the Peak and we forward packets to each Bc + Be of traffic at every Tc.

The formula for Peak is Peak Rate = AvgRate * (1+Be/Bc)

Router#conf ter
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#class-map ICMP
Router(config-cmap)#match protocol icmp
Router(config-cmap)#policy-map sAVERAGE
Router(config-pmap)#class ICMP
Router(config-pmap-c)#shape average 32000
Router(config-pmap-c)#policy-map sPEAK
Router(config-pmap)#
Router(config-pmap)#class ICMP
Router(config-pmap-c)#shape peak 32000
Router(config-pmap-c)#interface Serial1/0
Router(config-if)#service-policy output sAVERAGE
Router(config-if)#interface Serial1/1
Router(config-if)#service-policy output sPEAK

For the shape peak the result should be = 32000 * (1+8000/8000) = 64000 bps

Router#show policy-map int s1/0
Serial1/0

Service-policy output: sAVERAGE

Class-map: ICMP (match-all)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: protocol icmp
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
32000/32000 2000 8000 8000 250 1000

Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
– 0 0 0 0 0 no

Class-map: class-default (match-any)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: any
Router#show policy-map int s1/1
Serial1/1

Service-policy output: sPEAK

Class-map: ICMP (match-all)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: protocol icmp
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
64000/32000 2000 8000 8000 250 2000

Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
– 0 0 0 0 0 no

Class-map: class-default (match-any)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: any

CB shaping can adapt dynamically to available Frame Relay bandwidth by the use of BEC bit, the command “shape adaptive min-rate” uses the BECN signal and this causes that the shaping rate be reduced to 25% of the previous rate but not below the min-rate configured. One thing to considered here is that this command only works on Frame Relay interfaces.

 

Cheers

A Networker Blog

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