From: gladston@br.ibm.com
Date: Thu Sep 01 2005 - 11:08:50 GMT-3
Trying to understand the differences between 'shape average' and 'shape peak'. Any comments appreciated.
Byte limit and increment results are similar to FRTS when using shape average. Byte limit was Bc + Be
When using shape peak, byte limit and increment have the same value, no matter what value is used for Bc and Be. It is always Bc+Be.
From the teory, Bc and Be are sent each interval for shape peak.
As Be will have tokens only if there is no traffic for a while, I am wondering how come shape peak can send Bc+Be per interval.
Or maybe it means: 'in case there was no traffic and Be fills', each interval will send Bc+Be.
Tests:
Shape Average
Rack2R4(config-pmap-c)#shape average 64000 8192 16384
Rack2R4(config-pmap-c)#do sh pol int e0/0.46
Ethernet0/0.46
Service-policy output: CB-shaping-peak
Class-map: class-default (match-any)
403 packets, 27781 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: any
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
64000/64000 3072 8192 16384 128 1024
Shape Peak
Rack2R4(config-pmap-c)#shape pea 64000 8192 16384
Rack2R4(config-pmap-c)#do sh pol int e0/0.46
Ethernet0/0.46
Service-policy output: CB-shaping-peak
Class-map: class-default (match-any)
318 packets, 21892 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: any
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
192000/64000 3072 8192 16384 128 3072
Another test, I tried to see if the target rate goes further than 64000 for shape peak, as it shows "Target" equal 128000. Traffic is limited to 79000, a little more than when using shape average:
Rack2R4(config-pmap-c)#shape peak 64000 8192 8192
Rack2R4(config-pmap-c)#do sh pol int e0/0.46
Ethernet0/0.46
Service-policy output: CB-shaping-peak
Class-map: class-default (match-any)
963 packets, 67186 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: any
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
128000/64000 2048 8192 8192 128 2048
Rack2R4#sh int e0/0 | i output rate
5 minute output rate 79000 bits/sec, 116 packets/sec
Rack2R4#sh policy-map interface e0/0.46 | i drop rate
5 minute offered rate 127000 bps, drop rate 58000 bps
Strangely, shape average applyed to ethernet 0/1 does not let the rate reaches 64000. The maximum I got was 42000, whith shaping dropping anything above it.
Rack2R4(config-pmap-c)#shape average 64000
Rack2R4#sh pol int e0/1 | i drop rate
1 minute offered rate 102000 bps, drop rate 55000 bps
Rack2R4#sh int e0/1 | i output rate
1 minute output rate 42000 bits/sec, 69 packets/sec
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