QOS - MQC shape average vs shape peak

The operation of shape peak is exactly the same as shape average:it calculates the default bc in the same manner, except, that each interval it gets to fill up the Be bucket as well. With the shape average command the excess burst is only sent if the bc bucket is full i.e. after periods of inactivity.

If a network has additional bandwidth available (over the provisioned CIR) and the application can tolerate occasional packet loss, the extra bandwidth can be exploited through the use of peak rate shaping. There may be occasional packet drops when network congestion occurs.

If the traffic being sent to the network must strictly conform to the configured network provisioned CIR, then use average traffic shaping.

If you had: shape peak 8000

We get a default tc of 1/8th of a second which gives us a bc of 1000 and a be of the same value. So the sending rate equals bc + be per tc or 16000. The rate equation is as follows

peak rate = CIR * (1 + Be/Bc)
peak rate = 8000 * (1 + 10/10) = 16000


In summary

shape average 8000 equates to a tcp traffic flow of 8000 bps.
shape peak 8000 equates to tcp traffic flow of 16000 bps.

R1
policy-map RICH
class class-default
shape average 8000 1000 1000

int fa0/0
policy-map output RICH

show policy-map int fa0/0
Service-policy output: RICH

Class-map: class-default (match-any)
86 packets, 7295 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)
8000/8000 250 1000 1000 125 125

Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 0 86 7295 0 0 no

R1
policy-map RICH
class class-default
shape peak 8000 1000 1000

int fa0/0
policy-map output RICH


show policy-map int fa0/0
Service-policy output: RICH

Class-map: class-default (match-any)
159 packets, 13622 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)
16000/8000 250 1000 1000 125 250

Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 0 4 298 0 0 no