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Enthusiast

Basic Traffic Shaping

I'd like to limit a  host on my network from consuming too much bandwidth when the link is

saturated. This seems to be working as far as limiting bandwidth usage, but it doesn't seem to utilize excess bandwidth when available. For example, I have traffic roughly limited to 75 KBytes / sec, but it doesn't seem to use more than 150 KBytes / sec, even when our 6 meg pipe is idle. I've specified bandidth on the subinterface that I'm applying this policy-map to. Did I do something wrong?

Here is my current config:

Extended IP access list 110
    10 permit ip host 10.X.X.X any (261864 matches)

Class Map match-all COMVAULT (id 2)
   Match access-group  110

  Policy Map APPLICATION-CLASS-OUT
    Class COMVAULT
      Traffic Shaping
         Average Rate Traffic Shaping
         CIR 614400 (bps) Max. Buffers Limit 1000 (Packets)

!
interface FastEthernet0/0.1
description XXXXX Outside VLAN
bandwidth 6144
encapsulation dot1Q 101
ip address 207.X.X.X 255.255.255.0
ip access-group 100 in
no ip unreachables
ip nbar protocol-discovery
service-policy output APPLICATION-CLASS-OUT

#sh policy-map interface fa0/0.1
FastEthernet0/0.1

  Service-policy output: APPLICATION-CLASS-OUT

    Class-map: COMVAULT (match-all)
      254642 packets, 78860092 bytes
      30 second offered rate 3000 bps, drop rate 0 bps
      Match: access-group 110
      Traffic Shaping
           Target/Average   Byte   Sustain   Excess    Interval  Increment
             Rate           Limit  bits/int  bits/int  (ms)      (bytes)
           614400/614400    3840   15360     15360     25        1920

        Adapt  Queue     Packets   Bytes     Packets   Bytes     Shaping
        Active Depth                         Delayed   Delayed   Active
        -      0         253729    77524562  21937     29450402  no

    Class-map: class-default (match-any)
      27783984 packets, 23860332428 bytes
      30 second offered rate 3380000 bps, drop rate 0 bps
      Match: any

1 REPLY 1
Highlighted
Hall of Fame Guru

Jason

Traffic shaping is like traffic policing, the difference being poiicing drops excess packets (or remarks), shaping buffers the packets so they can be sent in a later time slot.

So what you are seeing is normal ie. the host will never be able to exceed the shaped limit within a certain time slot. If you want the host to be limited to a certain bandwidth in times of congestion but still be able to exceed it's configured bandwidth when there is spare capacity then shaping is the wrong tool.

You need to use CBWFQ and allocate that host's packets to a specific class and specify the bandwidth under that class.

Jon

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