Re: Doubt in QoS

From: Elias Chari (elias.chari@gmail.com)
Date: Thu Jun 29 2006 - 07:55:31 ART


Interesting question. I will add my thoughts and perhaps one of the gurus
can correct me.

1. priority and shaping commands are not allowed in the same class under the
policy map.

2. Bandwidth + priority not allowed.

3. So I will go with bandwidth and shape as follows. My thinking is that
under congestion you are quaranteed 84k, then you shape to an average of 84k
but allow bursts of 96k.

Formula for peak rate = CIR(1 + Be / Bc) which I used to work out the values
below.

-------------------------------------------------------------------------

policy-map QoS
 class critical
  bandwidth 84
  shape peak 84000 16000 2304

Rack1R1#sh policy-map int s0/1
 Serial0/1

  Service-policy output: QoS

    Class-map: critical (match-all)
      153 packets, 15394 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any
      Queueing
        Output Queue: Conversation 265
        Bandwidth 84 (kbps) Max Threshold 64 (packets)
        (pkts matched/bytes matched) 4/648
        (depth/total drops/no-buffer drops) 0/0/0
      Traffic Shaping
           Target/Average Byte Sustain Excess Interval Increment
             Rate Limit bits/int bits/int (ms) (bytes)
            96000/84000 2288 16000 2304 190 2288

        Adapt Queue Packets Bytes Packets Bytes Shaping
        Active Depth Delayed Delayed Active
        - 0 153 15394 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

On 6/29/06, Anderson Mota Alves <mota_anderson@hotmail.com> wrote:
>
> Hi gurus, The question I need to complish is the following:
>
> Which configuration provides the mission-critical traffic class with a
> minimum
>
> bandwidth guarantee of 84 kbps and a maximum upper bandwidth limit of 96
>
> kbps?
>
> I think I have to solution for this one but I'm not sure if I'm right:
>
> policy-map shape
> class mission-critical
> bandwidth 84
> shape peak 96000
>
> or
>
> policy-map shape
> class mission-critical
> priority 64
> bandwidth 96
>
> Could anyone tell me which one I could use? Also I don't know if in order
> to use the shape peak I need to first configure the shape cir ir order to
> make sure that this will be the peak above the Cir.
>
> Thanks
>
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