Re: RED/WRED Qeustion

From: shiran guez (shiranp3@gmail.com)
Date: Sat Jan 05 2008 - 16:43:15 ARST


that is where the wording of a question and understanding of the technology
come together, first you need to look at the question exactly to the word as
it was given to you as minor thing can impact. but to the point you cant
really estimate 80% based on WRED as you need to know your exact traffic
pattern and size of packets to calculate that and I do not think (I hope
:-)) that do not try to give you something you cant do in the time frame you
have for the test.

for your question if I would have this, I would set

policy-map CON-AVOIDE
 class class-default
  bandwidth percent 80
  random-detect

interface <CCC>
! do not forget to set the max reserved bandwidth to higher then default 75%
max-reserved-bandwidth 90
service-policy out CON-AVOIDE
!

 Serial0/1

  Service-policy output: CON-AVOIDE

    Class-map: class-default (match-any)
      9 packets, 590 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any
      Queueing
        Output Queue: Conversation 265
        Bandwidth 80 (%)
        Bandwidth 1235 (kbps)
        (pkts matched/bytes matched) 1/124
        (depth/total drops/no-buffer drops) 0/0/0
         exponential weight: 9
         mean queue depth: 0

  class Transmitted Random drop Tail drop Minimum Maximum
Mark
           pkts/bytes pkts/bytes pkts/bytes thresh thresh
prob
      0 3/72 0/0 0/0 20 40
1/10
      1 0/0 0/0 0/0 22 40
1/10
      2 0/0 0/0 0/0 24 40
1/10
      3 0/0 0/0 0/0 26 40
1/10
      4 0/0 0/0 0/0 28 40
1/10
      5 0/0 0/0 0/0 30 40
1/10
      6 6/518 0/0 0/0 32 40
1/10
      7 0/0 0/0 0/0 34 40
1/10
   rsvp 0/0 0/0 0/0 36 40
1/10

On Jan 5, 2008 6:36 PM, George Goglidze <goglidze@gmail.com> wrote:

> Hi There,
>
> Let's say I have a question on the lab, which says we need to avoid
> congestion,
> so when traffic utilization is at let's say 80 percent we have to start
> dropping packets.
>
> so we configure WRED, but the question is:
> In WRED we can put minimum threshold and maximum threshold,
> but they are given in queue size(how many packets we have in a queue right
> now.).
>
> So we can't be very precise as for 80 percent of bandwidth utilization.
> how do we calculate many packets we have in a queue when it gets to 80
> percent???
>
> Thanks,
>
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-- 
Shiran Guez
MCSE CCNP NCE1
http://cciep3.blogspot.com
http://www.linkedin.com/in/cciep3


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