Re: WRED thresholds and queue-limit

It depends on the version of IOS. Pre-HQF, queue-limit is ignored if
random-detect is configured under a class. In HQF, queue-limit WILL take
affect when configured with random-detect, but it simply sets a hard limit
and must be higher than Max Threshold.

Unfortunately I wasn't able to test this since I only had 12.4(15) in
Dynamips, but according to Cisco this is the case:

http://www.cisco.com/en/US/products/hw/routers/ps341/products_tech_note09186a0080af893d.shtml

-Yuri

On Tue, Jan 24, 2012 at 1:10 PM, Tom Kacprzynski <tom.kac_at_gmail.com> wrote:

> Hello,
> Is this a valid configuration of WRED, where the queue-limit is set to 64
> packets by default, the WRED Min Threshold is 100 (packets) and Max
> threshold is 400 (packets)? Would this configuration defeat the whole
> purpose of using WRED, as the average queue depth will never reach 100
> packets (min threshold)? Am I understanding this correctly?
>
>
> <sample output>
> R1#sh policy-map int gi0/0 out
> GigabitEthernet0/0
>
> Service-policy output: test-pmap
>
> Class-map: test1 (match-all)
> 0 packets, 0 bytes
> 5 minute offered rate 0 bps, drop rate 0 bps
> Match: none
> Queueing
> queue limit 64 packets
> (queue depth/total drops/no-buffer drops) 0/0/0
> (pkts output/bytes output) 0/0
> bandwidth 30000 kbps
> Exp-weight-constant: 9 (1/512)
> Mean queue depth: 0 packets
> dscp Transmitted Random drop Tail drop
> Minimum Maximum Mark
> pkts/bytes pkts/bytes pkts/bytes
> thresh thresh prob
>
> cs3 0/0 0/0
> 0/0 100 400 1/10
>
>
> <sample config of wred>
> policy-map test-pmap
> class test1
> bandwidth 30000
> random-detect dscp-based
> random-detect dscp 24 100 400
>
>
> Thank you,
>
> Tom Kacprzynski
>
>
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Received on Wed Jan 25 2012 - 22:32:29 ART