Comments on: Quick Notes on the 3560 Egress Queuing

By: Tmo

Tmo — Sat, 20 Feb 2010 04:01:46 +0000

Hi Petr

srr-queue bandwidth limit 20 – does this do policing or shaping?
Until recently i was pretty sure it does policing, but fallowing a post on some forum someone claims this is command actually does shaping.

Thank you

By: K

Wed, 23 Dec 2009 09:33:34 +0000

It is excellent article.And the examples is good for me to understand SRR.
thanks you very much again!

By: Didier from France

Didier from France — Sun, 23 Nov 2008 09:58:18 +0000

Hi Petr,

an another question please
if i enable q1 PQ (30% for example) but if there is no trafic for the PQ;
the bandwidth of other queues q2/q3/q4 is limited at 70%
or the bandwidth reserved PQ can be used by the others queues?

i think, the answer will be goog for ingress queues too ?

Thanks

By: Goyheneix Didier CCIP France

Goyheneix Didier CCIP France — Thu, 20 Nov 2008 16:30:04 +0000

Thanks for the explication “egress queues shared and shaped”.

but for the ingress queues, i don’t understand the notion of 2 queues when there is a priority queue.
Doc Cisco says, by default 90% q2 and 10% q1 whith a priority 10% for q2.
if q2 is priority with 10%, why q2 is too 10% in the SRR process ?

Thanks you

By: Daniel

Daniel — Tue, 14 Oct 2008 18:49:16 +0000

Hobbs: Your router platform could be the culprit. Like you, I got puzzling results at first when I used c3725 Routers. Then when I changed to the older C2600 routers, I was able to reproduce all of Petr’s above scenarios. Also manually set all interfaces to full-duplex, especially when your the router interfaces are Ethernet (i.e have max speed of 10MBps).

By: hobbs

hobbs — Mon, 29 Sep 2008 16:35:29 +0000

First, thanks for a wonderful explanation. I have followed this lab, and when I enable priority queuing in your second scenario, I get the same load distribution as in the first scenario. In other words, prec 5 is still being limited. I have verified that cos 5 maps to queue 1. Is there something else I am missing? I made sure to clear stats on R2 before testing. thanks

By: SRR bandwidth calculation | David Sudjiman

SRR bandwidth calculation | David Sudjiman — Wed, 27 Aug 2008 10:31:36 +0000

[...] you read this Quick Notes on the 3560 Egress Queuing by Petr Lapukhov, this table will complete the picture to show you how calculation [...]

By: Petr Lapukhov, CCIE #16379

Petr Lapukhov, CCIE #16379 — Tue, 19 Aug 2008 04:35:50 +0000

To: Pavel Stefanov

Shaping is always active, no matter whether the interface is congested or not. Thus, it performs function similar to egress policing on the older 3550 models.

By: Pavel Stefanov

Pavel Stefanov — Mon, 18 Aug 2008 19:37:21 +0000

Another great article!

Just a quick question – when there is no congestion present on the interface, the srr-queue bandwidth shaped command would not limit traffic that matches a queue that is shaped, correct?

Thank you!

By: Petr Lapukhov, CCIE #16379

Petr Lapukhov, CCIE #16379 — Fri, 27 Jun 2008 04:56:08 +0000

To Jo

Sort of But version 5 diagrams will probably have extra pictures of medieval castles, dragons, knights and fairies