From: Reza Toghraee (reza@toghraee.com)
Date: Tue Oct 28 2008 - 12:54:17 ARST
Bob,
Thanks for your reply.
I got a little confused, can you please kindly correct me?
1) default settings for a 3560's interface is :
Shaped queue weights (absolute) : 25 0 0 0
Shared queue weights : 25 25 25 25
2) The shape weight values are "inverse absolute" (e.g shape 25 means 1/25
of interface bandwidth which is 4Mbps for a 100Mbps interface)
3) Queues 2,3,4 will share the remaining bandwidth of (100-4==96) 96Mbps.
They share it equally (96/3=32) 32Mbps each queue.
Thanks
Reza Toghraee
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Bob
Sinclair
Sent: Tuesday, October 28, 2008 6:24 PM
To: Roger RPF
Cc: 'GS CCIE-Lab'
Subject: Re: question regarding queueing on Catalyst
Hi Roger,
In my experience you cannot induce congestion on this switch by changing
the software reference bandwidth on the interface. Instead, try
changing the port speed, or do an "srr-queue bandwidth limit" command.
Remember that the configured values for the srr-queue bandwidth share
command are not literally percentages, but relative weights. They
appear as percentages only when they happen to add to 100. You might
want to check the command reference on this one. Also keep in mind that
shaped weights override shared weights. By default queue 1 has a shaped
weight of 25, so the "40" weight in your example would not be used
unless you zero-out the default shaped weight for queue 1. With the
default shaping weights, queues 2, 3, and 4 would share remaining
bandwidth in the ratio 10/60, 20/60 and 30/60, respectively.
HTH,
-Bob Sinclair CCIE 10427 CCSI 30427
www.netmasterclass.net
Roger RPF wrote:
> Hi Group,
>
> I have a question regarding queueing on the switches, for example on a
3560.
> If I have a FastEthernet port and I enable srr-queueing as below:
>
> mls qos
> Int Fa0/15
> srr-queue bandwidth share 40 10 20 30
>
> The configured values, reflect the percentage which the queue in case of
> congestion is allocated. Which bandwidth value does the switch take to
> calculate the real values? The Interface bandwidth, in our case 100Mb?
If
> I configure for example bandwidth 10, are the calculations based on 10Mb?
So
> the switch will start already start queueing (think that he is concested)
> when traffic reaches 10Mb?
>
> many thanks in advance
>
> Roger
>
>
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