From: Bob Sinclair (bob@bobsinclair.net)
Date: Tue Oct 28 2008 - 13:18:28 ARST
Hi Roger,
It sounds to me like you might want to consider using the srr-queue
bandwidth shape approach outbound on the CPE switch. This would
guarantee, limit and queue the excess. Compared to policing on the
access switch which drops the excess, shaping would queue the excess.
-HTH,
-Bob
Roger RPF wrote:
Hi Bob, Reza,
Thanks a lot for your answer. So, ok, I could get the desired result with
setting the port speed, but then I can only set them to 10Mb / 100MB or even
1000MB.
Second option, using srr-queue bandwidth limit, this would cause
rate-limiting after the specified limit is reached if I understand that
right, isn't it?
http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/1 2.2_44_se/configuration/guide/swqos.html#wp1168422
Assume the following. I have a CPE connected to a Access-Swith. On the
access-switch I do an aggregate policing to the value which the customer
bought. Let's assume, the customer bought 5Mb of overall traffic.
On my CPE (still owned by the SP), I have a FastEthernet connecting to the
Access-Switch and I do srr-queueing in outgoing direction towards the SP
(shared mode).
So now, the queueing will never kick in because in regards to the interface
on the CPE, it is never congested (interface is 100Mb). But since I have
policing on the Access-Switch set to 5Mb, once the Customer traffic reaches
5Mb, it will start dropping.
I would like that the CPE starts queueing according to the "policing values"
which I've set on the Access Switch", without configuring CBWFQ. I was
thinking that this should somehow be possible with using the BW statement or
similar...
Maybe it's a strange case but is that somehow possible?
regards
Roger
-----Urspr|ngliche Nachricht-----
Von: Bob Sinclair [ mailto:bob@bobsinclair.net ]
Gesendet: Dienstag, 28. Oktober 2008 15:24
An: Roger RPF
Cc: 'GS CCIE-Lab'
Betreff: 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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