From: Martin Dean (mdean@diatac.co.uk)
Date: Tue Oct 03 2006 - 12:58:07 ART
In LLQ/CBWFQ the LLQ part and the CBWFQ section act differently.
If there are multiple classes in CBWFQ then they each get their own FIFO
queue and are policed appropriately.
However this does apply in LLQ. If there are multiple classes with the
priority command then all of the priority traffic goes into the same
priority FIFO queue. However they are policed separately. The order that
the packets are emptied from the priority FIFO queue is in the order that
the packets arrived in the LLQ, independent on which class they are for.
In the example given, if 2 packets arrive from class 1 followed by 1 from
class 2, then 1 from class 1, then that is how they are transmitted - as
long as they have not been dropped (or remarked if configured) by their
individual policer.
It is not true to say that class 1 and class 2 can only have 100k and 200k
respectively of the bandwidth.
In the example given, all non class 1 and 2 traffic is sent to the
class-default queue. If that traffic is not using its allotted bandwidth -
(BW of int)-(100k+200k) then both class 1 & 2 can get more, how much more
depends on the how much class-default does not use then ratioed between the
two classes.
This is a confusing part of LLQ, especially as some TAC engineers seem to
give out incorrect information regarding this subject.
But beware, I have recently discovered that the 7600 acts slightly
differently from the 'standard routers - 28s, 36s, 38s, 72s and 75s.
Hope this clears some thing up.
Martin
----- Original Message -----
From: "Vincent Mashburn" <vmashburn@fedex.com>
To: "Mohamed Saeed" <mohamed_saeed2@rayacorp.com>; <ccielab@groupstudy.com>
Sent: Tuesday, October 03, 2006 10:50 AM
Subject: RE: LLQ Question - Multiple Traffic Classes in the Priority Queue
> It is my understanding from your configuration that Class 1 has a
> priority bandwidth of 100 and class 2 has a priority bandwidth of 200.
> While it is true that both will be serviced in a FIFO manner since they
> are both in the priority queue, it is important to realize that the
> priority bandwidth is a policer. For instance, if class 1 attempts to
> prioritize more than 100k then the excess will be dropped. Class 2 is
> allowed to put up to 200k on the link before its excess is dropped. But
> they are both FIFO since there is only 1 priority queue. I hope that
> this helps.
>
> Vince Mashburn
> Voice / Data Engineer
> 901-263-5072
> CCVP, CCNP, CCDA,Network +
> Cisco IP Telephony Support Specialist
> Cisco IP Telephony Operations Specialist
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Mohamed Saeed
> Sent: Tuesday, October 03, 2006 5:55 AM
> To: ccielab@groupstudy.com
> Subject: RE: LLQ Question - Multiple Traffic Classes in the Priority
> Queue
>
> Why will CLASS1 be serviced first?
>
> Anyway, if this is the case then CLASS2 traffic would NOT have expedite
> forwarding processing, right?
>
> Regards
> Mohamed Saeed, CCNP - CCIP
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Gavin Lawson
> Sent: Tuesday, October 03, 2006 12:33 PM
> To: ccielab@groupstudy.com
> Subject: RE: LLQ Question - Multiple Traffic Classes in the Priority
> Queue
>
> Hi Mohamed
>
> With your example there are 2 software based Priority Queue's
> The CLASS1 priority Queue will be serviced first and then CLASS2
>
> GL
>
> ________________________________
>
> From: nobody@groupstudy.com on behalf of Mohamed Saeed
> Sent: Tue 3/10/2006 5:39 PM
> To: ccielab@groupstudy.com
> Subject: RE: LLQ Question - Multiple Traffic Classes in the Priority
> Queue
>
>
>
> Hi GL,
>
> Let me state an example to clarify my point:
>
> policy-map TEST
> class CLASS1
> priority 100
> class CLASS2
> priority 200
>
> With this setup, traffic of both CLASS1 and CLASS2 will be assigned to
> the priority queue. So, how will the router assign max BW of 100 to
> traffic of CLASS1 and assign max BW of 200 to traffic of CLASS2 although
> they are both in the same single queue and should be treated as FIFO.
>
> Regards
> Mohamed Saeed, CCNP - CCIP
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Gavin Lawson
> Sent: Tuesday, October 03, 2006 11:23 AM
> To: ccielab@groupstudy.com
> Subject: RE: LLQ Question - Multiple Traffic Classes in the Priority
> Queue
>
> HI Mohamed
>
> The priority queue will be serviced in a FIFO manner, no matter what the
> markings are of the packets in the queue.
>
> GL
>
> ________________________________
>
> From: nobody@groupstudy.com on behalf of Mohamed Saeed
> Sent: Tue 3/10/2006 4:57 PM
> To: ccielab@groupstudy.com
> Subject: LLQ Question - Multiple Traffic Classes in the Priority Queue
>
>
>
> Hi All,
>
>
>
>
>
>
>
> It is a fact that you can assign multiple traffic classes to the
> priority queue in the same policy map. All traffic from these classes is
> queued to the same, single, priority queue.
>
>
>
>
>
>
>
> I am a little bit confused, how will the system police different traffic
> classes to different rates although they are in the same priority queue.
>
>
>
> Does anyone has an idea?
>
>
>
>
>
> Regards
>
>
>
> Mohamed Saeed, CCNP - CCIP
>
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