From: Nick (seajay76@nate.com)
Date: Wed Jan 11 2006 - 14:32:21 GMT-3
Oh my God!! You are right!
I remember reading it on the CCO.(Exactly the part you quoted!!)
Well, I better study harder :)
Really appreciate your correction, Chris!
Regards,
Nick
----- Original Message -----
From: "Chris Lewis" <chrlewiscsco@gmail.com>
To: "Nick" <seajay76@nate.com>
Cc: <ccielab@groupstudy.com>
Sent: Wednesday, January 11, 2006 11:47 PM
Subject: Re: wrr-queue bandwidth command
> Nick,
>
> A good post, but I think one point of detail may be lost here. I think the
> point of detail is missed both in the original question and in the answer
> provided. So I think the person that wrote the requirement was missing a
> point of how priority-queue out works.
>
> The priority-queue out command configures the 3550 to use strict priotity
> scheduling for transmit queue 4. This means that any weighting assigned to
> queue 4 by the wrr-queue bandwidth is meaningless, as if there is any
> traffic in queue 4, it will be transmitted regardless of weighting
> configured for that queue. In essence, when priority-queue out is
> configured, the bandwidth allocation algorithm ignores weightings assigned
> to queue 4. The documentation for the priority-queue out command states the
> following:
>
> "When you configure the *priority-queue out* command, the weighted round
> robin (WRR) weight ratios are affected because there is one fewer queue
> participating in WRR. This means that *weight4* in the *wrr-queue
> bandwidth*interface configuration command is ignored (not used in the
> ratio
> calculation). The expedite queue is a priority queue, and it is serviced
> until empty before the other queues are serviced. "
>
> This is how it looks on a switch. I configure F0/1 as given.
>
> interface FastEthernet0/1
> switchport mode dynamic desirable
> wrr-queue bandwidth 4 6 5 5
> wrr-queue cos-map 1 6 7
> wrr-queue cos-map 2 0 1 2
> wrr-queue cos-map 3 4 5
> wrr-queue cos-map 4 3
> priority-queue out
> end
>
> Now I look at the following show command.
>
> Switch#sho mls qos int f0/1 queueing
> FastEthernet0/1
> Egress expedite queue: ena
> wrr bandwidth weights:
> qid-weights
> 1 - 4
> 2 - 6
> 3 - 5
> 4 - 5 when expedite queue is disabled
> Cos-queue map:
> cos-qid
> 0 - 2
> 1 - 2
> 2 - 2
> 3 - 4
> 4 - 3
> 5 - 3
> 6 - 1
> 7 - 1
>
> The important part to note is that queue 4 will have weighting 5 only if the
> expedite queue is disabled.
> What the configuration given means is that traffic in queue 4 will take
> whatever it wants, then the remaining queues will have bandwidth allocated
> as follows, as any weighting assigned to queue 4 when the priority-queue out
> command is configured, is ignored:
>
> Q1: 4/14 - (the figure 14 coming from the sum of weights fro queue 1, 2, 3)
> Q2: 6/14
> Q3: 5/15
>
> Now if I take off the priority-queue command, all your math looks correct to
> me, as verified by the output below:
>
> Switch(config)#int f0/1
> Switch(config-if)#no priority-queue out
> Switch(config-if)#do sho mls qos int f0/1 que
> FastEthernet0/1
> Egress expedite queue: dis
> wrr bandwidth weights:
> qid-weights
> 1 - 4
> 2 - 6
> 3 - 5
> 4 - 5
> Cos-queue map:
> cos-qid
> 0 - 2
> 1 - 2
> 2 - 2
> 3 - 4
> 4 - 3
> 5 - 3
> 6 - 1
> 7 - 1
>
> Chris
>
>
>
> On 1/11/06, Nick <seajay76@nate.com> wrote:
>>
>> Please disregard the last strange mail.
>>
>> (1) With the priority-queue out, the 4th queue of the interface becomes
>> the expedite queue.
>>
>> int fa0/4
>> priority-queue out
>>
>> (2) you need to put the COS-3 packet int eh 4th queue
>>
>> int fa0/4
>> wrr-queue cos-map 4 3 (they are the queue number and the CoS in order)
>>
>> (3) Then you can use the other remaining 3 queues.
>>
>> (4) Allocate the designated bandwidth to the queues.
>>
>> int fa0/4
>> wrr-queue bandwidth 4 6 5 5
>>
>> Here 4 means 4/(4+6+5+5) , 6 means 6/(4+6+5+5) , 5 means 5/(4+6+5+5)
>>
>> So you might put it this way.
>>
>> int fa0/4
>> wrr-queue bandwidth 20 30 25 25
>>
>> (5) Since you allocate the bandwidth to the queues,
>> just put the CoSed packets in each queue
>> You did it for the fourth queue already in (2)
>>
>> int fa0/4
>> wrr-queue cos-map 1 6 7
>> wrr-queue cos-map 2 0 1 2
>> wrr-queue cos-map 3 4 5
>>
>> HTH~~
>>
>> Regards,
>> Nick
>>
>> ----- Original Message -----
>> From: <Bill.McKenzie@bisys.com>
>> To: <ccielab@groupstudy.com>
>> Sent: Wednesday, January 11, 2006 10:17 PM
>> Subject: wrr-queue bandwidth command
>>
>>
>> > Here is the requirement :
>> > Cos-3 must be sent of everything else and match the following cos values
>> to
>> > according bandwidth.
>> >
>> > Cos 3 = 25%
>> > CoS 6,7 = 20%
>> > CoS 0,1,2 = 30%
>> > CoS 4,5 = 25%
>> >
>> > Here is the solution:
>> >
>> > wrr-queue bandwidth 4 6 5 5
>> > wrr-queue cos-map 1 6 7
>> > wrr-queue cos-map 2 0 1 2
>> > wrr-queue cos-map 3 4 5
>> > wrr-queue cos-map 4 3
>> > priority-queue out
>> >
>> >
>> > I don't understand the values in the wrr-queue bandwidth command and
>> trying
>> > to look at the doc cd is just confusing me more. Can anyone point me to
>> a
>> > better explanation of how the values were estimated?
>> >
>> > Thanks,
>> > Bill
>> >
>> >
>> >
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