From: Narbik Kocharians (narbikk@gmail.com)
Date: Sun Jul 13 2008 - 00:05:18 ART
**
*WFQ without the weight should be fair-queuing; the weight aspect of the WFQ
comes in when traffic is set with IP Precedence levels.*
*The formula that WFQ uses is as follows:*
* *
*If packets are 1500 Bytes and the IP Precedence is set to 0, then:*
*[32384 / (IP Precedence + 1)] X 1500 = 32384 / (0 + 1) = 48,576,000*
* *
*The 32384 is a set number.*
* *
*If packets are 1500 Bytes and the IP Precedence is set to 1, then:*
*[32384 / (IP Precedence + 1)] X 1500 = 32384 / (1 + 1) = 24,288,000*
* *
*Note the packets with IP Precedence of 1 appear to be half the size of
packets with IP Precedence of 0 and therefore they will receive twice as
much bandwidth as the packets that are set with IP Precedence level of 0.*
On Sat, Jul 12, 2008 at 4:01 PM, Anthony Sequeira <
Anthony_Sequeira@skillsoft.com> wrote:
> In the context of the CCIE Lab, not much to worry about here. WFQ is one
> of those "legacy" queuing mechanisms that does a good enough job to be
> the default for "low speed" interfaces still. It will indeed prevent a
> "top talker" from squeezing out a "low talker". <I think that was a
> Seinfeld episode!>
>
> There are some configurable parameters like the Congestive Discard
> Threshold and the number of Dynamic Queues, but one of the main problems
> with this queuing mechanism is that it does not support fixed bandwidth
> guarantees. If you want to ensure your voice traffic gets 256K across
> your WAN, this tool falls short.
>
> Class Based Weighted Fair Queuing came along and addresses the
> shortcomings of this mechanism. And then Low Latency Queuing further
> improved upon that. These are the Lab topics I would focus on.
>
> Interestingly, another place you see WFQ used today is in a LLQ config
> for the "catch all other traffic" class of class-default.
>
> I hope these comments helped you.
>
> Anthony J Sequeira
> #15626
> www.freeiestuff.com
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Joseph Brunner
> Sent: Saturday, July 12, 2008 4:38 PM
> To: 'John'; ccielab@groupstudy.com
> Subject: RE: WFQ
>
> Much to learn about google have you still...
>
> http://nislab.bu.edu/sc546/sc441Spring2003/wfq/wfq.htm
>
> Much Mystery there will be until you search with keywords correct
>
> Answers to questions find you will on this link and others.
>
> google
>
> cisco wfq scheduler
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> John
> Sent: Saturday, July 12, 2008 4:35 PM
> To: ccielab@groupstudy.com
> Subject: WFQ
>
> I don't know why I have a hard time getting this, but lets see if I have
> this
> right.
>
> WFQ will give low volume traffic "better treatment" then high volume
> traffic.
> It does this through some mysterious algorithm that I can't seem to
> find.
> WFQ
> is the default for all interfaces under E1 speeds. WFQ works with ip
> precedence and RSVP. WFQ is flow based. I cannot change the behaviour
> of
> WFQ
> through configuration. There are some QOS features I cannot configure
> on an
> interface with WFQ.
>
> Thats what I get. I would appreciate comments on anything I missed or
> got
> wrong
>
>
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-- Narbik Kocharians CCSI#30832, CCIE# 12410 (R&S, SP, Security) www.Net-Workbooks.com Sr. Technical Instructor
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