From: Richard Boover (rboover@cisco.com)
Date: Sun Jul 20 2003 - 19:52:31 GMT-3
Connie,
Yes that is correct -- it is recommended that CBWFQ should only use 75% of
the interface speed to allow for 25% for unclassified traffic (best effort)
and other control traffic. However, in the example below, the default
traffic was considered in the Custom Queue and CBWFQ calculations. The
only problem is the default queue (19000 / 256000 = 7%) did not meet the
25% rule in CBWFQ -- therefore some adjustment would have to be implemented
such as multiplying their CBWFQ answers by 75%.
Rick
At 10:50 AM 7/20/2003 -0400, Connie Nie wrote:
>There was a thread about this before. One opinion is that the CBWFQ
>bandwidth should (in telnet's example): 14.8%x256x75% ---because the total
>reservable bandwidth by default in CBWFQ is 75% of the bandwidth.
>
>Connie
>
>
>-----Original Message-----
>From: badger [mailto:badger@pongo.org]
>Sent: Sunday, July 20, 2003 9:33 AM
>To: Richard Boover
>Cc: Jim Phillipo; ccielab@groupstudy.com; 'brian@cyscoexpert.com'; 'Peter'
>Subject: Re[2]: QOS CBWFQ to Custom Queuing (again)
>
>Hello Richard,
>
>Saturday, July 19, 2003, 7:32:29 PM, you wrote:
>
>RB> Jim,
>
>RB> I'm not sure which lab this question comes from, but it seems they are
>RB> converting Customer Queuing to CBWFQ. When configuring CBWFQ, I believe
>
>RB> you can use either one (bandwidth or percent) and they give you the same
>
>RB> result. Priority is a little different in since that it will be always
>be
>RB> service first over CBWFQ (Priority + CBWFQ = LLQ). Note: Custom Queuing
>
>RB> does not support a priority queue, therefore keep this in mind when
>RB> converting Custom Queuing to CBWFQ.
>
>RB> This is how they came up with the numbers below (using the Telnet
>example):
>RB> 1) Custom Queuing - The total byte count for all traffic is 27k Bytes
>and
>RB> Telnet is allowed 4k bytes. Now lets convert this to a percentage (4/27
>=
>RB> 14.8%). Therefore, Telnet gets 14.8 percent of the total BW.
>
>RB> 2) When they converted Custom Queuing to CBWFQ, they elected to do it in
>BW
>RB> (Kbps) instead of percentage (which would have been a lot easier). Lets
>
>RB> convert Custom Queuing (KB) to CBWFQ (Kbps): 27KB x 8 = 216Kbps. Now
>lets
>RB> multiply the Telnet traffic percentage by the total BW = 14.8% x 216,000
>=
>RB> 31,968 bps (Notice this value is off from the answer 38Kbps). The
>problem
>RB> is the Custom Queuing total traffic did not add up to the speed of the
>RB> 256kbps interface (this is okay because it is all about percentages).
>They
>RB> derived their answer from 256,000 x 14.8% = 38kbps. Note: neither one
>of
>RB> these answer are wrong, the bottom line is the ratio between the
>numbers.
>
>RB> Hope this helps.
>
>RB> Rick
>
>
>RB> At 03:16 PM 7/19/2003 -0400, Jim Phillipo wrote:
> >>How do you know whether to use bandwidth or bandwidth percent ?
> >>
> >>-----Original Message-----
> >>From: Jim Phillipo [mailto:jim.phillipo@guardent.com]
> >>Sent: Saturday, July 19, 2003 3:08 PM
> >>To: ccielab@groupstudy.com
> >>Cc: 'brian@cyscoexpert.com'; 'Peter'
> >>Subject: QOS CBWFQ to Custom Queuing (again)
> >>
> >>
> >>I know this has been hashed to death but...... The answer they came
> >>up with in the answer configs was confusing so I wanted to throw this out.
> >>
> >>Here is the Scenario:
> >>
> >>Assume link speed is 256kbps with the folliwing configuration convert it
>to
> >>CBWFQ:
> >>
> >>r8# show queuing interface serial 0
> >>interface serial 0 queuing strategy: custom
> >>Output queue utilisation(queue/count)
> >>0/14 1/0 2/0 3/0 4/0 5/0 6/0 7/0 8/0
> >>9//0 10/0 1/0 12/0 13/0 14/0 15/0 16/2
> >>
> >>r8# show queuing custom
> >>Current custom queuing configuration:
> >>
> >>List Queue Args
> >>1 16 default
> >>1 1 protocol IP TCP WWW
> >>1 2 protocol IP TCP FTP
> >>1 3 protocol IP TCP Domain
> >>1 4 protocol DLSW
> >>1 5 protocol IP TCP Telnet
> >>1 6 protocol IP TCP SMTP
> >>1 1 byte-count 3000 limit 100
> >>1 2 byte-count 7000 limit 100
> >>1 3 byte-count 1000 limit 100
> >>1 4 byte-count 6000 limit 100
> >>1 5 byte-count 4000 limit 100
> >>1 6 byte-count 4000 limit 100
> >>1 16 byte-count 2000 limit 100
> >>
> >>Here is ther answer:
> >>
> >>I am at a loss as to how they came up with this, could we have used
>priority
> >>or bandwidth ?
> >>
> >>If you have the time could someone quickly go over the difference between
> >>bandwith vs priority ?
> >>!
> >>!
> >>!
> >>class-map match-all telnet
> >> match protocol telnet
> >>class-map match-all dlsw
> >> match protocol dlsw
> >>class-map match-all smtp
> >> match protocol smtp
> >>class-map match-all ftp
> >> match protocol ftp
> >>class-map match-all www
> >> match protocol http
> >>class-map match-all dns
> >> match protocol dns
> >>!
> >>!
> >>policy-map cq2cbwfq
> >> class dns
> >> bandwidth 9
> >> queue-limit 100
> >> class dlsw
> >> bandwidth 57
> >> queue-limit 100
> >> class telnet
> >> bandwidth 38
> >> queue-limit 100
> >> class smtp
> >> bandwidth 38
> >> queue-limit 100
> >> class www
> >> bandwidth 28
> >> queue-limit 100
> >> class ftp
> >> bandwidth 66
> >> queue-limit 100
> >> class class-default
> >> bandwidth 19
> >> queue-limit 100
> >>!
>
>RB> http://www.groupstudy.com/list/CCIELab.html
>
>Jim,
>
>How did you get the "8" in your:
>
>"convert Custom Queuing (KB) to CBWFQ (Kbps): 27KB x 8 = 216Kbps"
>
>--
>Best regards,
> badger mailto:badger@pongo.org
>
>
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