From: Richard Boover (rboover@cisco.com)
Date: Sat Jul 19 2003 - 23:32:29 GMT-3
Jim,
I'm not sure which lab this question comes from, but it seems they are
converting Customer Queuing to CBWFQ. When configuring CBWFQ, I believe
you can use either one (bandwidth or percent) and they give you the same
result. Priority is a little different in since that it will be always be
service first over CBWFQ (Priority + CBWFQ = LLQ). Note: Custom Queuing
does not support a priority queue, therefore keep this in mind when
converting Custom Queuing to CBWFQ.
This is how they came up with the numbers below (using the Telnet example):
1) Custom Queuing - The total byte count for all traffic is 27k Bytes and
Telnet is allowed 4k bytes. Now lets convert this to a percentage (4/27 =
14.8%). Therefore, Telnet gets 14.8 percent of the total BW.
2) When they converted Custom Queuing to CBWFQ, they elected to do it in BW
(Kbps) instead of percentage (which would have been a lot easier). Lets
convert Custom Queuing (KB) to CBWFQ (Kbps): 27KB x 8 = 216Kbps. Now lets
multiply the Telnet traffic percentage by the total BW = 14.8% x 216,000 =
31,968 bps (Notice this value is off from the answer 38Kbps). The problem
is the Custom Queuing total traffic did not add up to the speed of the
256kbps interface (this is okay because it is all about percentages). They
derived their answer from 256,000 x 14.8% = 38kbps. Note: neither one of
these answer are wrong, the bottom line is the ratio between the numbers.
Hope this helps.
Rick
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
>!
>
>
>
>Jim Phillipo, CCNP, CCDP
>Sr. Internetworking Engineer
>W: 401.456.1821 F: 401.456.0599 M: 508.982.8923
>90 Royal Little Drive, Providence, RI 02904
>www.guardent.com
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