From: Scott Morris (swm@emanon.com)
Date: Tue Sep 24 2002 - 22:02:00 GMT-3
Wasn't that my point?
Scott
-----Original Message-----
From: elping [mailto:elpingu@acedsl.com]
Sent: Tuesday, September 24, 2002 9:00 PM
To: swm@emanon.com
Cc: ccielab@groupstudy.com
Subject: Re: CB WFQ
my friend
CB-WFQ is used for congestion management
CB-WFQ will not do the trick
please read
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/
qos_c/qcprt2/qcdconmg.htm#xtocid16
Once a class has been defined according to its match criteria, you can
assign it characteristics. To characterize a class, you assign it
bandwidth, weight, and maximum packet limit. The bandwidth assigned to a
class is the guaranteed bandwidth delivered to the class during
congestion.
hope this helps
Elping
Scott Morris wrote:
> priority
> To give priority to a class within a policy map, use the priority
> policy-map class configuration command. To disable the strict priority
> queue, use the no form of this command.
>
> priority bandwidth
>
> no priority [bandwidth]
>
> Syntax Description bandwidth
> Guaranteed allowed bandwidth (in kbps) for the priority traffic.
> Beyond the guaranteed bandwidth, the priority traffic will be dropped
> in the event of congestion to ensure that the nonpriority traffic is
> not starved.
>
>
>
> That's an interesting way to interpret the wording, but not really how
> it works! Both bandwidth and priority demonstrate how a series of
> queues are emptied into an interface. (remember that if no
> congestion, no queuing, no problem)
>
> One major difference in how they're handled is what happens when the
> upper limit is reached. If you have:
>
> Class voice
> priority 128
> Class stuff
> bandwidth 128
>
> When 128k of class voice is reached, classified packets will get
> dropped to not impede other traffic. When 128k of class stuff is
> reached, overflow packets are reclassified into class default, which
> will benefit from whatever leftover bandwidth there is.
>
> >From a queuing scheme, you can allocate 75% of available bandwidth
> (changed with the max-allocate-bandwidth command).
>
> In the case of both commands, they are viewed as the maximum
> guaranteed bandwidth allowed. Anything in "priority" bandwidth will
> always get emptied before anything else does (strict priority), and
> therefore any extra is dropped. Anything in other queues will be
> emptied in a pseudo-weighted-round-robin fashion based on the
> configrations, and any overflow traffic is dropped into the "default"
> queue. If the default queue overflows then traffic is dropped.
>
> Also, when you use priority, the amount of guaranteed bandwidth is
> taken out of the available pool. This means if you have a 10 meg
> link, and guarantee 2000 to a priority queue, that means that 8000k is
> available for other queues. Of that, 75% of the 8000k is available by
> default for allocation.
>
> Hope that helps!
>
> Scott
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of stephen.paynter@bt.com
> Sent: Tuesday, September 24, 2002 11:33 AM
> To: elpingu@acedsl.com; adam.crisp@totalise.co.uk
> Cc: ccielab@groupstudy.com
> Subject: RE: CB WFQ
>
> if you want to divide equally use the priority keyword instead of
> bandwidth percent 50.
>
> ie on ethernet priority 5000
>
> if you use bandwidth percent that is classed as minimum, priority is
> classed as maximum
>
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgc
> r/
> qos_r/qrdcmd3.htm#1036072
>
> Stephen Paynter CCIE #10206
> Customer Engineer
> BT Ignite- Customer Engineering Unit, National Solutions
> T: +44 (0)1422 338881 F: +44 (0)1422 316637 M: +44 (0)7974 087949
> e-mail: stephen.paynter@bt.com
> pp HW A170, PO Box 200(HOM-NZ), London, N18 1ZF
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> -----Original Message-----
> From: elping [mailto:elpingu@acedsl.com]
> Sent: 24 September 2002 03:18
> To: Adam Crisp
> Cc: Ccielab
> Subject: Re: CB WFQ
>
> my friend
> CB-WFQ will not do the trick
>
> i though the same thing a while back ...here is the scoop on CB-WFQ.
> this method will only gurantee the allocated bandwithd during
> congestion .
>
> now the question says ..
> dived traffic exactly .....then CB-WFQ will not do the trick..
>
> try custom queeing ..or CAR
>
> Elping
> .
>
> Adam Crisp wrote:
>
> > Hi,
> >
> > If asked to divide up bandwidth EXACTLY, can I use CB-WFQ, with the
> > "bandwidth percent XX" command?
> >
> > eg
> >
> > class-map match-all my_class_queue_ip
> > match access-group 25
> > !
> > policy-map my_policy
> > class my_class_queue_ip
> > bandwidth percent 50
> >
> > OR does this call for Custom Queuing?
> >
> > thanks in advance...
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