RE: MQC class-default

Petr,

Hadn't seen your article :) nice one. I'm afraid I can't agree only with
this sentence " Notice that this behavior may seriously starve the
"class-default" traffic, as all user-defined classes have significantly
better weights compared to WFQ dynamic weights". Or probably what I
understand from your explanation is not very accurate.

--------------------------
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-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
Petr Lapukhov
Sent: Thursday, April 29, 2010 2:30 PM
To: Bit Gossip
Cc: ccielab
Subject: Re: MQC class-default

Hi,

The behavior is different for CBWFQ and HQF to be accurate. CBWFQ is
merely a WFQ extension and therefore all unclassified traffic is
serviced using WFQ strategy, unless you assign an explicit weight to
class-default. Notice that this behavior may seriously starve the
"class-default" traffic, as all user-defined classes have
significantly better weights compared to WFQ dynamic weights. You may
read more at:

http://blog.ine.com/2008/08/17/insights-on-cbwfq/

As for HQF, it uses some round-robin (min-max type) based scheduling,
which cisco never documented anywhere. By default, all unclassified
flows are assigned to a single queue with 1% bandwidth reservation
enforced by the algorithm. This prevents the starvation problem found
in CBWFQ. Not to mention performance optimizations in HQF compared to
CBWFQ.

HTH,

-- 
Petr Lapukhov, petr_at_INE.com
CCIE #16379 (R&S/Security/SP/Voice)
Internetwork Expert, Inc.
http://www.INE.com
Toll Free: 877-224-8987
Outside US: 775-826-4344
2010/4/29 Bit Gossip <bit.gossip_at_chello.nl>:
> Experts,
> the below quote from DocCD MQC class-default:
> "If no default class is configured, then by default the traffic that
> does not match any of the configured classes is flow classified and
> given best-effort treatment."
>
> 1) what does it mean: it is flow classified?
> Maybe that within the class-default itself WFQ is used to fair treat
all
> flows in the class
> 2) what does it mean best-effort in this context? that is served only
> after all CBFQ are service?
> Thanks,
> Bit
>
>
> Blogs and organic groups at http://www.ccie.net
>
>