From: Devi Mallampalli (Devi.Mallampalli@chubb.com.au)
Date: Sat Dec 04 2004 - 22:57:43 GMT-3
Thanks for your response , Tim/Gladston.
Yes I agree on your point. Indeed I forgot to mentioned that my example
of 64k on the wire is of 100% on the available bandwidth ( assuming I
have tweaked with reference B/W command and even though it is not a best
practice to creep in to last 25% of the available B/w which normally
dedicated to L2 encaps and L3 protocol mechanics).
So let me rephrase my Q. Assuming that 64k in my example is the total
available bandwidth on the wire , is there any difference between both
CQ config/functionality and CBWFQ config/functionality. And more
importantly is it necessary to have both the configs on the device (i.e.
can they interoperate some how on the same device) ?
And another point , as Gladston mentioned earlier, CQ algorithm will
consider the byte-count/size rather than packet count. So suppose you
have two queues , one of which supports an interactive session with many
short packets , while the other queue contains bulk transfer with few
large packets. If you configure the Router to service these 2 queues
with the same byte-count , it will tend to forward a lot more of small
packets. But the net share of the bandwidth will be roughly equal on
average.
Regards
Devi.
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Sunday, 5 December 2004 11:51 AM
To: Devi Mallampalli; ccielab@groupstudy.com
Subject: Re: Interoperability of CQ with CBWFQ
Hi,
One difference I can think of is this:
With MQC, the percent specified for a class of traffic is relative to
the available bandwidth, not the actual interface bandwidth. By
default, I believe 25% of the bandwidth is reserved, but that can be
changed.
Thus, with MQC, in your example, when you configured ftp for 30%, that's
30% of 75% of 64k, not 30 % of 64k.
HTH, Tim
----- Original Message -----
From: "Devi Mallampalli" <Devi.Mallampalli@chubb.com.au>
To: <ccielab@groupstudy.com>
Sent: Saturday, December 04, 2004 7:34 AM
Subject: Interoperability of CQ with CBWFQ
> Hi Group,
>
> I was wondering is it possible to make a CQ (with let us say 4 queues
,
> queue 1 = FTP , queue 2 = Telnet , queue 3 = dlsw , queue 16 =
default)
> interoperable with a CBWFQ so that CBWFQ can call any of CQ config
> parameters in any way ?
>
> From my understanding , CQ is a legacy way of deploying or
manipulating
> the " service threshold" a traffic type from default behavior of 20
> packets in the queue depth and 1500 bytes of pick up run by the
> scheduler on her each pass. And this mechanism I believe is
successfully
> taken over by CBWFQ algorithm which is more flexible (64 queues as
> oppose 16)and can offer better results. And CBWFQ can do almost all of
> things CQ does in terms of identifying the traffic types (class-maps)
> and deciding what to do with each traffic type (policy map) and then
> applying to an interface with a service policy.
>
> So in other words , to me they both are similar algorithms , one a
> legacy one and 2nd one is more sophisticated with better control.
There
> by I think you can not join CQ with CBWFQ in any manner ???
>
> Let me explain you with an example:
>
> B/W on wire = 64k
> Ftp to have = 30%
> Telnet to have = 20%
> Dlsw to have = 10 %
> Default to have = rest of B/W.
>
> So with the above info , I can calculate the required byte-count of
each
> queue with the below formula.
>
> Ftp = 30% of bandwidth to be given = 64 000 / 8 = 8000 bytes * 30/100
=
> 2400 byte-count , which will go in as "queue-list 1 queue 1
byte-count
> 2400 limit 100"
> telnet = 20% of bandwidth to be given = 64 000 / 8 = 8000 bytes
*20/100
> = 1600 byte-count , which will go in as queue-list 1 queue 2
> byte-count 1600 limit 100
> Dlsw = 10%% of bandwidth to be given = 64 000 / 8 = 8000 bytes *
> 10/100= 800 byte-count , which will go in as "queue-list 1 queue 3
> byte-count 800 limit 100"
> Default = 40% of bandwidth to be given = 64 000 / 8 = 8000 bytes *
> 40/100 = 3200 byte-count , which will go in as queue-list 1 queue
16
> byte-count 3200 limit 100
>
>
> And then these queues will then be applied on an interface with a
> custom-queue command.
>
>
> But now my Q is , since we can do the same thing with CBWFQ too with
the
> following config, am not sure how we can make these 2 algorithms
> interoperate (if at all there is a provision/necessity) the above
config
> of CQ to the below mentioned config of CBWFQ ?
>
> Ip cef
>
> Class-map ftp
> Match protocol ftp
> Class-map telnet
> Match protocol telnet
> Class-map dlsw
> Match protocol dlsw
>
> Policy-map cbwfq
> Class ftp
> Bandwidth percent 30
> Queue-limit 100
> Class telnet
> Bandwidth percent 20
> Queue-limit 100
> Class dlsw
> Bandwidth percent 10
> Queue-limit 100
> Class class-default
> Bandwidth percent 40
>
> Interface s0/0
> Service-policy output cbwfq
>
>
> I appreciate any feed back on this subject.
>
> Regards
>
> Devi
>
>
>
>
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