From: Petr Lapukhov (petr@internetworkexpert.com)
Date: Thu Dec 28 2006 - 07:03:03 ART
The difference is pretty strightforward:
First case, CBWFQ and GTS: typical scenario for oversubscription.
Lets say you have 1024Kbps interface rate, and two classes. You'd
like to guarantee the first class 768Kpbs, and 256K for second.
However, when your link is not congested, you would like to permit
every class to use up to 768k, if it's "available".
Therefore, you set up bandwidth limits to 768 and 256 K for respective
classes, the "minimum guarantee". However, you shape every class
to 768K, thereby permitting each to use up to 768K of line rate,
if it's available. In case of oversubscription, the bandwidth limits kick
in,
and enforces the agreements.
Second case, CBWFQ inside GTS. Use this one when you'd like to
enforce fine-grained queueing strategy inside a given class. That is,
if your class has 256k, and you'd like to provide priority service for
voice traffic inside the class, or share the bandwidth proportionally.
CBWFQ inside GTS is simply a replacement to classic WFQ used
inside legacy traffic-shaping, that permits you to enforce fine-grained
constrains for user classes. You usually may find this one used on
subinterfaces, which does not have the "narural" queueing mechanics,
and where GTS provides a sort of software queueing.
HTH
2006/12/27, Blastmor <alextols@gmail.com>:
>
> Hello GS
> What's the difference between "CBWFQ in Conjunction with GTS" and "CBWFQ
> Inside GTS"
> On UniverCD there are only old examples without any clarification
>
> 1.
>
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t2/clsbsshp.htm#wp1025965
> 2.
>
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t2/clsbsshp.htm#wp1025800
>
> UniverCD says that
>
> Router(config)# *policy-map shape-cbwfq
> *
>
> Router(config-pmap)# *class cust1
> *
>
> Router(config-pmap-c)# *shape average 384000
> *
>
> Router(config-pmap-c)# *bandwidth 256
> *
>
> Router(config-pmap)# *class cust2
> *
>
> Router(config-pmap-c)# *shape peak 512000
> *
>
> Router(config-pmap-c)# *bandwidth 384
> *
>
> is correct.
>
>
> But why I can't write smth. like:
>
> Router(config)# *policy-map shape-cbwfq
> *
>
> Router(config-pmap-c)# *class cust1
> *
>
> Router(config-pmap-c)# *shape average 384000*
>
> Router(config-pmap-c)# service-policy child1
>
>
> Router(config-pmap)# *class cust2
> *
>
> Router(config-pmap-c)# *shape peak 512000*
>
> Router(config-pmap-c)# service-policy child1
>
>
> Router(config)# *policy-map child1
>
> *Router(config-pmap-c)# class class-default
>
> Router(config-pmap-c)# bandwidth 256000
>
>
> Router(config)# *policy-map child2
>
> *Router(config-pmap-c)# class class-default
>
> Router(config-pmap-c)# bandwidth 384000
>
>
> Plz clarify...
>
>
> SY, Alexey
>
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-- Petr Lapukhov, CCIE #16379 (R&S/Security) petr@internetworkexpert.comInternetwork Expert, Inc. http://www.InternetworkExpert.com
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