From: Pierre-Alex (paguanel@hotmail.com)
Date: Sat Jun 03 2006 - 18:23:40 ART
Petr,
Just for info, I found an example on cco of using both the "shape" and
"bandwidth" to the same value. :)
Is my interpretation of this configurations correct:
"The shapper creates a congestion points for the sub-classes at 241K. 241 K
of bandwidth is allocated to the shapping queue, out of which ,
25 percent goes to each of the four customers."
It does make sense to have the same value for the shapping and the queue in
this example doesn't it?
=================================
Policy Map GTS_in_ModCLI Configuration
Router(config)# policy-map GTS_in_ModCLI
Router(config-pmap)# class shaped
Router(config-pmap-c)# bandwidth 241
Router(config-pmap-c)# shape average 241000
Router(config-pmap-c)# service-policy CBWFQ_in_GTS
Policy Map CBWFQ_in_GTS Configuration
The policy map called CBWFQ_in_GTS has four CBWFQ classes:
Router(config)# policy-map CBWFQ_in_GTS
Router(config-pmap)# class cust_A
Router(config-pmap-c)# bandwidth percent 25
Router(config-pmap)# class cust_B
Router(config-pmap-c)# bandwidth percent 25
Router(config-pmap)# class cust_C
Router(config-pmap-c)# bandwidth percent 25
Router(config-pmap)# class class-default
Router(config-pmap-c)# fair
In this second example, the Class-Based Shaping feature is configured for the
class called shaped in the policy map called GTS_in_ModCLI. The class shaped
is shaped to an average rate of 241,000 bits per second (bps). CBWFQ is also
enabled on the class, which guarantees a bandwidth of 241 kbps during times of
congestion at the interface.
The shaped class is a congestion point for all the subclasses that comprise
that class. Therefore, the subclasses can be further differentiated in the
shaped class. All these subclasses are part of the policy map, CBWFQ_in_GTS,
that is attached to the shaped class.
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fqos_
c/fqcprt4/qcfcbshp.htm#wp1002823
----- Original Message -----
From: Petr Lapukhov
To: Pierre-Alex
Cc: ccielab@groupstudy.com
Sent: Saturday, June 03, 2006 7:29 PM
Subject: Re: hierarchical shaping versus shaping in conjunction to cbwfq
Pierre,
I may put the things a bit unclear, sorry :) The main thing I want
to point at, is that "bandwith" and "shape" do quite different things.
You are correct, one may use "bandwith" to allocate resourses in case
of "oversubscription". It's just useless if you set "shape" and "bandwidth"
to equal values :)
Say, if we have 512K physical port speed, and we need to divide it equally
between two classes of traffic in case of congestion.
To achieve that, we issue "bandwidth 256" under each class.
But next, we want let every class use more of available bandwith, in case
if it's actually available, but not too much :)
So we shape every class to 384k:
policy-map policy
class class1
shape average 384000
bandwidth 256
class class2
shape average 384000
bandwidth 256
HTH
Petr
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