From: David Duncon (david_ccie@hotmail.com)
Date: Mon Dec 27 2004 - 04:54:29 GMT-3
Hi Group,
I got a Q on MQC 'c class class-default behavior. And appreciate your
guidance on this.
On production network, let us consider that we have end to end L3 MQC policy
which primarily aimed to protect Business critical apps such as Voice and
Citrix and bundled every other traffic type such as File transfers , HTTP
and Emails ..etc in to a common default class with random detect feature
enabled. Since there is a bit of concern on the email (MS Exchange & Lotus
Notes Domino) traffic with in a default class as we are seeing some drops
there. So If we were to segregate & prioritize email traffic from the rest
of default class traffic , then which of the following options is the better
way to go. Either to leave the email traffic with in class class-default and
assign a guaranteed bandwidth or to segregate email traffic in to separate
class-map with in policy-map. The reason I am asking this Q is to understand
any negative impacts the NON time sensitive email traffic can bring in to
policy maps processing where already time sensitive traffic types (Voice &
citrix) are being serviced.
Option 1:
=================
Policy-map data
Class voice
Match access-group xxx
Priority xxx
Class citrix
Match access-group xxx
Bandwidth xxx
Class email
Match access-group xxx
Bandwidth xxx
Class class-default
Random detect
Option 2:
==================
Policy-map data
Class voice
Match access-group xxx
Priority xxx
Class citrix
Match access-group xxx
Bandwidth xxx
Class class-default
Random detect
Bandwidth xxx ---------------------------------------> emails are bundled
together along with file transfers & HTTP traffic with in class default.
And my Qs are :
1) is there any way where we can create 2 class-maps with in class
class-default , one for email and the rest for all default traffic ? If yes
is there any benefit in doing that ?
2) or is it safe for me to create another class-map for email and slot that
in with policy-map itself along with voice & citrix and dedicate certain
amount of bandwidth to it.
3) Thirdly , what is the between a class class-default with a bandwidth
command and one with out a bandwidth command. And also what is the
difference between a class class-default with a random detect command and
one with out it. Though I do aware the functionality of congestion avoidance
techniques such as WRED and RED , I was in the impression that besides
configuring random detect , you need to map it to a relevant DSCP code which
underlines a certain level of drop probability. In other words, you are
telling the policy engine on what type of traffic you want her to drop
should she pick up any early congestion warnings.
Any feed back is much appreciated.
- David.
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