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RE: Class class-default posted 12/27/2004
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I think I'd go with solution 1.  Like Bob said, I don't think assigning
a bandwidth to the class-default makes any sense.  You don't want random
detect being applied to the email traffic either, which makes a better
case for solution 1 as well.  Of course with any complicated QOS
configuration, it's going to take some fine tuning to get the settings
you want.  Other things you can consider is policing or shaping your
less-than-normal-importance traffic, such as file-sharing apps, etc.
That'll lessen your WRED drops for your class-default traffic.  


Chuck Church
Lead Design Engineer
CCIE #8776, MCNE, MCSE
Netco Government Services - Design & Implementation Team
1210 N. Parker Rd.
Greenville, SC 29609
Home office: 864-335-9473
Cell: 703-819-3495
cchurch@xxxxxxxxxxxx
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x4371A48D 


-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
David Duncon
Sent: Monday, December 27, 2004 2:54 AM
To: ccielab@xxxxxxxxxxxxxx
Subject: Class class-default

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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