cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Announcements
Walkthrough Wednesdays
506
Views
9
Helpful
4
Replies
TyrosAdmin
Beginner

L3 bandwidth Queues for VOIP Traffic

This might be more of a question for QOS, but it does have to do with voice, so I'll give it a shot here.    We're a callmanager 7 environment using skinny and mcgp.

I have a 4x T1 MLPPP WAN solution at my main site, and in case I decide to increase my bandwidth, I want to be able to keep my same bandwidth allocations for tiered voice and data.

My WAN provider will automatically set the QOS on the links the way I have it set up, but if packets are to drop, I'd rather them drop at my router than against the wan where I have zero visibility.

I want my allocations to be in 4 tiers.    Top Tier gets 40%, and the other three tiers get 20% each   Class1 is for voice, Class2 is for VOIP Control/MCGP/Skinny, Class3 and Default are for remaining traffic.

I did some research, and tried this config.   However, what I got on the Class3 was an error that after setting priority percent 40 and 20 on the upper two classes, that there was only 15% of bandwidth remaining.   Last I checked, 40 and 20 equaled 60, not 85.   There must be something I'm missing.

Here's the policy map I'm wanting to set for my WAN traffic.

policy-map DV-L3-OUT

  class Class1

   priority percent 40

   set dscp 46

  class Class2

   priority percent 20

   set dscp 32

  class Class3

   priority percent 20

  class class-default

   fair-queue

I would appreciate any feedback that anyone might be able to offer.

James

4 REPLIES 4
jasyoung
Rising star

You don't really want to use "priority percent X" for anything except voice bearer traffic. Use "bandwith percent X" for your remaining guaranteed queues, including voice signaling traffic.

Hi,

The default maximum reservable bandwidth value of 75 percent is       designed to leave sufficient bandwidth for overhead traffic, such as routing       protocol updates and Layer 2 keepalives. It also covers Layer 2 overhead for       packets matching defined traffic classes or the class-default class. You now       can increase the maximum reservable bandwidth value on ATM PVCs using the       max-reserved-bandwidth command.

Thats exactly why the third priority command threw an error.

http://www.cisco.com/en/US/tech/tk543/tk757/technologies_tech_note09186a0080103eae.shtml

Here's a mind map which I personally like

http://cciev.wordpress.com/2006/05/25/qos-for-wan/

http://www.mindomo.com/view?m=1aa303cf33751870d7cba78aef9e0386 (Thanks to  Arden Packeer)

You should go thru the above doc. ... or just use AUTO QOS

/divin

PS:Rate only useful posts.!

dijohn
Cisco Employee

Sample Config

int se0/0/0

bandwidth X

max-reservable-bandwidth 80

policy-map DV-L3-OUT

  class Class1

   priority percent 40

   set dscp 46

  class Class2

   bandwidth percent 20

   set dscp 32

  class Class3

   bandwidth percent 20

  class class-default

   fair-queue

HTH

/divin

PS: Rate ONLY useful posts!

dijohn
Cisco Employee

Mark this as resolved if you have no more questions! I see redunant posts in to section on CSC

Content for Community-Ad

Spotlight Awards 2021