L3 bandwidth Queues for VOIP Traffic

[TyrosAdmin]

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

[jasyoung]

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.

[dijohn]

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]

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]

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