[c-nsp] VOIP QOS

[pelle]

On Thu, Nov 08, 2007 at 08:51:38PM -0500, Paul Stewart wrote:

> Our GigE interface has a bunch of customers off of it so if I set a "shape
> average" service-policy on the main interface that'll effect all users
> right?

Yes, it will affect all sub-interfaces on that main interface.

In your scenario, I would recommend a parent-child policy.

on the 2800:

class-map match-any VOIP
  match protocol rtp
  match protocol sip

class-map match-any EF
  match dscp ef

policy-map PARENT
  class class-default
    shape average 5000000
    service-policy child

policy-map CHILD
  class EF
    priority 2000000

policy-map CLASSIFY
  class VOIP
    set dscp ef
  class class-default
    set dscp default

interface fa0/0
  service-policy output PARENT

interface <LAN-port>
  service-policy input CLASSIFY


on the 7200:

class-map match-any EF
  match dscp ef

policy-map PARENT
  class class-default
    shape average 5000000
    service-policy child

policy-map CHILD
  class EF
    priority 2000000

interface gigabit0/0.101
  service-policy output PARENT

you must of course make sure the traffic is correctly marked before the
queuing on the 7200.


those policies separates the classification and queueing in two stages:
classification on ingress and queuing on egress, which is a good thing.
in that way, you could for example attach an policy which allows VOIP
traffic on a certain LAN-port/sub-interface, and do Best-Effort on other
ports/subinterfaces.

doing parent/child polices are documented here:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hqos_c/part40/qctmcli2.htm#wp1060235

on some platforms you can't do a "priority <bw>" and must be configured
as "priority" + "police <bw>".

-- 
pelle
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