[c-nsp] QoS on Serial T1 question

[Nick Voth]

Hello folks,

I'm trying to simplify some VoIP QoS on a Cisco 7206 VXR with a PA-MC-T3
card used for T1's.

On the far end of the T1s we have CPE equipment that sets the dscp class for
our VoIP traffic as it comes through to us. It's of course set to be "ef".

I'm wondering if this config on our T1's will work for classifying and
prioritizing that traffic:

class-map match-any RT
 match ip dscp ef 
 match ip dscp cs5 
class-map match-any BE
 match ip dscp cs1 
 match ip dscp default
class-map match-any NC
 match ip dscp cs6 
 match ip dscp cs7 
class-map match-any SG
 match ip dscp cs3 
 match ip dscp cs4 
 match ip dscp af31
 match ip dscp af41

policy-map Serial_T1
  class NC
  bandwidth percent 5
  class RT
  priority percent 90
  class SG
  bandwidth percent 5
  class class-default
  fair-queue

interface s4/0/.....
 max-reserved-bandwidth 100
 service-policy output Serial_T1

The one main thing I'm unclear of is the "priority percent 90" directive in
the Serial_T1 policy-map. I'm not familiar with the "priority" directive.

Plus, it seems to be classifying more dscp classes than I really need. We're
really just marking the VoIP (SIP & RTP) traffic with ef on the far end CPE.

What I want to make sure of is that the VoIP traffic can take up to 90% of
the overall pipeline if it needs it, BUT if VoIP traffic isn't present, the
full pipeline is available for use.

Am I missing something here?

Thanks very much,

-Nick Voth