Voice Configuration qos-map check and recommendation for a voice only deployment

[jamesd]

I was looking for a recommendation on max-reserved-bandwidth & qos-map

I am looking for the maximize a voice only on 900e 3rd gen. Is there a recommend max-reserved-bandwidth? Up to 90%??

THIS WAS DONE WITH THE MAX-RESERVED-BANDWIDTH at default, 75%

The balance of kbps works out exactly.

qos map VOICE 10

match dscp 46

match dscp cs3

match dscp 41

priority percent 70

exit

!

qos map VOICE 20

match dscp cs2

bandwidth percent 5

exit

!

interface ppp 1

  qos-policy out VOICE

AT PPP 1 INT MAX MAX-RESERVED-BANDWIDTH 85%

qos map VOICE 10

  match dscp 46

  match dscp cs3

  match dscp 41

  priority percent 80

qos map VOICE 20

  match dscp cs2

  bandwidth percent 5

  interface ppp 1

  description ppp 1

  ip address  xxxxxxxxxxxxxxxxxx

  media-gateway ip primary

  peer default ip address xxxxxxxxxxxxx

  max-reserved-bandwidth 85

  qos-policy out VOICE

  no shutdown

  cross-connect 1 t1 0/1 1 ppp 1

[jayh]

It's at 75% because that's a good compromise. You can go higher but if everything is voice and you're doing no data at all do you really need QoS? The idea of limiting it is to allow routing protocols, administrative access, etc. in the event of severe congestion. If you're using 75% of the pipe for priority traffic, you probably need a bigger pipe or will very soon.

Yes, you can go to 90%. Keep the RTP in a low-latency priority queue. SIP needs little bandwidth and can take buffering and latency but avoid drops with reserved bandwidth. I've run SIP at 2% on busy networks. Make sure your DSCP values are being set as intended and reset to 0 any DSCP from untrusted networks.