Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
You may experience some slow load times, errors, and slight inconsistencies. We ask for your patience as we finalize the launch. Thank you.

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

implementing TCCS and QoS across PTP T1

here's the scenario:


using TCCS to trunk the PBXs together. Can I use NBAR to identify the traffic that TCCS is using or what is the best way to implement QoS for this scenario. There is also data flowing across the same T1 from the ethernets.

  • Other Collaboration Voice and Video Subjects

Re: implementing TCCS and QoS across PTP T1

Create loopback interfaces on both routers and use the 'H323-gateway voip bind srcaddr' command as the source of all the VOIP traffic.

If using G729, assume 24 K per call and base your priority statements on the LLQ to suit. The D channel should have 64K available as some PBX's will send continual fill in packets (eg NEC No.7 signalling)

Next, use low latency queueing to match on an access list that specifies the source of the local loopback and destination loopback IP addresses. This will make the LLQ config quite simple.

access-list 100 permit ip host host

class-map voip

match access-group 100

policy-map TCCS_VOIP

class voip

priority 650


class class-default



apply the policy to the interface -

interface serial 1/0

ip address

service-policy output TCCS_VOIP

Make the VOIP dial peers point to the remote

loopback interface as well.

Add the voice vad time 100000 (10,000 msec) command so that if there is no audio after 10 seconds, the VAD will cut in on idle channels, saving bandwidth.

We have set up many site like this and they are working fine.