IP Communicator - How does it really work

[Steve Dussault]

We are deploying IP Communicator and have been told it works just like an "IP Phone". What does this mean from a QOS perspective? Are the COS / DSCP set like a hard phone? If COS is set, how is it done? (IP Communicator is able to modify the L2 transport of the PC NIC card?) Detailed insight on IP Communicator and how it works with QOS will be greatly appreciated.

[mcotrone]

It works like an IP Phone in regards to using SCCP unlike the older TAPI/CTI controlled softphones. Still you have the issue of voice on your data VLAN.

Here is a post I just did for another question regarding this topic...

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So here is the thing. The IP Phone is remarking all traffic from the Access port for COS=0. The Softphone is on the PC which is connected to the Access port. The softphone voice traffic is definetly being marked as COS=0.

At the switchport connecting to the phone you have to manually mark voice media and voice signaling traffic.

IE. 6500

set qos enable

set qos cos-dscp-map 0 8 16 26 36 46 48 56

set qos ipprec-dscp-map 0 8 16 26 36 46 48 56

set qos acl ip VOIP dscp 26 tcp any any range 2000 2002

set qos acl ip VOIP dscp 46 udp any any range 16384 32768

commit qos acl VOIP

set qos acl map VOIP (Make sure you are trusting this port)

This will manually mark the port for you.

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If you look at a sniffer trace from a softphone the packets look like cos=0 (from the IP phone rewrite) and AF31 (DSCP26) for Skinny and EF (DSCP46) for RTP Audio.

So you will have to manually set the cos level at the ingress switchport connecting to the phone based on the incoming DSCP values which are true from a softphone.

HTH,

Mike

[Steve Dussault]

Mike -

Thank you for your feedback.