QoS DSCP Marking from IP Phone PC port

[Jthind]

I'm working on a QoS strategy where I need to trust the DSCP value coming from the PC.  However the PC is plugged into the PC port of a Cisco IP Phone.  I know by default Cisco IP Phone mark VoIP traffic with the correct DSCP values.  So I want to use a trust DSCP model since I also trust the DSCP value coming from the PC (App will mark).

My question is will the IP Phone pass along the PC port DSCP marking without modifying it?  I'm pretty sure this is the case, however I can't find any documentation supporting this.  My end goal would be to trust the native DSCP markings from the IP Phone and connected PC.  The PC is running Webex so I need to support QoS for voice/video.

Thanks for your help!

[Georg Pauwen · Accepted solution]

Hello,

the IP Phone won't change anything, so the DSCP values from the PC remain intact. Keep in mind that if you keep the PC in the default VLAN, nothing will be tagged and any CoS (layer 2) will be lost...but from what you are saying it sounds like you only want DSCP anyway...

[Jthind]

Awesome thanks!! Yes I'm trusting DSCP.

[Joseph W. Doherty]

As Georg already notes, the expectation would be for the IP phone to pass IP ToS to/from a PC connected to it.