08-11-2010 02:47 PM
A couple of QoS questions for you.
If a IP phone is marking its voice traffic with a DSCP value of 46 and sending it to an FWS or an FCX, these switches will recognize this DSCP setting and map it to the appropriate queue correct? Assuming the “trust dscp” command is entered on the ports. And if this is correct, will an FWS pass this DSCP setting on when the traffic leaves the switch? So if a IP phone is connected to switch “A” and the IP PBX is connected to switch “B”, will switch “A” switch the traffic with the original DSCP marking? Both switches are connected via layer 2.
In your experience, what is the best way to address QoS when dealing with soft phones installed on laptops that reside in the data VLAN?
Thank you in advance for your help.
09-08-2010 07:40 PM
If you control switch "A" and switch "B", then I would recommend establishing 802.1q trunks (or MPLS) and use the priority fields there so that switch B will trust the markings from switch A, rather than just do DSCP. Note that the DSCP values are a local decision, using 46 is just a convention.
As for the soft phones on laptops --- it is, I think, a difficult question. I do not want them trusted, or on my voice network, particularly if they are running windoz. My preference would be to run diffedge/intserv to get the laptop to negotiate for the service it wants... in practice, I have no idea if this really works.
It's been in windows since win2k, but I don't know if it ever got really field tested.