Hello,
I've been searching the web and forums for awhile and cannot seem to find the answer to my questions regarding this topic. It seems there is a wide variety of opinions out there and was hoping someone could clear up my confusion.
To start I'm talking about 2960-x Cat. Switches
My phone vendor recommends I perform QoS at L2 and L3. This would require me to trust COS at the interface level and I'm not sure why. If I trust DSCP at the interface level this will be end to end. If a PC sitting behind a phone (none cisco btw) sends a COS value this will get remarked to DSCP zero correct? I know there's some risk for a PC to manipulate it's traffic to set DSCP to 46 besides that fact why else would I care to trust COS? From my understanding most applications wouldn't set a COS value nor have I sniffed any that send DSCP yet. If I was going to use NBAR to further break out my traffic it would be a the router level.
Thanks,
