We're implementing ip phones on our 3750 - the set up is as follows:
PC---ip phone---<l2 trunk>---3750---<l2 trunk>---3750---<routed l3>---3750---<routed l3>---6509---IP office
I had intended to put a service policy on the access-switch interface that the pc/phone connects into, marking VoIP traffic, VoIP signalling, certain critical-data protocols (for us this is ssh, rdp, telnet), BE traffic, and scavenger class (ftp etc). I was planning to do this with access-lists. Unfortunately when I implemented this no traffic was marked - I guess this is because I'm trying to mark layer 3 info on a layer 2 switchport. The QoS commands on my 3750s are extremely limited...therefore I am now thinking that I will:
-trunk dscp markings from the access switch ports (this will basically only be BE (data) and EF (VoIP) traffic - I have been analysis this for a few hours)
-apply egress prority queuing on the L2 trunk ports
-Mark all other interesting traffic on layer 3 interface using ACLs (SSH, etc) in an inbound service policy
-apply outboud priority queueing on L3 interface
What I can't understand is how to apply priority queueing with only 2 queues. On the L2 access switch I am basically going to have EF VoIP traffic, and then everything else as BE. I either need 2 queues (1 priority for EF) or 4 queues with 3 all handling BE traffic. Otherwise queues 2 and 3 will have zero traffic running on them. Not sure if this makes sense or whether I've not understood it properly...really hoping someone can help!