Hi All,
I have a 3750 switch with the following configuration on access ports:
switchport access vlan 1
switchport mode access
switchport voice vlan 2
srr-queue bandwidth share 10 10 60 20
srr-queue bandwidth shape 10 0 0 0
mls qos trust cos
auto qos voip cisco-phone
spanning-tree portfast
There are two voice vlans defined on this switch. I have two Cisco IP phones connected to access ports. If I put these access ports in the same voice VLAN and capture the traffic, I can see that incoming and outgoing traffics have EF DSCP tags on them. If I put these access port in different voice vlans and capture the traffic at each, incoming RTP traffic will lose the DSCP EF tag and DSCP will be set to zero, however the outgoing traffic will still have the EF dscp value.