I am currently studying for QOS 642-642 exam and I have a problem with the untrusted boundary. I have 2 sets of 2950G-12-EI in my lab running on IOS 12.1(22)EA12. As per Wendel Odom exam certification guide and 2950 Software configuration guide on 12.1(22)EA11, all packets that are received on untrusted ports will be marked with COS 0 which then maps to DSCP 0.
However, when simulating this among Cisco IP Communicators and Cisco hard IP phones, I get totally different results. Inspecting the packets via Wireshark, I get RTP packets with the original DSCP value of EF and skinny packets with DSCP value of AF31.
The following are the typical configuration on all the ports
switchport mode access
switchport access vlan 100
switchport voice vlan 200
sh mls qos int fa0/1
trust state: not trusted
trust mode: not trusted
COS override: dis
default COS: 0
trust device: none
The cos-dscp and dscp-cos mapping are at its original value.
Is there something wrong with the documentations, or my understanding on the subject or my equipments? Would someone able to shed some light on this matter? Thanks.