My customer has been using a working switchport config that included the same VLAN no. for voice & access. This is supported and documented, e.g. here: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/vlan/configuration_guide/b_vlan_152ex_2960-x_cg/b_vlan_152ex_2960-x_cg_chapter_0110.html#ID74
Now we are in the process of a platform exchange due to lifecycle reasons, with a similar config as much as possible. Surprisingly, the end devices (PC and phone, cascaded) connected to the new switch can't communicate anymore. The LED on the affected ports stay orange, the links are up/up and spanning tree wouldn't start changing state at all (the ports are missing in the 'sh spanning-tree vlan xxx' output). It's important to note that the new switch has the necessary VLANs configured.
As soon as I change the voice VLAN so that it differs from the access VLAN, or, as I remove the 'switchport voice vlan' command, the LEDs turn green and communication starts to flow. So it seems to me that there's some kind of bug or behaviour change on the new switch or its S/W.
Any idea what's happening here?
This is the configuration of the switches:
Old switch (WS-C3750-24PS-S, 12.2(44)SE2):
interface FastEthernet1/0/11
switchport access vlan 173
switchport mode access
switchport voice vlan 173
srr-queue bandwidth share 10 10 60 20
priority-queue out
mls qos trust device cisco-phone
mls qos trust cos
auto qos voip cisco-phone
spanning-tree portfast
service-policy input AutoQoS-Police-CiscoPhone
New switch (WS-C2960X-48LPS-L, 15.0(2)EX5):
interface GigabitEthernet1/0/35
switchport access vlan 173
switchport mode access
switchport voice vlan 173
spanning-tree portfast
[Yes, we've decided to try running VoIP without QoS to see how it'll turn out.]
Thanks for any hint
Toni
