Core issue
The show etherchannel detail command displays this output for all ports that are part of the EtherChannel:
switch#show etherchannel detail
Channel-group listing:
-----------------------
Group: 1
----------
Group state = L2
Ports: 2 Maxports = 8
Port-channels: 1 Max Port-channels = 1
Protocol: -
Ports in the group:
-------------------
Port: Fa0/43
------------
Port state = Up Unsuit Not-in-Bndl
Channel group = 1 Mode = On/FEC Gcchange = -
Port-channel = null GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 00d:04h:01m:43s
Probable reason: Access port with voice VLAN configured cannot be part of an etherchannel
This message indicates that the EtherChannel was not set up correctly. The cause is the switchport priority extend interface configuration command which sets the port priority for the incoming untagged frames.
Resolution
In order to make the EtherChannel work, use the no switchport priority extend interface configuration command on the interfaces that are part of the EtherChannel. In software releases earlier than Cisco IOS Software Release 12.1(13)EA1, use the switchport priority extend none interface configuration command.
