Core issue
The unknown status is displayed by the show trunk [mod/port] detail command in these fields:
- peer-port
- mode
- encapsulation
- status
Sample output:
Switch (enable) show trunk 2/1 detail
* - indicates vtp domain mismatch
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
2/1 auto dot1q not-trunking 15
Port Peer-Port Mode Encapsulation Status
-------- --------- ----------- ------------- ------------
2/1 unknown unknown unknown unknown
This is only a cosmetic issue and does not affect network functioning. The trunk link is up and passes traffic.
Resolution
In the show trunk detail command output, the Peer-Port field displays either the module and port number of the peer connection, or multiple or unknown. Multiple is displayed if connected to shared media, and unknown is displayed if Dynamic Trunking Protocol (DTP) does not run on the other side.
