Duplicate Etherchannel

[david de sousa]

                   hi all,

i have an small issue with etherchannel, when i create a port-channel in a VSS c6506, the main Po goes down and create another one in parallel with the letter A

Port-channel132        unassigned      YES unset  down                  down

Port-channel132A       unassigned      YES unset  up                    up

132    Po132(SD)       LACP

132    Po132A(SU)      LACP      Gi1/9/12(P)    Gi2/9/12(P)

so my question is, why this duplicate Po ? i know if there is a mismatch between 2 ports, it will create a second port-channel, but here, the two ports are in the same Po but not in the main Po...  if i shut this Po, it will renegociate the Po, sometimes the main Po becomes up, and sometimes no.

i read the Cisco document about the port-channel, but there is no explanation for this comportment. anyone can explain this?

thanks a lot

[daniel.dib]

Do you have this command?

mls qos channel-consistency

According to the document here http://docwiki.cisco.com/wiki/Issue_Description:_Creation_of_a_Secondary_portchannel_%22PortChannel_1_and_1A%22_with_LACP_channel_protocol
a secondary portchannel will be created if :

1. Adding a new port to an existing port channel. If any configuration mismatch is seen on the newly added port, it will be added to Secondary port-channel as you can see (Here, Po1A)

2. Configuration mismatch on the ports bundled in the port channel.

3. Configuration mismatch on the interfaces of the far end device can also create inconsistency between the ports bundled in the port channel.

This is expected behavior. The exact reason will be shown in the Logs while adding the port to port-channel.

Daniel Dib
CCIE #37149