Uplink

[glinskim]

I am trying to connect 2 9300 switches on separate floors, I have configured a port to uplink to the other port.  I am using a port channel in this connection.

I am getting an "ERR_DISABLE: channel-misconfig error detected on PoX" which puts the ports in an err-disable state and shuts them down.  They do recover but I need to remove the uplink to the 2nd switch in order to have the switch work properly.

I assume this is due to the MAC address on the original switch seeing another MAC from another switch and shutting down the ports

I read that this could be a spanning-tree issue but not sure how to resolve

[Flavio Miranda]

@glinskim 

  Can you share the configuration from both switch? If not all at least the port-channel config?

 On the interface, use the command

channel-group X  mode active

[Reza Sharifi]

Sometimes, Portchannel configuration can be cumbersome. So, follow these steps and try to rebuild it.

shutdown the physical interfaces

Delete the PO completely.

Delete the PO config under the interfaces

now

go under each interface and add a new PO number. This should create the PO for you.

now under the po interface, issue the command "no sh." This should bring up the po-interface as well as the physical.

If not, bring up the physical interface by issuing the same command (no sh). Now check the PO status.

HTH

[Cristian Matei · Accepted solution]

Hi,

   You're seeing that error, most probably because you've configured the portchannel using "on" mode; what happens is that the side where portchannel is configured considers those physical links as one logical link, while the side which is not configured considers those physical links as independent; the non configured side sends BPDU's on all links, and the side which is configured does not except this, thus puts the links in err-disabled state to avoid loops and save the network from melting down. You'll see people recommending to enable "errdisable recovery cause channel-misconfig" to fix this; while it actually fixes it, it opens the door for loops in case you have a portchannel misconfiguration.

   So, best way, configure the portchannel using negotiation, namely LACP, by using "channel-group X mode active" on both sides, on all links. Links will be bundled into portchannel only when both sides have been configured, portchannel interface will come up when at least one physical link has been successfully added to the bundle. Also, recommended to configure fast LACP timers, by using "lacp fast-switchover" under the portchannel interface, on both sides.

Best,

Cristian.

[glinskim]

Thank you Cristian, this makes sense from what I was reading on spanning tree and the BPDU's

[MHM Cisco World]

I am with you it issue of stp.

Stp make PO misconfig errdisable happened.

So first 

Share 

Show spanning tree summary 

It can one SW use different stp mode

Or 

It can one SW use extended system id 

It not PO issue at all.

MHM

[glinskim · Accepted solution]

Actually as it turns out the port channel was the same on both switch from the uplink port, ie. switch 1 port 1 and port channel 8 and switch 2 port1 had port channel 8, I needed to rename as port channel 8 was already in use.  I still am trying to grasp concept of port-channeling, previous regime used them alot and have come to find not really necessary when only uplinking 1 switch to another.  Thanks everyone for feedback, much appreciated.