Portchannel issue (strange behaviour)

[enriquebs]

HI all,

We have a couple of 3750 switches (stacked) with an etherchannel link to a 7304 router.

This etherchannel is configured with two ports.

In the 3750 stack each port is connected to a different switch (g1/0/25 and g2/0/25).

In the 7304 the ports are g0/1 and g2/1 wich belong to different processors.

The thing is when the etherchannel is not configured the router works fine but 1 minute after configuring it the 7304 shows a very strange behaviour, there are lots of changes in the processors redundancy operations and if you see a sh redund output you can see a processor in "standby cold" status, while doing the same without the etherchannel configured the status is a normal "standby hot".

By the way, if you reset the router and don´t save the etherchannel config all seems fine, works in a normal basis...

Any idea about what is happening?

Thanks in advance

[ndarnell]

How's the etherchannel configured?

When using ports on different switches in a stack the mode has to be set to on so that PagP is used

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_guide_chapter09186a008017ed2f.html#36775

Check out the etherchannel configuration guidelines section in the above link for further details

HTH

N

[enriquebs]

Yes, etherchannel is ok, it works fine if I change the 7304 for a 6500 or whatever.

The problem seems to be related to the two processors in the 7304. Somebody knows if this Cisco routers supports an etherchannel in two ports each of one belonging to a different processor? They are working in SSO mode.