GEC Bundle on 3750

[s.gilbrook]

I am in the process if connecting two 3750's, each with 2 1GB uplinks, to the copper 10/100/1000 ports on a 4507R.

I have split the uplinks from the two 3750's into two seperate cards on the 4507 and have set-up a port-group with the following configuration:

interface Port-channel2

switchport

switchport trunk encapsulation dot1q

switchport mode trunk

end

I have then applied this to the physical ports on the 4507, which has now got four 10/100/1000 ports with the following configuration:

interface GigabitEthernet5/31

switchport trunk encapsulation dot1q

switchport mode trunk

speed 1000

channel-group 2 mode desirable

end

I am able to get one of the 3750's to create a bundle and appear as a 2GB interface, but when I try to connect the second 3750, the ports on both ends go into a 'suspend' state.

The logs on the 3750 states that one of the uplink ports is not compatible with the other.

Is there a restriction on the number of physical ports allowed in the port-channel interface ?

Any help appreciated.

Thanks.

[glen.grant]

It looks as if you are trying to use the same channel group for both uplinks which I don't think you can do , just create another channel group and apply it to the other ports that went suspended , make one 3750 channel group 2 and the other channel group 3 and do the same on the 4500 . Channel group 2 on the one 3750 would go to the channel group 2 configured links on the 4500 and the channel group 3 links on the other 3750 would go to the links configured for channel group 3 on the 4500.Don't think you can have the same channel group going to two different switches.