Charles Hooper

Thoughts and projects from a site reliability engineer

EtherChannel Trunking Between a Foundry Switch and Cisco Catalyst

In my other article, LACP on Cisco Catalysts & Foundry switches, I describe how to configure aggregated links using LACP (802.3ad) on a Cisco Catalyst and Foundry switch. In this howto, I will be describing how to configure trunked ports using EtherChannel — LACP’s predecessor.

Before starting, one thing that you should be aware of is that Foundry’s configure EtherChannel trunks as dot1q-encapsulated VLAN trunks by default. Cisco Catalysts (or IOS, rather) configure all ports as access ports by default.

On a Cisco Catalyst switch running IOS, once logged in, you will need to perform the steps below. It is important that you perform these steps without the other device connected.

Password: *enter password*
cisco#config term
cisco(config)#int Gi0/1
cisco(config-if)#channel-group 1 mode on
cisco(config-if)#int Gi0/2
cisco(config-if)#channel-group 1 mode on
cisco#write mem

If your other device is another Cisco Catalyst, then just repeat the steps above, connect your newly bonded ports, and disconnect any non-bonded ports connecting the two devices.

If you are configuring a Foundry switch, there are several rules you must follow. Among these rules, is that you can only start your trunked ports on the first port of each group of 4.

Password: *enter password*
BR-telnet@foundry#config term
BR-telnet@foundry(config)#trunk ethe 1 to 2
BR-telnet@foundry(config)#trunk deploy
BR-telnet@foundry#write mem

Provided you correctly configured your VLANs prior to setting up EtherChannel, you may connect your cables starting with the primary port. The primary port is always the lowest-numbered port in the trunk, in our example, this is 1. Once connected, you can verify operation of your EtherChannel trunk with show etherchannel summary on the Cisco or show trunk on the Foundry in enable mode.