Etherchannel 802.1q trunk between Cisco and Foundry

Foundry and Cisco both implement port grouping (load sharing) but are very different.  The following code snippets describe the configuration needed between the two very different platforms to create a working Etherchannel trunk.

On the Cisco, ports 23 and 24 form the group for port-channel1:

port-channel load-balance src-dst-ip

interface Port-channel1
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 2,3
 switchport mode trunk
!
interface GigabitEthernet1/0/23
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 2,3
switchport mode trunk
channel-group 1 mode on
!
interface GigabitEthernet1/0/24
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 2,3
switchport mode trunk
channel-group 1 mode on
!

Note that in Cisco, load balancing is per-stream and not per-packet like in Foundry. Therefore you must choose the load sharing type. I found that src-dst-ip balanced traffic the best. The default is MAC based which is terrible in a layer3 routed network.

On the foundry, using ports 47 and 48:

vlan 2 by port
 tagged ethe 1 ethe 47 to 48
!
vlan 3 by port
 tagged ethe 1 ethe 47 to 48
!
trunk ethe 47 to 48

And that’s it. But don’t forget to issue the following command the first time you set it up:

trunk deploy

I didn’t see any issues with the different load sharing algorythms on each end with some limited testing. I suspect that as long as the latency is the same across both links in the group there shouldn’t be any issues with out of order packets and such. Send and receive loads on both lines appears well balanced.

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