Create a VLAN Trunk between Cisco CatOS and a Foundry BigIron

Unfortunately Cisco and Foundry disagree on the definition of a “trunk”. Awhile ago I had to find a way to trunk multiple vlans between a Cisco 5000 CatOS and a Foundry BigIron switch. I made a quick call to a Foundry Systems Engineer to find out what was needed to make this happen.

Cisco CatOS Configuration

Go to Enable mode
cswitch> enable
Create Trunk
cswitch> set trunk 6/5 on dot1q 2-3,10,20,30,69,96,99
*** This example sets port 6/5 to the 802.1q standard, and only allows VLANs 2-3,10,20,30,69,96, and 99 to go across it.

Foundry BigIron Configuration

Go to Enable mode
fswitch> enable

Go to Config Mode
fswitch> config terminal

Go to first VLAN you want to configure
fswitch> vlan 10

Add the trunk port (i.e. 1/1) to this VLAN
fswitch> tagged ethe 1/1

Add “host” ports to this VLAN (NOT ports that are being trunked)
fswitch> untagged ethe 4/1 to 4/20

Now go to the next VLAN
fswitch> vlan 20

Continue to add the “trunk” port as a “tagged” interface to each VLAN. Add “host” ports as “untagged” interfaces to each VLAN.

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