Unfortunately Cisco and Foundry disagree on the definition of a "trunk". I recently 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 802.1Q Trunking

Foundry VLAN Tagging

Outline :

• Cisco CatOS Configuration
• Foundry BigIron Configuration

• Cisco CatOS Configuration
  • Go to Enable mode
    • cswitch> enable
  • Create Trunk
    • cswitch> set trunk {port to trunk on} on dot1q {vlans to allow}
      • EXAMPLE: 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.