Passport 1000 Series routing switches support the IEEE 802.1D Spanning Tree Protocol. Later versions of the hardware (A and B modules and chassis) also support Nortel Networks MultiLink Trunking feature. The MultiLink Trunking feature groups ports to be treated as a single logical link for using Spanning Tree Protocol, learning MAC addresses, forwarding frames, and filtering.

Note: MultiLink Trunking requires hardware with ARU2 or above ASICs. If the device has earlier hardware, the required fields are grayed out.