When Layer 2 Protocol Tunneling (L2PT) is not used, protocol packets (e.g., STP) are flooded to 802.1Q access ports on the same edge switch, but filtered from 802.1Q tunnel ports. This creates disconnected protocol domains in the customer’s network.
L2PT can be used to pass various types of protocol packets belonging to the same customer transparently across a service provider’s network. In this way, normally segregated network segments can be configured to function inside a common protocol domain.
Configuring the L2PT Tunnel Address
Use the VLAN > L2PT (Configure Global) page to configure the destination MAC address for Layer 2 Protocol Tunneling.
The switch rewrites the destination MAC address in all upstream L2PT protocol packets (e.g., STP BPDUs) to this value, and forwards them on to uplink ports. (Format xx-xx-xx-xx-xx-xx or xxxxxxxxxxxx; Default: 01-12-CF-.00-00-02, proprietary tunnel address)
Enabling L2PT for Selected Interfaces
Use the VLAN > L2PT (Configure Interface) page to enable Layer 2 Protocol Tunneling on selected interfaces.
Port or trunk identifier
Cisco Discovery Protocol
Link Layer Discovery Protocol
Cisco Per VLAN Spanning Tree Plus
Spanning Tree (STP, RSTP, MSTP)
Cisco VLAN Trunking Protocol