L2PT Configuration

introduction introduction l2pt (layer 2 protocol transparent transmission) is a technology used to extend local area network (lan) connections across wide area networks (wan) simply put, it allows layer 2 protocol packets from user networks in different geographical locations (such as corporate headquarters and branch offices) to be transparently transmitted through the carrier network (or large enterprise backbone network) as if passing through a "dedicated tunnel explanation of principles explanation of principles on the user access side of the backbone network, the multicast destination mac address of the original layer 2 protocol packet is replaced with a specific multicast mac address after the mac address is modified, the packet traverses the backbone network depending on the configured transparent transmission mode, the network decides whether to process the packet or not when the layer 2 protocol packet reaches the egress node, the device matches the packet against the configured mapping relationship between the special multicast destination mac addresses and the layer 2 protocols it then restores the packet's multicast destination mac address to the standard one defined for that specific layer 2 protocol finally, based on the configured transparent transmission mode, it decides whether to process the packet l2pt configuration l2pt configuration configure tasks instructions enter the interface configuration view interface ethernet id configure the protocol packet to be discarded l2protocol packet {stp|lacp} disable enable l2pt l2protocol tunnel {stp|lacp|cdp|pvstp} enable configuration example configuration example the ce devices are the edge devices of the enterprise located in different geographical networks, while pe1 and pe2 are the edge devices of the carrier network the two enterprise networks are layer 2 networks and are interconnected through the carrier network to prevent loops in the layer 2 network, the spanning tree protocol (stp) is enabled, and the enterprise requires stp to run only within its own networks to form a correct spanning tree procedure procedure the configuration of ce1 and ce2 is the same, here is the example of ce1 create vlan 100, 200 and add the corresponding physical interfaces to the vlan sonic(config)# vlan 100 sonic(config)# interface ethernet 2 sonic(config if 2)# switchport trunk vlan 100 sonic(config if 2)# exit sonic(config)# stp mode stp sonic(config)# mstp enable add ethernet3 interfaces of pe1 and pe2 to vlan 100, and enable layer 2 protocol tunneling on the pe devices sonic(config)# interface ethernet 3 sonic(config if 3)# l2protocol packet stp disable sonic(config if 3)# l2protocol tunnel stp enable verify configuration sonic# show stp status spanning tree mode stp vlan mst instance port role state \ vlan100 0 ethernet2(root)(forw)