After PWE3 FRR is configured, the L2VPN traffic is rapidly switched to the secondary path when a fault occurs on the primary path. After the fault on the primary path is rectified, the L2VPN traffic is switched back to the primary path based on a revertive switchover policy.
On the network where CEs are asymmetrically connected to PEs, the secondary PW cannot transmit data when the primary path and secondary path work properly. If the AC interface of the secondary PW borrows the IP address of the AC interface of the primary PW, note the following points:
The switching policy No revertive switchover cannot be configured.
The local CE has two equal-cost and direct routes to the remote CE. The destination addresses and next hops of the two routes are the same. The route that passes through the secondary PW is unreachable.
If the CEs exchange routing information using routing protocols, change the cost or metric value of the AC interface of the secondary path to a value greater than that of the AC interface of the primary path. The local CE may be unable to communicate with the remote CE, but can communicate with other remote user devices.
If CEs use static routes and the AC links are Ethernet links, BFD for static routes needs to be configured on CEs.
Before configuring PWE3 FRR, complete the following tasks:
Configure primary and secondary PWs of the same type on the network where CEs are asymmetrically connected to PEs.
Configure CEs to exchange routing information using routing protocols or static routes.
Set up an LSP tunnel or TE tunnel between the PEs.
You also need to configure tunnel policies when PWE3 services need to be transmitted over TE tunnels or when PWE3 services need to be load balanced among multiple tunnels to fully use network resources. For details, see step 1 in Configuring and Applying a Tunnel Policy.