Configuring PW Redundancy in a Scenario Where CEs Are Asymmetrically Connected to PEs

Context

In a scenario where CEs are asymmetrically connected to PEs, two CEs connected through a packet switched network (PSN) are connected to three PEs in different ways. One CE is single-homed to a PE, and the other CE is dual-homed to two PEs. This scenario is mainly used to transparently transmit end-to-end PW services on the bearer network.

As shown in Figure 1, CE1 is connected to user devices and is single-homed to PE1. Service data is transmitted over the PSN. PW redundancy is deployed on the PSN to provide PW protection. A bypass PW is configured between PE2 and PE3 to forward service traffic in bypass mode. CE2 is dual-homed to PE2 and PE3, the master/slave status of which is determined by the E-Trunk.

Figure 1 Networking diagram of PW redundancy in the scenario where CEs are asymmetrically connected to PEs (single-hop PWs)

E-Trunk needs to be configured to determine the master/backup status of the AC links between CE2 and PE2, and between CE2 and PE3. The bypass PW between PE2 and PE3 needs to be associated with the E-Trunk. Currently, PE2 and PE3 to which a CE is dual-homed support the E-Trunk and only a single bypass PW can be configured between them.

Pre-configuration Tasks

Before configuring PW redundancy, complete the following tasks:

• Configure IP addresses and an Interior Gateway Protocol (IGP) on PEs.

• Establish public network tunnels between PEs.

  The public network tunnel can be:

  • LDP tunnel: To establish LDP tunnels, you must enable MPLS and MPLS LDP globally and in the interface view on each node of the public network. If two PEs are indirectly connected, establish a remote LDP session between them.

  • TE tunnel: To establish TE tunnels, you must enable MPLS, MPLS TE, and RSVP-TE globally and in the interface view on each node of the public network, and enable CSPF in the MPLS view of the ingress of each tunnel to be created.

    

    Because PWE3 uses LDP to distribute VPN labels, you must globally enable MPLS LDP on PEs and establish MPLS LDP sessions if TE tunnels are used as public network tunnels.

    If the public network tunnels are not LDP tunnels, you must configure tunnel policies and apply them to these tunnels.

    Only the VPLSs in PWE3 mode support PW redundancy.

• Enable MPLS L2VPN on PEs.

Configuration Procedure

Perform the following operations to configure PW redundancy on PEs.