Configuring VPLS Multihoming

VPLS multihoming allows you to connect a customer site to multiple PE routers to provide redundant connectivity while preventing the formation of Layer 2 loops in the service provider’s network. A VPLS site multihomed to two or more PE routers provides redundant connectivity in the event of a PE router-to-CE device link failure or the failure of a PE router. For more information about VPLS multihoming, see VPLS Multihoming.

Note: If you want to enable multihoming for a VPLS routing instance, you cannot also enable LDP signaling. You can only enable BGP signaling.

The following sections describe how to configure VPLS multihoming. Some information is also provided on single-homed site configuration versus multihomed site configuration.

VPLS Multihomed Site Configuration

The following describes the requirements for a VPLS multihomed site configuration:

Assign the same site ID on all PE routers connected to the same CE devices.
Assign the same route distinguisher on all PE routers connected to the same CE devices.
Reference all interfaces assigned to the multihomed VPLS site on each PE router. Only one of these interfaces is used to send and receive traffic for this site at a time.
Either designate a primary interface or allow the router to select the interface to be used as the primary interface.
If the router selects the interface, the interface used to connect the PE router to the site depends on the order in which interfaces are listed in the PE router’s configuration. The first operational interface in the set of configured interfaces is chosen to be the designated interface. If this interface fails, the next interface in the list is selected to send and receive traffic for the site.
Configure multihoming for the site.

The following configuration shows the statements you need to configure to enable VPLS multihoming:

[edit routing-instances routing-instance-name]instance-type vpls;interface interface-name;interface interface-name;protocols vpls {site site-name {active-interface {any;primary interface-name;}interface interface-name;interface interface-name;multi-homing;site-identifier number;}}route-distinguisher (as-number:id | ip-address:id);

Note: If you add a direct connection between CE devices that are multihomed to the same VPLS site on different PE routers, the traffic can loop and a loss of connectivity might occur. We do not recommend this topology.

Most of these statements are explained in more detail in the rest of this chapter. The following sections explain how to configure the statements that are specific to VPLS multihoming:

Specifying an Interface as the Active Interface

You need to specify one of the interfaces for the multihomed site as the primary interface. If there are multiple interfaces, the remaining interfaces are activated only when the primary interface goes down. If no active interfaces are configured at the site level, all traffic for a VPLS site travels through a single, non-multihomed PE router.

You must configure one of the following options for the active-interface statement:

any—One configured interface is randomly designated as the active interface for the VPLS site.
primary—Specify the name of the multihomed interface to be used as the primary interface by the VPLS site.

To specify a multihomed interface as the primary interface for the VPLS site, include the active-interface statement:

active-interface {any;primary interface-name;}

You can include this statement at the following hierarchy levels:

[edit routing-instances routing-instance-name protocols vpls site site-name]
[edit logical-systems logical-system-name routing-instances routing-instance-name protocols vpls site site-name]

Configuring Multihoming on the PE Router

When a CE device is connected to the same VPLS site on more than one PE router, include the multi-homing statement on all associated PE routers. Configuration of this statement tracks BGP peers. If no BGP peer is available, VPLS deactivates all active interfaces for a site. To specify that the PE router is part of a multihomed VPLS site, include the multi-homing statement:

multi-homing;

You can include this statement at the following hierarchy levels:

[edit routing-instances routing-instance-name protocols vpls site site-name]
[edit logical-systems logical-system-name routing-instances routing-instance-name protocols vpls site site-name]

Include the multi-homing statement on all PE routers associated with a particular VPLS site.

VPLS Single-Homed Site Configuration

All VPLS single-homed sites are connected to the same default VE device. All interfaces in a VPLS routing instance that are not configured as part of a multihomed site are assumed to be single-homed to the default VE device.