Configuring VPLS Multihoming

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.

  When two PE routers use the same site ID, VPLS assumes multihoming behavior by default. The site preference value is used to signal the primary and backup PE router. In such cases, when multihoming is explicitly configured using the multi-homing statement , it is only used for tracking the BGP peer status, such as to prevent isolation of the PE router from the core or split brain. There are scenarios, however that require preventing of BGP peer tracking, such as in a two-PE-router topology. In such cases, multihoming should not be explicitly configured as it can break node redundancy.

  When identical site IDs are used without configuring multihoming, a collision log message is generated at each signaling: RPD_L2VPN_SITE_COLLISION: Same site ID 2 configured on remote PE (RD 8.8.8.1:1013:) and local PE in VPN 1013 (non-multihomed site 2). This is expected behavior.

• Assign unique route distinguishers for each multihomed PE router.

• 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.

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);

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
• Configuring Multihoming on the PE Router

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

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.