Configure the Route Distinguisher

Each routing instance that you configure on a PE router must have a unique route distinguisher associated with it. Both Layer 2 and Layer 3 VPNs need a route distinguisher to help Border Gateway Protocol (BGP) distinguish overlapping network layer reachability information (NLRIs) from different VPNs.

We recommend that you use unique route distinguishers for each routing instance that you configure. Although you can use the same route distinguisher on all PE routers in the same VPN, if you use a unique route distinguisher, you can determine the PE router from which a route originated.

To configure a route distinguisher on a PE router, include the route-distinguisher statement at the [edit routing-instances routing-instance-name] hierarchy level:

[edit routing-instances routing-instance-name]

route-distinguisher (as-number:number | ip-address:number); 

The route distinguisher is a 6-byte value that you can specify in one of the following formats:

• as-number:number, where as-number is an autonomous system (AS) number (a 2-byte value) and number is any 4-byte value. The AS number can be in the range 1 through 65,535. We recommend that you use an Internet Assigned Numbers Authority (IANA)-assigned, nonprivate AS number, preferably the Internet service provider's (ISP's) own or the customer's own AS number.
• ip-address:number, where ip-address is an IP address (a 4-byte value) and number is any 2-byte value. The IP address can be any globally unique unicast address. We recommend that you use the address that you configure in the router-id statement, which is a nonprivate address in your assigned prefix range.

If you configure the route-distinguisher-id statement at the [edit routing-options] hierarchy level, a route distinguisher is automatically assigned to the routing instance. If you configure the route-distinguisher statement in addition to the route-distinguisher-id statement, the value configured for route-distinguisher supersedes the value generated from route-distinguisher-id.

The route-distinguisher-id statement is configured as follows:

[edit]

routing-options {

    route-distinguisher-id ip-address;

}

When configured, a type 1 route distinguisher is automatically assigned to the routing instance using the format ip-address:number. The IP address is specified by the route-distinguisher-id statement and the number is unique for the routing instance.