Each routing instance must have a unique route distinguisher associated with it. The route distinguisher is used to place bounds around a VPN so the same IP address prefixes can be used in different VPNs without having them overlap.
We recommend that you use a unique route distinguisher for each routing instance that you configure. Although you could use the same route distinguisher on all PE routers for the same VPN, if you use a unique route distinguisher, you can determine the CE router from which a route originated.
To configure a route distinguisher, include the route-distinguisher statement:
- route-distinguisher (as-number:number | ip-address:number);
You can include the statement at the following hierarchy levels:
The route distinguisher is a 6-byte value that you can specify in one of the following formats:
Note: Beginning with JUNOS Release 9.1, the numeric range for AS numbers has been extended to provide BGP support for 4-byte AS numbers, as defined in RFC 4893, BGP support for Four-octet AS Number Space. The JUNOS software continues to support 2-byte AS numbers.
Beginning with JUNOS Release 9.2, you can also configure a 4-byte AS number using the AS-dot notation format of two integer values joined by a period: <16-bit high-order value in decimal>.<16-bit low-order value in decimal>. For example, the 4-byte AS number of 65,546 in plain-number format is represented as 1.10 in the AS-dot notation format.