Specifying A Route Distinguisher; Defining Route Targets For Vrfs - Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual

JUNOSe 11.1.x BGP and MPLS Configuration Guide

Specifying a Route Distinguisher

The route distinguisher enables you to establish unique VPN-IPv4 addresses to
accommodate the possibility that more than one VPN might use the same IP address
from their private address spaces.
rd

Defining Route Targets for VRFs

BGP uses an extended-community attribute, the route target, to filter appropriate
VPN routes into the correct VRFs. You configure the export list on the VRF to specify
export route targets. When BGP advertises a route from this VRF's forwarding table,
it associates the list of export route targets with the route and includes this attribute
in the update message that advertises the route.
You also configure a route-target import list on each VRF to specify import route
targets. When a PE router receives a route, BGP compares the route target list
associated with the route (and carried in the update message) with the import list
associated with each VRF configured in the PE router.
For VPN-IPv4 routes received from another PE router, if any route target in the export
list matches a route target in a VRF's import list, then the route is installed in that
VRF's forwarding table.
For the most common configuration, do the following:
1.
2.
422
Configuring BGP VPN Services
Use to specify a route distinguisher to a VRF.
You can specify either an AS number or an IP address as the first part of the
route distinguisher. Specify some unique integer as the second part.
You must specify a route distinguisher for a VRF. Otherwise, the VRF will not
operate.
After you have configured the route distinguisher, you can change it only by
removing and recreating the VRF.
Example
host1:vr1(config-vrf)#rd 100:100
There is no no version.
See rd.
Allocate one route-target extended-community value per VPN.
Define the route-target import list and a route-target export list to include only
the route-target extended-community values for the VPN(s) to which the VRF
belongs:
host1:vr1(config-vrf)#route-target export 777:100
host1:vr1(config-vrf)#route-target import 777:100