Distribution Of Routes And Labels With Bgp; Figure 71: Route And Label Distribution - Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual

JUNOSe 11.1.x BGP and MPLS Configuration Guide
A route-target import list is applied before any inbound routing policy (route map)
is applied. If an inbound route map contains a set extcommunity clause, the clause
replaces all extended communities in the received route. BGP applies the default
route-target export list associated with the VRF if the route does not have any
route-target extended-community attributes after the inbound policy has been applied.
On the other hand, the default export list is not applied if either a valid route-target
export list is received or the inbound route map sets one or more route targets.

Distribution of Routes and Labels with BGP

The extensions to BGP include enhancements to update messages that enable them
to carry the route distinguishers, route-target extended-community information, and
MPLS labels required for BGP/MPLS VPNs.
Consider the simple example shown in Figure 71 on page 386. The customer edge
devices are connected with their associated provider edge routers by external BGP
sessions (CE 1–PE 1 and CE 3–PE 2). PE 1 and PE 2 are BGP peers by an internal
BGP session across the service provider core in AS 777.
In this example, the PE routers run EBGP to the CE routers to do the following:

Figure 71: Route and Label Distribution

Rather than running EBGP between the PE routers and the CE routers, you can do
either of the following:
386
Overview
Learn the prefixes of the networks in the local customer site.
Advertise routes to networks and remote customer sites.
Run an IGP (such as IS-IS, OSPF, or RIP) between the CE router and the PE router.
Configure static routes on the CE and PE routers (on the CE router this would
typically be a default route).