Figure 72: Standard and Extended BGP Update Messages
Using the next-hop-self option on PE 1 causes PE 1 to set the next-hop attribute to
its own address, 172.32.12.1. Doing so is necessary because the next hop provided
by CE 1 is from VPN A’s private address space and has no meaning in the service
provider core. In addition, PE 2 must have PE 1’s address so that it can establish an
LSP back to PE 1. The next-hop address must also be carried in the MP-Reach-NLRI
attribute, according to MP-BGP.
The extended update also has the extended-communities attribute, which identifies
the VPN to which the routes are advertised. In this example, the route target is
777:1001, identifying VPN A.
388 â– Overview
JUNOSe 11.1.x BGP and MPLS Configuration Guide