VPRN Service Overview
Page 552 7210-SAS M Services Guide
BGP Support
BGP is used with BGP extensions mentioned in Routing Prerequisites on page 551 to distribute 
VPRN routing information across the service provider’s network.
BGP was initially designed to distribute IPv4 routing information. Therefore, multi-protocol 
extensions and the use of a VPN-IPv4 address were created to extend BGP’s ability to carry 
overlapping routing information. A VPN-IPv4 address is a 12-byte value consisting of the 8-byte 
route distinguisher (RD) and the 4-byte IPv4 IP address prefix. The RD must be unique within the 
scope of the VPRN. This allows the IP address prefixes within different VRFs to overlap.