Cell-Mode MPLS over ATM Overview, Configuration, and Verification

Case Study 10 BGP Site of Origin

Site of Origin (SoO) is one of the attributes a PE router assigns to a prefix prior to redistributing any VPNv4 prefixes. SoO in BGP is configured at neighbor level and is used to manage MPLS VPN traffic and to prevent transient routing loops from occurring in complex and mixed network topologies. SoO uniquely identifies the site from which the PE router learned the prefix. All prefixes learned from a particular site must be assigned the same site of origin attribute, even if the site is multiply connected to a single PE, or is connected to multiple PEs. The objective of this case study is to demonstrate SoO configuration when BGP PE-CE routing protocol is used In this case study, CE1-A and CE2-A belong to the same site, and this site is connected to multiple PE routers PE1-AS1 and PE2-AS1. Figure 14-55 shows the topology where all Customer A sites belong to BGP AS 65001.

Figure 14-55. SoO in BGP PE-CE Based MPLS VPN Network

Figure 14-56 shows the relevant configuration to configure and verify SoO in BGP PE-CE based MPLS VPN network.

Figure 14-56. Configure and Verify BGP SoO