BGP Cost Community

This post explores the use of BGP cost community to prefer one path over the other in a multipath environment as shown in the figure. BGP cost community is a nontransitive extended community attribute that is passed to iBGP peers only. This feature allows us to customize the BGP best

Continue reading

MPLS VPN BGP AS Override

This configuration scenario demonstrates the use of BGP AS override in an MPLS VPN. In MPLS VPN network shown in the figure below, two customer sites connected to service provider MPLS network and using BGP as its PE-CE routing protocol. Implementing BGP PE-CE routing for customer imposes an issue when

Continue reading

BGP No Route to Peer

Scenario is three routers – R1, R2 and R3; R1 and R3 are on AS100 and AS200 respectively. R1 and R3 have default route pointing to R2. R2 knows how to reach R1 and R3’s Loopback1 network via static route. R1 and R3 are peering to and sourcing BGP traffic

Continue reading