Effect of Route Reflection on IBGP Convergence and an approach to reduce convergence time

Request for Comments (RFCs) for Border gateway Protocol (BGP) suggest that the network topology using BGP must have full mesh of IBGP sessions to avoid routing loops. Routing loop is a condition where packets are routed between two or more routers resulting in slow convergence and routing instability. Route reflection is one of the strategies to avoid full mesh of internal BGP sessions between BGP speaking routers in an autonomous system. This paper focuses on demonstrating an effect of using route reflection on convergence time in a small network. A mixed network scenario of external and internal BGP sessions is considered for demonstration. Results of the simulation have shown that, route reflection can significantly increase the convergence time avoiding full mesh. Also an approach to reduce the convergence time has been proposed. Proposed algorithm is based on the principle of creating logical group of router reflectors. The same concept can be scaled for larger networks for different scenarios