Stable iBGP through Selective Path Dissemination

In Internet, routing between Autonomous Systems (ASes) is performed by Border Gateway Protocol (BGP). Neighboring routers in different ASes share their routing information by using external BGP (eBGP), while routers in the same AS share their routing information about external destinations by using internal BGP (iBGP). iBGP employs route reflection clustering to solve the scalability problems due to number of iBGP peering sessions required. This clustering, however can cause anomalies such as routing loops and a failure to converge to a stable set of paths. In this paper, we present a Selective Path Dissemination (SPD) protocol, which avoids iBGP anomalies specific to clustering, and we also prove the correctness of the SPD protocol. Our solution requires minor changes to route reflection clustering method. In our proposed method, each border router would act as the reflector and each interior router is clustered with its nearest border router. Furthermore, each border router selectively disseminates paths to each of interior routers in border router’s cluster.