BGPSep_D: An Improved Algorithm for Constructing Correct and Scalable IBGP Configurations Based on Vertexes Degree

摘要

IBGP configurations based on the route reflection may lead to forwarding loops and sub-optimal paths. Although the IBGP configuration generated by BGPSep guarantees three correctness properties of complete visibility, loop-free forwarding, robustness to IGP failures, and the number of IBGP sessions is smaller than in a full-mesh configuration, BGPSep does not reduce the number of IBGP sessions of its top level route reflectors. We improve BGPSep by removing some vertexes, whose degrees satisfy some conditions, from the IGP graph gradually. The improved algorithm is called BGPSep_D. We prove that BGPSep_D satisfies the three correctness properties. The performance of BGPSep_D is evaluated on several real-world backbone topologies. Experimental results indicate that BGPSep_D can generate an IBGP topology with much smaller maximum degree and a much smaller number of IBGP sessions than that produced by BGPSap.