Reliability-Aware IBGP Route Re.ection Topology Design

In the Internal Border Gateway Protocol (IBGP), route reflection is widely used as an alternative to full mesh IBGP sessions inside an AS for scalability reason. However, some important issues, such as the impact of route reflection on the reliability of IBGP and the construction of reliable reflection topology with unreliable routers or links, have not been well investigated. This paper addresses the problem of finding reliable route reflection topologies for IBGP networks, which is of great importance in order to increase the robustness of IBGP operations. We first present a novel reliability model and two new metrics (IBGP expected lifetime and expected session loss) to evaluate the reliability of reflection topologies, and further to investigate the design problem. After studying the solvability conditions under the router capacity constraints, we prove the NP-hardness of the problem, and then design and implement three heuristic solutions using randomization techniques: heuristic selection, greedy search and simulated annealing. Our extensive computational experiments show that the reliability of IBGP reflection network can be significantly improved by our solutions.