Empirical Analysis of Core-Edge Separation by Decomposing Internet Topology Graph

Border Gateway Protocol (BGP) is the de facto standard protocol for the inter-domain routing. Due to multi-homing and traffic engineering, the BGP routing table size of default free zone (DFZ) is growing rapidly. Inter-domain routing is facing the scaling challenge. Many solutions have been proposed. Among them, the core-edge separation scheme gets more attentions than others due to its practical advantages. It separates specific prefixes of edge networks from entering into transit core, and reduces the DFZ BGP routing table size. However, there has less evaluation on how much scalability can be improved from core-edge separation. In this paper, we take the further step to quantifying the impact of the core-edge separation on Internet inter-domain routing. We find that separation at stub-transit can reduce 43% routing table size and prevent more than half of BGP updates. We decompose the topology graph by k-core and customer-provider based decomposition methods, and analyze the impact of deploying separation at different level of topological hierarchy. We believe that complicated separation deployment strategies (not the simple stub-transit split) are feasible to approaching an optimal effect.