The impact of BGP dynamics on intra-domain traffic
Sharad Agarwal, Chen‐Nee Chuah, Supratik Bhattacharyya, Christophe Diot · 2004
Recent work in network traffic matrix estimation has focused on generating router-to-router or PoP-to-PoP (Point-of-Presence) traffic matrices within an ISP backbone from network link load data. However, these estimation techniques have not considered the impact of inter-domain routing changes in BGP (Border Gateway Protocol) . BGP routing changes have the potential to introduce significant errors in estimated traffic matrices by causing traffic shifts between egress routers or PoPs within a single backbone network. We present a methodology to correlate BGP routing table changes with packet traces in order to analyze how BGP dynamics affect traffic fan-out within a large "tier-1" network. Despite an average of 133 BGP routing updates per minute, we find that BGP routing changes do not cause more than 0.03% of ingress traffic to shift between egress PoPs. This limited impact is mostly due to the relative stability of network prefixes that receive the majority of traffic -- 0.05% of BGP routing table changes affect intra-domain routes for prefixes that carry 80% of the traffic. Thus our work validates an important assumption underlying existing techniques for traffic matrix estimation in large IP networks.