BGP session lifetime modeling in congested networks

The reliable Border Gateway Protocol (BGP) is essential for supporting high quality Internet data communication. In present Internet, due to the lack of differentiation mechanism in packet forwarding, BGP sessions are sensitive to severe network congestion. It is thus important to understand the reliability of BGP in congested networks, for the purposes of system reliability evaluation and failure avoidance. In this paper, we investigate the lifetime of BGP sessions in two types of network congestion scenarios: (1) the TCP bandwidth saturation caused by traffic engineering failures; (2) the UDP bandwidth saturation caused by worm attacks. Using statistical analysis based on intensive simulation results, we find that in most cases the BGP session lifetime can be characterized using exponential distributions and Weibull distributions. In the case of TCP bandwidth saturation, if all TCP connections have the same round trip time, the tail of the BGP lifetime tends to be power law. Furthermore, we propose an approximate model for the expected lifetime of BGP sessions, and show that by slightly changing the TCP retransmission parameters, the robustness of BGP sessions can be improved significantly.