边界网关协议BGP4路由收敛问题研究进展

Research Progress of Convergence Problem of Border Gateway Protocol 4 (BGP4)

边界网关协议BGP4是目前Internet最主要的域间路由协议,其路由正确性和稳定性直接关系到Internet能否正常运行.作为一个域间路由协议,BGP协议必须支持策略路由,允许各个自治系统独立的制定他们的路由策略,而且允许这些策略优先于路径尺度.由于各个自治系统制定策略的角度不同,这些路由策略之间可能存在冲突,从而导致BGP协议发散及路由振荡.此外,BGP协议本身也存在一些内在机制的不完善,并可能导致在某些情况下路由不收敛或收敛速度缓慢.随着网络规模越来越大,拓扑越来越复杂,BGP路由收敛问题日趋严重,目前国内外对此展开了大量的研究,并提出了多种分析模型和解决方案.本文首先全面总结了BGP协议面临的主要的收敛问题,主要包括策略冲突和协议机制造成的不收敛问题和收敛缓慢问题,然后全面介绍了针对这些问题的现有的解决方案,分析比较了这些方案的优点和缺点,最后提出了进一步的研究设想.

Border Gateway Protocol Version 4 （BGP-4） is the most primary inter-domain routing protocol in the Internet, its stability and correctness has directly impact on the normal process of the Internet. As an inter-domain routing protocol, BGP must support policy-routing, enable autonomous systems to independently define their routing policies , and allow these policies to override distance-based metrics. But because of the different point of view among the autonomous systems, these policies always have collisions, and may cause BGP divergence and route oscillation. Moreover, BGP has its own internal defects, sometimes they lead to route divergence or slow convergence. As the size of the Internet increasing, topology getting more and more complicate, the BGP convergence problem become severe, researchers have made a lot of studies and described many kinds of models and solutions. This paper started from summarizing the BGP convergence problem, mainly including routing divergence and slow convergence problem which caused by policy collisions and BGP internal defects, then introduce existing solutions to these problems at present, and at last discussed their future research possibilities.