环回地址引发的EBGP振荡分析与研究

Study and analysis of EBGP oscillation induced by loopback addresses

BGP协议是一个带有许多可增强特性与控制机制的距离向量路由协议.它为自治系统(AS)提供无环的域间路由信息,并能对进出AS的数据根据特定的策略进行调控.随着BGP服务在骨干网络应用的加强,BGP的稳定直接关系到互联网的稳定运行,是使互联网络具有可扩展性和可持续性发展的基础.在EBGP对等体中,通过环回口更易在多条连接上实现负载均衡,但同时,在特定的网络拓扑和配置下,会引发路由振荡.分析了使用环回地址建立的2个AS间的EBGP路由,会出现导致BGP路由振荡的产生的情况,并展示了多种导致振荡的可能性,提出了如何避免该类路由振荡的一般方法.

Border Gateway Protocol （BGP） is a path vector protocol with plenty of expansibility and control mechanisms. It provides loop-free inter-domain route information to autonomy systems （AS）, and control the data transit between ASes with given policies. With the applications of BGP serves in backbone network, BGP stability is directly concerns on internet＇s stable operation and it is the basis of expansibility and sustain- able development for internet. The EBGP peering with loopback address facilitate load balancing over multiple links. However, the router oscillations may occur under special network configuration. This paper has ana- lyzed the condition lead to BGP routing oscillation in the EBGP peering with loopback addresses, and has shown various oscillating possibility. In addition, it has brought forward the common method how to avoid this kind of route oscillation.