基于过滤机制的抑制BGP路由表增长的方法

Approach to Restraining Growth of BGP Routing Table by Filtration

经过对BGP路由表进行分析,发现在BGP路由表中包含大量前缀长度大于地址分配策略所规定值的路由·给出了一种减缓路由表增长的方法,该方法基于前缀长度对路由进行过滤·对前缀长度大于地址分配策略所规定值的路由,只允许其在指定的距离范围内被通告,一旦该路由穿越了指定数目的AS,它就将被过滤掉,不再被通告·通过修改BGP协议,为其增加一个新的属性来记录被过滤路由的最大通告距离,实现对路由过滤·通过模拟实验证明所给方法可行,对抑制路由表增长效果明显·

The results of analyzing BGP routing tables show that there are a large number of routes of which the mask length of prefix exceeds the maximum mask length as specified by the address allocation policies. Based on the mask length of prefix, a method is presented to slow the growth of BGP routing table down so as to filter routes. For the prefixes of which the mask lengths are longer than those specified by the address allocation policies,they are only allowed to be announced in a certain range of distance. Once the route is traversing the range of given number of autonomous systems, it will be filtered out without announcement. In order to implement the filtering mechanism, the BGP is modified to add a new route attribute in it so as to record the maximum announced distance of the filtered route, thus implementing the route filtration. The method is proved feasible through simulation using actual BGP routing tables and efficient for restraining the growth of BGP routing tables.