关于BGP 的一些总结 ·BGP是一种路径向量路由选择协议。路由更新带有到达一个远程网络所需通过网络的全部列表 ·peer根据本地AS号的关系进行定义。在相同AS内的对等体形成了一个内部BGP关系，而在不同AS内的对等体则使用EBGP. ·IBGP对等体彼此交换可到达信息，并把BGP信息重新分发给运行在相同AS内的IGP。 ·IBGP对等体必须和IGP保持同步以确保IGP 路由通过本地AS传播。 ·MED是一种没有单位的量度，可以用Router map 进行修改 ·指定本地优先级属性来控制路径选择进程。本地首选采用网络前缀在AS中广播，也就是说只在AS中有意义。 ·weight同样只对本地路由器有意义。 ·最佳路径的选择参照上一个帖子 ·BGP使用UDP端口179和TCP端口179 形成对等体或邻居之间的可靠传输 关于聚合 R2#sh ip bgp BGP table version is 5, local router ID is 2.2.2.2 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPRf Weight Path *> 192.1.24.0 192.1.1.1 0 0 100 i *> 192.1.25.0 192.1.1.1 0 0 100 i *> 192.1.26.0 194.1.1.1 0 0 300 i *> 192.1.27.0 194.1.1.1 0 0 300 i
R2(config-router)#aggregate-address 192.1.24.0 255.255.252.0 ? advertise-map Set condition to advertise attribute as-set Generate AS set path information attribute-map Set attributes of aggregate route-map Set parameters of aggregate summary-only Filter more specific routes from updates suppress-map Conditionally filter more specific routes from updates
R2(config-router)#aggregate-address 192.1.24.0 255.255.252.0 as R2(config-router)#aggregate-address 192.1.24.0 255.255.252.0 as-set R2(config-router)#end R2# 01:00:17: %SYS-5-CONFIG_I: Configured from console by console R2# R6#2 [Resuming connection 2 to r3 ... ]
R3> R3> R3>en PassWord: R3#sh ip bgp BGP table version is 6, local router ID is 3.3.3.3 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path *>i192.1.24.0 193.1.1.1 0 100 0 100 i *>i192.1.24.0/22 193.1.1.1 100 0 {100,300} i *>i192.1.25.0 193.1.1.1 0 100 0 100 i *>i192.1.26.0 193.1.1.1 0 100 0 300 i *>i192.1.27.0 193.1.1.1 0 100 0 300 i ==========================================================================
ip classless no ip http server ! ! line con 0 transport input none line aux 0 transport input all line vty 0 4 password cisco login ! end
R2# R6#2 [Resuming connection 2 to r3 ... ]
R3#clear ip bgp * R3# 04:49:01: %BGP-5-ADJCHANGE: neighbor 193.1.1.1 Down User reset R3# 04:49:29: %BGP-5-ADJCHANGE: neighbor 193.1.1.1 Up sh R3#show ip bgp BGP table version is 2, local router ID is 3.3.3.3 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path *>i192.1.24.0/22 193.1.1.1 100 0 {100,300} i
