边界网关协议(BGP) 心得

1/23/2008来源:网络协议人气:2591


  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
  ==========================================================================
  
  router bgp 200
  no synchronization
  bgp log-neighbor-changes
  aggregate-address 192.1.24.0 255.255.252.0 as-set summary-only
  neighbor 192.1.1.1 remote-as 100
  neighbor 193.1.1.2 remote-as 200
  neighbor 193.1.1.2 next-hop-self
  neighbor 194.1.1.1 remote-as 300
  !

  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
  
  BGP 正则表达式
  _300_ 匹配所有经过AS300的路由
  
  _300$ 匹配所有来自AS300中的路由
  
  ^300_ 匹配接受的路由
  
  ^300$ 仅指那些源于AS300未经过其他任何AS的路由
  
  .* 所有路由