BGP路由反射器

      在同一个AS域内，由于水平分割导致要想学习到整个区域内的BGP路由，则要和区域内所有BGP设备建立互联关系，这样就会有很多的报文交互。为了减少资源的浪费，从众多路由器中选择一个性能好的作为反射器，它为其他的路由器服务，其他路由器称为它的客户端。

       它接受所有客户端和非客户端的路由更新信息，收到信息后会向所有的客户端和非客户端反射该信息，让其他的客户端和非客户端都知道。但是它接受非客户端的更新信息不会向非客户端反射，也就是非客户端接收不了其他非客户端的路由更新信息。 

   peer 邻居 reflect-client     //反射器选择谁成为它的客户就把谁的地址填在邻居的位置

例如： peer 1.1.1.1 reflect-client  //即AR3选择AR1成为它的客户端

配置如下：

#
interface GigabitEthernet0/0/0
 ip address 13.1.1.1 255.255.255.0 

interface LoopBack0
 ip address 1.1.1.1 255.255.255.255 
#
bgp 200
 router-id 1.1.1.1
 peer 3.3.3.3 as-number 200 
 peer 3.3.3.3 connect-interface LoopBack0
 #
 ipv4-family unicast
  undo synchronization
  network 1.1.1.1 255.255.255.255 
  network 13.1.1.0 255.255.255.0 
  peer 3.3.3.3 enable
  peer 3.3.3.3 next-hop-local 
#
ospf 1 router-id 1.1.1.1 
 area 0.0.0.0 
  network 1.1.1.1 0.0.0.0 
  network 13.1.1.1 0.0.0.0 

interface GigabitEthernet0/0/0
 ip address 23.1.1.2 255.255.255.0 
#
interface GigabitEthernet0/0/1
 ip address 25.1.1.2 255.255.255.0 

interface LoopBack0
 ip address 2.2.2.2 255.255.255.255 
#
bgp 200
 router-id 2.2.2.2
 peer 3.3.3.3 as-number 200 
 peer 3.3.3.3 connect-interface LoopBack0
 peer 25.1.1.5 as-number 100 
 #
 ipv4-family unicast
  undo synchronization
  network 2.2.2.2 255.255.255.255 
  network 23.1.1.0 255.255.255.0 
  network 25.1.1.0 255.255.255.0 
  peer 3.3.3.3 enable
  peer 3.3.3.3 next-hop-local 
  peer 25.1.1.5 enable
#
ospf 1 router-id 2.2.2.2 
 area 0.0.0.0 
  network 2.2.2.2 0.0.0.0 
  network 23.1.1.2 0.0.0.0 
  network 25.1.1.2 0.0.0.0 

interface GigabitEthernet0/0/0
 ip address 23.1.1.3 255.255.255.0 
#
interface GigabitEthernet0/0/1
 ip address 13.1.1.3 255.255.255.0 
#
interface GigabitEthernet0/0/2
 ip address 34.1.1.3 255.255.255.0 


interface LoopBack0
 ip address 3.3.3.3 255.255.255.255 
#
bgp 200
 router-id 3.3.3.3
 peer 1.1.1.1 as-number 200 
 peer 1.1.1.1 connect-interface LoopBack0
 peer 2.2.2.2 as-number 200 
 peer 2.2.2.2 connect-interface LoopBack0
 peer 4.4.4.4 as-number 200 
 peer 4.4.4.4 connect-interface LoopBack0
 #
 ipv4-family unicast
  undo synchronization
  network 3.3.3.3 255.255.255.255 
  network 13.1.1.0 255.255.255.0 
  network 23.1.1.0 255.255.255.0 
  network 34.1.1.0 255.255.255.0 
  peer 1.1.1.1 enable
  peer 1.1.1.1 reflect-client
  peer 1.1.1.1 next-hop-local 
  peer 2.2.2.2 enable
  peer 2.2.2.2 reflect-client
  peer 2.2.2.2 next-hop-local 
  peer 4.4.4.4 enable
  peer 4.4.4.4 reflect-client
  peer 4.4.4.4 next-hop-local 
#
ospf 1 router-id 3.3.3.3 
 area 0.0.0.0 
  network 3.3.3.3 0.0.0.0 
  network 13.1.1.3 0.0.0.0 
  network 23.1.1.3 0.0.0.0 
  network 34.1.1.3 0.0.0.0 

interface GigabitEthernet0/0/0
 ip address 34.1.1.4 255.255.255.0 
#
interface GigabitEthernet0/0/1
 ip address 46.1.1.4 255.255.255.0 

interface LoopBack0
 ip address 4.4.4.4 255.255.255.255 
#
bgp 200
 router-id 4.4.4.4
 peer 3.3.3.3 as-number 200 
 peer 3.3.3.3 connect-interface LoopBack0
 peer 46.1.1.6 as-number 300 
 #
 ipv4-family unicast
  undo synchronization
  network 4.4.4.4 255.255.255.255 
  network 34.1.1.0 255.255.255.0 
  network 46.1.1.0 255.255.255.0 
  peer 3.3.3.3 enable
  peer 3.3.3.3 next-hop-local 
  peer 46.1.1.6 enable
#
ospf 1 router-id 4.4.4.4 
 area 0.0.0.0 
  network 4.4.4.4 0.0.0.0 
  network 34.1.1.4 0.0.0.0 
  network 46.1.1.4 0.0.0.0 

interface GigabitEthernet0/0/0
 ip address 25.1.1.5 255.255.255.0 
#
interface GigabitEthernet0/0/1
 ip address 192.168.1.254 255.255.255.0 

interface LoopBack0
 ip address 5.5.5.5 255.255.255.255 
#
bgp 100
 router-id 5.5.5.5
 peer 25.1.1.2 as-number 200 
 #
 ipv4-family unicast
  undo synchronization
  network 5.5.5.5 255.255.255.255 
  network 25.1.1.0 255.255.255.0 
  network 192.168.1.0 
  peer 25.1.1.2 enable

interface GigabitEthernet0/0/0
 ip address 46.1.1.6 255.255.255.0 
#
interface GigabitEthernet0/0/1
 ip address 192.168.2.254 255.255.255.0 

interface LoopBack0
 ip address 6.6.6.6 255.255.255.255 
#
bgp 300
 router-id 6.6.6.6
 peer 46.1.1.4 as-number 200 
 #
 ipv4-family unicast
  undo synchronization
  network 6.6.6.6 255.255.255.255 
  network 46.1.1.0 255.255.255.0 
  network 192.168.2.0 
  peer 46.1.1.4 enable