模拟三个自治域互通

省略IP配置步骤

OSPF

R2

ospf 1
area 0
network 23.23.23.1 0.0.0.0
network 2.2.2.2 0.0.0.0
qu

R3

ospf 1
area 0
network 23.23.23.2 0.0.0.0
network 3.3.3.3 0.0.0.0
qu

BGP

R1 宣告自身AS100域与自身IP段，同时与AS200建立连接

bgp 100
peer 12.12.12.2 as-number 200
address-family ipv4
network 192.168.1.1 255.255.255.25
peer 12.12.12.2 enable

R2 宣告自身AS200域以及与AS100建立连接

bgp 200
peer 12.12.12.1 as 100
address-family ipv4 
peer  12.12.12.1 enable 

R2 确定R3的AS200域，以及指定与R3的BGP通讯接口为LoopBack 0， 指定来自R3的下一跳为自身。

bgp 200
peer 3.3.3.3 as 200
peer 3.3.3.3 connect-interface LoopBack 0
address-family ipv4
peer  3.3.3.3 enable 
peer  3.3.3.3 next-hop-local 

R3 宣告自身AS200域，指定与同域R2的通讯接口为LoopBack 0，指定R4的自治域为AS300，指定来自R2的下一跳为自身

bgp 200
peer 2.2.2.2 as 200
peer 34.34.34.2 as 300
peer  2.2.2.2 connect-interface LoopBack 0
address-family ipv4
peer  2.2.2.2 enable
peer  34.34.34.2 enable 
peer  2.2.2.2 next-hop-local 

R4宣告自身AS300域与自身IP段，并建立与R3的通讯

bgp 300
peer 34.34.34.1 as 200
address-family ipv4
peer  34.34.34.1 enable 
network 172.16.1.0 24 

R1与R4测试通讯

 ping -a 192.168.1.1 172.16.1.1