BGP修改AS-Pach选路实验

实验拓扑

图1-1

实验需求

AS100设备1单独跑一个AS，设备2、3、4跑AS200
使用OSPF跑IGP
每个接口启用LookBack口并用LookBack建立IBGP邻居
设备4 LookBack口1、2模拟两个业务网段使设备1可以学到
设备1学到设备4的业务网段用路由策略改变AS-Pach实现路由选路

实验步骤

所有设备先做开局配置；建立EBGP、IBGP，观察BGP路由表下一跳以及AS-Pach路径；最后做策略并重置BGP刷新BGP路由表在观察BGP路由表下一跳及AS-Pach

实验解法

Rt1开局配置:

<H3C>sys
System View: return to User View with Ctrl+Z.
[H3C]sys AR01 
[AR01]int g0/0
[AR01-GigabitEthernet0/0]ip add 100.1.1.1 24 
[AR01-GigabitEthernet0/0]int g0/1 
[AR01-GigabitEthernet0/1]ip add 100.2.2.1 24 
[AR01-GigabitEthernet0/1]int lo 0 
[AR01-LoopBack0]ip add 1.1.1.1 32

Rt1 EBGP对等体建立配置:

[AR01]bgp 100 
[AR01-bgp-default]peer 100.1.1.2 as 200 
[AR01-bgp-default]peer 100.2.2.2 as 200 
[AR01-bgp-default]address-family ipv4 
[AR01-bgp-default-ipv4]peer 100.1.1.2 enable 
[AR01-bgp-default-ipv4]peer 100.2.2.2 enable

Rt1 建立路由策略并应用到BGP配置:

[AR01]acl basic 2000
[AR01-acl-ipv4-basic-2000] rule 10 permit source 192.168.1.1 0
[AR01]route-policy 1222 permit node 10
[AR01-route-policy-wdy-10] if-match ip address acl 2000
[AR01-route-policy-wdy-10]apply as-path 800 900 1000
[AR01]bgp 100 
[AR01-bgp-default]address-family ipv4 
[AR01-bgp-default-ipv4] peer 100.1.1.2 route-policy 1222 import
<AR01>reset bgp all 
Reset BGP sessions? [Y/N]:Y

Rt2开局配置:

<H3C>sys
System View: return to User View with Ctrl+Z.
[H3C]sys AR02
[AR02]int lo 0 
[AR02-LoopBack0]ip add 2.2.2.2 32
[AR02-LoopBack0]ospf 1 ar 0 
[AR02-LoopBack0]int g0/0
[AR02-GigabitEthernet0/0]ip add 100.1.1.2 24 
[AR02-GigabitEthernet0/0]int g0/1 
[AR02-GigabitEthernet0/1]ip add 100.3.3.1 24 
[AR02-GigabitEthernet0/1]ospf 1 ar 0

Rt2 EBGP对等体建立\IBGP对等体建立配置:

[AR02]bgp 200 
[AR02-bgp-default]peer 100.1.1.1 as 100 
[AR02-bgp-default]peer 4.4.4.4 as 200 
[AR02-bgp-default]peer 4.4.4.4 connect-interface LoopBack0
[AR02-bgp-default]address-family ipv4 
[AR02-bgp-default-ipv4]peer 100.1.1.1 enable 
[AR02-bgp-default-ipv4]peer 4.4.4.4 enable 
[AR02-bgp-default-ipv4]peer 4.4.4.4 next-hop-local

Rt3开局配置:

<H3C>sys
System View: return to User View with Ctrl+Z.
[H3C]sysn AR03
[AR03]int lo 0 
[AR03-LoopBack0]ip add 3.3.3.3 32 
[AR03-LoopBack0]ospf 1 ar 0 
[AR03-LoopBack0]int g0/0
[AR03-GigabitEthernet0/0]ip add 100.2.2.2 24 
[AR03-GigabitEthernet0/0]int g0/1 
[AR03-GigabitEthernet0/1]ip add 100.4.4.1 24 
[AR03-GigabitEthernet0/1]ospf 1 ar 0

Rt3 EBGP对等体建立\IBGP对等体建立配置:

[AR03]bgp 200 
[AR03-bgp-default]peer 100.2.2.1 as 100 
[AR03-bgp-default]peer 4.4.4.4 as 200 
[AR03-bgp-default]peer 4.4.4.4 connect-interface LoopBack0
[AR03-bgp-default]ad ipv4 
[AR03-bgp-default-ipv4]peer 4.4.4.4 enable 
[AR03-bgp-default-ipv4]peer 4.4.4.4 next-hop-local 
[AR03-bgp-default-ipv4]peer 100.2.2.1 enable

Rt4开局配置:

<H3C>sys
System View: return to User View with Ctrl+Z.
[H3C]sysname AR04
[AR04]
[AR04]int lo 0 
[AR04-LoopBack0]ip add 4.4.4.4 32 
[AR04-LoopBack0]ospf 1  ar 0 
[AR04-LoopBack0]int lo 1 
[AR04-LoopBack1]ip add 192.168.1.1 32 
[AR04-LoopBack1]int lo 2 
[AR04-LoopBack2]ip add 192.168.2.1 32 
[AR04-LoopBack2]int g0/0
[AR04-GigabitEthernet0/0]ip add 100.4.4.2 24 
[AR04-GigabitEthernet0/0]ospf 1 ar 0 
[AR04-GigabitEthernet0/0]int g0/1 
[AR04-GigabitEthernet0/1]ip add 100.3.3.2 24 
[AR04-GigabitEthernet0/1]ospf 1 ar 0

Rt4 IBGP对等体建立配置:

[AR04]bgp 200 
[AR04-bgp-default]peer 2.2.2.2 as-number 200
[AR04-bgp-default]peer 2.2.2.2 connect-interface LoopBack0
[AR04-bgp-default]peer 3.3.3.3 as-number 200
[AR04-bgp-default]peer 3.3.3.3 connect-interface LoopBack0
[AR04-bgp-default]address-family ipv4
[AR04-bgp-default-ipv4]peer 3.3.3.3 enable
[AR04-bgp-default-ipv4]peer 2.2.2.2 enable
[AR04-bgp-default-ipv4]network 192.168.2.1 255.255.255.255
[AR04-bgp-default-ipv4]network 192.168.1.1 255.255.255.255