一、实验拓扑图

二、实验要求
1、AS1、AS3不进行IGP配置;
2、AS2内部使用IGP(OSPF、RIP等)进行配置,使得AS2内部全通;
3、AS1、AS2、AS3之间使用BGP进行连接;
4、除R5的5.5.5.0环回外,其他所有的环回均可互相访问。
三、IP地址规划
| 设备名称 | 接口名称 | IP地址/子网掩码 |
|---|---|---|
| R1 | GE0/0/0 | 12.1.1.1/24 |
| R1 | LoopBack0 | 1.1.1.1/24 |
| R2 | GE0/0/0 | 12.1.1.2/24 |
| R2 | GE0/0/1 | 23.1.1.1/24 |
| R2 | LoopBack0 | 2.2.2.2/24 |
| R3 | GE0/0/0 | 23.1.1.2/24 |
| R3 | GE0/0/1 | 34.1.1.1/24 |
| R3 | LoopBack0 | 3.3.3.3/24 |
| R4 | GE0/0/0 | 34.1.1.1/24 |
| R4 | GE0/0/1 | 45.1.1.1/24 |
| R4 | GE0/0/2 | 54.1.1.1/24 |
| R4 | LoopBack0 | 4.4.4.4/24 |
| R5 | GE0/0/0 | 45.1.1.2/24 |
| R5 | GE0/0/1 | 54.1.1.2/24 |
| R5 | LoopBack0 | 5.5.5.5/24 |
| R5 | LoopBack1 | 99.1.1.1/24 |
四、实验步骤
注:在进行所有配置之前,可进行永不超时配置,具体配置如下
bash[r1]user-interface console 0 [r1-ui-console0]idle-timeout 0 0 [r1-ui-console0]q
(1)基础配置:接口IP与环回
bash
r1
[r1]int g0/0/0
[r1-GigabitEthernet0/0/0]ip ad 12.1.1.1 24
[r1-GigabitEthernet0/0/0]int lo0
[r1-LoopBack0]ip ad 1.1.1.1 24
[r1-LoopBack0]q
r2
[r2]int g0/0/0
[r2-GigabitEthernet0/0/0]ip ad 12.1.1.2 24
[r2-GigabitEthernet0/0/0]int g0/0/1
[r2-GigabitEthernet0/0/1]ip ad 23.1.1.1 24
[r2-GigabitEthernet0/0/1]int lo0
[r2-LoopBack0]ip ad 2.2.2.2 24
[r2-LoopBack0]q
r3
[r3]int g0/0/0
[r3-GigabitEthernet0/0/0]ip ad 23.1.1.2 24
[r3-GigabitEthernet0/0/0]int g0/0/1
[r3-GigabitEthernet0/0/1]ip ad 34.1.1.1 24
[r3-GigabitEthernet0/0/1]int lo0
[r3-LoopBack0]ip ad 3.3.3.3 24
[r3-LoopBack0]q
r4
[r4]int g0/0/0
[r4-GigabitEthernet0/0/0]ip ad 34.1.1.2 24
[r4-GigabitEthernet0/0/0]int g0/0/1
[r4-GigabitEthernet0/0/1]ip ad 45.1.1.1 24
[r4-GigabitEthernet0/0/1]int g0/0/2
[r4-GigabitEthernet0/0/2]ip ad 54.1.1.1 24
[r4-GigabitEthernet0/0/2]int lo0
[r4-LoopBack0]ip ad 4.4.4.4 24
[r4-LoopBack0]q
r5
[r5]int g0/0/0
[r5-GigabitEthernet0/0/0]ip ad 45.1.1.2 24
[r5-GigabitEthernet0/0/0]int g0/0/1
[r5-GigabitEthernet0/0/1]int lo0
[r5-LoopBack0]ip ad 5.5.5.5 24
[r5-LoopBack0]q
[r5]int g0/0/1
[r5-GigabitEthernet0/0/1]ip ad 54.1.1.2 24
[r5-GigabitEthernet0/0/1]q
注:配置结束后,使用命令行:[r1]display ip interface brief 查看IP地址表,例如:

(2)AS2区域OSPF协议配置
bash
r2
[r2]ospf 1 router-id 2.2.2.2
[r2-ospf-1]ar 0
[r2-ospf-1-area-0.0.0.0]network 23.1.1.0 0.0.0.255
[r2-ospf-1-area-0.0.0.0]network 2.2.2.0 0.0.0.255
[r2-ospf-1-area-0.0.0.0]q
[r2-ospf-1]q
r3
[r3]ospf 1
[r3-ospf-1]ar 0
[r3-ospf-1-area-0.0.0.0]network 23.1.1.0 0.0.0.255
[r3-ospf-1-area-0.0.0.0]network 34.1.1.0 0.0.0.255
[r3-ospf-1-area-0.0.0.0]network 3.3.3.0 0.0.0.255
[r3-ospf-1-area-0.0.0.0]q
r4
[r4]ospf 1 router-id 4.4.4.4
[r4-ospf-1]area 0
[r4-ospf-1-area-0.0.0.0]network 34.1.1.0 0.0.0.255
[r4-ospf-1-area-0.0.0.0]network 4.4.4.0 0.0.0.255
[r4-ospf-1-area-0.0.0.0]q
[r4-ospf-1]q
注:配置结束后,查看邻居关系是否是FULL状态:display ospf peer brief
或查看ospf路由表: dis ip ro pr os



(3)配置BGP连接AS1、AS2、AS3区域
1、R1和R2之间使用直连接口IP地址来建立EBGP对等体关系:
r1
[r1]bgp 1
[r1-bgp]router-id 1.1.1.1
[r1-bgp]peer 12.1.1.2 as-number 2
[r1-bgp]q
r2
[r2]bgp 2
[r2-bgp]router-id 2.2.2.2
[r2-bgp]peer 12.1.1.1 as-number 1
[r2-bgp]q
2、R2、R3、R4使用环回接口建立非直连的IBGP对等体关系:
bash
r2
[r2]bgp 2
[r2-bgp]peer 3.3.3.3 as-number 2
[r2-bgp]peer 3.3.3.3 connect-interface lo0
[r2-bgp]peer 4.4.4.4 as-number 2
[r2-bgp]peer 4.4.4.4 connect-interface lo 0
[r2-bgp]peer 3.3.3.3 next-hop-invariable
[r2-bgp]peer 4.4.4.4 next-hop-invariable
r3
[r3]bgp 2
[r3-bgp]peer 2.2.2.2 as-number 2
[r3-bgp]peer 2.2.2.2 connect-interface lo 0
[r3-bgp]peer 4.4.4.4 as-number 2
[r3-bgp]peer 4.4.4.4 connect-interface lo 0
[r3-bgp]peer 2.2.2.2 next-hop-invariable
[r3-bgp]peer 4.4.4.4 next-hop-invariable
r4
[r4]bgp 2
[r4-bgp]peer 2.2.2.2 as-number 2
[r4-bgp]peer 2.2.2.2 connect-interface lo 0
[r4-bgp]peer 3.3.3.3 as-number 2
[r4-bgp]peer 3.3.3.3 connect-interface lo 0
[r4-bgp]peer 2.2.2.2 next-hop-invariable
[r4-bgp]peer 3.3.3.3 next-hop-invariable
3、R4和R5之间使用环回接口建立EBGP对等体关系,并补充配置缺省路由,然后修改TTL数值,确保TCP会话正常建立:
bash
[r4]bgp 2
[r4-bgp]pe
[r4-bgp]peer 5.5.5.5 as
[r4-bgp]peer 5.5.5.5 as-number 3
[r4-bgp]pe
[r4-bgp]peer 5.5.5.5 co
[r4-bgp]peer 5.5.5.5 connect-interface lo 0
[r4-bgp]pe
[r4-bgp]peer 5.5.5.5 eb
[r4-bgp]peer 5.5.5.5 ebgp-max-hop 2
[r4-bgp]
Jan 25 2026 14:03:44-08:00 r4 %%01BGP/3/STATE_CHG_UPDOWN(l)[0]:The status of the
peer 5.5.5.5 changed from OPENCONFIRM to ESTABLISHED. (InstanceName=Public, Sta
teChangeReason=Up)
[r5]bgp 3
[r5-bgp]rou
[r5-bgp]route-select
[r5-bgp]router-id 5.5.5.5
[r5-bgp]ope
[r5-bgp]pe
[r5-bgp]peer 4.4.4.4 as
[r5-bgp]peer 4.4.4.4 as-number 2
[r5-bgp]pe
[r5-bgp]peer 4.4.4.4 co
[r5-bgp]peer 4.4.4.4 connect-interface lo 0
[r5-bgp]pe
[r5-bgp]peer 4.4.4.4 eb
[r5-bgp]peer 4.4.4.4 ebgp-max-hop
[r5-bgp]q
[r5]
Jan 25 2026 14:03:45-08:00 r5 %%01BGP/3/STATE_CHG_UPDOWN(l)[0]:The status of the
peer 4.4.4.4 changed from OPENCONFIRM to ESTABLISHED. (InstanceName=Public, Sta
teChangeReason=Up)
(4)在r1与r5上各写一个环回,作为固定网关,并且宣告在ebgp中:
bash
[r1]bgp 1
[r1-bgp]net
[r1-bgp]network 1.1.1.1 24
[r1-bgp]q
[r5]bgp 3
[r5-bgp]net
[r5-bgp]network 5.5.5.5 24
[r5-bgp]q
[r5]