BGP及IBGP的基本配置
一、基本配置
R1(config)#interface serial 1/1
R1(config-if)#ip address 12.1.1.1 255.255.255.0
R1(config-if)#no shut
R1(config)#interface loopback 0
R1(config-if)#ip address 1.1.1.1 255.255.255.0
R1(config-if)#exit
R2(config)#in serial 1/1
R2(config-if)#ip address 23.1.1.1 255.255.255.0
R2(config-if)#no shut
R2(config)#interface serial 1/0
R2(config-if)#ip address 12.1.1.2 255.255.255.0
R2(config-if)#no shut
R2(config)#in loopback 0
R2(config-if)#ip address 2.2.2.2 255.255.255.0
R1/R2/R3/R4/R5都一样，分别为12/23/34/45网段，并且一个环回
二、配置igp，R2/R3/R4均属AS2,并且运行eigrp协议
R2(config)#router eigrp 88
R2(config-router)#no auto-summary
R2(config-router)#network 2.2.2.0
R2(config-router)#network 23.1.1.0
测试一下
R2#ping 4.4.4.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/100/172 ms
三、
1、配置R1/R2的EBGP环境，用其物理接口，（直连BGP）
R1(config)#router bgp 1
R1(config-router)#bgp router-id 1.1.1.1（此路由器在BGP 中的身份）
R1(config-router)#neighbor 12.1.1.2 remote-as 2
R2(config)#router bgp 2
R2(config-router)#bgp router-id 2.2.2.2
R2(config-router)#neighbor 12.1.1.1 remote-as 1
R2(config-router)#
*Nov 21 21:39:33.559: %BGP-5-ADJCHANGE: neighbor 12.1.1.1 Up
邻居关系建立，发送了open报文
R2#show ip bgp summary
BGP router identifier 2.2.2.2, local AS number 2
BGP table version is 1, main routing table version 1
R2#show ip bgp summary
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.1 4 1 7 7 1 0 0 00:03:19 0
2、同样，将R4/R5配置为非直连邻居
R5(config)#ip route 4.4.4.0 255.255.255.0 serial 1/0
R4(config)#ip route 5.5.5.0 255.255.255.0 serial 1/1
配静态时接口必须为本路由器的出接口
R4#ping 5.5.5.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
!!!!!
四、R2/R3/R4要有IGP 环境，
R2(config)#router bgp 2
R2(config-router)#bgp router-id 2.2.2.2
R2(config-router)#neighbor 3.3.3.3 remote-as 2
R2(config-router)#neighbor 3.3.3.3 update-source loopback 0
R2#show ip bgp summary
BGP router identifier 2.2.2.2, local AS number 2
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
3.3.3.3 4 2 6 6 1 0 0 00:02:15 0
12.1.1.1 4 1 60 59 1 0 0 00:51:05 0
R2#
R3#show ip bgp su
R3#show ip bgp summary
BGP router identifier 3.3.3.3, local AS number 2
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
2.2.2.2 4 2 6 6 1 0 0 00:02:37 0
4.4.4.4 4 2 5 3 1 0 0 00:01:04 0
五、配置BGP 的邻居
R1(config)#router bgp 1
R1(config-router)#network 12.1.1.0 mask 255.255.255.0
R2(config)#router bgp 2
R2(config-router)#network 12.1.1.0 mask 255.255.255.0
R2(config-router)#
1、R1/R2有了BGP表，成为BGP邻居
R2#show bgp
BGP table version is 3, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 12.1.1.1 0 0 1 i
*> 2.2.2.0/24 0.0.0.0 0 32768 i
同样R4/R5也要有bgp邻居关系，
neighbor 5.5.5.5 remote-as 3
neighbor 5.5.5.5 ebgp-multihop 255
neighbor 5.5.5.5 update-source Loopback 0
router bgp 3
bgp router-id 3.3.3.3
neighbor 4.4.4.4 remote-as 2
neighbor 4.4.4.4 ebgp-multihop 255
neighbor 4.4.4.4 update-source Loopback0
!
!
所以完成基本配置后，network，此时邻居关系建立
2、IBGP为了防环，有了水平分割，所以要打破水平分割。并且
解决方法：改变路由器的下一跳
R2(config-router)#neighbor 3.3.3.3 next-hop-self
R3(config)#router bgp 2
R3#show 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,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
R3(config-router)#neighbor 4.4.4.4 next-hop-self
R3(config-router)#neighbor 2.2.2.2 next-hop-self
最后全网可通
R5# show 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,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 4.4.4.4 0 2 1 i
*> 2.2.2.0/24 4.4.4.4 0 2 i
*> 3.3.3.0/24 4.4.4.4 0 2 i
r> 4.4.4.0/24 4.4.4.4 0 0 2 i
*> 5.5.5.0/24 0.0.0.0 0 32768 i
R5#
R1#
R1#show bgp
BGP table version is 6, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 0.0.0.0 0 32768 i
*> 2.2.2.0/24 12.1.1.2 0 0 2 i
*> 3.3.3.0/24 12.1.1.2 0 2 i
*> 4.4.4.0/24 12.1.1.2 0 2 i
*> 5.5.5.0/24 12.1.1.2 0 2 3 i
、ping时的注意事项
R1#ping 5.5.5.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R1#ping 5.5.5.5 source 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
Packet sent with a source address of 1.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 48/78/108 ms