非直连IBGP邻居路由更新的解决办法-------路由反射器

Posted 2020-09-04

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如上图所示，R1/R2/R3在同一个IBGP内，这种情况下，路由更新，从IBGP邻居学习的路由不会被传递给其他的IBGP邻居。这样的解决办法有三种：

1、IBGP完全互连

2、路由反射器（Route Reflector）

3、联盟

案例一、非直连邻居通过路由反射器（直连邻居省略）

R1配置信息：

interface Loopback10

ip address 10.1.1.1 255.255.255.0

interface Loopback100

ip address 100.1.1.1 255.255.255.0

interface FastEthernet0/0

ip address 1.1.1.1 255.255.255.0

duplex auto

speed auto

！

router bgp 100

no synchronization

bgp log-neighbor-changes

network 10.1.1.0 mask 255.255.255.0

network 100.1.1.0 mask 255.255.255.0

neighbor 20.1.1.1 remote-as 100

neighbor 20.1.1.1 update-source loopback 10

no auto-summary

ip route 20.1.1.0 255.255.255.0 1.1.1.2

R2配置信息：

interface Loopback20

ip address 20.1.1.1 255.255.255.0

interface FastEthernet0/0

ip address 1.1.1.2 255.255.255.0

duplex auto

speed auto

interface FastEthernet0/1

ip address 2.2.2.2 255.255.255.0

duplex auto

speed auto

router bgp 100

no synchronization

bgp log-neighbor-changes

network 1.1.1.0 mask 255.255.255.0

network 2.2.2.0 mask 255.255.255.0

network 20.1.1.0 mask 255.255.255.0

neighbor 2.2.2.3 remote-as 100

neighbor 2.2.2.3 route-reflector-client

neighbor 10.1.1.1 remote-as 100

neighbor 10.1.1.1 update-source Loopback20

neighbor 10.1.1.1 route-reflector-client

no auto-summary

ip classless

ip route 10.1.1.0 255.255.255.0 1.1.1.1

R3配置信息：

interface Loopback30

ip address 30.1.1.1 255.255.255.0

interface FastEthernet0/1

ip address 2.2.2.3 255.255.255.0

duplex auto

speed auto

router bgp 100

no synchronization

bgp log-neighbor-changes

network 30.1.1.0 mask 255.255.255.0

neighbor 2.2.2.2 remote-as 100

no auto-summary

查看R1的路由信息：

R1#show ip route

*Mar 14 08:16:33.956: %SYS-5-CONFIG_I: Configured from console by console

R1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, FastEthernet0/0

2.0.0.0/24 is subnetted, 1 subnets

B 2.2.2.0 [200/0] via 20.1.1.1, 02:47:19

100.0.0.0/24 is subnetted, 1 subnets

C 100.1.1.0 is directly connected, Loopback100

20.0.0.0/24 is subnetted, 1 subnets

S 20.1.1.0 [1/0] via 1.1.1.2

10.0.0.0/24 is subnetted, 1 subnets

C 10.1.1.0 is directly connected, Loopback10

30.0.0.0/24 is subnetted, 1 subnets

B 30.1.1.0 [200/0] via 2.2.2.3, 02:42:23

R1#show ip bgp

BGP table version is 50, local router ID is 100.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

r>i1.1.1.0/24 20.1.1.1 0 100 0 i

*>i2.2.2.0/24 20.1.1.1 0 100 0 i

*> 10.1.1.0/24 0.0.0.0 0 32768 i

r>i20.1.1.0/24 20.1.1.1 0 100 0 i

*>i30.1.1.0/24 2.2.2.3 0 100 0 i

*> 100.1.1.0/24 0.0.0.0 0 32768 i

R2的路由信息：

R2#show ip bgp

BGP table version is 8, local router ID is 20.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 1.1.1.0/24 0.0.0.0 0 32768 i

*> 2.2.2.0/24 0.0.0.0 0 32768 i

r>i10.1.1.0/24 10.1.1.1 0 100 0 i

*> 20.1.1.0/24 0.0.0.0 0 32768 i

*>i30.1.1.0/24 2.2.2.3 0 100 0 i

*>i100.1.1.0/24 10.1.1.1 0 100 0 i

R2#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, FastEthernet0/0

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, FastEthernet0/1

100.0.0.0/24 is subnetted, 1 subnets

B 100.1.1.0 [200/0] via 10.1.1.1, 00:01:57

20.0.0.0/24 is subnetted, 1 subnets

C 20.1.1.0 is directly connected, Loopback20

10.0.0.0/24 is subnetted, 1 subnets

S 10.1.1.0 [1/0] via 1.1.1.1

30.0.0.0/24 is subnetted, 1 subnets

B 30.1.1.0 [200/0] via 2.2.2.3, 00:01:50

R2#show ip bgp 100.1.1.0

BGP routing table entry for 100.1.1.0/24, version 6

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Advertised to non peer-group peers:

2.2.2.3 -----表示把100.1.1.0/24的路由发布给IBGP邻居2.2.2.3

Local, (Received from a RR-client)

10.1.1.1 from 10.1.1.1 (100.1.1.1)

Origin IGP, metric 0, localpref 100, valid, internal, best

R3的路由信息：

R3#show ip bgp

BGP table version is 6, local router ID is 30.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.0/24 2.2.2.2 0 100 0 i

r>i2.2.2.0/24 2.2.2.2 0 100 0 i

* i10.1.1.0/24 10.1.1.1 0 100 0 i

*>i20.1.1.0/24 2.2.2.2 0 100 0 i

*> 30.1.1.0/24 0.0.0.0 0 32768 i

* i100.1.1.0/24 10.1.1.1 0 100 0 i

R3#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

1.0.0.0/24 is subnetted, 1 subnets

B 1.1.1.0 [200/0] via 2.2.2.2, 00:03:03

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, FastEthernet0/1

20.0.0.0/24 is subnetted, 1 subnets

B 20.1.1.0 [200/0] via 2.2.2.2, 00:03:03

30.0.0.0/24 is subnetted, 1 subnets

C 30.1.1.0 is directly connected, Loopback30

可以看到R1上通告的100.1.1.0/24和10.1.1.0/24 网段路由虽然通过BGP学习成功，但是在路由加载的时候添加路由失败，R3上未学习到next hop。

因为在路由同步的规则当中，需要把IGP的路由必须同步到IBGP，如果不能同步就会造成路由黑洞。因此需要在R2上把静态路由重分布

在R2上配置信息：

router bgp 100

no synchronization

bgp log-neighbor-changes

network 1.1.1.0 mask 255.255.255.0

network 2.2.2.0 mask 255.255.255.0

network 20.1.1.0 mask 255.255.255.0

redistribute static metric 10

neighbor 2.2.2.3 remote-as 100

neighbor 2.2.2.3 route-reflector-client

neighbor 10.1.1.1 remote-as 100

neighbor 10.1.1.1 update-source Loopback20

neighbor 10.1.1.1 route-reflector-client

no auto-summary

R3的路由信息：

R3#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

1.0.0.0/24 is subnetted, 1 subnets

B 1.1.1.0 [200/0] via 2.2.2.2, 00:12:08

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, FastEthernet0/1

100.0.0.0/24 is subnetted, 1 subnets

B 100.1.1.0 [200/0] via 10.1.1.1, 00:00:01

20.0.0.0/24 is subnetted, 1 subnets

B 20.1.1.0 [200/0] via 2.2.2.2, 00:12:08

10.0.0.0/24 is subnetted, 1 subnets

B 10.1.1.0 [200/10] via 1.1.1.1, 00:00:11

30.0.0.0/24 is subnetted, 1 subnets

C 30.1.1.0 is directly connected, Loopback30

R3#show ip bgp

BGP table version is 8, local router ID is 30.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.0/24 2.2.2.2 0 100 0 i

r>i2.2.2.0/24 2.2.2.2 0 100 0 i

*>i10.1.1.0/24 1.1.1.1 10 100 0 ?

*>i20.1.1.0/24 2.2.2.2 0 100 0 i

*> 30.1.1.0/24 0.0.0.0 0 32768 i

*>i100.1.1.0/24 10.1.1.1 0 100 0 i

在IGP路由同步到IBGP中之后，IBGP邻居就能够正常通过RR学习到相应的路由信息。

初次了解学习BGP，可能理解或解释的不够准确详细，望各位看官见谅！欢迎一起交流探讨~~~

本文出自 “遨天之鹰” 博客，请务必保留此出处http://205091.blog.51cto.com/195091/1906322

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