[experiment sharing] CCIE BGP routing black hole experiment]

​ The experiment purpose :

l master BGP How routing black holes work

l How to solve the routing black hole

Experimental instructions ：

l Practice through this experiment , We can better understand the principle of routing black hole

Experimental environment ：

l Three support SPSERVICES Of IOS The router

l Through line

The topology ：

The experimental steps ：

R1(config)#interface f0/0

R1(config-if)#ip address 12.1.1.1 255.255.255.0

R1(config-if)#no shutdown

R1(config-if)#int lo 0

R1(config-if)#ip address 1.1.1.1 255.255.255.255

R1(config)#router ospf 110

R1(config-router)#router-id 1.1.1.1

R1(config-router)#network 12.1.1.1 0.0.0.0 a 0

R1(config-router)#network 1.1.1.1 0.0.0.0 a 0

R1(config)#int lo 11

R1(config-if)#ip address 11.11.11.11 255.255.255.255

R1(config)#router bgp 100

R1(config-router)#bgp router-id 1.1.1.1

R1(config-router)#neighbor 3.3.3.3 remote-as 100

R1(config-router)#neighbor 3.3.3.3 update-source lo 0{ establish IBGP Neighborhood , It needs to be manually specified through Loop Set up a conversation .}

R1(config-router)#network 11.11.11.11 mask 255.255.255.255{ Announce a 11.11.11.11 The routing }

R2(config)#interface f0/0

R2(config-if)#ip address 12.1.1.2 255.255.255.0

R2(config-if)#no shutdown

R2(config-if)#int f1/0

R2(config-if)#ip address 23.1.1.2 255.255.255.0

R2(config-if)#no shutdown

R2(config)#router ospf 110

R2(config-router)#router-id 2.2.2

R2(config-router)#router-id 2.2.2.2

R2(config-router)#network 12.1.1.2 0.0.0.0 a 0

R2(config-router)#network 23.1.1.2 0.0.0.0 a 0

R3(config)#interface f1/0

R3(config-if)#ip address 23.1.1.3 255.255.255.0

R3(config-if)#no shutdown

R3(config-if)#int lo 0

R3(config-if)#ip address 3.3.3.3 255.255.255.255

R3(config)#router ospf 110

R3(config-router)#router-id 3.3.3.3

R3(config-router)#network 23.1.1.3 0.0.0.0 a 0

R3(config-router)#network 3.3.3.3 0.0.0.0 a 0

R3(config)#router bgp 100

R3(config-router)#bgp router-id 3.3.3.3

R3(config-router)#neighbor 1.1.1.1 remote-as 100

R3(config-router)#neighbor 1.1.1.1 update-source lo 0

R3(config-router)#network 33.33.33.33 mask 255.255.255.255

R3(config)#int lo 33

R3(config-if)#ip address 33.33.33.33 255.255.255.255

here R1 To receive 33.33.33.33 R3 received 11.11.11.11

R1#show ip bgp

Network Next Hop Metric LocPrf Weight Path

*> 11.11.11.11/32 0.0.0.0 0 32768 i{R1 Generate your own route locally }

*>i33.33.33.33/32 3.3.3.3 0 100 0 i{ there i Said by ibgp Acquire }{ adopt R3 Acquire 33.33.33.33}

R3 Empathy

test ：R1 Source 11.11.11.11 ping R3 Of 33.33.33.33

R1#ping 33.33.33.33 source lo 11

…

analysis ：

because R1 You can get R3 The routing , So I will go to 33.33.33.33 The traffic is sent to R2, And then R2 When this traffic is received , Find the destination position 33.33.33.33

because R2 No IBGP neighbor , Therefore, we cannot receive 33.33.33.33. therefore R2 Discard the traffic without any route matching . This phenomenon is a routing black hole

resolvent ：

1, stay R2 Admiral BGP Redistribute to ospf bring R2 To receive 33.33.33.33

2,R2 Manually generate information about 33.33.33.33 The routing and 11.11.11.11 The routing

Such as ：R2 ip route 33.33.33.33 255.255.255.255 23.1.1.3

3,R1,R2,R3 do IBGP All connected

4,Mpls Marking