I-BGP USING FULL MESH NEIGHBORSHIP & BGP SPLIT HORIZON RULE - LAB
I-BGP USING FULL MESH NEIGHBORSHIP & BGP SPLIT HORIZON RULE
Assign the basic IP Addressing as per the routers!
Router>enable Router#configure terminal Router(config)#hostname R-1R-1(config)#interface gig0/0R-1(config-if)#ip add 1.1.1.1 255.0.0.0R-1(config-if)#no shut R-1(config-if)#exitR-1(config)#interface gig0/1R-1(config-if)#ip add 4.4.4.2 255.0.0.0R-1(config-if)#no shut R-1(config-if)#exitR-1(config)#interface gig0/2R-1(config-if)#ip add 10.1.1.1 255.0.0.0R-1(config-if)#no shut R-1(config-if)#exit.
Router>enable Router#configure terminal Router(config)#hostname R-2
R-2(config)#interface gig0/0R-2(config-if)#ip add 1.1.1.2 255.0.0.0R-2(config-if)#no shut R-2(config-if)#exitR-2(config)#int gig0/1R-2(config-if)#ip add 2.2.2.1 255.0.0.0R-2(config-if)#no shut R-2(config-if)#exitR-2(config)#interface gig0/2R-2(config-if)#ip add 20.1.1.1 255.0.0.0R-2(config-if)#no shut R-2(config-if)#exitRouter>enable Router#configure terminal Router(config)#hostname R-3R-3(config)#interface gig0/0R-3(config-if)#ip add 2.2.2.2 255.0.0.0R-3(config-if)#no shut R-3(config-if)#exitR-3(config)#int gig0/1R-3(config-if)#ip add 3.3.3.1 255.0.0.0R-3(config-if)#no shut R-3(config-if)#exitR-3(config)#int gig0/2R-3(config-if)#ip add 30.1.1.1 255.0.0.0R-3(config-if)#no shut R-3(config-if)#exit& Now finally the last which IP implementations of R-4Router>enable Router#configure terminal Router(config)#hostname R-4R-4(config)#interface gig0/0R-4(config-if)#ip add 4.4.4.1 255.0.0.0R-4(config-if)#no shut R-4(config-if)#exitR-4(config)#int gig0/1
R-4(config-if)#ip add 3.3.3.2 255.0.0.0
R-4(config-if)#no shut R-4(config-if)#exit
R-4(config)#int gig0/2
R-4(config-if)#ip add 40.1.1.1 255.0.0.0
R-4(config-if)#no shut R-4(config-if)#exit
Now we’ll implement I-BGP on all the routers.
R-1(config)#router bgp 500 R-1(config-router)#no sync R-1(config-router)#no auto-sumR-1(config-router)#neighbor 1.1.1.2 remote-as 500R-1(config-router)#neighbor 4.4.4.1 remote-as 500R-1(config-router)#network 1.0.0.0R-1(config-router)#network 4.0.0.0R-1(config-router)#network 10.0.0.0R-1(config-router)#exit
R-2(config)#router bgp 500
R-2(config-router)#no auto-sumR-2(config-router)#no syncR-2(config-router)#neighbor 2.2.2.2 remote-as 500R-2(config-router)#neighbor 1.1.1.1 remote-as 500R-2(config-router)#network 1.0.0.0R-2(config-router)#network 20.0.0.0R-2(config-router)#network 2.0.0.0
R-3(config-router)#no auto-sum
R-3(config-router)#no sync
R-3(config-router)#neighbor 3.3.3.2 remote-as 500
R-3(config-router)#neighbor 2.2.2.1 remote-as 500
R-3(config-router)#network 2.0.0.0
R-3(config-router)#network 3.0.0.0
R-3(config-router)#network 30.0.0.0
R-4(config)#router bgp 500
R-4(config-router)#no auto-sumR-4(config-router)#no syncR-4(config-router)#neighbor 4.4.4.2 remote-as 500R-4(config-router)#neighbor 3.3.3.1 remote-as 500R-4(config-router)#network 4.0.0.0R-4(config-router)#network 3.0.0.0R-4(config-router)#network 40.0.0.0
So, as per the implementations of i-BGP we can see that there’s a trouble in our verifications which is that –
R-1 is not having the routing entry for the network 30.0.0.0 which is on R-3.
R-3 is not having the routing entry for the network 10.0.0.0 which is on R-1.
R-2 is not having the routing entry for the network 40.0.0.0 which is on R-4.
R-4 is not having the routing entry for the network 20.0.0.0 which is on R-2.
Now as per this, the routes are shared via the directly connected neighbors.But something we discussed “BGP Split Horizon Rule” is here –By-default as per i-BGP the default rule says that an update sent by one i-BGP neighbor should not be sent back to another i-BGP neighbor.To overcome this cause, we’ll use full-mesh neighborship.R-1(config)#router bgp 500R-1(config-router)#neighbor 2.2.2.2 remote-as 500R-3(config)#router bgp 500R-3(config-router)#neighbor 1.1.1.1 remote-as 500R-3(config-router)#exit
& here’s the routing table verification after defining full-mesh neighborship between R-1 & R-3
#BGP #cisco #lab #practice #learn #useful