BGP neighbors : basic configuration

This is about basic configuration for how to establish eBGP and iBGP neighbors.
Note:

• For iBGP, R4 should use loopback address to establish neighbor relationship between R1 and R4.
• BGP use port 179
• When a routers try to establish neighbor relationships, it takes 60 seconds because BGP is very slow protocol.

R1>

interface Loopback0
 ip address 1.1.1.1 255.255.255.255
 ip ospf network point-to-point
!
interface Serial0/2
 ip address 10.1.12.1 255.255.255.0
 clock rate 2000000
!
interface Serial0/3
 ip address 10.1.13.1 255.255.255.0
 clock rate 2000000
!
router ospf 1
 router-id 1.1.1.1
 log-adjacency-changes
 network 1.1.1.1 0.0.0.0 area 0
 network 10.1.12.1 0.0.0.0 area 0
 network 10.1.13.1 0.0.0.0 area 0
!
router bgp 5500
 no synchronization
 bgp log-neighbor-changes
 neighbor 4.4.4.4 remote-as 5500
 neighbor 4.4.4.4 update-source Loopback0
 no auto-summary

R2>

interface Serial0/1
 ip address 10.1.12.2 255.255.255.0
 clock rate 2000000
!
interface Serial0/4
 ip address 10.1.24.2 255.255.255.0
 clock rate 2000000
!
router ospf 1
 router-id 2.2.2.2
 log-adjacency-changes
 network 10.1.12.2 0.0.0.0 area 0
 network 10.1.24.2 0.0.0.0 area 0

R3>

interface Serial0/1
 ip address 10.1.13.3 255.255.255.0
 clock rate 2000000
!
interface Serial0/4
 ip address 10.1.34.3 255.255.255.0
 clock rate 2000000
!
router ospf 1
 router-id 3.3.3.3
 log-adjacency-changes
 network 10.1.13.3 0.0.0.0 area 0
 network 10.1.34.3 0.0.0.0 area 0

R4>

interface Loopback0
 ip address 4.4.4.4 255.255.255.255
 ip ospf network point-to-point
!
interface Serial0/2
 ip address 10.1.24.4 255.255.255.0
 clock rate 2000000
!
interface Serial0/3
 ip address 10.1.34.4 255.255.255.0
 clock rate 2000000
!
interface Serial0/5
 ip address 10.1.45.4 255.255.255.0
 clock rate 2000000
!
router ospf 1
 router-id 4.4.4.4
 log-adjacency-changes
 passive-interface default
 no passive-interface Serial0/2
 no passive-interface Serial0/3
 network 4.4.4.4 0.0.0.0 area 0
 network 10.1.24.4 0.0.0.0 area 0
 network 10.1.34.4 0.0.0.0 area 0
!
router bgp 5500
 no synchronization
 bgp log-neighbor-changes
 neighbor 1.1.1.1 remote-as 5500
 neighbor 1.1.1.1 update-source Loopback0
 neighbor 10.1.45.5 remote-as 6500
 no auto-summary

R5>

interface Serial0/4
 ip address 10.1.45.5 255.255.255.0
 clock rate 2000000
!
router bgp 6500
 no synchronization
 bgp log-neighbor-changes
 neighbor 10.1.45.4 remote-as 5500
 no auto-summary

================================================================
Configuration to use loopback address on eBGP
Note: eBGP must be connected directly to establish neighbor relationship.(This will show how to solve the problem.)

R4>

interface Loopback0
 ip address 4.4.4.4 255.255.255.255
 ip ospf network point-to-point
!
interface Serial0/2
 ip address 10.1.24.4 255.255.255.0
 clock rate 2000000
!
interface Serial0/3
 ip address 10.1.34.4 255.255.255.0
 clock rate 2000000
!
interface Serial0/5
 ip address 10.1.45.4 255.255.255.0
 clock rate 2000000
!
router ospf 1
 router-id 4.4.4.4
 log-adjacency-changes
 passive-interface default
 no passive-interface Serial0/2
 no passive-interface Serial0/3
 network 4.4.4.4 0.0.0.0 area 0
 network 10.1.24.4 0.0.0.0 area 0
 network 10.1.34.4 0.0.0.0 area 0
!
router bgp 5500
 no synchronization
 bgp log-neighbor-changes
 neighbor 1.1.1.1 remote-as 5500
 neighbor 1.1.1.1 update-source Loopback0
 neighbor 5.5.5.5 remote-as 6500
 neighbor 5.5.5.5 ebgp-multihop 2
 neighbor 5.5.5.5 update-source Loopback0
 no auto-summary
!
ip forward-protocol nd
ip route 5.5.5.5 255.255.255.255 10.1.45.5

R5>

interface Loopback0
 ip address 5.5.5.5 255.255.255.255
!
interface Serial0/4
 ip address 10.1.45.5 255.255.255.0
 clock rate 2000000
!
router bgp 6500
 no synchronization
 bgp log-neighbor-changes
 neighbor 4.4.4.4 remote-as 5500
 neighbor 4.4.4.4 ebgp-multihop 2
 neighbor 4.4.4.4 update-source Loopback0
 no auto-summary
!
ip forward-protocol nd
ip route 4.4.4.4 255.255.255.255 10.1.45.4