Learning points:
- Used IGP protocols, e.g. OSPF to run I-BGP.
- Create a loopback interface for all I-BGP routers. Reason being is to ensure that BGP peering address is always available to provide an update, e.g. not dependent on physical interface which affects BGP neighbor when the interface went down.
- Utilized update source Loopback 0 between I-BGP routers
R1:
R1#sh run | sec bgp
router bgp 2
bgp log-neighbor-changes
network 1.1.1.1 mask 255.255.255.255
neighbor 192.168.12.2 remote-as 1
R2:
IGP Configs:
R2#sh run | sec ospf
router ospf 1
network 2.2.2.2 0.0.0.0 area 0
network 192.168.23.0 0.0.0.255 area 0
network 192.168.24.0 0.0.0.255 area 0
I-BGP configs
R2#sh run | sec bgp
router bgp 1
bgp log-neighbor-changes
network 192.168.12.0
neighbor 3.3.3.3 remote-as 1
neighbor 3.3.3.3 update-source Loopback0
neighbor 4.4.4.4 remote-as 1
neighbor 4.4.4.4 update-source Loopback0
neighbor 5.5.5.5 remote-as 1
neighbor 5.5.5.5 update-source Loopback0
neighbor 192.168.12.1 remote-as 2 <<< Network between R1 and R2 is advertise into I-BGP.
R3:
IGP Configs:
R3#sh run | sec ospf
router ospf 1
network 3.3.3.3 0.0.0.0 area 0
network 192.168.23.0 0.0.0.255 area 0
network 192.168.35.0 0.0.0.255 area 0
I-BGP configs
R3#sh run | sec bgp
router bgp 1
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 update-source Loopback0
neighbor 5.5.5.5 remote-as 1
neighbor 5.5.5.5 update-source Loopback0
R4:
IGP Configs:
R4#sh run | sec ospf
router ospf 1
network 4.4.4.4 0.0.0.0 area 0
network 192.168.24.0 0.0.0.255 area 0
network 192.168.45.0 0.0.0.255 area 0
I-BGP configs:
R4#show run | sec bgp
router bgp 1
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 update-source Loopback0
neighbor 5.5.5.5 remote-as 1
neighbor 5.5.5.5 update-source Loopback0
R5:
IGP Configs:
R5#sh run | sec ospf
router ospf 1
network 5.5.5.5 0.0.0.0 area 0
network 192.168.35.0 0.0.0.255 area 0
network 192.168.45.0 0.0.0.255 area 0
I-BGP configs:
R5#sh run | sec bgp
router bgp 1
bgp log-neighbor-changes
network 192.168.56.0
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 update-source Loopback0
neighbor 3.3.3.3 remote-as 1
neighbor 3.3.3.3 update-source Loopback0
neighbor 4.4.4.4 remote-as 1
neighbor 4.4.4.4 update-source Loopback0
neighbor 192.168.56.6 remote-as 3 << Network between R5 & R6 is advertise into IBGP.
R6:
R6#sh run | sec bgp
router bgp 3
bgp log-neighbor-changes
network 6.6.6.6 mask 255.255.255.255
neighbor 192.168.56.5 remote-as 1
Routing Table:
R1#show ip route 6.6.6.6
Routing entry for 6.6.6.6/32
Known via “bgp 2”, distance 20, metric 0
Tag 1, type external
Last update from 192.168.12.2 00:16:30 ago
Routing Descriptor Blocks:
* 192.168.12.2, from 192.168.12.2, 00:16:30 ago
Route metric is 0, traffic share count is 1
AS Hops 2
Route tag 1
MPLS label: none
R1#show ip route
Codes: L – local, 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, H – NHRP, l – LISP
+ – replicated route, % – next hop override
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
6.0.0.0/32 is subnetted, 1 subnets
B 6.6.6.6 [20/0] via 192.168.12.2, 00:18:39
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, Serial3/0
L 192.168.12.1/32 is directly connected, Serial3/0
B 192.168.56.0/24 [20/0] via 192.168.12.2, 00:19:09
R1#
R1#traceroute 6.6.6.6
Type escape sequence to abort.
Tracing the route to 6.6.6.6
VRF info: (vrf in name/id, vrf out name/id)
1 192.168.12.2 [AS 1] 320 msec 240 msec 268 msec
2 192.168.23.3 368 msec 336 msec 364 msec
3 192.168.35.5 504 msec 528 msec 504 msec
4 192.168.56.6 [AS 1] 608 msec 664 msec 652 msec
R1#ping 6.6.6.6 source 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 6.6.6.6, 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 = 460/500/544 ms
R1#
here’s the one of the I-BGP routers Routing table..
R2#show ip route
Codes: L – local, 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, H – NHRP, l – LISP
+ – replicated route, % – next hop override
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [20/0] via 192.168.12.1, 00:49:15
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
3.0.0.0/32 is subnetted, 1 subnets
O 3.3.3.3 [110/2] via 192.168.23.3, 00:26:21, FastEthernet0/0
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/2] via 192.168.24.4, 00:25:54, FastEthernet2/0
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/3] via 192.168.24.4, 00:25:23, FastEthernet2/0
[110/3] via 192.168.23.3, 00:25:23, FastEthernet0/0
6.0.0.0/32 is subnetted, 1 subnets
B 6.6.6.6 [200/0] via 192.168.56.6, 00:19:43
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, Serial3/0
L 192.168.12.2/32 is directly connected, Serial3/0
192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.23.0/24 is directly connected, FastEthernet0/0
L 192.168.23.2/32 is directly connected, FastEthernet0/0
192.168.24.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.24.0/24 is directly connected, FastEthernet2/0
L 192.168.24.2/32 is directly connected, FastEthernet2/0
O 192.168.35.0/24 [110/2] via 192.168.23.3, 00:32:24, FastEthernet0/0
O 192.168.45.0/24 [110/2] via 192.168.24.4, 00:30:49, FastEthernet2/0
B 192.168.56.0/24 [200/0] via 5.5.5.5, 00:19:48
**************************End of Lab********************************
NETWORK LESSON 
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