1. CCNP Network Route BGP Part -II

2. BGP ROUTE REDISTRIBUTION Scenario: R1 R2, R3 in AS 1000 with IP addresses of 192.168.10.1 and loopback 1.1.1.1, 192.168.10.2 & loopback 2.2.2.2 and R3 with [FE 0/0 192.168.10.3 & s0/0 10.1.1.1 & 3.3.3.3] respectively. R4 is in AS 2000 with ip address of 10.1.1.2 and loopback address of 4.4.4.4 Lets enable BGP and Create Neighbors first. R4: R4(config)#router bgp 2000  R4(config-router)#neighbor 10.1.1.1 remote-as 1000 Now we confirm it by the command

3. CCNP Network Route BGP Part -II R4(config-router)#do show ip bgp summ BGP router identifier 1.1.1.3, local AS number 2000 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxR 10.1.1.1 4 1000 0 0 0 0 0 never Active As we can see at the moment it is in Active state, meaning its actively looking for neighbor which is not present. The reason is that we have not configured R3 or its neighbor. So lets configure R3 R3: R3(config)#router bgp 1000 R3(config-router)#neighbor 10.1.1.2 remote-as 2000 Now lets confirm that the relationship has started.

4. CCNP Network Route BGP Part -II R3(config)#do show ip bgp summary BGP router identifier 192.168.10.3, local AS number 1000 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/Pf 10.1.1.2 4 2000 5 5 1 0 0 00:01:12 0 We can see that the state has changed from Active to a number “0” and Up/Down timer has started. Now to reach to loop back of R4 from R3: We add a static route to R3 and R4 as below: R3: R3(config)#ip route 4.4.4.0 255.255.255.0 10.1.1.2 R4: R4(config)#ip route 3.3.3.0 255.255.255.0 10.1.1.1

5. CCNP Network Route BGP Part -II Now Ping to Confirm: R4#ping 3.3.3.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/90/192 ms Wonderful working !! Now on R3: R3(config-router)#neighbor 4.4.4.4 remote-as 2000 R3(config-router)#neighbor 4.4.4.4 update-source loopback 0 R3(config-router)#neighbor 4.4.4.4 ebgp-multihop 2

6. CCNP Network Route BGP Part -II R4: R4(config-router)#neighbor 3.3.3.3 remote-as 1000 R4(config-router)#neighbor 3.3.3.3 update-source loopback 0 R4(config-router)#neighbor 3.3.3.3 ebgp-multihop 2 Note: ebgp-multihop means that loopback address is 2 hops away, if we don’t write it then the TTL value will fail and so does our reachability. Now we confirm our settings. R4#show ip bgp summary BGP router identifier 10.1.1.2, local AS number 2000 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 3.3.3.3 4 1000 4 4 1 0 0 00:00:20 0 10.1.1.1 4 1000 30 30 1 0 0 00:26:12 0 All working fine and neighbor relation is formed.

7. CCNP Network Route BGP Part -II Now if we look at the routes we can see that there is no BGP R4#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 3.0.0.0/24 is subnetted, 1 subnets S 3.3.3.0 [1/0] via 10.1.1.1 4.0.0.0/32 is subnetted, 1 subnets C 4.4.4.4 is directly connected, Loopback0 10.0.0.0/24 is subnetted, 1 subnets C 10.1.1.0 is directly connected, Serial0/0

8. CCNP Network Route BGP Part -II To solve this routing issue we issue command redistribute connected as below on both routers R4 and R3: R4: R4(config)#router bgp 2000 R4(config-router)#redistribute connected Now if we look at BGP R4#show ip bgp BGP table version is 3, local router ID is 10.1.1.2 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 *> 4.4.4.4/32 0.0.0.0 0 32768 ? *> 10.1.1.0/24 0.0.0.0 0 32768 ?

9. CCNP Network Route BGP Part -II *> means the best routes. Now If we look at our routes R3#show ip route Gateway of last resort is not set 3.0.0.0/32 is subnetted, 1 subnets C 3.3.3.3 is directly connected, Loopback0 4.0.0.0/8 is variably subnetted, 2 subnets, 2 masks B 4.4.4.4/32 [20/0] via 4.4.4.4, 00:00:20 S 4.4.4.0/24 [1/0] via 10.1.1.2 C 192.168.10.0/24 is directly connected, FastEthernet0/0 10.0.0.0/24 is subnetted, 1 subnets C 10.1.1.0 is directly connected, Serial0/0 Hurrah !! We can see a “B” which is BGP

10. CCNP Network Route BGP Part -II Now we need to repeat the same step on R3 R3: R3(config)#router bgp 1000 R3(config-router)#redistribute connected Now when we check ip routes on R4 it will show as below R4#show ip route Gateway of last resort is not set 3.0.0.0/8 is variably subnetted, 2 subnets, 2 masks B 3.3.3.3/32 [20/0] via 10.1.1.1, 00:00:02 S 3.3.3.0/24 [1/0] via 10.1.1.1 4.0.0.0/32 is subnetted, 1 subnets C 4.4.4.4 is directly connected, Loopback0 B 192.168.10.0/24 [20/0] via 10.1.1.1, 00:00:02 10.0.0.0/24 is subnetted, 1 subnets C 10.1.1.0 is directly connected, Serial0/0

11. CCNP Network Route BGP Part -II Everything working and BGP is now active. Next we will configure R1 and R2 but we will cover it in Part- III Thanks, Salman Aftab www.itpings.com Linuxworld.co