Learning points:

• Update-source  – BGP updates will be redirected to the any interface, e.g. Loopback

• ebgp-multihop – Extend the TTL for External BGP (default value is 1).

 
  
 R1:

R1#sh run | inc ip route
ip route 20.20.20.20 255.255.255.255 192.168.12.2

R1#sh run | sec bgp
router bgp 10
 bgp log-neighbor-changes
 network 11.11.11.11 mask 255.255.255.255  <<< Advertise a new Loopback
 neighbor 20.20.20.20 remote-as 20
 neighbor 20.20.20.20 ebgp-multihop 5
 neighbor 20.20.20.20 update-source Loopback1

R2:

R2#sh run | inc ip route
ip route 10.10.10.10 255.255.255.255 192.168.12.1

R2#sh run | sec bgp
router bgp 20
 bgp log-neighbor-changes
 neighbor 10.10.10.10 remote-as 10
 neighbor 10.10.10.10 ebgp-multihop 5  <<< Extended the TTL values from 1 to 5
  neighbor 10.10.10.10 update-source Loopback2
 

 BGP Peering is established:

 R1#sh ip bgp sum
R1#sh ip bgp summary
BGP router identifier 10.10.10.10, local AS number 10
BGP table version is 1, main routing table version 1

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
20.20.20.20     4           20      12      12        1    0    0 00:07:23        0

  Routing Table on R2:




R2#show ip route bgp
!
Gateway of last resort is not set

      11.0.0.0/32 is subnetted, 1 subnets
B        11.11.11.11 [20/0] via 10.10.10.10, 00:02:30BGP database:

 R2#show ip bgp
BGP table version is 7, local router ID is 20.20.20.20
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
              x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *>  11.11.11.11/32   10.10.10.10              0             0 10 i
 *>  20.20.20.20/32   0.0.0.0                  0         32768 i

********************END OF LAB*********************************************