Hello Sims
If you use the show ip bgp command you will see that it includes an origin code. Cisco states the following:
This is the origin of the entry. The origin code is placed at the end of each line in the table. It can be one of the following values:
a—Path is selected as an additional path.
i—Entry originated from an Interior Gateway Protocol (IGP) and was advertised with a network router configuration command.
e—Entry originated from an Exterior Gateway Protocol (EGP).
?—Origin of the path is not clear. Usually, this is a router that is redistributed into BGP from an IGP.
Now if you use the show ip bgp <network> command where network is a particular IP address, you will be able to see more information about the origin. For example, this output from the lesson:
R2#show ip bgp 1.1.1.1
BGP routing table entry for 1.1.1.0/24, version 2
Paths: (1 available, best #1, table default)
Not advertised to any peer
1
192.168.12.1 from 192.168.12.1 (192.168.12.1)
Origin IGP, metric 0, localpref 100, valid, external, best
It shows that the origin is IGP, and it states the IP address of the router from which it was learned (192.168.12.1).
I hope this has been helpful!
Laz