Updates that have looped through the network and returned to the same node are easily detected and discarded.
In BGP, the autonomous system boundary routers (ASBR) send path-vector messages to advertise the reachability of networks.
It modifies the message to add its AS number and to replace the next router entry with its identification.
It has three phases: BGP is commonly referred to as an Exterior Gateway Protocol (EGP) given its role in connecting Autonomous Systems (AS).
This being said, BGP can be used within an AS, which typically occurs within very large organizations such as Facebook or Microsoft.