Even though BGP works like any other routing protocol, it differs from them a lot. IGPs (Interior Gateway Protocols) such as RIP, OSPF, and EIGRP are enabled interface-wise. The network statement in the routing protocol configuration is used to mention a network IP address, and all interfaces' IP addresses that fall within the specific network range have a particular protocol enabled. On these enabled interfaces, these IGPs send out broadcast or multicast messages containing network route information. For this to work, two routers running IGPs have to be directly connected. The metrics used by IGPs to choose the best path are the number of hops, bandwidth, delay, and so on.

On the other hand, BGP doesn't have the concept of interfaces because the entire router is considered to be in the AS. Its neighbors are not automatically discovered and have to be mentioned statically with the neighbor command. After this, BGP messages are unicasted to TCP packets...