What protocol does EIGRP primarily use for neighbor discovery and maintaining adjacency?

EIGRP, or Enhanced Interior Gateway Routing Protocol, primarily uses the User Datagram Protocol (UDP) for neighbor discovery and maintaining adjacency among routers in a network. This is significant because EIGRP employs multicast communications to send hello packets, which are essential for discovering and establishing neighbor relationships. Using UDP allows EIGRP to operate efficiently in an unreliable, connectionless environment, which is suitable for network discovery and updates since retransmission can be managed at the higher layers if needed.

UDP, being a lightweight protocol, reduces the overhead involved in establishing and maintaining connections, thus allowing EIGRP to react quickly to network changes by promptly sending routing updates. Compared to traditional TCP, which involves connection establishment and error recovery that can slow down processes, UDP's inherent simplicity and speed are advantageous for real-time protocol operations like those within EIGRP.

While the other protocols mentioned may have their specific uses in networking, they are not the ones EIGRP relies upon for the critical task of neighbor discovery and adjacency maintenance. TCP, for instance, is connection-oriented and not conducive to the requirements of a routing protocol needing quick updates. ICMP is primarily used for error reporting and diagnostics, and IP serves as the base-layer protocol for routing but does not directly facilitate the