Which protocol is preferred for larger networks requiring complex interconnections between various systems?

The preferred protocol for larger networks requiring complex interconnections is indeed BGP, or Border Gateway Protocol. This protocol is specifically designed to handle routing between autonomous systems (AS), which makes it ideal for the interconnected nature of the Internet and large-scale enterprise networks. BGP is capable of managing thousands of routes and can make routing decisions based on multiple attributes, allowing for greater flexibility and optimization according to the needs of the network.

Unlike distance-vector protocols such as RIP, which is limited in scalability and has a maximum hop count, and OSPF, which functions effectively within a single autonomous system but can become less efficient in very large setups, BGP focuses on inter-domain routing. This enables it to handle policy-based routing decisions, making it suitable for environments that require complex connectivity and routing policies.

EIGRP, while a hybrid protocol that provides faster convergence than traditional distance-vector protocols, is generally used within a single autonomous system and may not scale as well as BGP when it comes to routing across diverse networks. BGP’s design to maintain a robust and scalable routing infrastructure across varied and often large and complex networks is what makes it the preferred choice in scenarios that exceed the capabilities of the other listed routing protocols.