EIGRP, or Enhanced Interior Gateway Routing Protocol, is a Cisco proprietary routing protocol used in computer networks, particularly in IP networks. It is designed to support multiple network layer protocols and facilitate efficient routing within a network. EIGRP operates within a single autonomous system (AS), allowing routers within the same AS to dynamically share routing information. Unlike distance vector protocols, EIGRP uses a diffusing update algorithm (DUAL) to calculate the shortest path to a destination, considering both the minimum hop count and network link metrics such as bandwidth and delay. This enables faster convergence and more efficient use of network resources compared to traditional routing protocols.
EIGRP is used primarily in enterprise networks to provide scalable and efficient routing. It offers advantages such as rapid convergence, reduced bandwidth consumption through incremental updates, and support for multiple routed protocols like IP and IPX. EIGRP’s use of DUAL ensures that routers can quickly adapt to changes in network topology, making it suitable for networks where reliability and speed are critical requirements. Additionally, EIGRP supports features like unequal cost load balancing, route summarization, and authentication, enhancing network security and performance.
There are two types of EIGRP: Classic EIGRP and Named EIGRP. Classic EIGRP, also known as Autonomous System Border Router (ASBR) EIGRP, uses autonomous system numbers and is the original version of the protocol. Named EIGRP, introduced in later versions of Cisco IOS, simplifies configuration by allowing routers to be grouped under a named instance of EIGRP rather than using numeric AS numbers. Named EIGRP retains all the capabilities of Classic EIGRP but offers enhanced configuration flexibility and ease of management in large-scale networks. Both types of EIGRP operate on the same underlying principles but differ in how they are configured and managed within a network environment.
