Content

| Overview

Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco-proprietary routing protocol based on IGRP. Unlike IGRP, which is a classful routing protocol, EIGRP supports CIDR, allowing network designers to maximize address space by using CIDR and VLSM. Compared to IGRP, EIGRP boasts faster convergence times, improved scalability, and superior handling of routing loops.

EIGRP has been described as a hybrid routing protocol offering the best of distance vector and link-state algorithms. Technically, EIGRP is an advanced distance vector routing protocol that relies on features commonly associated with link-state protocols. The best traits of OSPF, such as partial updates and neighbor discovery, are similarly used by EIGRP. However, some benefits of OSPF, especially its hierarchical design, come at the price of administrative complexity. Multiarea implementation of OSPF requires mastery of a complex terminology and command set. Yet, the advanced features of EIGRP can be easily implemented and maintained. Although it does not mirror the classic hierarchical design of OSPF, EIGRP is an ideal choice for large, multiprotocol networks build primarily on Cisco routers.

This module surveys the key concepts, technologies, and data structures of EIGRP. This conceptual overview is then followed by a study of EIGRP convergence and basic operation. Finally, this module shows how to configure and verify EIGRP and the use of route summarization.