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.
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