Enhanced IGRP (1)
Replaced its predecessor IGRP in early 1990s (by Cisco Systems)
Integrates capabilities of link-state protocol into distance-vector protocols
Incorporates Diffusing Update Algorithm (DUAL)
E-IGRP inter-operates with older IGPR routers and consumes less bandwidth than IGRP routers
E-IGRP supports
- partial updates ( no periodic updates; only for routers that need info; only when the metric for a route changes)
- multiple network layer protocols (IP, Appletalk, NetWare; for IP: implementation rebuilds routes learned from OSPF, RIP, IS-IS, EGP, BGP)
- variable-length subnet mask
- fast convergence (E-IGRP router stores all its neighboring tables)