EIGRP operates quite differently from IGRP. EIGRP is an advanced distance vector routing protocol and acts as a link-state protocol when updating neighbors and maintaining routing information. The advantages of EIGRP over simple distance vector protocols include the following:

• Rapid convergence
• Efficient use of bandwidth
• Support for variable-length subnet mask (VLSM) and classless interdomain routing (CIDR). Unlike IGRP, EIGRP offers full support for classless IP by exchanging subnet masks in routing updates.
• Multiple network-layer support
• Independence from routed protocols. Protocol-dependent modules (PDMs) protect EIGRP from lengthy revision. Evolving routed protocols, such as IP, may require a new protocol module but not necessarily a reworking of EIGRP itself.

EIGRP routers converge quickly because they rely on DUAL. DUAL guarantees loop-free operation at every instant throughout a route computation allowing all routers involved in a topology change to synchronize at the same time.

EIGRP makes efficient use of bandwidth by sending partial, bounded updates and its minimal consumption of bandwidth when the network is stable. EIGRP routers make partial, incremental updates rather than sending their complete tables. This is similar to OSPF operation, but unlike OSPF routers, EIGRP routers send these partial updates only to the routers that need the information, not to all routers in an area. For this reason, they are called bounded updates. Instead of using timed routing updates, EIGRP routers keep in touch with each other using small hello packets. Though exchanged regularly, hello packets do not use up a significant amount of bandwidth.

EIGRP supports IP, IPX, and AppleTalk through protocol-dependent modules (PDMs). EIGRP can redistribute IPX RIP and SAP information to improve overall performance. In effect, EIGRP can take over for these two protocols. An EIGRP router will receive routing and service updates, updating other routers only when changes in the SAP or routing tables occur. Routing updates occur as they would in any EIGRP network, using partial updates.

EIGRP can also take over for the AppleTalk Routing Table Maintenance Protocol (RTMP). As a distance vector routing protocol, RTMP relies on periodic and complete exchanges of routing information. To reduce overhead, EIGRP redistributes AppleTalk routing information using event-driven updates. EIGRP also uses a configurable composite metric to determine the best route to an AppleTalk network. RTMP uses hop count, which can result in suboptimal routing. AppleTalk clients expect RTMP information from local routers, so EIGRP for AppleTalk should be run only on a clientless network, such as a wide-area network (WAN) link.