because it contains features that are usually seen in link-state and distance-vector protocols.
protocols is updates. EIGRP does not send updates at regular intervals in the same fashion as
IGRP and RIP. Not doing regular updates saves bandwidth and CPU resources. EIGRP uses
link-state features to determine neighbor reachability. The convergence properties for EIGRP
are better than IGRP. EIGRP provides compatibility and seamless interoperation with IGRP
routers. EIGRP sends partial updates instead of the entire routing table. Updates are sent only
to the neighbors that need it. EIGRP sends updates only when the network topology changes.
EIGRP can be enabled without disruption to IGRP performance. An automatic redistribution
mechanism allows IGRP and EIGRP to be imported and exported seamlessly. IGRP routes take
precedence over EIGRP routes by default. This can be changed with a configuration command
that does not require the routing processes to restart.
must also discover when their neighbors become unreachable or inoperative. This process is
achieved with low overhead by periodically sending small hello packets. As long as hello
packets are received, a router can determine that a neighbor is alive and functioning. As soon
as this is determined, the neighboring routers can exchange routing information.
discovered, the neighbor's address and interface are recorded. This information is stored in the
neighbor data structure. The router keeps a local routing table and an active routing table for each
neighbor. Knowing the neighbor's routing table allows EIGRP to make fast routing decisions.
to differentiate it from other routing technologies:
directly attached networks. In addition to knowing when a neighbor is functioning, a router
must also be able to determine when a neighbor is unreachable or unresponsive. Neighbor
discovery/recovery is achieved with low overhead by periodically sending small hello packets.
As long as hello packets are received, a router can determine that a neighbor is alive and
functioning. As soon as this status is determined, the neighboring routers can exchange
routing information.