EIGRP main features

EIGRP is based on IGRP created by Cisco and uses the Diffusion Update Algorithm(DUAL) which guarantees loop-free operation.

EIGRP stores data in three tables: Neigbor table, Topology table and Routing table.

Attributes
Type	Distance Vector
Internal AD	90
External AD	170
Summary AD	5
Protocols	IP, IPX, Appletalk
Transport	IP/88
Hello Timers	5/60
Hold Timers	15/180
Authentication	MD5
Multicast	224.0.0.10
Standards	Cisco proprietary
Algorithm	DUAL

Terminology
Reported Distance	The metric for a route advertised by a neighbor
Feasible Distance	The distance advertised by a neighbor plus the cost to get to that neighbor
Stuck in Active (SIA)	The condition when a route becomes unreachable and not all queries for it are answered; adjacencies with unresponsive neighbors are reset
Passive Interface	An interface which does not participate in EIGRP but whose network is advertised
Stub Router	A router which advertises only a subset of routes, and is omitted from the route query process

Packet Types
1	Update
3	Query
4	Reply
5	Hello
8	Acknowledge

Source PacketLife

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