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Enhanced Interior Gateway Routing Protocol (EIGRP). Really just an enhanced version of IGRP A Cisco proprietary routing protocolCalled a hybrid protocol, but really just an advanced distance vector protocol.Fast convergenceVariable length subnet masksPartial updates - only when the metric for a route changesMultiple network layer support - IP, IPX, and AppleTalkA router running EIGRP stores all its neighbor's routing tables so that it can quickly adapt or alternate routes..
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1. Routing & EIGRP CCNA 3.0
3. EIGRP Concepts Every EIGRP router maintains a topology table for each configured network protocol.
All learned routes to a destination are maintained in the topology table.
5. IGRP & EIGRP They work together and routes are redistributed automatically
RTB(config)# router igrp 2446
RTB(config-router)#network 192.168.1.0
RTB(config)#router eigrp 2446
RTB(config-router)# network 10.1.1.0
RTB(config-router)# network 172.16.1.0
7. EIGRP Terminology
8. Improvements from IGRP Neighbor discovery & recovery
Use small hello packets to estab. adjacencies sent every 5 seconds
Dynamically learn routes that way
Reliable Transport Protocol (RTP)
A transport layer protocol that guarantees delivery order
EIGRP is protocol independent, so has its own guarantee (compare to TCP)
9. Improvements from IGRP Dual finite-state machine
An algorithm that EIGRP uses to calculate routes
Tracks all routes advertised by neighbors and uses a composite metric of each route to compare them
Protocol-dependent modules
Each module is responsible for all functions related to its specific routed protocol
In other words, there is an IP PDM, an IPX PDM, an AppleTalk PDM, etc.
10. Feasible Successors
11. EIGRP Design Features
12. EIGRP Technologies Neighbor discovery and recovery
Reliable Transport Protocol
DUAL finite-state machine algorithm
Protocol-dependent modules
By forming adjacencies, EIGRP routers:
Dynamically learn of new routes that join their network
Identify routers that become either unreachable or inoperable
Rediscover routers that had previously been unreachable
19. Select Routes If a link goes down, DUAL looks for an alternative route path, or feasible successor, in the topology table.
If a feasible successor is not found, the route is flagged as Active, or unusable at present.
Query packets are sent to neighboring routers requesting topology information.
DUAL uses this information to recalculate successor and feasible successor routes to the destination.
21. EIGRP Packet Types
22. Data Structures
24. EIGRP Routing Table
27. Verifying EIGRP
28. EIGRP debug Commands