NETWORK

1. EIGRP
ENHANCED INTERIOR GATWAY PROTOCOL
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2. OBJECTIVES:
 Describe the background and history of Enhanced Interior
Gateway Routing Protocol (EIGRP).
 Define EIGRP Terminology.
 explain control packets in EIGRP
 Calculate the composite metric used by EIGRP.
 Describe the concepts and operation of DUAL.
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3. EIGRP
 It is an enhancement of IGRP.
 Hybrid routing protocol (distance vector + link-state)
 Developed in 1985 to overcome RIPv1’s limited hop count.
 Was an cisco proprietary routing protocol till 2013, now open standard.
 Classless protocol.
 Symbol in routing table is ‘D’.
 Administrative distance = 90.
 Fast convergence : use DUAL.
 METRIC is determined by (B.W, delay, load, and reliability).
 Max hop count = 224.
 Support multiple network layer protocol ( IP, IPX, AppleTalk).
 Uses multicast address 224.0.0.10
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4. EIGRP TERMINOLOGY
 Neighbor table:-
table contain all neighbors.
 Topology table:-
table contain all routes to all networks.
 Routing table:-
table contain the best route to all networks.
 Successor:-
best route.
 Feasible successor:-
backup for best route.
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5. control packets in EIGRP
 Hello packet:–
used to discover & form adjacencies with neighbors, UDP, Multicast.
 Query packet:-
ask neighbors about routing information, TCP, Unicast/ Multicast.
 Update packet:-
send routing update, TCP, Unicast/ Multicast.
 Reply packet:-
respond to the query packet, TCP, Unicast.
 Acknowledgment packet:-
used to acknowledge receipt of update, query & reply packets , UDP,
Unicast.
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6. METRIC
 Composite metric
 metric = [ K1 * bandwidth + (K2 * bandwidth)/256 - load) + K3 * delay] * [
K5/(reliability + K4)]
 It don’t consider single criteria to calculate the metric but uses numbers
of criteria which includes bandwidth, load, delay, reliability, and maximum
transfer unit (MTU).
 K value for B.W and delay by default equal to 1, and other values of k is
zero.
 metric = [ K1 * bandwidth + K3 * delay]
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7. DIFFUSION UPDATE ALGORITHM(DUAL)
 This algorithm stores neighbor’s routing information in a local
topology table.
 If a primary route in the routing table fails, Dual can take a backup
path from the topology table and place it in the routing table.
 If no backup route is found in the topology table, it will generate a
query packet sent to the neighbor.
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