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5.3 | ![]() |
EIGRP Components | |
5.3.2 | ![]() |
EIGRP tables |
DUAL can select alternate routes based on the tables kept by EIGRP. By
building these tables, every EIGRP router can track all the routing
information in an AS, not just the best routes.
The following sections examine the neighbor table, the routing table, and the topology table in detail and provide an example of each. In addition, the various packet types used by EIGRP to build and maintain these tables will be investigated. The Neighbor Table The neighbor table contains information about adjacent neighboring EIGRP routers. Whenever a new neighbor is discovered, the address of that neighbor and the interface used to reach it are recorded in a new neighbor table entry. A neighbor table is used to support reliable, sequenced delivery of packets. One field in each row of the table includes the sequence number of the last packet received from that neighbor. EIGRP uses this field to acknowledge a neighbor's transmission and to identify packets that are out of sequence. An EIGRP neighbor table includes the following key elements:
Note that an EIGRP router can maintain multiple neighbor tables,
one for each PDM running, for example, IP, IPX, and AppleTalk.
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