EIGRP routers keep route and topology
information readily available in RAM so they can react quickly to changes.
Like OSPF, EIGRP keeps this information in several tables, or databases.
The following terms are related to EIGRP and its tables and are used
throughout this chapter:
- Neighbor table - Each EIGRP router
maintains a neighbor table that lists adjacent routers. This table is
comparable to the adjacency database used by OSPF. There is a neighbor
table for each protocol that EIGRP supports.
- Topology table - Every EIGRP router
maintains a topology table for each configured network protocol. This
table includes route entries for all destinations that the router has
learned. All learned routes to a destination are maintained in the
topology table. Each EIGRP router maintains a topology table for each
network protocol
- Routing table - EIGRP chooses the
best routes to a destination from the topology table
and places these routes in the routing table. Each EIGRP router maintains
a routing table for each network protocol.
- Successor - A successor is a route
selected as the primary route to use to reach a destination. Successors
are the entries kept in the routing table. Multiple successors for a
destination can be retained in the routing table.
- Feasible successor - A feasible
successor is a backup route. These routes are selected at the same time
the successors are identified, but are kept in the topology table.
Multiple feasible successors for a destination can be retained in the
topology table.
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