EIGRP stores routing-related information in three tables, each dedicated to the organization and storage of network data. These tables are as follows:
Neighbor Table Neighbor relationships are tracked in this table and provide the basis for all of EIGRP's routing update and convergence activities.
Routing Table This contains least-cost routes that DUAL calculated for all known destinations. EIGRP tracks up to six routes to each destination.
Topology Table This stores all information needed to calculate a set of distances and vectors to all known and reachable destinations. This information includes the following:
Topology table entries are in one of two states:
Active A route currently being recomputed; the process of recalculating routes in search of new successors. This process is time- and resource-intensive. DUAL is designed to use any and all available feasible successors before recomputing routes. Recomputing will occur only when there are no successors, feasible or otherwise, to a route.
Passive A route currently stable and available for use.
Technical Note: Cisco IOS CommandIf upon executing the show ip eigrp topology all command several routes continue to appear to be in ACTIVE states, this in an indication of an unstable network and should be investigated immediately. |