what is the difference betwwen the Routing table & the Topology table in EIGRP?
10xs for ur great info.
The EIGRP protocol builds a topology table based on the advertisements that it receives from neighbors. Everything that EIGRP learns goes into the topology table, whether it is a route that actually gets used (has the best metric) or a route with a worse metric that will not actually be used. EIGRP looks through the topology table to find the best route, based on the metric (bandwidth and delay by default). EIGRP then gives its best routes to the process that manages the routing table.
The routing table is maintained by a separate process and not by EIGRP, or OSPF, or BGP, or RIP or any of the routing protocols. The process receives information from each protocol about its best routes. When the protocol managing the routing table receives the same prefix from 2 different protocols then it uses administrative distance to decide which one to put into the routing table.
So the routing table is used to make forwarding decisions for IP packets. The routing table may contain information from multiple protocols. The EIGRP topology table is not used to make forwarding decisions for IP packets. It is used by EIGRP to accumulate information about all the prefixes advertised by any EIGRP neighbor and to identify the best routes that EIGRP has learned.