More confusion on my part, help also appreciated. BSCN (Paquet/Teare), p. 254: "When the router dynamically discovers a new neighbor, it sends an update about the routes that it knows to its new neighbor and receives the same table from the new neighbor. *The topology table contains all destinations advertised by the neighboring routers.* The show ip eigrp topology all-links command displays all the IP entries in the topology table. The show ip eigrp topology command displays only the successor and feasible successor for IP routes." http://www.cisco.com/cpress/cc/td/cpress/fund/ith2nd/it2436.htm#xtocid224866 : "The topology table contains all destinations advertised by neighboring routers. The protocol-dependent modules populate the table, and the table is acted on by the DUAL finite-state machine. Each entry in the topology table includes the destination address and a list of neighbors that have advertised the destination." My summary: 1. Neighbors send the destinations and metrics from their routing tables, minus anything that would violate split horizon. 2. Information from neighbors goes into topology table. 3. Using all the raw material in the topology table, DUAL calculates the metrics for all the possible routes for a given destination, decides what the successor(s) and feasible successor(s) are, and puts the successor(s) in the routing table. BSCN Book, p. 256: "EIGRP selects primary and backup routes and injects those routes into the topology table (up to 6 per destination)." Aren't they already there? What, exactly does "injects" mean? I could understand it "marking" these routes as primary and backup, i.e. successor and feasible successor. But, "injects?" BSCN Book, p. 258: "DUAL is the finite-state machine that selects which information will be stored ***in the topology table***. As such, DUAL embodies the decision process for all route computations. It tracks all routes advertised by all neighbors. DUAL uses the distance information, known as a metric, to select an efficient, loop-free path to each destination and inserts that choice in the routing table." Shouldn't the part between the *** read, "... in the *routing* table?" My confusion boils down to 3 different ways of asking the same question: 1) Is the topology table a complete list of information received from the EIGRP neighbors, as the Cisco web link says, or is it a subset of this information chosen by DUAL, as the BSCN book seems to say? 2) Does DUAL "inject" successor and feasible successor information INTO the topology table, or simply mark/choose routes that are already there after it calculates its metrics for them? 3) Does DUAL decide "which information will be stored in the topology table," or not? Thanks in advance, doctorcisco the confused _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=4377&t=4377 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
