Copyright 2003 Comparing EIGRP with IGRP Comparisons between EIGRP and IGRP fall into the following major categories: –Compatibility mode –Metric calculation –Hop count –Automatic protocol redistribution –Route tagging
Copyright 2003 EIGRP Technologies Neighbor discovery and recovery Reliable Transport Protocol DUAL finite-state machine algorithm Protocol-dependent modules By forming adjacencies, EIGRP routers: –Dynamically learn of new routes that join their network –Identify routers that become either unreachable or inoperable –Rediscover routers that had previously been unreachable
Copyright 2003 Data Structure The five EIGRP packet types are as follows: 1. Hello (used to discover, verify, and rediscover neighbor routers) 2. Acknowledgment 3. Update 4. Query 5.Reply
Copyright 2003 Select Routes If a link goes down, DUAL looks for an alternative route path, or feasible successor, in the topology table. If a feasible successor is not found, the route is flagged as Active, or unusable at present. Query packets are sent to neighboring routers requesting topology information. DUAL uses this information to recalculate successor and feasible successor routes to the destination.
Copyright 2003 Troubleshooting Process 1. When analyzing a network failure, make a clear problem statement. 2. Gather the facts needed to help isolate possible causes. 3. Consider possible problems based on the facts that have been gathered. 4. Create an action plan based on the remaining potential problems. 5. Implement the action plan, performing each step carefully while testing to see whether the symptom disappears. 6. Analyze the results to determine whether the problem has been resolved. If it has, the process is complete. 7. If the problem has not been resolved, create an action plan based on the next most likely problem in the list. Return to Step 4, change one variable at a time, and repeat the process until the problem is solved. 8. Once the actual cause of the problem is identified, try to solve it.
Copyright 2003 Troubleshooting RIP Configuration Layer 1 or Layer 2 connectivity issues exist. VLSM subnetting is configured. VLSM subnetting cannot be used with RIPv1 Mismatched RIPv1 and RIPv2 routing configurations exist. Network statements are missing or incorrectly assigned. The outgoing interface is down. The advertised network interface is down.