1. 1 CCNA 3 v3.1 Module 3 EIGRP Claes Larsen, CCAI

2. 222 Objectives

3. 333 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

4. 444 Using EIGRP with IGRP

5. 555 EIGRP and IGRP Metric Calculation

6. 666 Comparing show ip route for EIGRP and IGRP

7. 777 EIGRP Concepts The following three tables are maintained by EIGRP: Neighbor table Topology table Routing table

8. 888 The EIGRP Topology Table

9. 999 EIGRP Concepts Every EIGRP router maintains a topology table for each configured network protocol. All learned routes to a destination are maintained in the topology table.

10. 10 EIGRP Design Features

11. 11 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

12. 12 Data Structure The five EIGRP packet types are as follows:

13. 13 Default Hello Intervals and Hold Times for EIGRP

14. 14 EIGRP Successors and Feasible Successors

15. 15 Successor – Current Route 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. Feasible Successor - A backup route A feasible successor is a backup route. These routes are selected at the same time the successors are identified, but they are kept in the topology table. Multiple feasible successors for a destination can be retained in the topology table. Let’s see how this works! EIGRP Terminology and Operations

16. 16 Successors and Feasible Successors Feasible distance (FD) is the minimum distance (metric) along a path to a destination network. Reported distance (RD) is the distance (metric) towards a destination as advertised by an upstream neighbor. Reported distance is the distance reported in the queries, the replies and the updates. A neighbor meets the feasible condition(FC) if the reported distance by the neighbor is smaller than or equal to the current feasible distance (FD) of this router. "If a neighbors metric is less than mine, then I know the neighbor doesn't have a loop going through me." A feasible successor is a neighbor whose reported distance (RD) is less than the current feasible distance (FD). Feasible successor is one who meets the feasible condition (FC). Your route (metric) to the network (RD to me) must be LESS than my current route (my total metric) to that same network. If your route (metric) to the network (RD to me) is LESS than my current route (my total metric), I will include you as a FEASIBLE SUCCESSOR. If your route (metric) to the network (RD to me) is MORE than my current route (my total metric), I will NOT include you as a FEASIBLE SUCCESSOR. Successors and Feasible Successors

17. 17 Successors og Feasible Successors RTA kan nå netværk 24 på tre forskellige måder. Via RTX, RTY og RTZ

18. 18 Successors og Feasible Successors Advertised or Destination Feasible Dist. Reported. Dist. Nabo Netværk 24 40 30 RTX I Topolog Tabel Netværk 24 31 21 RTY I Routing Tabel Netværk 24 230 220 RTZ Ikke i Topologi Tabel

19. 19 Successors og Feasible Successors RTY er successor med en computed cost på 31. “31” er Feasible Distance (FD).

20. 20 Successors og Feasible Successors RTX er feasible successor fordi dens RD er mindre end eller lig med FD. - RTX’s RD (30) er mindre end RTA’s FD (31) via RTY.

21. 21 Successors og Feasible Successors Der er tre trin når der vælges Feasible successor: Bestem hvilken nabo der har en RD til net værket der er mindre end FD. Bestem den vej der har den mindste cost værdi på nær den der er valgt som successor. Vælg den vej som opfylder begge kriterier.

22. 22 Successors og Feasible Successors RTZ er ikke Feasible Successor, da RD220 ikke< FD31

23. 23 DUAL example

24. 24 DUAL example

25. 25 DUAL example

26. 26 DUAL example

27. 27 DUAL example

28. 28 DUAL example

29. 29 Configuring EIGRP

30. 30 EIGRP Automatically Summarizes Based on Class

31. 31 Manual Summarization with EIGRP

32. 32 Verifying EIGRP

33. 33 EIGRP debug Commands

34. 34 Building Neighbor Tables

35. 35 Discover Routes

36. 36 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.

37. 37 Troubleshooting Process 1.Analyze the 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.

38. 38 Use show Commands and TCP/IP Tools

39. 39 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.

40. 40 Troubleshooting IGRP Configuration

41. 41 Troubleshooting EIGRP Configuration

42. 42 Troubleshooting EIGRP Configuration

43. 43 Troubleshooting OSPF Configuration

44. 44 Summary