1 ccna 3 v3.1 module 3 eigrp claes larsen, ccai. 222 objectives
TRANSCRIPT
1
CCNA 3 v3.1 Module 3 EIGRP
Claes Larsen, CCAI
222
Objectives
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
444
Using EIGRP with IGRP
555
EIGRP and IGRP Metric Calculation
666
Comparing show ip route for EIGRP and IGRP
777
EIGRP Concepts
• The following three tables are maintained by EIGRP:
Neighbor table
Topology table
Routing table
888
The EIGRP Topology Table
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.
101010
EIGRP Design Features
111111
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
121212
Data Structure
The five EIGRP packet types are as follows:
131313
Default Hello Intervals and Hold Times for EIGRP
141414
EIGRP Successors and Feasible Successors
151515
• 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
161616
Successors and Feasible SuccessorsFeasible 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
171717
Successors og Feasible Successors
RTA kan nå netværk 24 på tre forskellige måder. Via RTX, RTY og RTZ
181818
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
191919
Successors og Feasible Successors
• RTY er successor med en computed cost på 31.• “31” er Feasible Distance (FD).
202020
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.
212121
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.
222222
Successors og Feasible Successors
• RTZ er ikke Feasible Successor, da RD220 ikke< FD31
232323
DUAL example
242424
DUAL example
252525
DUAL example
262626
DUAL example
272727
DUAL example
282828
DUAL example
292929
Configuring EIGRP
303030
EIGRP Automatically Summarizes Based on Class
313131
Manual Summarization with EIGRP
323232
Verifying EIGRP
333333
EIGRP debug Commands
343434
Building Neighbor Tables
353535
Discover Routes
363636
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.
373737
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.
383838
Use show Commands and TCP/IP Tools
393939
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.
404040
Troubleshooting IGRP Configuration
414141
Troubleshooting EIGRP Configuration
424242
Troubleshooting EIGRP Configuration
434343
Troubleshooting OSPF Configuration
444444
Summary