Outline

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Module 5: Layer 3 Troubleshooting

Module Overview |

5.1

Troubleshooting Network Layer Problems

5.1.1 | What are network layer problems?
5.1.2 | Isolating the problem methodology
5.1.3 | Static routes, dynamic routing, summarization, redistribution, and combinations

5.2

Troubleshooting Static Routes

5.2.1 | Static routes and classful lookups
5.2.2 | Static routes and intermediate addresses
5.2.3 | Static routes optimization with serial networks
5.2.4 | Static routes optimization with Ethernet networks
5.2.5 | Recurring static route installation and deletion
5.2.6 | Using discard routes

5.3

Common IGP Routing Protocol Issues, Causes, and Solutions

5.3.1 | Introduction
5.3.2 | Missing or incorrect network or neighbor statement
5.3.3 | Layer 1 or 2 down
5.3.4 | Distribute-list in/out blocking
5.3.5 | Access list blocking
5.3.6 | Advertised network interface is down
5.3.7 | Passive interface

5.4

Troubleshooting RIP

5.4.1 | Incompatible RIP version types
5.4.2 | Mismatched authentication key
5.4.3 | Reaches RIP hop count limit
5.4.4 | Discontiguous networks
5.4.5 | Invalid source address
5.4.6 | Flapping routes
5.4.7 | Large routing tables

5.5

Troubleshooting IGRP

5.5.1 | Discontiguous networks
5.5.2 | AS mismatch
5.5.3 | Misconfigured neighbor statement
5.5.4 | Maximum paths
5.5.5 | Candidate default

5.6

Troubleshooting EIGRP

5.6.1 | Mismatched K values
5.6.2 | Mismatched AS number
5.6.3 | Stuck in active – determining the problem
5.6.4 | Stuck in active – methodology for troubleshooting
5.6.5 | Stuck in active – the ultimate solution
5.6.6 | Duplicate router IDs
5.6.7 | EIGRP error messages

5.7

Troubleshooting OSPF

5.7.1 | Mismatched parameters
5.7.2 | OSPF state issues
5.7.3 | One side of point-to-point link is unnumbered
5.7.4 | ABR not generating Type 4 summary LSA
5.7.5 | Forwarding address is not known through the intra-area or interarea route
5.7.6 | Route summarization problems
5.7.7 | CPUHOG problems
5.7.8 | SPF calculation and route flapping

5.8

Troubleshooting IS-IS

5.8.1 | IS-IS adjacency problems
5.8.2 | Some or all of the adjacencies are not coming up
5.8.3 | Adjacency is stuck in INIT state
5.8.4 | ES-IS adjacency instead of IS-IS adjacency formed
5.8.5 | Route advertisement problems
5.8.6 | Route flapping problem

5.9

Troubleshooting BGP

5.9.1 | Troubleshooting BGP neighbor relationships
5.9.2 | Troubleshooting BGP route advertisements
5.9.3 | Troubleshooting routes not being installed in the IP routing table
5.9.4 | The BGP next hop is not reachable
5.9.5 | BGP routes getting dampened
5.9.6 | Troubleshooting outbound and inbound BGP policy issues
5.9.7 | Traffic takes a different interface than what is shown in routing table

5.10

Troubleshooting Redistribution

5.10.1 | Redistribution problems with RIP
5.10.2 | Redistribution problems with IGRP/EIGRP
5.10.3 | Redistribution problems with OSPF
5.10.4 | Redistribution problems with IS-IS
5.10.5 | Redistribution problems with BGP

Module Summary |
Module Quiz |

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