Module : Layer 3 Troubleshooting
Module Overview
Troubleshooting Network Layer Problems
What are network layer problems?
Isolating the problem methodology
Static routes, dynamic routing, summarization, redistribution, and combinations
Troubleshooting Static Routes
Static routes and classful lookups
Static routes and intermediate addresses
Static routes optimization with serial networks
Static routes optimization with Ethernet networks
Recurring static route installation and deletion
Using discard routes
Common IGP Routing Protocol Issues, Causes, and Solutions
Introduction
Missing or incorrect network or neighbor statement
Layer 1 or 2 down
Distribute-list in/out blocking
Access list blocking
Advertised network interface is down
Passive interface
Troubleshooting RIP
Incompatible RIP version types
Mismatched authentication key
Reaches RIP hop count limit
Discontiguous networks
Flapping routes
Large routing tables
Troubleshooting EIGRP
Mismatched K values
Mismatched AS number
Stuck in active – determining the problem
Stuck in active – methodology for troubleshooting
Stuck in active – the ultimate solution
Duplicate router IDs
EIGRP error messages
Troubleshooting OSPF
Mismatched parameters
OSPF state issues
One side of point-to-point link is unnumbered
ABR not generating Type 4 summary LSA
Forwarding address is not known through the intra-area or inter-area route
Route summarization problems
CPUHOG problems
SPF calculation and route flapping
Troubleshooting IS-IS
IS-IS adjacency problems
Some or all of the adjacencies are not coming up
Adjacency is stuck in INIT state
ES-IS adjacency instead of IS-IS adjacency formed
Route advertisement problems
Route flapping problem
Troubleshooting BGP
Troubleshooting BGP neighbor relationships
Troubleshooting BGP route advertisements
Troubleshooting routes not being installed in the IP routing table
The BGP next hop is not reachable
BGP routes getting dampened
Troubleshooting outbound and inbound BGP policy issues
Traffic takes a different interface than what is shown in routing table
Troubleshooting Redistribution
Redistribution problem with RIP
Redistribution problems with EIGRP
Redistribution problems with OSPF
Redistribution problems with IS-IS
Redistribution problems with BGP
Module: Summary
Module: Quiz



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