NET4009-Module_9-_Troubleshooting_IS-ISver3

What show command displays IS-IS protocol information

show isis protocol

What show command enables you to verify the configuration of an active CLNS interface?

show clns interface

What show command enables you to verify the status of adjacencies?

show isis neighbor [detail]

What show command enables you to check for the presence of all expected LSPs?

show isis database

What show command displays a list of all connected routers in all areas?

show isis topoogy

What command is used to help debug is-is adjacency problems?

debug isis adj-packets

What command can be used to troubleshoot missing IS-IS routes?

debug isis update-packets

What are six common IS-IS neighbor adjacency issues?

1. Mismatched Level 1 and Level 2 intercaces

2. Duplicate system IDs

3. Mismatached MTUs

4. Misconfigured IP addresses and subnets

5. Misconfigured Authentication

6. Link failure

What are a few common causes for IS-IS missing routes?

1. Interface is not advertised in IS-IS

2. Discontinuous Level 2 Subdomains

3. LSP corruption storm

How does an IS-IS router advertise routeing information to the rest of the network?

1. Route is a subnet connected to the router, and the interface is enabled for IS-IS

2. Passive Interface

3. External routes by means of redistribution from another routing source

4. Route summarization

What is the IS-IS level 1 domain similar to in OSPF?

OSPF Totally Not So Stubby Area (Totally NSSA), since it doesn’t allow any exernal or summary information but allows redistribution

What command is required on an interface to advertise into IS-IS?

ip router isis

How to fix a LSP corruption storm?

router level command “ignore-lsp-errors”

How to troubleshoot discontinuous level 2 subdomains?

Areas have to be connected through level 2 connections, if there is a level 1 router in the way then it will not be able to communicate to the other areas, resulting in a discontinuous network