Objectives

4.6 Given a scenario, implement the following network troubleshooting methodology

• Information gathering—identify symptoms and problems

• Identify the affected areas of the network

• Determine if anything has changed

• Establish the most probable cause

• Determine if escalation is necessary

• Create an action plan and solution identifying potential effects

• Implement and test the solution

• Identify the results and effects of the solution

• Document the solution and the entire process

4.7 Given a scenario, troubleshoot common connectivity issues and select an appropriate solution

• Physical issues:

  • Cross talk

  • Near End crosstalk

  • Attenuation

  • Collisions

  • Shorts

  • Open impedance mismatch (echo)

  • Interference

• Logical issues:

  • Port speed

  • Port duplex mismatch

  • Incorrect VLAN

  • Incorrect IP address

  • Wrong gateway

  • Wrong DNS

  • Wrong subnet mask

• Issues that should be identified but escalated:

  • Switching loop

  • Routing loop

  • Route problems

  • Proxy ARP

  • Broadcast storms

• Wireless Issues:

  • Interference (bleed, environmental factors)

  • Incorrect encryption

  • Incorrect channel

  • Incorrect frequency

  • ESSID mismatch

  • Standard mismatch (802.11 a/b/g/n)

  • Distance

  • Bounce

  • Incorrect antenna placement

What You Need to Know

• Use troubleshooting steps to isolate and correct a problem.

• Identify and troubleshoot topology-specific errors.

• Use troubleshooting techniques to identify and isolate client connectivity errors.

• Use troubleshooting techniques to identify and isolate network wiring/infrastructure problems.