Jon Rumsey
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Partner Power Hour - TShooting With the OSI Model
Speaker: Matt Raio
IT Operations, more or less, since 1997.
Worked at startup GNS3 (virtual networking software).
Summary Notes and Key Takeaways
OSI Model is conceptual.
7-layer model where each layer adds header information, so facilite communications.
Application - End user, software
Presentation - Encryption, decryption, and data arrangement
Session - Synchronization and Port addressing
Transport - TCP and other un/connected nodes
Network - Primary addressing layer
Data Link - Hardware addressing layer
Physical - Actual interfaces link network cards
Top-down troubleshooting approach:
- Start with application information including error messages
Bottom-up troubleshooting approach:
- Check the physical hardware, power, and physical connections
- Then look at switching and routing equipment
Divide and Conquer
- Pick-and-choose a layer that might be source of the problem
How well can you articulate the problem?
- Talking through the issue will help you to see the gaps in understanding of the problem
Try to select a tactic to resolve the problem.
- top-to-bottom
- bottom-to-top
Implement tests
- Will help find boundaries of the problem
- Will help confirm when the problem has the resolved
Review results
- A desired result might not be the full solution
- False Negative: Results come back, but not as anticipated
Tools for Troubleshooting
- Utilize tools that are proper for the environment the problem is in
- WiFi network? Access a wifi router or WAP logs for hints
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