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ISO Networking Model made easy

Post office and the ISO Model

7 - Application

Your Message: Dear Mom

6 - Presentation

Spelling, Punctuation, Grammar

5 - Session

Name, Date, Stamp

4 - Transport


3 - Network

Postal/Zip Code

2 - Data Link

Street Address

1 - Physical

Mailman,Trucks, Airplanes, Leather Bag

(C) this is from a 1991 Novell training manual

Common unofficial extensions are for layers 8, 9, 10 and possibly higher that are best described as Religion/Faith, Politics, and Price. Unfortunately these extensions are not the clearest to deal with, but understanding that they are usually present in some form can help reduce the chance that they blind side you.