OSI vs TCP/IP model

Know And Understand The Fundamentals!

Video #1 jumps right into the theory of networking models. Here's nice diagram illustrating the differences between the two:

Here's how the OSI model works:

Application Layer (Layer 7)

1. Ensures remote communication parter is available
2. Required communication resources exist
3. Both ends agree on procedures involving data integrity, privacy and error recovery
4. Authentication also runs here at layer 7

Presentation Layer (Layer 6)

1. Compatibility with OS
2. Proper encapsulation of data for network transmission
3. Data formatting (binary, ascii)
4. Data encryption, compression and translation

Session Layer (Layer 5)

1. Handles creation, maintenance and teardown of communications between hosts

Transport Layer (Layer 4)

1. Establish end-to-end connection bewteen two systems
2. Segment data received from the upper layers
3. Make sure data gets to the destination in correct order and free of errors (error recovery)

Network Layer (Layer 3)

1. What valid paths exist from local router to given destination?
2. What is the best path to get there?

Data Link Layer (Layer 2)

1. Error detection
2. Switches run at this layer

Physical Layer (Layer 1)

1. Bits (ones and zeros)
2. Anything to do with cables, power, connectors, pins etc