“Data Layers And Transport Protocols”

 

The Open System was developed by the International Organization for Standardization. The Open Systems Interconnection standard (OSI) was developed in 1977 as a model for computer communications architecture. It's become the most widely accepted model for understanding network communication. According to the OSI model, the following rules apply:

1. How do network devices communicate with one another if they have different languages?

2. How do devices on a network know when to transmit data and when not to?

3. How to make sure network transmissions get to the right people?

4. What's the arrangement and connection of the physical transmission media?

 The OSI model does not perform any functions in communication processes. The actual work is done with the appropriate software and hardware. The OSI model simply defines which task needs to be done and which protocols will handle those tasks at each of the seven layers.

The seven layers of the model are:

1. Physical

2. Data Link

3. Network

4. Transport

5. Session

6. Presentation

7. Application

 Protocols

A set of rules that govern the operation of functional units to achieve better communication.

Or

A protocol is an agreement between communication parties on how to proceed with communication.

1. There are many protocols and each protocol allows basic communication.

Example:

A certain protocol works at the physical layer. The protocol at that layer ensures data packets pass through the network adapter card and out onto the network cable.

Common protocol's name:

1. SMTP (Simple Mail Transfer Protocol).

2. TCP/IP (Transmission Control Protocol/ Internet Protocol)

3. FTP ( File Transfer Protocol)

4. HTTP (HyperText Transfer Protocol).

5. WAP (Wireless Access Protocol).

Objectives

1. Determine the primary function of each layer.

2. Identify the OSI layer at which a particular network activity takes place.

3. Describe protocols and their functions.