ISO and OSI Network Model

ISO and OSI Model:

• ISO Developed a standard for data communication called Open System Interconnection.
• OSI has seven layers.

1. o  Physical Layer
2. o  Data Link Layer
3. o  Network Layer
4. o  Transport Layer
5. o  Session Layer
6. o  Presentation Layer
7. o  Application Layer

Physical Layer:

• This layer deals with system of bits.
• Collect data from upper layer and send it to required computer in the form of bits.
• RS-232 connector is used for data transmission.

Data Link Layer:

• Responsible for node-to-node delivery of message.
• Control the rate of flow of data.

Network Layer:

• It decides which path of data should send from one node to other.
• Switches, Routers and NIC Cards (Network interface card) decides the routing based on network conditions, priority of service and other factors.
• TCP/IP is very important protocol of this layer.

Transport Layer:

• Responsible for end-to-end delivery of entire message.
• If the link goes down then this layer send data into other link (Path).
• Arrangement of data in its order.
• Remove errors.
• Control rate of flow of data.

Session Layer:

• Establish a connection between two-application across network.
• Its function is performing

1. o  Security
2. o  Logging
3. o  Administration

Presentation Layer:

• This layer represents data in user understandable form.
• Techniques used are

1. o  Translation
2. o  Encryption
3. o  Compression

Application Layer:

• This layer serves the user.
• User can control it directly.
• It includes services such as o E-mail

1. o  File sharing
2. o  File printing and other software