OSI Model
The Open System Interconnection (OSI) Model provides an abstract description of the network communication process. International Organization for Standard (ISO) develops it to provide a road map for non-proprietary protocol development. The OSI model is just a reference model and many of OSI protocols are no longer in use. There are seven layers in OSI Model. Those are as follows:
Layer 7 -
Application
Performs services for
the application used by the end users.
Layer 6 - Presentation
Provides data format
information to the application.
Layer 5 - Session
Manages session between
users.
Layer 4 - Transport
Defines data segments and
numbers them at the source, transfers the data, and reassembles the data at the
destination.
Layer 3 - Network
Creates and addresses packets for end-to-end
delivery through intermediary devices in other network.
Layer 2 - Data Link
Creates and addresses
frames for host-to-host delivery on the local LANs and between WAN devices.
Layer 1 - Physical
Transmits binary data over
media between devices. Physical layer protocols define media specifications.
TCP/IP Model
TCP / IP is an open standard. The rules and implementation of the TCP/IP model were cooperatively developed by members of the industry using Request for Comments (RFC) documents. There are four layers in TCP/IP Model. Those are as follows:
Layer 4 – Application
Represents application data to the user.
Layer 3 – Transport
Supports communication between devices and performs error correction.
Layer 2 – Internet
Finds the best path through the network.
Layer 1 – Network access
Controls hardware devices and media.
Comparison of OSI Model and TCP/IP Model
7 Application
|
Application
|
6 Presentation
|
|
5 Session
|
|
4 Transport
|
Transport
|
3 Network
|
Internet
|
2 Data Link
|
Network Access
|
1 Physical
|
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