1. Devices to communicate
2. Vendors to have more marketable products
3. Customers to insist on standards based equipment
The OSI is a reference model whilst TCP/IP is the suite which is the most widely used.
Description of Open Systems Interconnection (OSI Model)
Developed by the International Organization for Standardization (ISO)
It is made up of seven layers and each layer:
1. performs a subset of the required communication functions
2. relies on the next lower layer to perform more primitive functions
3. provides services to the next higher layer
4. Changes in one layer should not require changes in other layers
The layers can be summarized as overleaf:
Layer Functions Main features
1 Physical Concerned with transmission of unstructured bit stream over physical medium; deals with the mechanical, electrical, functional, and procedural characteristics to access the physical medium Physical interface between devices
1. Mechanical
2. Electrical
3. Functional
4. Procedural
2 Data link Provides for the reliable transfer of information across the physical link; sends blocks (frames) with the necessary synchronisation, error control and flow control Means of activating, maintaining and deactivating a reliable link
Error detection and control
Higher layers may assume error free transmission
3 Network Provides upper layers with independence from the data transmission and switching technologies used to connect systems; responsible for establishing, maintaining and terminating connections Transport of information
Higher layers do not need to know about underlying technology
Not needed on direct links
4 Transport Provides reliable, transparent transfer of data between end points; provides end-to-end error recovery and flow control. Exchange of data between end systems
Error free
In sequence
No losses
No duplicates
Quality of service
5 Session Provides the control
References: http://saraalgoe.hubpages.com/hub/TCPIP-network-access-and-internet-layers http://www.scribd.com/doc/14206202/Difference-Between-OSI-and-TCPIP-Models http://forums.techarena.in/technology-internet/1113879.htm