- Physical layer
- Data link layer
- Network layer
Wednesday, June 26, 2013
Without rules governing the exchange of data and establishment of connections between networks, there would have a big chaos in the industry. These rules are called line protocols and are very crucial for the inter-networking and communication across the networks.
The mode and the speed of communication are controlled by what are called the communications software packages. These network protocols are defined by the international standards. However, having international standards for the protocols has got both advantages and disadvantages.
- A number of standard network protocols for carrying out several functions such as routing, packetizing, and addressing and so on.
- All these protocols lay out a standard definition of how the routing and addressing has to be done.
- They also define the specifications for the structure of the packets to be transferred between different hosts.
- Some commonly used routing protocols are:
Ø IPX/ SPX
Ø TCP/ IP
- The OSI stands for open systems interconnection.
- Early networking systems had a big problem which was that there was a lack of consistency between the protocols employed by several types of different computers.
- As a consequence of this problem, the international standards came in to the picture.
- Thus, international standards were established for the various data transmission protocols.
- For example, OSI is a set of standard protocols developed by ISO (international standards organization).
- In this model, the functionalities of the network protocols have been divided in to seven layers of the communication rules or protocols.
- The purpose of this model is to identify the functions being offered by the system.
- The following three layers appear in the host systems and other units such as processor and control unit etc.:
- The leftover layers are found in the host systems only.
Advantages of having International Standards
Ø If all the systems are following the same standard, it becomes easy for everyone to connection to everyone else. In other words, the international standards provide easy interconnectivity.
Ø If any standard is widely used, it gains economies of scale. For example, VLSI chips etc.
Ø With all the systems using the same standard, the installation and the maintenance of the connections become quite easy.
Ø Software designed by the developers from all over the world, won’t have any problem in interfacing with the host system and the other software. They will work well with a wide range of operating systems and hardware since both are using the same standard.
Disadvantages of having International Standards
Ø Poor standards may be formed as a result of the frequent standardization.
Ø Once the standard is adopted internationally, it’ll be difficult to make changes to it. It will be difficult to introduce new and better techniques in to it.
Ø If a problem occurs, it has to be seen as an international problem.
Ø The manufacturers and companies will be bound to follow the same international standards and so they won’t be able to develop something better of their own.
Ø Large multinational companies won’t be able to pool everyone in to using their proprietary protocols and therefore no huge profits.
TCP/ IP protocol was developed to make communication easy between the dissimilar systems. A number of hardware and software vendors support this protocol ranging from mainframes to microcomputers. A number of corporations, universities and govt. agencies are making use of this protocol.