When two computers owned by the same company or organization and are located close to each other to communicate, it is often easiest just to run a cable between them. LAN’s were in this way. However, when the distances are large or there are many computers or the cables would have to pass through a public road or other public places, the cost are usually very high. Consequently the network designers...

Data Link Layer has number of specific functions to carryout. These functions include:- Providing a well defined service interface to the Network Layer. Determining how the bits of the Physical Layer are grouped into frames. Dealing with transmission errors. Regulating the flow of frames so that slow receiver are not overcome by a fast sender.

This protocol also provides for one directional flow of data from sender to receiver. The communication channel is once again assumed to be error-free, as in protocol Unrestricted Simplex Protocol. However, in this case the receive has only a finite buffer capacity and a finite processing speed, so the protocol must explicitly prevent the sender from flooding the receiver with data faster than it can...

It is the simplest though unrealistic protocol with the nick name “UTOPIA“. In this case data is transmitted in one direction only. Both the transmitting and receiving Network Layer are always ready and the proceeding time can be ignored. An infinite buffer space is available and also communication between a Data Link Layer never damages or looses frames.

The design issues deals with how to make sure all frames are eventually delivered to the Network Layer at the destination and in the proper order. The usual way to ensure reliable delivery is to provide the sender with some feedback about whatever happening at the other end of the line. Typically the protocol calls of the receiver to send back special control frames bearing positive and negative acknowledgments...

A network contains a large number of computers and various intermediate devices. All these devices and computers must be joined so as to transfer data from one computer of network to any other computer. This can be possible by using two methods:- The first method is to create an individual wire link from every computer to every other computer (like fully connected topology) this method requires a lot...

Networks can be divided into two categories i.e. those using point-to-point connections and those using broadcast channels. Broadcast channels are sometimes referred to as multi-access channels or random access channels. The protocols used to determine who goes next on a multi-access channel belong to a sublayer of the data link layer called the MAC (Medium Access Control) sublayer. The MAC sublayer...

In order to provide services to the Network Layer, the Data Link Layer must use the service provided to it by the Physical Layer. What the Physical Layer does is, to accept a raw bit stream and attempt to deliver the data to the destination. The bit stream is not guaranteed to be error free. the numbers of bits received may be less than or equal to or more than number of bits were transmitted and they...

Common uses of internet are:- (i). Transfer of data (ii). Remote accessing (iii). E-mailing (iv). File sharing (v). Audio, Video and Graphics (vi). World Wide Web (vii). FTP (viii). Chat (ix). Telnet (x). Newsgroup

Transmission modes is the way data flows from the source to the destination. There are three modes of data transmission . Data can be transmitted in any one of them. These are as follows:- Simplex Mode Half-Duplex Mode Full-Duplex Mode