Development of an Adaptive File Transfer Protocol (AFTP )


File is one of the main storing units of information. There is a great need to transferfile through computer network especially the internet. The model that is used inInternet is the TCP-IP. The TCP-IP model consists of four layers. The lowest layer isthe host network layer, the second layer is the internet layer (IP handling); while thethird layer is transport layer which contains TCP and UDP. The last layer is theapplication layer. This paper is concerned on the User Datagram Protocol (UDP). TheUDP is mainly used to transfer messages. It is asynchronous, connectionless andunreliable protocol. The UDP is not suited for transferring files because of the erroror loose that could prevent us from reconstruct the original file. In order to overcomethis problem new field and configuration is applied in the application layer forguarantee file sending and receiving. This field is the Cyclic Redundant Check (CRC)which is computed for each block of data and all these checks were sent over anotherport. At the end of receiving data the receiver checks the check matrix in order todetermine the error and requesting that block from the sender. The proposed protocolis implemented using the Winsock and Visual Basic programming language