In this new approach, the authors consider the data network as a channel with several layers. The suggested 'global' approach to coding in a network is consequently connected with other network procedures, such as protocols, and this determines complexity and originality of the problems of coding within the network. The authors distinguish different coding processes at 3 network layers and investigate the impact of coding from one layer to another. Thus the problem of reconciliation of coding of different network layers arises and the authors suggest enlightening solutions to this problem. The book consists of two parts - Part 1 is mainly devoted to a review of coding theory and its applications. This part differs from the traditional monographs available on coding theory, as it focuses on nonbinary codes and the correction of special configurations of errors, dictated by a class of problems. Part 2 discusses how to solve the problems raised in part 1 and is the main focus of the book. It shows how, with the help of coding which adds redundant packets to the message, it is possible to decrease the mean time of message delivery and increase the probability of not exceeding the acceptable delay limit. Methods of construction of a model of the discrete data channel and choice of the code for the data channel are presented.