Abstract-The paper deals with the data transmission network of the Krasnoyarsk Railway, its structure, the topology of data transmission and the routing protocol, which supports its operation, as well as the specifics of data transmission networking. The combination of the railway automation applications and the data transmission network make up the automation systems, making it possible to improve performance, increase the freight traffic volume, and improve the quality of passenger service. The objective of this paper is to study the existing data transmission network of the Krasnoyarsk Railway and to develop ways of its modernization, in order to improve the reliability of the network and the automated systems that use this network. It was found that the IS-IS and OSPF routing protocols have many differences, primarily due to the fact that the IS-IS protocol does not use IP addresses as paths. On the one hand, it makes it possible to use the IS-IS protocol for the operation in IPv6 networks, whereas OSPF version 2 doesn't provide this opportunity; therefore, OSPF version 3 was developed to solve this problem. However, on the other hand, in case of using IPv4, the routing configuration by means of the IS-IS protocol will imply the need to study a significant volume of information and use unusual methods of routing configuration.