A new campus network, called S-net, which is constructed in Shinshu University, is introduced. The configuration of S-net is duplicate ring topology, including rings in buildings and a backbone ring connecting each buildings. A backbone ring can have 32 rings with up to 32 node per ring. A new access control protocol for S-net, which is not susceptible to collisions, is proposed. Personal computers can be interfaced to S-net via terminal servers. When the attached nodes are widely dispersed, plural S-nets are effective which can be linked each other. The transmission rate of a backbone ring is 1Mbps, the rate of another rings is 76.8Kbps, and personal computers can translate data by 9.6Kbps.