Abstract: A communication network in an underground system comprises a ring network computers which is connected to an aboveground central system computer unit, each computer having an overview of the overall structure of the ring network and an allocated network status. Plural network computers are configured to, in the event of a connection interruption between networked nodes, seek an alternative communication path in order to maintain the communications. Plural network computers are coupled to at least one sensor in order to pick up information relating to the environment and are configured to pass it on to other network computers of the ring network and/or to the aboveground central system. In normal operation, the network computers pass on current information relating to the environment to the aboveground central system and to other network computers.