A method for transmitting messages in a redundantly operable communication network which includes a first subnetwork with a tree topology and a second subnetwork, wherein messages are transmitted in the first subnetwork in accordance with a spanning tree protocol. Here, communication devices associated with network nodes of the first subnetwork interchange messages containing topology information with one another to form a tree topology, messages are transmitted in the second subnetwork in accordance with a parallel or ring redundancy protocol, communication devices associated with network nodes of the second subnetwork interchange messages containing topology information for the first subnetwork with one another in accordance with the parallel or ring redundancy protocol and compare the messages with locally available topology information for the first subnetwork, and communication devices associated with network nodes of the second subnetwork determine resultant topology information for the first subnetwork based on a comparison result.