Method for transmitting messages in an industrial communication network which can be redundantly operated, in which - messages are transmitted in a first subnetwork with a tree topology in accordance with a spanning tree protocol, communication devices associated with network nodes of the first subnetwork interchanging messages containing topology information with one another in order to form a tree topology, and a root network node being determined as the basic element of a tree topology by the communication devices associated with the network nodes of the first subnetwork on the basis of the interchanged topology information, and loop-free connections being set up from the root network node to the remaining network nodes of the first subnetwork, - messages are transmitted in a second subnetwork in accordance with a parallel or ring redundancy protocol, - the first and second subnetworks (1, 2) are coupled to one another via a plurality of communication devices (101, 104, 105, 110, 202, 203, 205, 206), - 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, compare said messages with locally available topology information for the first subnetwork and determine resultant topology information for the first subnetwork on the basis of a comparison result, - the resultant topology information for the first subnetwork being consistently determined by all communication devices associated with the network nodes of the second subnetwork, - the communication devices associated with the network nodes of the second subnetwork use the determined resultant topology information for the first subnetwork to adapt their configuration with respect to closed and/or open connections to the first subnetwork, - the communication devices associated with the network nodes of the second subnetwork provide consistent resultant topology information for use of the spanning tree protocol in the first subnetwork. - messages are transmitted in a first subnetwork with a tree topology in accordance with a spanning tree protocol, communication devices associated with network nodes of the first subnetwork interchanging messages containing topology information with one another in order to form a tree topology, and a root network node being determined as the basic element of a tree topology by the communication devices associated with the network nodes of the first subnetwork on the basis of the interchanged topology information, and loop-free connections being set up from the root network node to the remaining network nodes of the first subnetwork, - messages are transmitted in a second subnetwork in accordance with a parallel or ring redundancy protocol, - the first and second subnetworks (1, 2) are coupled to one another via a plurality of communication devices (101, 104, 105, 110, 202, 203, 205, 206), - 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, compare said messages with locally available topology information for the first subnetwork and determine resultant topology information for the first subnetwork on the basis of a comparison result, - the resultant topology information for the first subnetwork being consistently determined by all communication devices associated with the network nodes of the second subnetwork, - the communication devices associated with the network nodes of the second subnetwork use the determined resultant topology information for the first subnetwork to adapt their configuration with respect to closed and/or open connections to the first subnetwork, - the communication devices associated with the network nodes of the second subnetwork provide consistent resultant topology information for use of the spanning tree protocol in the first subnetwork.