Method for data transmission between a network and a mobile data transmission unit, - the network comprising at least one data processing unit such as a server (3, 4), - and the mobile data transmission unit comprising at least one data processing unit such as a client (15, 16), - the network having at least two access points (6, 7) and the mobile data transmission unit having at least two modules (10, 11) for wireless data link (8, 9) of the network and the mobile data transmission unit, - the mobile data transmission unit having a switching device that can switch between a plurality of switching states, - one module being active in each switching state, such that payload data (19, 22) can be transmitted by means of said active module, and all the other modules being passive, such that no payload data (19, 22) can be transmitted by means of said passive modules, - the active module switched into the active state transmitting at least one update message immediately after the switching between two switching states, - and the update message outputting said active module as the sender or recipient of payload data (19, 22) of at least one data processing unit of the mobile data transmission unit as at least one client (15, 16), - and each data processing unit of the network, each access point (6, 7), each active and passive module (10, 11) and each data processing unit of the mobile data transmission unit having its own address in the form of its own MAC address (a, b, c, d, e, f, g, h), characterised in that - as the source, the update message contains the MAC address (g, h) of at least one data processing unit of the mobile data transmission unit instead of the MAC address (e, f) of the active module, - the payload data (19, 22) being transmitted between the data processing units of the mobile data transmission unit and the switching device, and between the access points (6, 7) and the data processing units of the network in each case via a switching component (5, 14), in which a table stores which the destination is to be reached via which wireless data link (8, 9), - and in that the table of the switching component connected to the access points (6, 7) is updated after receipt of the update message. - the network comprising at least one data processing unit such as a server (3, 4), - and the mobile data transmission unit comprising at least one data processing unit such as a client (15, 16), - the network having at least two access points (6, 7) and the mobile data transmission unit having at least two modules (10, 11) for wireless data link (8, 9) of the network and the mobile data transmission unit, - the mobile data transmission unit having a switching device that can switch between a plurality of switching states, - one module being active in each switching state, such that payload data (19, 22) can be transmitted by means of said active module, and all the other modules being passive, such that no payload data (19, 22) can be transmitted by means of said passive modules, - the active module switched into the active state transmitting at least one update message immediately after the switching between two switching states, - and the update message outputting said active module as the sender or recipient of payload data (19, 22) of at least one data processing unit of the mobile data transmission unit as at least one client (15, 16), - and each data processing unit of the network, each access point (6, 7), each active and passive module (10, 11) and each data processing unit of the mobile data transmission unit having its own address in the form of its own MAC address (a, b, c, d, e, f, g, h), - as the source, the update message contains the MAC address (g, h) of at least one data processing unit of the mobile data transmission unit instead of the MAC address (e, f) of the active module, - the payload data (19, 22) being transmitted between the data processing units of the mobile data transmission unit and the switching device, and between the access points (6, 7) and the data processing units of the network in each case via a switching component (5, 14), in which a table stores which the destination is to be reached via which wireless data link (8, 9), - and in that the table of the switching component connected to the access points (6, 7) is updated after receipt of the update message.