The invention relates to a rear panel bus, with a number of plugs which may be plugged into the modules and a fibre optic cable, for guiding light signals, whereby the fibre optic cable has a number of interruptions in the propagation direction of the light signals, into which means, for injection and decoupling of light signals running in the fibre optic cable may be inserted. The interruptions in the fibre optic cable are arranged such that a plug may be allocated to an interruption. The invention further comprises a module which may be plugged into an optical rear panel bus and means for injection and decoupling of light signals running in an optical fibre cable whereby the means for injecting and decoupling are arranged such as to be able to be inserted in interruptions in the fibre optic cable, to decouple light signals from the fibre optic cable and to inject light signals into the fibre optic cable in the propagation direction.