A concentrator or data concentrator(DKZ) is a device that concentrates the connecting lines of many end devices into a few, typically a multiplexer or hub.
The concentrator reduces the number of transmission lines because it is generally the starting point of a star topology. Terminal equipment, LAN segments or rings can be connected to it directly. The concentrator increases the connection capacity of a transmission line and enables traffic load balancing, if necessary through buffering.
Depending on the area of application, a distinction is made between working group hubs, department hubs or company hubs and those used in distribution rooms and in the network center.