Add-drop benes networks

1. Benes networks having an add-drop function, the Benes networks comprising:

an input stage having a plurality of input ports;

an input connection stage configured to receive output signals of the input stage;

an add connection stage configured to receive outputs of the input connection stage and to receive inputs from add ports corresponding in number to the number of the plurality of input ports;

a drop connection stage configured to connect a portion of outputs of the add connection stage to an output connection stage and to connect remaining outputs of the add connection stage to drop ports;

the output connection stage configured to connect a portion of outputs of the drop connection stage to an output stage; and

the output stage configured to output outputs of the output connection stage to output ports.

2. The Benes networks according to claim 1 , wherein the add connection stage includes a plurality of 2×2 switches configured to connect packets input through the input stage and to connect packets input through the add ports, and the number of switches configuring the add connection stage is twice the number of switches configuring the input stage.

3. The Benes networks according to claim 1 , wherein the drop connection stage includes a plurality of 2×2 switches configured to connect packets output through the output stage and to connect packets dropped through the drop ports, and the number of switches configuring the drop connection stage is twice the number of switches configuring the output stage.

4. The Benes networks according to claim 1 , further comprising a switch controller configured to process time slot-based packets, to control physical connections of input-output pairs, and to perform an add-drop looping algorithm for switch connection to provide an add function or a drop function at the add ports or the drop ports.

5. The Benes networks according to claim 4 , wherein the add-drop looping algorithm arranges packets inputted during a time slot in order of precedence, in which packets to be outputted to the output ports through the output connection stage and the output stage are first arranged and packets to be dropped to the drop ports through the drop connection stage are arranged latest.

6. The Benes networks according to claim 5 , wherein the add-drop looping algorithm performs to connect between inputs inputted from the add connection stage and outputs outputted to the output ports through the output connection stage and the output stage.

7. The Benes networks according to claim 6 , wherein the add-drop looping algorithm processes packets to be dropped to the drop ports at the drop connection stage after connecting between the inputs inputted from the add connection stage and the outputs outputted to the output ports through the output connection stage and the output stage.

8. The Benes networks according to claim 7 , wherein the add-drop looping algorithm processes packets to be added to the output ports through the output connection stage and the output stage after processing the packets to be dropped to the drop ports at the drop connection stage, allows processing of the packets to be added to wait for a next time slot if output ports which are destinations of the packets to be added are occupied by the connection between input and output packets, and processes packets to be added by using an algorithm for determining add ports if the output ports which are destinations of the packets to be added are not occupied by other packets.