What is Cut-through switching?

In data communications, cut-through switching is a method of switching data frame or data packets, where the switching device (bridge or switch) forwards the frames or packets as soon as the destination address is available without waiting for the rest of the data to arrive.

Working Principle

Cut-through switching is used in packet switching systems. In packet-switching, the message is divided into a number of units called packets that are individually routed from the source to the destination. There is no need to establish a dedicated circuit for communication, since it is a connectionless network switching technique.

In cut − through switching, when the data frame or a packet starts arriving at a bridge or a switch, data transmission can start as soon as destination address field has arrived. The switch performs a look – up at the address table stored in it to check whether the destination address is valid. If the address is valid and the outgoing link is available, the switching device immediately starts to transmit the frame to the destination port, even before rest of the frame has arrived.

Here, the switching device acts as mere forwarder of frames. As the total frame is not yet available, it cannot perform error checks when it starts forwarding. It depends upon the on the destination devices for error handling.

Advantages

The advantages of cut-through switching are −

• Low − latency − Since, the switching device does not wait for the entire frame to arrive, the latency of passing through the bridge is reduced considerably.
• Less storage requirement − The switching devices do not require to store the data packets or data frames in it. So, they can operate with reduced internal storage capacity.

Uses

Cut-through switching is mainly used for communications via fiber channel. It is also used for SCSI traffic for the low latency transmission.