What is the difference between a storeand forward switch and

What is the difference between a store-and forward switch and a cut-through switch?

Solution

Store and forward is a telecommunicationstechnique in which information is sent to an intermediate station where it is kept and sent at a later time to the final destination or to another intermediate station. The intermediate station, or node in a networkingcontext, verifies the integrity of the message before forwarding it. In general, this technique is used in networks with intermittent connectivity, especially in the wilderness or environments requiring high mobility. It may also be preferable in situations when there are long delays in transmission and variable and high error rates, or if a direct, end-to-end connection is not available.

In computer networking, cut-through switching is a method for packet switchingsystems, wherein the switch starts forwarding a frame (or packet) before the whole frame has been received, normally as soon as the destination address is processed. Compared to store and forward, this technique reduces latency through the switch and relies on the destination devices for error handling. Pure cut-through switching is only possible when the speed of the outgoing interface is equal to the incoming interface speed.

Adaptive switching dynamically selects between cut-through and store and forward behaviors based on current network conditions.

Store-and-Forward: Store-and-Forward switchingwill wait until the entire frame has arrived prior to forwardingit. This method stores the entire frame in memory. Once the frameis in memory, the switch checks the destination address, sourceaddress, and the CRC. If no errors are present, the frame isforwarded to the appropriate port. This process ensures that thedestination network is not affected by corrupted or truncatedframes.

Cut-Through: Cut-Through switching will beginforwarding the frame as soon as the destination address isidentified. The difference between this and Store-and-Forward isthat Store-and-Forward receives the whole frame before forwarding.Since frame errors cannot be detected by reading only thedestination address, Cut-Through may impact network performance byforwarding corrupted or truncated frames. These bad frames cancreate broadcast storms wherein several devices on the networkrespond to the corrupted frames simultaneously.