Fragment free cut-through
|
|
Fragment-free switching is suitable for backbone applications in a congested network, or when connections are allocated to a number of users. The switching device checks the source and destination MAC address of a packet, and sends the packet to the port corresponding to the destination.
The packets are sent through the switch as a continuous flow of data--the transmit and receive rates are always the same. Because of this, fragment-free switching cannot pass packets to higher speed networks, for example, to forward packets from a 10 Mbit/s to a 100 Mbit/s Ethernet network. Therefore, if you opt for fragment-free switching, you cannot make direct connections to higher speed networks from that port.
Fragment-free switching offers a compromise between cut through (which offers the fastest possible forwarding at the expense of any error checking) and store-and-forward (which offers maximum error checking at the expense of latency), to provide an average latency of approximately 60µs and sufficient error checking to eliminate most common errors.