store-and-forward - technical definition

A transmission method by which a device receives a complete message or protocol data unit (PDU) and temporarily stores it in a buffer before forwarding it toward the destination. Having the whole message allows the device to check for errors and discard an errored frame or packet before forwarding it and wasting bandwidth on the next hop. A switch or router, for example, may have buffers to store incoming frames or packets of data until internal computational resources are available to process them and buffers to store outgoing frames or packets until bandwidth is available on a circuit in the forward direction. That way the device can mitigate issues of switch and circuit congestion. Messaging systems add significant value by storing voice, e-mail, and image (e.g., fax) messages when the intended recipient is unavailable and forwarding them on demand when the recipient is available. Facsimile systems also may store international fax messages until off-peak hours, when calling rates are lowest.