Store and forward
Encyclopedia
Store and forward is a telecommunications technique 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 networking
context, 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.
This technique originates the delay-tolerant networks. No real-time services are available for these kinds of networks.
equipment was used to send messages which were stored at the receiving end on punched paper tape at a relay center. A human operator at the center removed the message tape from the receiving machine, read the addressing information, and then sent it toward its destination on appropriate outbound point-to-point teleprinter link. If the outbound link was in use, the operator placed the message in tape in a physical queue, usually consisting of a set of clips or hooks. A major relay center in the mid 1900s might have dozens of inbound and outbound teleprinters, scores of operators, and thousands of messages in the queues during peak periods. Operators referred to these centers as "torn-tape relay
centers," a reference to removing the received message from the inbound teleprinter by tearing the paper tape to separate one message from the next. The U.S. military term for such a center was "Non-Automated Relay Center" (NARC).
was an automatic, electromechanical store and forward message switching system. All message storage was performed by paper tape punches paired with paper tape readers, with a bin in between.
, computers were connected via a variety of point-to-point techniques, with many smaller computers using dial-up connections. The UUCP store-and-forward protocols allowed a message (typically e-mail) to move across the collection of computers and eventually reach its destination. Late in the 20th century, store and forward techniques evolved into packet switching
which replaced it for most purposes.
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...
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
Node (networking)
In communication networks, a node is a connection point, either a redistribution point or a communication endpoint . The definition of a node depends on the network and protocol layer referred to...
in a networking
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
context, verifies the integrity
Data integrity
Data Integrity in its broadest meaning refers to the trustworthiness of system resources over their entire life cycle. In more analytic terms, it is "the representational faithfulness of information to the true state of the object that the information represents, where representational faithfulness...
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.
This technique originates the delay-tolerant networks. No real-time services are available for these kinds of networks.
Manually-operated relay
Store and forward networks predate the use of computers. Point-to-point teleprinterTeleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
equipment was used to send messages which were stored at the receiving end on punched paper tape at a relay center. A human operator at the center removed the message tape from the receiving machine, read the addressing information, and then sent it toward its destination on appropriate outbound point-to-point teleprinter link. If the outbound link was in use, the operator placed the message in tape in a physical queue, usually consisting of a set of clips or hooks. A major relay center in the mid 1900s might have dozens of inbound and outbound teleprinters, scores of operators, and thousands of messages in the queues during peak periods. Operators referred to these centers as "torn-tape relay
Tape relay
A tape relay is a method of retransmitting teletypewriter traffic from one channel to another, in which messages arriving on an incoming channel are recorded in the form of perforated tape, this punched tape then being either fed directly and automatically into an outgoing channel, or manually...
centers," a reference to removing the received message from the inbound teleprinter by tearing the paper tape to separate one message from the next. The U.S. military term for such a center was "Non-Automated Relay Center" (NARC).
Automatic relay
Plan 55-APlan 55-A
Plan 55-A was a store and forward message switching system developed by Western Union and used from 1948 to 1976. Western Union's own system handled telegrams, and a military version of the system was used by the U.S...
was an automatic, electromechanical store and forward message switching system. All message storage was performed by paper tape punches paired with paper tape readers, with a bin in between.
UUCP
Prior to the deployment of the InternetInternet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
, computers were connected via a variety of point-to-point techniques, with many smaller computers using dial-up connections. The UUCP store-and-forward protocols allowed a message (typically e-mail) to move across the collection of computers and eventually reach its destination. Late in the 20th century, store and forward techniques evolved into packet switching
Packet switching
Packet switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams over a shared network...
which replaced it for most purposes.
See also
- Cut-through switchingCut-through switchingIn computer networking, cut-through switching is a method for packet switching systems, wherein the switch starts forwarding a frame before the whole frame has been received, normally as soon as the destination address is processed...
- Delay-tolerant networking
- Email forwardingEmail forwardingEmail forwarding generically refers to the operation of re-sending an email message delivered to one email address on to a possibly different email address...
- FidoNetFidoNetFidoNet is a worldwide computer network that is used for communication between bulletin board systems. It was most popular in the early to mid 1990s, prior to the introduction of easy and affordable access to the Internet...
- Fragment free
- Hop-by-hop transportHop-by-hop transportHop-by-hop transport is a principle of controlling the flow of data in a network. With hop-by-hop transport, chunks of data are forwarded from node to node in a store-and-forward manner....
- Internet faxInternet faxInternet fax uses the Internet to receive and send faxes.Internet faxing, "e-Fax" or "online faxing" is a general term which refers to sending a document facsimile using the Internet, rather than using only phone networks with a fax machine.Depending on the specific method/implementation ,...
- Network switchNetwork switchA network switch or switching hub is a computer networking device that connects network segments.The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer of the OSI model...
- Packet radioPacket radioPacket radio is a form of packet switching technology used to transmit digital data via radio or wireless communications links. It uses the same concepts of data transmission via Datagram that are fundamental to communications via the Internet, as opposed to the older techniques used by dedicated...
- StoforStoforStofor, pronounced as in "Stow Four", is a store and forward message switching system designed by Fenwood Designs Ltd, UK in 1980.-Market and specification:...
- Store and forward delay
- Store-and-forward switching centerStore-and-forward switching centerIn telecommunication, a store-and-forward switching center is a message switching center in which a message is accepted from the originating user, i.e., sender, when it is offered, held in a physical storage, and forwarded to the destination user, i.e., receiver, in accordance with the priority...
- Wormhole routingWormhole routingWormhole flow control, also called wormhole switching or wormhole routing is a system of simple flow control in computer networking based on known fixed links. It is a subset of flow control methods called Flit-Buffer Flow Control....