Connectionless communication
This article needs additional citations for verification. (February 2018) |
Connectionless communication, often referred to as CL-mode communication,
Attributes
Under connectionless communication between two network endpoints, a message can be sent from one endpoint to another without prior arrangement. The device at one end of the communication transmits data addressed to the other, without first ensuring that the recipient is available and ready to receive the data. Some protocols allow for error correction by requesting retransmission.
Connectionless protocols are
In connectionless transmissions the service provider usually cannot guarantee that there will be no loss, error insertion, misdelivery, duplication, or out-of-sequence delivery of the packet. However, the effect of errors may be reduced by implementing error correction within an application protocol.
In connectionless mode, there is less opportunity for optimization when sending several data units between the same two peers. By establishing a connection at the beginning of such a data exchange the components (routers, bridges) along the network path would be able to pre-compute (and hence cache) routing-related information, avoiding re-computation for every packet. In connection-oriented communication, network components can also reserve capacity for the transfer of the subsequent data units of a video download, for example.
Architecture and implementations
Distinction between connectionless and connection-oriented transmission may take place at several layers of the OSI Reference Model:
- transport protocol. UDPis connectionless.
- Network layer.
- network protocols (such as SNA's Path Control in its early stages) require a connection-oriented data link layer. Others (like IP) do not. (After the appearance of APPN, SNA could operate on a connectionless data link service as well.)
Notable connectionless protocols are: Internet Protocol (IP), User Datagram Protocol (UDP), Internet Control Message Protocol (ICMP), Internetwork Packet Exchange (IPX), Transparent Inter-process Communication, NetBIOS, and Fast and Secure Protocol (FASP).
References
- ^ Information Processing Systems - Open Systems Interconnection, "Transport Service Definition - Addendum 1: Connectionless-mode Transmission", International Organization for Standardization, International Standard 8072/AD 6, December 1986.
- This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on 2022-01-22.