Connection-oriented protocol
Encyclopedia
A connection-oriented
networking protocol is one that establishes a communication session, then delivers a stream of data in the same order as it was sent. It may be a circuit switched connection, or a virtual circuit
connection in a packet switched network. In the latter case, it identifies traffic flows by some connection identifier rather than by explicitly listing source and destination addresses. Typically, this connection identifier is a small integer (10 bits for Frame Relay, 24 for ATM, for example). This makes network switches substantially faster (as routing tables are just simple look-up tables, and are trivial to implement in hardware). The impact is so great, in fact, that even characteristically connectionless protocols, such as IP traffic, are being tagged with connection-oriented header prefixes (e.g., as with MPLS
, or IPv6
's built-in Flow ID field). Example of a connection-oriented protocol at the transport layer is the TCP
protocol.
Connection-oriented protocols are not necessarily reliable
protocols. ATM and Frame Relay, for example, are both examples of a connection-oriented, unreliable
protocol. There are also reliable connectionless protocols as well, such as AX.25
when it passes data in I-frames. But this combination is rare, and reliable-connectionless is uncommon in commercial and academic networks.
Connection-oriented protocols handle real-time traffic substantially more efficiently than connectionless protocols, which is why ATM has yet to be replaced with Ethernet for carrying real-time, isochronous traffic streams, especially in heavily aggregated networks like backbones, where the motto "bandwidth is cheap" fails to deliver on its promise. Experience has also shown that over-provisioning bandwidth does not resolve all quality of service issues. Hence, (10-)gigabit Ethernet is not expected to replace ATM at this time.
Some connection-oriented protocols have been designed or altered to accommodate both connection-oriented and connectionless data.
Connection-oriented
Connection-oriented communication is a data communication mode in telecommunications whereby the devices at the end points use a protocol to establish an end-to-end logical or physical connection before any data may be sent. In case of digital transmission, in-order delivery of a bit stream or...
networking protocol is one that establishes a communication session, then delivers a stream of data in the same order as it was sent. It may be a circuit switched connection, or a virtual circuit
Virtual circuit
In telecommunications and computer networks, a virtual circuit , synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication...
connection in a packet switched network. In the latter case, it identifies traffic flows by some connection identifier rather than by explicitly listing source and destination addresses. Typically, this connection identifier is a small integer (10 bits for Frame Relay, 24 for ATM, for example). This makes network switches substantially faster (as routing tables are just simple look-up tables, and are trivial to implement in hardware). The impact is so great, in fact, that even characteristically connectionless protocols, such as IP traffic, are being tagged with connection-oriented header prefixes (e.g., as with MPLS
Multiprotocol Label Switching
Multiprotocol Label Switching is a mechanism in high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. The labels identify virtual links between...
, or IPv6
IPv6
Internet Protocol version 6 is a version of the Internet Protocol . It is designed to succeed the Internet Protocol version 4...
's built-in Flow ID field). Example of a connection-oriented protocol at the transport layer is the TCP
Transmission Control Protocol
The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
protocol.
Connection-oriented protocols are not necessarily reliable
Reliability (computer networking)
In computer networking, a reliable protocol is one that provides reliability properties with respect to the delivery of data to the intended recipient, as opposed to an unreliable protocol, which does not provide notifications to the sender as to the delivery of transmitted data.A reliable...
protocols. ATM and Frame Relay, for example, are both examples of a connection-oriented, unreliable
Reliability (computer networking)
In computer networking, a reliable protocol is one that provides reliability properties with respect to the delivery of data to the intended recipient, as opposed to an unreliable protocol, which does not provide notifications to the sender as to the delivery of transmitted data.A reliable...
protocol. There are also reliable connectionless protocols as well, such as AX.25
AX.25
AX.25 is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks....
when it passes data in I-frames. But this combination is rare, and reliable-connectionless is uncommon in commercial and academic networks.
Connection-oriented protocols handle real-time traffic substantially more efficiently than connectionless protocols, which is why ATM has yet to be replaced with Ethernet for carrying real-time, isochronous traffic streams, especially in heavily aggregated networks like backbones, where the motto "bandwidth is cheap" fails to deliver on its promise. Experience has also shown that over-provisioning bandwidth does not resolve all quality of service issues. Hence, (10-)gigabit Ethernet is not expected to replace ATM at this time.
Some connection-oriented protocols have been designed or altered to accommodate both connection-oriented and connectionless data.
List of connection-oriented protocols
- TCPTransmission Control ProtocolThe Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
- SMTP
- DCCPDatagram Congestion Control ProtocolThe Datagram Congestion Control Protocol is a message-oriented Transport Layer protocol. DCCP implements reliable connection setup, teardown, Explicit Congestion Notification , congestion control, and feature negotiation. DCCP was published as RFC 4340, a proposed standard, by the IETF in March,...
- Connection-oriented EthernetConnection-oriented EthernetConnection-oriented Ethernet refers to the transformation of Ethernet, a connectionless communication system by design, into a connection-oriented system. The aim of connection-oriented Ethernet is to create a networking technology that combines the flexibility and cost-efficiency of Ethernet with...
- ATMAsynchronous Transfer ModeAsynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
- Frame RelayFrame relayFrame Relay is a standardized wide area network technology that specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology...
- TIPCTIPCTransparent Inter-process Communication is a network communications protocol for inter-process communication that was specially designed for intra-cluster communication.- Features :Some features of TIPC:...
- SCTP
- IPX/SPXIPX/SPXIPX/SPX stands for Internetwork Packet Exchange/Sequenced Packet Exchange. IPX and SPX are networking protocols used primarily on networks using the Novell NetWare operating systems.-Protocol Layers:...