Link (telecommunications)
Encyclopedia
In telecommunications a link is the communications channel
that connects two or more communicating devices. This link may be an actual physical link or it may be a logical link that uses one or more actual physical links. When the link is a logical link the type of physical link should always be specified (e.g., data link
, uplink
, downlink, fiber optic link, point-to-point link, etc.) This term is widely used in computer networking (see Data link
) to refer to the communications facilities that connect nodes of a network.
of a network, an intercom station at an entryway with a single internal intercom station, a radio path between two points, etc.).
is an example.
and Frame Relay
links, as well as X.25
networks when used as links for a network layer protocol like IP
.
Unlike broadcast links, there is no mechanism to efficiently send a single message to all other nodes without copying and retransmitting the message.
This term is also often used as a synonym for multipoint, as defined above.
Channel (communications)
In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...
that connects two or more communicating devices. This link may be an actual physical link or it may be a logical link that uses one or more actual physical links. When the link is a logical link the type of physical link should always be specified (e.g., data link
Data link
In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver and the interconnecting data telecommunication circuit...
, uplink
Uplink
A telecommunications link is generally one of several types of information transmission paths such as those provided by communication satellites to connect two points on earth.-Uplink:...
, downlink, fiber optic link, point-to-point link, etc.) This term is widely used in computer networking (see Data link
Data link
In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver and the interconnecting data telecommunication circuit...
) to refer to the communications facilities that connect nodes of a network.
Point-to-point
A point-to-point link is a dedicated link that connects exactly two communication facilities (e.g., two nodesNode (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...
of a network, an intercom station at an entryway with a single internal intercom station, a radio path between two points, etc.).
Broadcast
Broadcast links connect two or more nodes and support broadcast transmission, where one node can transmit so that all other nodes can receive the same transmission. EthernetEthernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
is an example.
Multipoint
Also known as a "multidrop" link, a multipoint link is a link that connects two or more nodes. Also known as general topology networks, these include ATMAsynchronous Transfer Mode
Asynchronous 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...
and Frame Relay
Frame relay
Frame 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...
links, as well as X.25
X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
networks when used as links for a network layer protocol like IP
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
.
Unlike broadcast links, there is no mechanism to efficiently send a single message to all other nodes without copying and retransmitting the message.
Point-to-multipoint
A point-to-multipoint link is a specific type of multipoint link which consists of a central connection endpoint (CE) that is connected to multiple peripheral CEs. Any transmission of data that originates from the central CE is received by all of the peripheral CEs while any transmission of data that originates from any of the peripheral CEs is only received by the central CE.This term is also often used as a synonym for multipoint, as defined above.
Private and Public - Accessibility and Ownership
Links are often referred to by terms which refer to the ownership and / or accessibility of the link.- A private link is a link that is either owned by a specific entity or a link that is only accessible by a specific entity.
- A public link is a link that uses the Public switched telephone networkPublic switched telephone networkThe public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
or other public utility or entity to provide the link and which may also be accessible by anyone.