Virtual Circuit Identifier
Encyclopedia
A Virtual Channel Identifier (VCI) is a unique identifier
which indicates a particular virtual circuit
on a network. It is a 16-bit field in the header of an ATM
cell. The VCI, together with the Virtual Path Identifier (VPI) is used to identify the next destination of a cell as it passes through a series of ATM switches on its way to its destination.
ATM switches use the VPI/VCI fields to identify the Virtual Channel Link (VCL) of the next network that a cell needs to transit on its way to its final destination. The function of the VCI is similar to that of the data link connection identifier (DLCI) in frame relay
and the Logical Channel Number & Logical Channel Group Number in X.25
.
Unique identifier
With reference to a given set of objects, a unique identifier is any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose...
which indicates a particular 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...
on a network. It is a 16-bit field in the header of an ATM
Asynchronous 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...
cell. The VCI, together with the Virtual Path Identifier (VPI) is used to identify the next destination of a cell as it passes through a series of ATM switches on its way to its destination.
ATM switches use the VPI/VCI fields to identify the Virtual Channel Link (VCL) of the next network that a cell needs to transit on its way to its final destination. The function of the VCI is similar to that of the data link connection identifier (DLCI) in 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...
and the Logical Channel Number & Logical Channel Group Number in 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...
.