virtual channel identifier (ATM) (VCI)
The Virtual Channel Identifier (VCI) data field is a channel identifier of virtual channels in ATM. It is an identification number for the logical connection, the virtual channel( VC).
In the ATM cell, the VCI data field is a 16 bits long data field, in the Distributed Queue Dual Bus( DQDB) header, the VCI data field is 20 bits long. In ATM networks, the VCI data field is inserted by the ATM switching units.