Introduction to Tandem X.25 Capabilities

Glossary
Glossary–2 065307 Tandem Computers Incorporated
call accepted packet. Packet that a remote entity sends to the network in response to an
incoming call packet, if a circuit can be established.
call clearing. Descriptive phrase for the activities required for disconnecting a switched
virtual circuit.
call connected packet. Packet that the network sends to a caller in response to receiving
a call accepted packet from a remote entity.
call redirection. Optional network facility allowing the network to pass a call to another
subscriber number.
call request packet. Packet that a caller sends to a network addressed to a remote entity
to initiate a call on a switched virtual circuit.
call setup. Descriptive phrase for the activities required to establish a switched virtual
circuit, involving call request, incoming call, call accepted, and call connected packets.
Data transmission between the caller and the remote entity can begin after the circuit is
established.
called address. Network address of a remote device or system (the entity being called).
calling address. Network address of a local device or system (the entity making the
call).
call user data (CUD) . Optional field, which can be included in call setup packets, such as
call request and incoming call In standard format packets, the CUD can be specified
for a maximum of 16 bytes, depending on the protocol configured for the particular
subdevice. If the extended packet format has been configured, a CUD field of up to
128 packets can be sent, using the fast select optional facility. See also user data and
fast select.
CCITT. Comité Consultatif International Télégraphique et Téléphonique (International
Telegraph and Telephone Consultative Committee). Standards-setting group.
Operates under auspices of the United Nations to support common standards for
international communications.
channel. A path over which data and messages are sent.
character. Letter, figure, number, punctuation mark, or other symbol contained in a
message or used in a control function.
circuit. Means of two-way communications between two network entities.
CIU. Communications Interface Unit. Each 3650/6100 family controller has a physical
or logical pair of CIUs. A CIU interfaces between the main controller logic and the line
control unit (LIU).
clear-confirmation packet. Packet sent by the network to the caller when a call has been
disconnected in response to the caller request to disconnect.
clear-indication packet. Packet sent by the network when a call is disconnected.
clear-request packet. Packet sent by the caller to disconnect the call.