Loss of Signal (LOS)
An error that occurs when a device is not receiving a T1 signal.
Specifically, Access-T declares Loss of Signal when it receives 175
±
75 consecutive ZEROS. LOS ends when Access-T receives at least one
ONE.
Loss of Sync
See Loss of Frame.
Master
The operation mode for an Access-T which is to act as a poller and
manager for a chain of up to 29 slave Access-Ts.
Master Clock
The clock providing the timing reference for the Access-T, including
all DTE and T1 interfaces.
Minimum Pulse Density
The minimum frequency of ONES pulses that is necessary to ensure
reliable timing in a T1 signal. The minimum pulse density, as defined
by AT&T, equals N pulses in every 8(N+1) bits, where N ranges from
1 to 23. This formula allows the maximum number of ZEROS to be
15 and a minimum pulse density of about 12.5% (1 in 8).
Multiplexer
A device that combines two or more signals for transmission over a
single facility.
Multipoint Connections
In a multipoint connection, an FT1 network routes communication
channels to three or more locations through DACS nodes. Framing,
CRC, and data link channels are not propagated through the DACS
nodes.
Network Interface Module (NIM)
The portion of the Access-T that provides the interface to the T1 line.
Network Management System (NMS)
A centralized computer-based system from which network equip-
ment such as Access-T can be configured, monitored, and controlled.
Node
A particular Access-T in a chain of up to 30 units. See Chain Port.
Out-of-Frame (OOF)
An Out of Frame condition occurs when Access-T detects 2 out of 5
consecutive framing bits in error.
ACST-0351-005
Appendix B
June 1996
Glossary
B-7