363-206-295
Glossary
GL-20
Issue 1
December 1997
STS-1 SPE
STS-1 Synchronous Payload Envelope — A 125-microsecond frame structure composed
of STS path overhead and the STS-1 payload.
STS-3c
Synchronous Transport Level 3 Concatenated Signal. See OC-3c.
Subnetwork
Group of SONET network elements that share a SONET data communications channel.
Synchronization Messaging
SONET synchronization messaging is used to communicate the quality of network timing,
internal timing status, and timing states throughout a subnetwork.
SYSCTL
The system controller circuit pack that provides overall administrative control of the
terminal.
T
T1EXT
T1 Carrier Extension Circuit Pack
T1X1 and T1M1
The ANSI committees responsible for telecommunications standards.
TA
Bellcore Technical Advisory
TARP
Target ID Address Resolution Protocol
TCA
Threshold-Crossing Alert — A condition set when a performance-monitoring counter
exceeds a user-selected threshold. A TCA does not generate an alarm but is available on
demand through the CIT and is shown by TBOS and causes a message to be sent to
NMA via the X.25/TL1 interface.
TCVCXO
Temperature-Compensated Voltage-Controlled Crystal Oscillator — A highly stable and
accurate clock source used in the DDM-2000 TGS circuit pack.
TGS
The timing generator circuit pack generates clock signals for distribution to the transmit
circuits. It operates in the free-running, loop-timing, phase-lock, and holdover modes.
TID
Target Identifier — The Bellcore name for the system name.
