Verilink AS2000: The Basics (880-502981-001) Product Manual - Manual (Page 163)

Acronyms and Definitions
Verilink Access System 2000: Basics Glossary-43
S
secondary synchronization The first alternate source for clock
synchronization of the node.
SEFS See severely errored framing
second (SEFS) .
seized See off-hook .
select interval Option available to specify the
time interval for alarm
monitoring—from the most
current 15-minute time period to
the previous 24 hours. Node
Manager displays the available
time and most recent 15 minutes
as a bar and as a percentage.
Send Timing (ST) The transmit clock signal provided
by a DSU or multiplexer. In the
case of a Verilink DTE clock option;
a selection which causes the
sampling of transmit data during
the negative going transition of
the transmit clock.
SES See severely errored second
(SES) .
severely errored framing second (SEFS) The second in which two or more
framing bit errors occur within a 3-
millisecond period. For Extended
Superframe Format (ESF) , this
interval may or may not coincide
with an ESF (i.e, six framing bits).
severely errored second (SES) An SES is declared when 320 or
more Extended Superframe
Format (ESF) error events occur
within one second, or when an
out-of-frame second (OOFS)
occurs. One second contains 333-
1/3 Extended Superframes. As
defined by AT&T Publication
54016, a sequence of three
seconds will contain two
consecutive seconds of 333 ESFs
and one of 334 ESFs.
Serial Line Interface Protocol (SLIP) A protocol that allows a computer
to use the Internet protocols over
RS-232. Often used over dial-up
modem connections.
SF See Superframe (SF/D4) .
shelf controller The controller module used to
control the other modules in the
same shelf. In an NCM node, the
shelf controller could be another
NCM, or a DIDCSU, Dual CSU or
Quad/IMUX.
short-haul connection 0 to 633 feet.