Carrier Access Wide Bank 28 DS3 User Manual page 434

Glossary
Slip
Stratum
STS-1
STS-N
Stuffing
Subnet Mask
Superframe
Synchronous
Synchronous Digital
Hierarchy
Synchronous Optical
Network
Syntran
Telnet
Glossary-12
An overflow (deletion) or underflow (repetition) of one frame of a signal in a receiving
buffer.
Stratum or Stratum Level refers to the accuracy of the clock source used to synchronize
SONET communications systems. Accuracy is important in maintaining communications
across a network. During local network failures, a backup clock source is used to maintain
network timing. But when the backup clock becomes temporarily isolated because of an
equipment or line failure, the clock phase will drift slowly until the communications link
eventually falls out of synchronization. Stratum 1 is the primary SONET clock source
obtained from a Cesium beam time standard located in Paris, France. Stratum 2 is less
accurate but can keep a network synchronized for 3 to 5 days. Stratum 3 and Stratum 4 are
each less accurate (and less expensive) and can provide backups for shorter time periods.
Synchronous Transport Signal level 1. The basic SONET building block signal transmitted
at 51.84 Mb/s data rate.
Synchronous Transport Signal level N. The signal obtained by multiplexing integer
multiples (N) of STS-1 signals together.
M13 multiplexing uses bit stuffing to bring each asynchronous DS1/DS2 up to a common
data rate for transmission. M13 multiplexing forces the seven DS2s to be synchronous to
each other at a rate that causes 100-percent pulse stuffing in the M23 frame. This allows the
"stuff" indicator bits in the M23 frame to be used as a maintenance link between the end
points. The C-bit frame does not have a "stuff" indicator because stuffing is always present.
A bit-mapped number, in xxx.xxx.xxx.xxx format, indicating which bits in an IP address
identify the physical network and which bits should be ignored.
SF. Any structure made of multiple lower-rate frames. A DS1 frame format (also called
D4) comprising 193 bit positions used to multiplex 24 DS0 channels.
A network where transmission system payloads are synchronized to a master (network)
clock and traced to a reference clock.
SDH. The ITU-T defined world standard of transmission whose base transmission rate is
52 Mb/s (STM-0) and is equivalent to SONET's STS-1 or OC-1 transmission rate. SDH
standards were published in 1989 to address interworking between the ITU-T and ANSI
transmission hierarchies.
SONET. A standard for optical transport that defines optical carrier levels and their
electrically equivalent synchronous transport signals. SONET allows for a multi-vendor
environment and positions the network for transport of new services, synchronous
networking, and enhanced OAM&P.
Synchronous Transmission of restructured DS3 signals in North American format at
44.736 Mbps.
A telecommunications network application protocol providing virtual terminal service
within the Internet protocol suite.
July 2004 Wide Bank 28 DS3 - Release 2.4