Glossary
Glossary-11
addresses. The standards in this
field are still not fully stable.
SNMP
Simple Network Management
Protocol. A protocol used to
gather activity information on a
TCP/IP network for monitoring
and statistical purposes.
SONET
Synchronous Optical Network.
A U.S. and Canadian standard
for optical digital transmission
at hierarchical rates from
155 Mbits/sec to 2.5 Gbits/sec
and beyond.
SVC
Switched Virtual Connection/
Circuit. A logical (not physical)
connection between endpoints
established by the ATM network
on demand after receiving a
connection request from the
source/root, which it transmits
using the Q.2931 signaling
protocol. See PVC.
T
T1/T3
T1 is a 1.544 Mbits/sec
multichannel digital
transmission system for voice or
data provided by long distance
carriers. T3 is similar but
operates at 44.736 Mbits/sec.
Also referred to as DS1 and DS3
(Data Service).
TAXI
A standardized 100 Mbits/sec
fiber physical interface for ATM.
TC
Transmission Convergence. A
sublayer in the ATM physical
layer before the PMD. Performs
functions as cell delineation, cell
rate decoupling, HEC
generation and checking and
various OAM functions.
TCP
Transmission Control Protocol.
See IP.
Token Ring
An industry standard (Project
802.5 of the IEEE) that specifies
protocols for connection and
transmission in LANs. As a
media access method, it operates
at layers 1 and 2 in the OSI
model. Token Ring transmits at 4
or 16 Mbits/sec.
U
UNI
User-Network Interface.
Generally described as any
connection that directly links a
user’s device to an ATM
network, through an ATM
switch. At the ATM layer, the
UNI differs from the NNI by
replacing the first 4 bits of the
VPI with a GFC field.
UTP/STP
Unshielded Twisted Pair/
Shielded Twisted Pair. Two types
of copper cable. STP has
insulating material wrapped
around the twisted wires for
immunity to magnetic
interference. UTP (which is the
