Appendix G. Glossary
61200305L1-1 ATLAS 550 User Manual G-9
SNA
Systems Network Architecture. Network architecture developed by IBM in the 1970s.
SNMP
Simple Network Management Protocol. A control and reporting scheme widely used to manage
devices from different vendors. SNMP operates on top of the Internet protocol.
SVC
Switched Virtual Circuit. Virtual circuit within the frame relay network that is created only when
needed. Bandwidth parameters are defined each time the circuit is created.
synchronous
1. The condition occurring when two events happen in a specific time relationship with each other,
both under control of a master clock.
2. A method of data transmission requiring the transmission of timing pulses to keep the sender and
receiver synchronized in their communication used to send blocks of information. Synchronous
data transmission is used in high speed data circuits because there is less overhead than asynchro-
nous transmission of characters which contain two extra bits per character to affect timing.
T1 circuit
Also T-1. A digital transmission link with a capacity of 1.544 Mbps. T1 uses two pairs of normal
twisted wires. T1 normally can handle 24 voice conversations with each conversation being digitized
at 64 kbps. With more advanced digital voice encoding techniques, it can handle more voice channels.
T1 is a standard for digital transmission in North America.
T1 Network Interface Module
OneoftheATLAS550networkinterfacemodules.TheT1NetworkInterfaceModule(NIM)provides
a single channelized T1 or PRI interface. It can operate in DS-1 or DSX-1 mode and can serve as the pri-
mary or backup timing source for the entire system.
T391
Defines the time in seconds between frame relay link integrity polls.
T392
Defines the time in seconds the frame relay switch will wait for a poll from the user before declaring
the poll bad.
TBOP
Transparent Bit Oriented Protocol. ADTRAN proprietary method for transmitting HDLC traffic across
a frame relay network.
TCP
Transmission Control Protocol. Connection oriented protocol that provides error control of IP traffic.
TCP/IP
Transmission Control Protocol/Internet Protocol. A set of communications protocols that encom-
passes media access, packet transport, session communications, file transfer, electronic mail, and ter-
minal emulation.
