ATT DEFINITY Communications System Generic 3 Instructions Manual

Data Management
Issue  3   March 1996
2-15
The EIA RS-232D protocol provides two interface connectors. The female side 
connector is known as data communications equipment (DCE). The male side 
connector is known as data terminal equipment (DTE). Data equipment 
manufacturers design either the DCE or DTE interface into their products. 
Products such as modems, data service units (DSUs), Digital Terminal Data 
Modules (DTDMs), and Processor Data Modules (PDMs) have a built-in DCE 
interface. Products such...

Functional Description
2-16Issue  3   March 1996 
the maximum cable length is 5,000 feet (1,524 meters). When voice and data 
transmission is carried over the same data link, as when a 510D terminal, 515 
BCT, or a DTDM is used , the cable length is limited by the voice transmission 
distance.
The D CP sends digitized voice and digital d ata in frames. Each frame consists of 
four fields or channels (see Figure 2-3). The first field is a unique three-bit framing 
pattern that defines the frame boundary....

Data Management
Issue  3   March 1996
2-17
The BX.25 protocol is similar to the ITU-T X .2 5   protocol and, from a user 
perspective, is compatible with the standard . The BX.25 protocol has three 
layers that are not specified for the X.25 protocol. These layers are Application, 
Presentation, and Session. The A pp lication and Presentation layers are defined 
in the Transa ction-Oriente d Protocol (TOP) of the BX.25.
The TOP is a high-level protocol, intended to standardize communications 
between...

Functional Description
2-18Issue  3   March 1996 
Figure 2-4. BX.25 Packet-Switching Protocol
USER
APPLICATION
LAYER
PRESENTATION
LAYER
SESSION
LAYER
NETWORK
LAYER
DATA L IN K
LAYER
PHYSICAL
LAYER
TRANSPORT
LAYER
------ ------
---
BX.25 Protocol LayersUSER
PACKET
LAYER
LINK
LAYER
PHYSICAL
LAYER
SESSION
LAYER
T
O
P* 

Data Management
Issue  3   March 1996
2-19
Figure 2-5. X.25 Packet-Switching Protocol
USER
PACKET
LAYER
LINK
LAYER
PHYSICAL
LAYERNot
Specified
by
ProtocolUSER
APPLICATION
LAYER
PRESENTATION
LAYER
SESSION
LAYER
NETWORK
LAYER
DATA LI N K
LAYER
PHYSICAL
LAYER
TRANSPORT
LAYER
------ ------
---
X.25 Protocol Layers 

Functional Description
2-20Issue  3   March 1996 
International Telecommunications
Union - Telecommunications,
Specifications Sector (ITU-T) Interface
X.25 Packet-Switching Protocol
The ITU-T (formerly CCITT) i s one  of  three divisions of the International 
Telecommunications Union, an agency of the United Nations. The standards set 
by the ITU-T generally deal with public networks. Two series of standards or 
recommendations specifically deal with data transmission:
nThe V-series p rovides...

International Telecommunications Union - 
Telecommunications, Specifications Sector (ITU-T) 
Interface
Issue  3   March 1996
2-21
Wideband Switching
Wideband Switching  provides a range of data transmission sp eeds (from 128 to 
1984 k b ps for E1 services, 128 to 1536 kbps for T1 services). The higher 
transmission rates are needed for applications such as video conferencing, data 
backup, scheduled batch processing, and primary data connectivity. 

Functional Description
2-22Issue  3   March 1996 
Data Management Features
The following features are associated with Data Management:
nAdministered Connections 
nAlphanumeric Dialing 
nData Call Setup [including Default Dialing  and Alphanumeric Dialing]
nData Hot Line
nData-Only Off-Premises Extensions
nData Privacy
nData Restriction
nDefault Dialing 
nDigital Multiplexed Interface
nDS1/E1 Tie Trunk Servic e
nEIA Interface
nInformation System Network (ISN) Interface
nModem Poolin g
nPC Interface...

Network Services
Issue  3   March 1996
2-23
Network Services
Network Services allows a group of switches (consisting of DEFINITY  Generic 1, 
Generic 2, Generic 3, System 75 and System 85, and/or other systems) to be 
configured to meet the communications needs of a medium- to larg e-size 
corporation. Possible arrangements include an Electronic Tandem Network 
(ETN), Distributed Communications System (DCS), and Main/Satellite/Tributary. 
Each is briefly described in this chapter.
Do not assume that the...

Functional Description
2-24Issue  3   March 1996 
nForced Entry of CDR Ac count Codes
nGeneralized Route Selection
nIntegrated Services  Digital  Network — Primary Rate Interface
nNetwork Access — Private
nNetwork Access — Public
nOff-Premises Station
nQSIG Global Networking
nRestriction — Toll
nSubnet Trunkin g
nTime of Day Routing
nUniform Dial Plan
Private Network Configurations
A p rivate network is a configuration of trunk and switching facilities d e dicated to 
the use of a b usiness or...