Outside Trunks - AT&T MERLIN LEGEND Release 2.0 Equipment And Operations Manual

Data Communications Support
Connectivity to a Local Host Computer
Figure 5-1 shows DHGs assigned to modem-only and 7500B Data Module-only
modem pools that provide access to a local host computer.
These modem pools and the host computer are connected by EIA type RS-232
interfaces. Each modem provides the T/R interface to the 012 module on the
control unit, and each 7500B Data Module connects to the 008 MLX or 408
GS/LS-MLX module (Release 2.0 only) on the control unit. Terminating resistors
are required for 7500B Data Module connection.
Connectivity to a LAN
A LAN is an interconnected chain of terminals or PCS that pass data to and from
a mainframe computer or interconnected workstations using some topology
arrangement.
The communications system connects to the LAN through a workstation that
functions as a gateway, The gateway provides the ports for the modem and
data module connections to the communications system and the connection to
the LAN. It also accommodates the protocols needed for the transfer of data
between a data endpoint on communications system and a workstation (or data
terminal) on the LAN.
The modems connect to the gateway via ElA-type RS-232 (or other type)
interfaces and provide the T/R interface to the 012 module on the control unit.
The 7500B Data Modules connect to the gateway
interfaces (or other type) and on the communications system end connect to the
008 MLX, 408 MLX, or 408 GS/LS-MLX module (Release 2.0 only) on the control
unit. Terminating resistors are required for the 7500B Data Module connection.
Once a connection is established between a data endpoint on the
communications system side and a workstation within the LAN, all of the
features and capabilities of the LAN environment are available to the originating
data endpoint on the communications system side. However, limitations or
hardware requirements may restrict the usage of some LAN facilities.

Outside Trunks

Figure 5-1 shows the types of outside trunks that can be used to make and
receive data calls to and from data stations outside the system. (In the figure,
the trunk types are displayed to the left of the control unit and are labeled
1. Ground-start (GS) trunks and loop-start (LS) trunks are used to
communicate with outside analog data stations. A loop-start trunk is the
standard for home and small businesses is the least expensive trunks in
some areas LS trunks have the following disadvantages:
ElA-type RS-232
via
Outside Trunks
1-4.)
5-13