Nortel Networks Circuit Card - Manual (Page 381)

NT6D70 SILC Line card Page 381 of 906
Circuit Card Description and Installation
A logical terminal is any terminal that can communicate with the system over
a DSL. It can be directly connected to the DSL through its own physical
termination or be indirectly connected through a common physical
termination.
The length of a DSL depends on the specific terminal configuration and the
DSL wire gauge; however, it should not exceed 1 km (3,280 ft).
The SILC interface uses a four-conductor cable that provides a differential
Transmit and Receive pair for each DSL. The SILC has options to provide a
total of two watts of power on the Transmit or Receive leads, or no power at
all. When this power is supplied from the S/T interface, the terminal devices
must not draw more than the two watts of power. Any power requirements
beyond this limit must be locally powered.
Other functions of the SILC are:
• support point-to-point and multi-point DSL terminal connections
• execute instructions received from the MISP to configure and control the
S/T interfaces
• provide channel mapping between ISDN BRI format (2B+D) and system
bus format
• multiplex 4 D-channels onto one timeslot
• perform activation and deactivation of DSLs
• provide loopback control of DSLs
• provide a reference clock to the clock controller
Micro Controller Unit (MCU)
The Micro Controller Unit (MCU) coordinates and controls the operation of
the SILC. It has internal memory, a reset and sanity timer, and a serial control
interface.
The memory consists of 32 K of EPROM which contains the SILC operating
program and 8 K of RAM used to store interface selection and other functions
connected with call activities.