Nortel Circuit Card Installation Manual page 387

The serial control interface is an IPE bus that communicates with the
U transceivers.
IPE interface logic
The IPE interface logic consists of a Card-LAN interface, a IPE bus interface,
a maintenance signaling channel interface, a digital pad, and a clock
converter.
The Card-LAN interface is used for routine card maintenance, which includes
polling the line cards to find in which card slot the UILC is installed. It also
queries the status and identification of the card and reports the configuration
data and firmware version of the card.
The IPE bus interface connects one IPE bus loop that has 32 channels
operating at 64 kbps and one additional validation and signaling bit.
The Maintenance Signaling Channel (MSC) interface communicates
signaling and card identification information from the system CPU to the
UILC MCU. The signaling information also contains maintenance
instructions.
The digital pad provides gain or attenuation values to condition the level of
the digitized transmission signal according to the network loss plan. This sets
transmission levels for B-channel voice calls.
The clock converter converts the 5.12 MHz clock from the IPE backplane into
a 2.56 MHz clock to time the IPE bus channels and an 8-kHz clock to provide
PCM framing bits.
U interface logic
The U interface logic consists of a transceiver circuit. It provides loop
termination and high-voltage protection to eliminate the external hazards on
the DSL. The U interface supports voice and data terminals, D-channel packet
data terminals, and NT1s. A UILC has eight transceivers to support eight
DSLs for point-to-point operation.
NT6D71 UILC Line card
Circuit Card Description and Installation
Page 387 of 906