Nortel Communication Server 1000S Installation And Configuration Manual page 337

NTAK93 D-Channel Handler Interface (DCHI) daughterboard
The NTAK93 DCHI daughterboard interfaces with the system Central
Processing Unit (CPU) and mounts on the NTBK50 PRI card for PRI (but not
ISL) applications. The equivalent circuit resides on-board the NTAK79 2.0
Mb PRI card. The DTI/PRI digital trunk card is installed in the MG 1000S.
Digital trunk cards are not supported in MG 1000S Expansions.
The DCHI is responsible for performing the Q.921 layer 2 protocol
information. It transfers layer 3 signaling information between two adjacent
network switches.
The NTAK93 DCH daughterboard, when installed on the NTBK50 circuit
card, is addressed in the same slot as the NTBK50.
A minimum of one NTAK93 is required for each PRI link. If more than one
PRI link connects to the same end location, a single DCHI circuit card can
support up to a maximum of sixteen PRI connections for the system. This
allows for the support of 495 B-Channels or PRI trunks.
NTBK51 Downloadable D-Channel (DDCH) daughterboard
The NTBK51 DDCH daughterboard interfaces with the system Central
Processing Unit (CPU) and mounts on the NTBK50 2.0 Mb PRI circuit card
for PRI D-Channel applications.
For CS 1000S, it is installed in slots 11-14, 21-24, 31-34, 41-44 of the first,
second, third and fourth MG 1000S, respectively.
Digital trunk cards are not supported in MG 1000S Expansions.
The DDCH is equivalent to the MSDL card on larger systems, but it only
supports D-channel applications (no SDI or ESDI).
The NTBK51 DDCH daughterboard, when installed on the NTBK50 circuit
card, is addressed in the same slot as the NTBK50.
2.0 Mb PRI implementation
ISDN Primary Rate Interface
Page 337 of 394
Installation and Configuration