Nortel Networks Circuit Card - Manual (Page 830)

Page 830 of 906 NTRB21 DTI/PRI/DCH TMDI card
553-3001-211 Standard 3.00 August 2005
Foreign and surge voltage protection
Lightning protectors must be installed between an external T1 carrier facility
and the system. For public T1 facilities, this protection is provided by the
local operating company. In a private T1 facility environment (a campus, for
example), the NTAK92 protection assembly can be used.
The NTRB21 circuit card conforms to safety and performance standards for
foreign and surge voltage protection in an internal environment.
Functional description
NTRB21 provides the following features and functions:
• configurable parameters, including A-Law and µ-Law operation, digital
pads on a per channel basis, and Superframe or Extended Superframe
formats
• AMI or B8ZS line coding
• 1.5 Mb Digital Trunk Interface and 1.5 Mb Primary Rate Interface
• 1.5 Mb Clock recovery and distribution of reference clocks
• DG2 or FDL yellow alarm methods
• card status and alarm indication with faceplate-mounted LED
• automatic alarm monitoring and handling
• Card-LAN for maintenance communication
• loopback capabilities for both near-end and far-end
• echo canceler interface
• integrated trunk access (both D-channel and in-band A/B signaling can
be mixed on the same PRI)
• faceplate monitor jacks for T1 interface
• configurable D-channel data rate with 64 kbps, 56 kbps or
64 kbps inverted
• self-test