Overview - Nortel Enterprise 1000 Reference Manual

Page 26 of 236 NTAK20 clock controller daughterboard

Overview

553-3023-211 Standard 1.00 June 2001
Digital trunking requires synchronized clocking so that a shift in one clock
source results in an equivalent shift in all parts of the network. In the
Succession Communication Server for Enterprise (CSE) 1000 system,
synchronization is accomplished with an NTAK20 clock controller
daughterboard located in each Media Gateway that contains a digital trunk
card.
The NTAK20 clock controller daughterboard mounts directly on the
following cards:
• NTAK09 1.5Mb DTI/PRI
• NTBK50 2.0 Mb PRI
• NTRB21 DTI/PRI/DCH TMDI
The NTAK20 clock controller card can support 1.5 Mb, 2.0 Mb, and 2.56 Mb
clock recovery rates.
Each Media Gateway that has a digital trunk must have a
clock controller clocked to an external reference clock.
Note: Clocking slips can occur between Media Gateways that are
clocked from different COs, if the COs are not synchronized. The slips
can cause degraded voice quality.
The clock controller circuitry synchronizes the Succession CSE 1000 system
to an external reference clock, and generates and distributes the clock to the
system. The Succession CSE 1000 can function either as a slave to an external
clock, or as a clocking master. The NTAK20AD version of the clock
controller meets the AT&T Stratum 3 and Bell Canada Node Category D
specifications. The NTAK20BD version meets CCITT Stratum 4
specifications.
The NTAK20 card performs the following functions:
• phase lock to a reference, generation of the 10.24 Mhz system clock, and
distribution of the clock to the CPU through the backplane
IMPORTANT