Nortel Networks NN43001-301 - Manual (Page 157)

Description 157
When only two switches are interconnected, synchronization can be
achieved by operating the two systems in a master/slave mode whereby one
system derives its timing from the other. However, in a network of digital
systems, slips can be better prevented by forcing all digital systems to use
a common reference clock (see
Figure 59 "Hierarchical Synchronization"
(page 159) ).
Supported Clock Controllers
For Large Systems, the following clock controllers are supported:
• NTRB53
• QPC471
• QPC775
NTRB53 Clock Controller
The NTRB53 Clock Controller is a replacement for the QPC471 and
QPC775 Clock Controllers. The NTRB53 clock controller retains existing
functionality.
Software configuration of the clock remains unchanged. A PSDL object
allows field upgrades of the clock’s firmware. Overlay changes allow for
force download and status checking. Support for the IDC command and
hardware inventory are also included.
System Initialization During system initialization, the system software will
verify if the clock controllers equipped in the system are the downloadable
clock controllers (NTRB53) or not. If the clock controllers are identified as
the downloadable clock controller cards, then both downloadable clock
controller cards will be checked for the software version number they are
running with. This is compared with the version number of the PSDL file
stored in the system software database.
If there is a mismatch between the two version numbers and the system
database has the higher version number, the card will be put in the PSDL
downloading tree. Once the entry is added in the PSDL tree, the preprocess
step is done. The next step is for the system to initiate the downloading in
the background, using the PSDL tree. As soon as the download complete
message is received from the card, the CPU sends a message to reset the
clock controller card so that it boots with the new software. Once a self-test
is complete the core sends an enable base message to enable the card.
Maintenance Overlays Downloading can be initiated from LD 60 for the
inactive clock controller card as part of the enabling sequence of the card. A
download can be forced by specifying the optional parameter FDL (Force
Download) when enabling the card. At the prompt, enter:
Nortel Communication Server 1000
ISDN Primary Rate Interface Installation and Commissioning
NN43001-301 02.03 Standard
Release 5.5 7 December 2007
Copyright © 2003-2007, Nortel Networks
.