Nortel Networks 1000 - Manual (Page 816)

816 NTAK20 Clock Controller daughterboard
If the command "track to primary" is given, the clock controller tracks
to the primary reference and continuously monitors the quality of both
primary and secondary references. If the primary goes out of specification,
the clock controller automatically tracks to secondary if that is within
specifications. On failure (both out of specification), the clock controller
enters the HOLDOVER mode and continuously monitors both references.
An automatic switchover is initiated to the reference that recovers first.
If the secondary recovers first, then the clock controller tracks to the
secondary; however, it switches over to the primary when the primary
recovers. If the primary recovers first, the clock controller tracks to the
primary and continues to do so even if the secondary recovers.
If the command "track to secondary" is given, the clock controller tracks
to the secondary reference and continuously monitors the quality of
both primary and secondary references. If the secondary goes out of
specification, the clock controller automatically tracks to primary provided
that is within specifications. On failure (both out of specification), the
clock controller enters the HOLDOVER mode and continuously monitors
both references. An automatic switchover is initiated to the reference that
recovers first. If the primary recovers first, the clock controller tracks to the
primary, but switches over to the secondary when the secondary recovers.
If the secondary recovers first, the clock controller tracks to the secondary
and continues to do so even if the primary recovers.
To prevent chatter due to repeated automatic switching between primary
and secondary reference sources, a time-out mechanism of at least 10
seconds is implemented.
If the command "track to primary" is given, the clock controller tracks to the
primary reference and continuously monitors the quality of both primary
and secondary references. If the primary goes out of specification, the
clock controller automatically tracks to secondary when the secondary
is within specifications. On failure (both out of specification), the clock
controller enters the HOLDOVER mode and continuously monitors both
references. An automatic switchover is initiated to the reference that
recovers first. If the secondary recovers first, then the clock controller
tracks to the secondary, then switches over to the primary when the
primary recovers. If the primary recovers first, the clock controller tracks to
the primary and continues to do so even if the secondary recovers.
If the command "track to secondary" is given, the clock controller tracks
to the secondary reference and continuously monitors the quality of
both primary and secondary references. If the secondary goes out of
specification, the clock controller automatically tracks to primary provided
that is within specifications. On failure (both out of specification), the
clock controller enters the HOLDOVER mode and continuously monitors
both references. An automatic switchover is initiated to the reference that
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
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