Nortel Networks 311

950 NTAK792.0 Mb PRI card

that it 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,but switches over to the primary when the primary

recovers. If the primary recovers ﬁrst, the clock controller tracks to the

primary.

If the software 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 becomes

out of speciﬁcation, the clock controller automatically tracks to primary

provided that it is within speciﬁcations. On failure (both out of spec.), 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, then the clock controller tracks to

the primary, but switchesover to the secondary whenever the secondary

recovers. If the secondary recovers ﬁrst, then the clock controller tracks

to the secondary.

A time-out mechanism prevents chatter due to repeated automatic switching

between primary and secondary reference sources.

If the software 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 becomes out of

speciﬁcation, the clock controller automatically tracks to secondary provided