Alcatel-Lucent 9500 MXC, User Manual, Page: 767 / 916

9500 MXC User Manual
3DB 23063 ADAA - Rev 004 July 2007 Vol. VI-B-41
input.
Auxiliary Channel (n) Clock Failure
Auxiliary channel clock failure, where ‘n’ may be 1 to 3 for a Node, or 1 for a
Terminal. This is a warning alarm.
Probable Cause
No clock has been detected on an auxiliary port configured for synchronous data.
Recommended Actions
This alarm will only be activated when an AUX port has been configured for an
external clock and no clock is detected on the customer interface .
The loss of external clock normally indicates a failed connection to external
equipment, which is providing the clock.
Alternatively, if it is a new configuration, the external clock selection in the AUX
plug-ins screen may be incorrect.
Additional Information
The AUX acts as a DCE (data communication equipment). A general rule is that
DCE devices provide the clock (internal clocking) and that the DTE (data
termination equipment), such as a PC, synchronizes on the provided clock
(external clocking).
Normally, on any given synchronous data circuit one DCE device is configured
as the master device, and has internal clock selected. This master DCE ensures
all other DCE devices, which have external clock selected, and DTEs, are
maintained in synchronization.
Where the AUX sync circuit is providing connection between two DTEs (such as
two PCs) one AUX must be set for internal clock, the other external.
Where an AUX sync circuit is used to extend a circuit which includes other
(external) DCEs, again, just one DCE must be configured to provide an internal
clock. This DCE may be one of the AUX plug-ins, or an external DCE device,
such as a modem.
If more than one DCE is selected to provide an internal clock, data slippage will
occur.
When internal clocking is used, the Tx clock is phase locked to an internal
oscillator. When external clocking is used the phase of the outgoing Tx clock is
locked to the clock signal provided from the received (external) clock.
When connecting from a DCE to a DTE, a straight cable is used. When
connecting from a DCE to another DCE, a cross-over cable must be used.