User guide

August 2001 135
Troubleshooting
Handling Synchronization Errors
When a trunk loses synchronization, any bits the trunk receives
are invalid. After a loss of synchronization, terminate all calls
and check the trunk status using QUERY_CARRIER_STAT.
When the trunk is synchronized with the network, the
application can proceed.
QUERY_CARRIER_STAT returns information about the
current alarm and synchronization status of the line in the
structure RTNI_E1carrierStatus_s. It also returns any errors
that have occurred since the last time the application called that
function. This information can help you measure the quality of
the link to the network. If the data returned indicates the line
is not synchronized or that alarms are present and the condition
persists for longer than a few hundred milliseconds, the
application should terminate all calls and issue an error
message.
RTNI_E1carrierStatus_s returns the following information
about the line:
Alarm Indicates whether there are any alarms on the line. There are
three alarm types:
Frame Zero Timeslot 16 of frame zero contains an alarm bit. The remote end
sets this bit to signal an alarm.
Timeslot 16 All Ones Indicates that all bits in timeslot 16 are ones. Since timeslot 16
carries signaling bits for all channels, a timeslot 16 all ones
means that the signaling bits are not valid.
This alarm is usually accompanied by a loss of synchronization,
since the framing information on timeslot 16 is necessary to
identify the E1 multiframe.
All Ones Indicates that all bits received are ones. In this situation, all
framing information is lost. An all ones signal is usually sent as
a test pattern to verify the quality of the data link.
Slips Buffer slips indicate that the E1 board is not reading and
writing data to the line at the same rate as the remote end.
Usually, an incorrect clock setting or faulty clock source are
responsible for buffer slips. For more information about setting
the clock, see Setting the Clock on page 100.