Service Potential impact
Voice Band Data Transmission Errors for 0.01 to 2 s. Drop Call.
Voice Possible Click.
Clock synchronization can be tracking, on the primary or secondary reference clock, or non-
tracking (free-run). In LD 73 (prompts PREF and SREF), the 2.0 Mb DTI which supports the
active clock controller is defined as the primary clock reference.
Another 2.0 Mb DTI can be
defined as the secondary clock reference. The clock controller synchronizes from the primary
or secondary's incoming pulse stream. The clock controller in turn supplies clocking to all other
2.0 Mb DTI cards.
2.0 Mb DTI hardware detects frame slips in tracking and free-run modes. For tracking mode,
running the midnight routines prints the number of overflows and clears the counter. For free-
run mode, running the midnight routines prints the number of slips and clears the counters.
Frame Alignment Problem (FAP). A Frame Alignment Problem is counted when a bit error
occurs within the framing pattern.
Group 2
Loss of Frame Alignment Signal (LFAS). A Loss of Frame Alignment condition occurs when
frame alignment is lost on three consecutive frame alignment errors. This condition can occur
as a result of the far end of the E1 span going completely out of serviced (due to a power
interruption, for example) or any other reason resulting in the loss of the incoming pulse stream.
The B3 alarm is sent to the far end after the persistence time expires.
Loss of Frame Alignment Thresholds. 2.0 Mb DTI hardware detects out-of-frame conditions.
Running the midnight routines prints the number of occurrences when frame alignment was
lost and clears the counters.
Alarm Indication Signal (AIS). AIS is defined as receiving all "ones" without framing. The
detection algorithm for AIS is two or less zeros per two frames. This allows detection of AIS in
the presence of a 10E-3 error rate, while not detecting all ones with framing as AIS.
When the AIS is detected, the prompt maintenance alarm indication associated with LFAS and
excessive bit error rates are inhibited. B3 alarm is sent to the far end after persistence time
expires.
Alarm Indication Signal 64 Kilobit (AIS64). There are specific AIS requirements for CNET
(France). The first requirement relates to the transmission of AIS in TS16. In that case, all
"ones" should be transmitted in the event that abcd signaling is not supported.
With respect to the reception of AIS in TS16, AIS 64 Kbits must be detected when multiframe
alignment has been lost and the binary content of TS16 is 95 percent 1, counting on 256 or
512 bits.
2.0 Mb DTI maintenance
134 ISDN Primary Rate Interface Maintenance November 2011
Comments? infodev@avaya.com
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