Intermittent calls dropping

[47458]

Hi all
We are currently having a nightmare with this issue and was hoping for some advise after this issue is currently in month 2.
We are being alerted to the below alert, which drops calls and takes down inbound calls

Minor alarm DTA0203:CS
Time of Event: 14/05/2013 05:05:17
JobID: 1883
Source Machine Name: LON0VIVDIAG02
Event Severity: 20
KS Name: NortelCS_Alarms_HostName_Critical
Object Name: Call Server
Detail Message: NTP index: DTA0203 Nortel CS device: Landor:Landor:CS Alarm: 20 3 2    Help for DTA0203 loop x y: A Group 2 error has been detected by the PRI2 card. The error information is decoded as follows, where x : 4 = LOS (loss of signal) 3 = AIS (alarm indication signal)2 = LFAS (loss of frame)1 = LMAS (loss of CRC multiframe)0 = RAI (remote alarm indication) Where y: 2 = alarm occurred1 = alarm persisted 0 = alarm clearedExample: DTA203 7 4 2 - PRI loop 7 loss of signal occurred.  

We have had the carrier complete end to end testing which have come back as clear, the PRI card has been changed (but continues to have a flashing yellow light displayed) so we are running out of ideas regarding next steps.

Any help would be appreciated.
Many thanks in advance.

 

[lgjc]

You are having loss of framing errors on your PRI. Has anyone checked the clocking? Is it clocking to the primary clock source or in free run. If it is free run you will eventually get slipping. The PRI must be clocking to the primary or secondary (if you have one)source.

 

[Tman45]

Agree with lgjc - flashing yellow needs to be green solid If you issue a trck pck 7 4 2 in LD 60 it should lock on and stay - do a stat in LD 60 to check and if you see DTI 58 or something like that it is in free run.

DTA0203 loop e A Group 2 error has been detected by the DTI card. Error (e) = 1 to 127 (Decimal).
Listed below are various error types (e) and their value in decimal. Error Type
(e);Abbreviation;Decimal Value Loss of CRC4 Multiframe Alignment;CF;1 64 kb
Alarm Indication Signal;AS;2 B6 TS0 non-FAS (far-end OOS); C3;4 Loss of
Frame Alignment;LF;8 Loss of Multiframe Alignment;LM;16 Alarm Indication
Signal;AI;32 B3 TS16 Frame 0 (far-end OOS);C6;64 To interpret any given value
of (e), you must translate (e) to binary. For example, if (e) = 24 (decimal), the
translated binary value = 0 0 1 1 0 0 0. This binary value may now be interpreted
as follows: 0 = C6 0 = AI 1 = LM 1 = LF 0 = C3 0 = AS 0 = CF Therefore, the errors
are for LF and LM.
Action: R9
Severity: Info. Critical to Monitor: Yes
DTA0203 loop x y A Group 2 error has been detected by the PRI2 card. The error information is
decoded as follows, where x : 4 = LOS (loss of signal) 3 = AIS (alarm indication
signal)2 = LFAS (loss of frame)1 = LMAS (loss of CRC multiframe)0 = RAI
(remote alarm indication) Where y: 2 = alarm occurred1 = alarm persisted 0 =
alarm clearedExample: DTA203 7 4 2 - PRI loop 7 loss of signal occurred.
Action:
Severity: Minor. Critical to Monitor: Yes

 

[47458]

Thanks for your help guys, this is the response from our maintainer. The carrier has also been testing throughout the week and see no issues on the circuit. Any thoughts as both the carrier and maintainer are out of ideas. Many thanks as always

Maintainer reponse
The PRI, MSDL and Clock Controller were changed on 2nd May and the AIS alarms were still appearing after this was done. AIS alarms aren't generated by the PRI card, they are usually injected by the NTE or carrier when there is a problem on the line. I've checked the clocking and the CC is locked to the PRI. There were AIS alarms between 06:00 and 08:00 this morning and the d-channel went down and established a couple of time during this period. Can you get the carrier to investigate please.

 

[Firebird Scrambler]

I think it's a carrier problem.

All the best

Firebird Scrambler
Meridian 1 / Succession and BCM / Norstar Programmer in the UK

http://www.linkedin.com/in/davidbromley

If it's working, then leave it alone!.