A Second Quarter of Reliability, Performance, and Capacity

It's been a while since the last entry. Since that time the focus has been on managing 500+ circuits when four critical resources are lost and recovered. Those four resources are: signal gateway (ss7boxd), media gateway (sangoma_mgd), SS7 route, and bearer channel spans (E1 or T1).

Initial designs were found to be flawed when taken to high capacity test and some field trials. Two revisions followed and now the basic design is settled. The system, called Circuit Maintenance Manager (CMM) is now undergoing high capacity test and field trials. It currently supports loss/recovery of signal gateway, media gateway, and SS7 routes. The bearer channel span management function is ready for development now that underlying support is available from the Sangoma device driver as of this past week.

The CDR Logger is under going a change. The points in ss7boost where information is injected to the logger has been reduced and is now coupled tightly to the ss7boost message input/output functions and timer function. This change ensures no loss of info to the logger. The call serial number field is no longer provided because it did not make sense in some situations. Log entries are correlated into circuit event using the call setup id , span/chan and timestamps for outbound calls, and span/chan/timestamps for inbound calls. The reason for the change is that CDR Logger began as a tool for creating call records only but has also been valuable as a protocol analyser. The older logger missed some messages events which were not important to creating CDRs but were important for protocol analysis. The new logger improves the analyser function while retaining the call record creation function.

Another activity this summer has been load testing with 16 E1 loaded fully with 30 second calls. A number of bugs were found and fixed and the overall quality has improved noticeably.

There are now two release versions of SMG: stable and beta. This is more work but the time has come to provide options for SMG users. Stable releases will only receive small fixes and now new features. Beta releases will contain all fixes and new features. Stable releases that are closed will be reproducible. This marks a significant change from the past when development was much faster and installations were smaller and more change tolerant. As SMG has become more stable, users have indicated the SMG must change in a more controlled manner.

SMG ANSI installations are growing and bring new challenges. The circuit continuity test appears to be used more often in these locations. The procedure is slightly different from the ITU method. The final stage of COT reception functionality for four-wire circuits is being completed to comply with requirements from a major western USA service provider.

The third quarter 2008 will see initial development, testing, and field trials of the long awaited clustering function where asterisk boxes are clustered around an SMG box (already available) and SMG boxes are clustered around an ss7box box. Following cluster development will be the re-introduction of ss7box redundancy.

Other features in the works are expanded conformance testing and expanded ISUP parameter decoding. In particular are the calling party category and the generic number parameters. Asterisk does not have a convenient container for the many ISUP parameters so SMG is sneaking the information in and out of Asterisk using a char long string.