Hi Matt and asterisk-ss7 members, Looking at the dahdi-linux code, there seems to be an important feature lacking on the dahdi mtp2 feature: Should the mtp channel go down, without the E1/T1 span go down (no alarms), there's no notification sent to the application (usually asterisk). I suggest an inactivity timer be implemented on dahdi, so if no new mtp2 messages get received over a 100ms period, a HDLC Abort message (or any other specific message) gets send to userland. This way should libss7 receive say, 2 messages in close proximity it will consider the link dead and initiate realignment. Additionally should this error condition be raised to userland, upon receiving a valid repeated message, it would be sent to userland to indicate things are back to normal. Without this, technically libss7 isn't compliant with a few of Q.7xx specs. I've seen real world situations where lack of this feature would cause serious problems. Specially this would be a serious issue with E1 links between Asterisk and a TDM switch, where the signalling link is switched to a STP using a semi permanent call. Should the STP or the link between the TDM switch and the STP die, the only available indication would be that the signalling link would go dead (with perhaps one HDLC Abort or CRC error being detected, should the link go down preciselly between FISUs, then no error at all might be detected). This is very common in Brazil, the largest carriers use this layout exclusively on interconnects. Matt, what do you think ? Do you have a better suggestion than an Abort message ? Regards, Marcelo Pacheco
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