DLM seems to be having some fun with my connection today, had 4 resyncs all "Remote Defect Indicator/DLM" but not sure why
It seems to me that the majority of people see this reason, and immediately discard the "remote defect indicator" as being a valid cause.
A "Remote Defect Indicator" is a bit in the OH frames sent between modem and DSLAM; if the DSLAM triggers a resync because of an RDI it is because it has seen the RDI bit set to 0 in the incoming OH bitstream from the end-user modem. In turn, the end-user modem chooses to set RDI to 0 when it has detected a flaw in the synchronisation of the incoming bitstream from the DSLAM (labelled officially as a "sever errored frame").
So an RDI becomes a valid possibility when the end-user modem could be receiving a particularly bad bitstream.
It always struck me that, on a line with bad faults or noise, even if only intermittent, an RDI could be a more likely explanation than DLM.
DLM should only be suspected if there is also a significant change to other framing parameters. In older times, that would be just the INP and delay parameters, but now we need to also watch for target SNRM adjustments. It hasn't happened here, so I would discount DLM.
edit: Looking further each time the snrm crashes there is 10,000's of CRCs. Fortunately it's only a small amount of ES.
Something that causes tens of thousands of CRCs in a few seconds would be just the kind of thing that will bring out a "sever errored frame" and a consequent "remote defect indicator".
It doesn't look promising. The line appears to still be showing the plummeting snrm prior to each resync.
That's certainly not normal behaviour.
The line also jumped in attenuation by 0.9dB after the last resync. All the waiting in the world won't fix that. The attenuation should not change like that.
Definitely still something wrong...