On this page,
https://kitz.co.uk/adsl/maxdsl2.htm, Kitz wrote:
Fault Threshold Rate.
Once your MSR has been set, BTw use this figure to calculate your Fault Threshold Rate which is in the region of 70% of your MSR. BTw will only investigate speed related faults if your speed drops to below the Fault Threshold Level.
I wonder why this says ‘in the region of’ ? Is it calculated as a variable fraction of some agreed max rate? I thought it was just 70% of the <whatever/> max, but I don’t know where I got that from, probably from this page but I never noticed that imprecise wording.
AA’s definition of FTR in their web pages seems to be just under 80% (~78% ?) of an older long-established max sync rate. They light up an FTR error message in a list of problem lines if a downstream synch rate goes too low, It could be based on the MLF (max load factor) as I term it, fraction of the max at which they drive the ingress into a link, and that is currently set to be 98% so if so that would explain the fact that it seems to be a bit lower, about 2%, than the round number of 80%. (That sounds like a bug to me.) I could ask them. I’m surprised that it’s doesn’t match BT’s definition of 70%. Anyway, they consider downstream synch rates of around 78% below max sync rate to be a fault. They list all slow lines at the top of the main page in clueless.aa.net.uk so you can see at a glance which are the problem lines if any.
