sevenlayermuddle
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Posts: 507
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« Reply #22 on: January 25, 2010, 09:34:43 PM » |
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DLM's normal sampling period, prior to margin reduction, seems to be 14 days, though it's not really documented.
Jeff's advice is always good and, as he says, you could choose your time to tweak (or even resync), and get yourself a good connection speed. I hope Jeff won't mind if I add, however, that 'fighting' DLM may give you a higher speed, but a faster speed also means a higher error rate, which may reduces the chances of DLM reducing your target. DLM may also (sorry for all the 'may's, we just don't know!) look to see how you actual SNRM compares with its target and, if it is always less than the target, it may be less inclined to reduce it.
I put up with a 15dB margin for over a year, then one day my line resynced, after a power cut, about 1.5Mbps lower than it's usual speed. Instead of reconnecting to get the speed back I left it at the lower speed, but with an actual margin of 18-22 or so. Within two weeks DLM rewarded me with a 3dB target reduction. I subsequently re-enacted the same scenario by deliberately tweaking my line to a slower speed, and DLM this time reacted in less than a week, with another 3dB cut. These reductions have been permanent, my line is now happily managed by DLM, and maintains impressive connection speed.
Another aspect that's cropped up several times, is that if you ask your ISP to get your margin reduced, as opposed to waiting for a natural reduction, the reduction commonly evaporates after 48 hours. We don't know why that happens, but its a common scenario, DLM may just be programmed to be hyper-sensitive following ISP-requested adjustments. It may be a thing of the past now, as per other threads on CCSNR, but that's something subtly different.
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