does this PHYR dynamically apply the latency overhead or just the speed overhead?
to me the latency penalty is bigger than the sync speed penalty as many people dont understand the impact of latency on speed.
eg. load a site hosted in asia and one might think asia has some tiny backbone or something and that why its slow, when the real reason is the high latency means the tcp ramps up so slow that the effective speed is slower.
another way I can put it.
a 10mbit connection with 10ms latency to say london will load most websites faster than a 100mbit with 30ms latency. The 10mbit connection will be faster than the 100mbit connection for pretty much all activity that deals with small packets and will hit its max speed quicker on downloads. The 100mbit would win on large file downloads. By small I dont mean tiny as in 1kB, even eg. images that are 250kB will load faster on the first connection as the speed will ramp up quicker.
this is especially apparent when uploading as many applications still use a hard set static low upload buffer size, meaning latency is king on throughput in those situations.
The reasons I consider BTw DLM better than openreach is simple, increasing the snrm still allows the user to overide, (better for user, worse for operator) whilst line banding is a hard cap on sync speed that cannot be overidden (better for operator, worse for user). BTw DLM prefers to raise snrm first ahead of applying interleaving, this to me is a better first choice than applying interleaving. Openreach prefers to apply interleaving ahead of banding. Finally BTw DLM can be reset by the isp, Openreach DLM cannot. BTw DLM also (as I remembered it on adsl max, not sure about 21CN adsl) doesnt forcefully drop line sync to apply new settings, they only applied when the line drops for some other reason, whilst Openreach DLM is disruptive it will drop a line to apply new settings. Ironic since DLM is supposed to help stability yet it causes instability to apply settings.
To me these are all logical reasons why the BTw DLM is better, yet many on here consider openreach's better, I would like to know why.
BT Infinity 2 Since Dec 2012 - BQM
Edited by Chrysalis (Sat 31-Aug-13 22:24:48)