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Sync Speeds and reliability

Moderator
Moderator
Posts: 18,100
Thanks: 2,640
Fixes: 193
Registered: 06-04-2007

Sync Speeds and reliability

In my thread House Move x2 we are trying to find out why I am not getting the sync speeds I should be with an Att of 46. I don't wish to repeat all that here or encroach on that thread but I have some other questions related to it but don't want to confuse the issues already being discussed there.
Mods, if you feel that I shouldn't have posted this here then please correct my mistake by merging, deleting or whatever is necessary Smiley
Having now got a DG834G v3 router I am wondering about getting it set up for the optimum performance on ADSL2+. I have read a fair bit here but would like a little further advice.
I have set the DSL line to ADSL2+ but am now wondering wther that should be set to multimode?
What about MTU and other tweaks should I try playing with them or leave things as they are.
Cheers

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4 REPLIES
manastro
Grafter
Posts: 101
Registered: 25-01-2009

Re: Sync Speeds and reliability

When I set up my DG834 v4 it defaulted to a MTU of 1452 (or was it 1458?).
Changing this to the max of 1500 didn't seem to do any harm.
Superuser
Superuser
Posts: 9,575
Thanks: 947
Fixes: 54
Registered: 06-04-2007

Re: Sync Speeds and reliability

I suggest setting mode to multimode could be preferable since if the higher frequencies used by ADSL2+ prove to be of no benefit during sync the router will use ADSL2 and not have to waste time "managing" those useless higher frequencies. I think multimode was probably the default setting on the router, and a factory reset would cause it to revert to that.
I don't think MTU and RWIN have any bearing on sync speeds. Whether mode is ADSL, ADSL2 or ADSL2+ obviously does (or should do).
For actual throughput my thoughts are that no change to MTU is needed specifically for ADSL2+, MTU applies all the way to target websites and the same data is being transmitted whichever of the three modes is being used for the copper-wire segment.
If sync speeds are increased for ADSL2+ potentially RWIN needs to be increased in proportion to the factor on sync speed to avoid losing out on throughput capability (reducing delays waiting for acknowledgements of receipt). However if noise is a problem, speculatively the larger segment size could be more prone to uncorrectable damage requiring more retransmissions and reduced throughput. Swings and roundabouts?
Hope this helps
David
David
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: Sync Speeds and reliability

even if i set my dg834g v4 to adls2+ the dlm still forces a adsl2 sync but thats on 50db atten i suppose you may be getting into the adsl2+ terioity and i echo what spraxyt says about if only few tones in adsl2+ band are used it might be better to sync with adsl2
edit just had look at your thread
Quote
ADSL Link Downstream Upstream
Connection Speed 4998 kbps 1004 kbps
Line Attenuation 46 db 13 db
Noise Margin 9 db 6 db

highest sync ive had so far on 50db atten is 4544 at 9db on fastpath
Community Veteran
Posts: 1,981
Thanks: 5
Fixes: 3
Registered: 01-08-2007

Re: Sync Speeds and reliability

YOu wanna see this!!!!  I have an ongoing fault, but current stats
<173> May 29 02:21:57 xDSL linestate up (ITU-T G.992.5; downstream: 2269 kbit/s,
upstream: 58 kbit/s; output Power Down: 19.5 dBm, Up: 11.5 dBm; line Attenuatio
n Down: 47.0 dB, Up: 26.0 dB; snr Margin Down: 13.0 dB, Up: 9.0 dB)
now owrse of than I was on 20CN.  Odd thing is no matter what SNR, I am stuck on a downstream of 2269