strange internet behaviour

[glen_m_32]

Hi all,

I have not been here a while. but i am having issues again with my broadband. i am with bt ADSL max on an exchange which is not LLU'd and there is no plan for 21CN ADSL2+ yet. since before xmas our internet has been very iffy, slow (evenings i cant download anything faster than 100KBps whereas at 6am i get 600KBps).

my setup is as follows, Belkin N1Vision Router, Mini-ITX pc and PS3 connected to router at 1gigabit, 2 laptops both using N1 Network adaptors connected at 135mbps and 260mbps.

 i am usually synced at 8128Kbps, but as you can see from my router stats i am synced at 6304Kbps. Looking at the attenuation (28, but used to be  26) and the Max Speed Calculator i should be synced at 8128Kbps. Currently my exchange is currently showing virtual paths as "red". does this cause some of the problems i have described.

i dont know this will help, but i have also attached my routers system log.


I really hope someone can help?

Thanks

Glen

[waltergmw]

Hi Glen,

I'd give them a few days but then rattle their cage as they're supposed to have fixed the problem.

However the following might also be having an effect at present:-

19/10/2006     BT have set a target date of Q4 2009 for the switch to 21CN for the Warboys exchange

Kind regards,
Walter

[glen_m_32]

Thank you for your quick reply.

last time i rang up and complained about VP problems no one knew anything about VP's.

"19/10/2006     BT have set a target date of Q4 2009 for the switch to 21CN for the Warboys exchange", if you now look at samknows that information has been removed and replaced with a red cross! i assume they have decided that we are not special enough to get the 21CN yet.

When they do hit the 21CN switch will that mean that ADSL2+ will be initiated?

thanks again

Glen

FYI my IP profile is 5500Kbps

[waltergmw]

I am unsure quite how reliable various dates etc. are. Perhaps others might comment as well.

You'll see below a screen picture of the history from the bottom of the Samknows page for your exchange.

Kind regards,
Walter

[glen_m_32]

Is there anyway of telling if the switchover has occured?

Thanks

Glen

[jeffbb]

Hi
quote i am usually synced at 8128Kbps, but as you can see from my router stats i am synced at 6304Kbps

could be that  because of your problems interleave has been activated
: D:      32      4

Regards Jeff

[glen_m_32]

Thanks for your suggestion, I am pretty sure that interleaving has been turned on from day 1! My sync speed has increased a little to 6500! My download speeds are still eratic!

My router has a screen on it which can instantly tell me the throughput ofmy connection, last night I was downloading a ps3 game and it kept jumping from 200Kbps up to 3700Kbps. It was never stable!

My current SNR is 13.1dB!
Thanks again

[orainsear]

The normal maximum synchronization rate with interleaving activated is 7616 kbps.

With interleaving deactivated (fastpath mode) the maximum synchronization rate is 8128 kbps.  See http://www.kitz.co.uk/adsl/interleaving.htm

If you were usually synchronized at 8128 kbps then it would appear that you were previously on fastpath mode and for whatever reason (usually line instability) interleaving has been activated.


>>>Is there anyway of telling if the switchover has occured?

Have you queried your ISP about this?

Edit: Do you notice any correlation between your throughput rates and the time of the day?

[duckson]

You can sync at 8128kbps with Interleaving ON, mine has been for years on different routers.

[glen_m_32]

Yes, in the evenings the through put is very slow. if i then check it at 6 in the morning i get very fast downloads and the net flys.

This makes me think that it is a contention issue, but a friend on the same exchange does not have a drop in speed like mine.

no i have asked BT about the 21CN thing, i havent had time. hopefully tomorrow i will be able to!

Thanks

Glen

[orainsear]

>>>You can sync at 8128kbps with Interleaving ON, mine has been for years on different routers.

Probably something to do with the hardware being able to support S=1/2 mode and the maximum attainable rate being high enough to allow the overheads to be taken from that chunk of bandwidth between the max attainable rate and the max reported sync speed; max attainable rate depending on the line attenuation.


>>>This makes me think that it is a contention issue.

It does sound like congestion.

[glen_m_32]

Thank you for that, but I don't understand what s=1/2 mode means?

Thank you for your help

[jeffbb]

Hi
A bit more info courtesy Of Kitz

If you have a router that supports s=1/2 mode... and the dslam you are on is also configured to supposrt s=1/2 mode (not all are), and  if your line is good enough to be able to load sufficient bits per subchannel.... then an interleaved line can over-ride the maximum 'normal' limitation of 7616 for an interleaved line.  You wont ever get more than 8128 though, since that will be a hardcoded maximum configuration of BTs dslams.


found  here 

regards Jeff

[orainsear]

S represents the number of data frames for every Reed-Solomon codeword.  S=1/2 mode is when 2 data frames are mapped to a single Reed-Solomon codeword (max 510 bytes). http://www.kitz.co.uk/adsl/interleaving.htm

[duckson]

Thanks Jeff, i didnt know that and always wondered why my interleaved line syncs at 8128kbps...well when the current noise problems arent stopping it doing so.