Does this sound like banding to you?

[#1]

Hi folks.
My modem syncs consistently with a SNR margin of 10.5 or 11dB.
I can think of 3 scenarios offhand...
1. I've got a target SNR margin of 9dB and I've got banding limiting my sync rate to under 2200kbps.
2. I've got a target SNR margin of 12dB and my line is too poor for the modem to maintain it.
3. My modem is just crap, period.
The reason I even notice this... is that with a fraction more kbps, I'd get into a higher bras profile band.
If any plusnet guru is reading this... could you check for banding please and nuke it
Can anybody think of other reasons why a speedtouch 585v7 would leave a target SNR margin of 10.5 dB?  Seems an odd value.
Thanks.
-- gyre --

[#2]

When I was banded I synced at the same rate every time, no matter what the time was. Also had fairly high SNR values at about 15+.

[#3]

I am confused
my router always showed snr 13.5db what should it be?
I sync at 8128 but can only download at 5970 today (just done a BT speedtest)
If it was lowered could I get at least 7500 down speeds I know I wont get 8mg
Puddy

[#4]

Puddy, you are syncing at the maximum possible on ADSL1 so the SNR margin will have no effect and it cannot (and does not need to) go any lower. Your speed fluctuations are either cause by your IP profile changing or contention on the BT/PlusNet network. You might benefit from going onto 21CN which can give speeds up to 20Mbs, you should certainly get higher than you have now. This does depend on the product you are on as the lower nd products are limited to ADSL1 (ADSL Max 8Mbs) speeds.
When I was on a banded profile I always synced at 2272 with a SNR of around 11.5/12, there was no fluctuation on sync speeds.

[#5]

When your router syncs with the exchange at 8128 kbps the maximum throughput speed will be up to 7.15Mbps
The SNR figure appears higher in instances where the attenuation figure is very small (short line to the exchange)

[#6]

Now I understand.
But looking at it another way the up to 8mg is unachievable if I cannot get it no one in the UK can
Why do we allow BT to get away with short changing us?
Puddy

[#7]

It depends on what 'up to 8Mbps' means. Since you are syncing at 8128kbps the digital bits will be transferred to your router at 8128kbps, the headline speed. You require those bits to be correct and none missed so the ATM protocol has to include overheads to ensure that. That overhead is quite significant,
ATM packets consist of 53 cells, with 5 header cells and 48 payload cells. That means 5/53 x 100 = 9.4% overhead.
The ATM cells carry TCP/IP packets which are MTU bytes long, 1500 bytes being the Windows default. TCP and IP have their own headers, normally 20 bytes each, 40 bytes total. That's another 40/1500 x 100 = 2.7% overhead.
Combined, 8128kbps sync speed carries at most 8128 x 48/53 x 1460/1500 = 7164kbps useful data, which BT round to 7150kbps and refer to as the IP Profile.
In real life there are additional considerations, ATM packets cannot contain parts from more than one TCP packet, for instance - so potentially there is additional unused space (higher overhead) in the last one. Additionally connections have to be established, data requested and receipt of packets has to be acknowledged, damaged or missed packets retransmitted, so real speeds are less the the idealised data transfer speed represented by the IP Profile.

[#8]

Seems a lot of maths to work out, saying that what do you think my download speeds should be? taking in to account of what you have written.
Am I being short changed by BT?
I know I am very lucky than most other customers do you think people who are moving should not only consider how many bedrooms their new house has they should also ask how far is the BT exchange/what speed can you get on your internet connection as too
Puddy

[#9]

Quote from: puddy

Am I being short changed by BT?

Not in my opinion, though I think your last BT speedtest result might have been affected by a small amount of network contention.

[#10]

Have just heard back from plusnet... apparently I'm not on a banded profile.  In which case I'm at a loss to explain why I can't get over a 2144-ish sync, any my snr margin is 11 instead of 9.  I'll just mark it down to the 585v7 I think for now, and try another modem later
-- gyre --