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[roseway]

There's nothing particularly unusual in that graph. You have a highish attenuation, and it's inevitable that some bitswapping will take place to maintain the integrity of the connection.

Although your package is described as 'up to 12 Mbps' it will still be ADSL2+ but capped to 12 Mbps by the ISP.

[silversurfer44]

Thank you again Eric. I understand more now. I was a bit concerned about the gaps that appeared in less than 24 hours.
Ha well I'll just have to move house.

[roseway]

>> Ha well I'll just have to move house.

Unfortunately that's sometimes the only way to get a better internet connection.

[kitz]

>> According to the display I have an ADSL2+ connection, yet the package I have been given by O2 is a 12meg connection

adsl2+ is rate adaptive and your line will sync as high as it can up to 24Mb.  The longer the line then the more the sync speed will reduce and its only the shortest lines that are able to sync at the full 24Mb.
Its possible to have a long line syncing at 2Mb that could be on adsl2+, since this is the specification of the technology used and the limitation of the line length.

>> 'ADSL(1&2) has a maximum available 223 downstream subchannels. 223 x 56kbps = 12Mbps.'  Huh?
>> I am not over bothered about this it just confuses me a little.

adsl1 and adsl2 has sufficient channels for a line to theoretically sync downstream at up to 12 Mb.  However overheads needed for such things as Error Correction and limitations of ATM packet sizes mean that there is a physical limitation of 8Mb set on the line at the dslam.

Theres something called S=1/2 mode which makes the Error Correction more efficient and switching to S=1/2 mode on adsl1 will allow a higher sync.  S=1/2 mode combines 2 RS codewords into one making Error correction more efficient with regards to overheads.
Both the router and the dslam have to be able to cope with s=1/2 mode though for this to work... and its the reason why some interleaved lines will sync higher than the 7616 often quoted.   However the 8128 is then a restriction set on the dslam which is why it wont sync higher than this for adsl1.

adsl 2 & adsl2+ already make use of s=1/2mode so no point fiddling with that any further if you are already using adsl2 or 2+

Just found this which explains S=1/2 mode a bit more.
Although in that article it says by using this it yeild up to a maximum 16Mbps for adsl2.  Therefore Im not 100% certain why adsl2 is still set at 12Mb.. its very likely they are talking about the ideal world situation and no problems with crosstalk and no neighbouring lines to contend with.
Because of crosstalk certain channels cant be used for downstream.. so when that article refers to 16Mb it could mean total speed.. because adsl2 allows 12Mb downstream and 3.5Mb upstream on the channel allocation.  Add those together and also add in the bands that cant be used (the stop bands and for POTs) then you are looking at 16Mb.
In the UK (and other countries) certain bands just simply cant be used for downstream and masks are applied to ensure that they arent used... or else anyone with a strong downstream signal at those frequencies would simply drown out any neighbouring upstream signals and vice versa.

I believe a very simplified way to look at this is

adsl(1) allows up to 8Mb downstream sync
adsl 2 uses S=1/2 mode to increase the downstream sync to 12Mb
adsl 2+ doubles the available frequencies allowing a maximum downstream sync of up to 24Mb

[silversurfer44]

Strangely enough I am beginning to understand quite a lot of what you are saying about adsl in general. I am also understanding what I am looking at in the graphs. Do I get a degree at the end of this please?
Just one more question and that is is it a good idea to reboot these modems every couple of days or so? I know I don't have to worry about IP Profiles, but, am I likely to upset the dslam or something by doing this? The reason I ask is whilst the sync rate stays the same the throughput does degrade over time.

[kitz]

>> is it a good idea to reboot these modems every couple of days or so?

I normally recommend you leave the modem/router to settle at its own level,  only rebooting if you have a low or bad sync for some reason.

There may be times after a bad noise incident where the router can mark certain channels as unusable, which in turn can cause bit swapping perhaps not to be as efficient as it could be.. and in these cases it does no harm to do a resync or power-cycle. 
The main thing is not to do it too often particularly if you are on a BTw based product or it may trick the DLM into thinking you have a more serious problem.  Resyncing every few days though should be fine.

[silversurfer44]

Thank you for the advice yet again. I am now on a LLU based product which is why I said that I'm not worried with ip profiles now. I understand about not re-syncing for the sake of it and not too often, I was thinking a couple or three days in between. I asked the question as I noticed in the graph that quite a few more gaps had appeared, however I will let it run and see what happens.

[jid]

I normally recommend you leave the modem/router to settle at its own level,  only rebooting if you have a low or bad sync for some reason.

I have learnt from this

Leave you router as it is and "let it do its thing" !

Yes with LLU there are no LLU profiles to worry about.