Your sync speed is the speed at which you connect (synchronise) to the local exchange at. This speed is negotiated between your router and the DSLAM at the exchange and will be subject to line conditions such as your SNR Margin and line length.
With maxDSL it is quite possible that your sync speed may vary each time you connect. - It is not unusual to get better sync speeds during the early hours of the day/night than in the evening.
Various factors can cause more noise on the line in the evening, which may result in a lower sync speed.
When an End User logs on with maxdsl an "Event" will be sent to the DSLAM. Your modem/router will negotiate with the DSLAM what speed your line can achieve. Details of these events are monitored by the DLM.
Many users may notice a slight increase in the time it takes to sync to the exchange due to this negotiation process.
Maximum Stable Rate. (MSR)
During the first 10 days on MAX details of your logon/sync events are recorded in an Event Collector which every 15 minutes then sends this information to RAMBO.
RAMBO collates events from all users and analyses each users data over a 10 day period to find the Maximum Stable Rate (MSR) for their particular line. The MSR is set from the lowest achieved rate over this 10 day period rounded down to the nearest 0.5Mb. A notification after this period is sent to the RAP profile and your ISP.
During your first ever log in to maxdsl, information is sent from RAMBO over to RAP which forwards the details over to the DSLAM at the exchange in order to set your sync speed.
Sync speeds (and Data Rates) for poorer lines can and will vary over the 10 day training period and these users may experience frequent disconnects and slower speeds until their most stable rate is found.
There's a lot of talk about the MSR, but in day to day use it doesn't really do much as its main purpose is to set your Fault Threshold Rate.
Your MSR will generally stay the same throughout MAXdsl, although a BTw engineer can request the MSR process can be restarted. There has also been some rumours that the MSR process can be restarted during migration between ISPs, but this is not always the case.
With Datastream products, BTw will collate the relevant information but not send it over to the bRAS since this equipment is owned by the DS provider. Instead the information is sent in a report to the DS ISPs so that they can apply the speed to their own bRAS. Once the 10 days have passed BT will also advise the DS provider the stable rate.
Fault Threshold Rate.
Once your MSR has been set, BTw use this figure to calculate your Fault Threshold Rate which is in the region of 70% of your MSR.
BTw will only investigate speed related faults if your speed drops to below the Fault Threshold Level.
Data Rate (bRAS profile)
The Data Rate is the fastest speed (throughput) that you will be able to download at and is profiled by BT at the bRAS.
A maximum throughput level is needed to stop more data than your line can physically achieve being sent down the backhaul and being dropped at the DSLAM.
The DLM continually monitors your sync speed and line performance... and the system should react to any decreases within 75 minutes and any increases within 3 days.
According to BTw, the first Data Rate should be set within 75 mins of going live on maxDSL, but from personal experience and that of many others, this does not appear to be happening.
Most customers do seem to find that their line has a Data Rate profiled at the bRAS within 3 days, although its not uncommon for some users to find that they have been profiled at 2Mb speeds for anything up to the full 10 days.
Personal observations tend to show that it is the better lines that seem to have a delay in setting the Data Rate on the bRAS profile and are "stuck" with their old 2Mb speed possibly because their SNR is better and they suffer from fewer fluctuations, therefore it takes longer for the kit to realise that a change has occurred. :/
The Data Rate should not be confused with the MSR.
Some ISPs allow you to check your Data Rate. PlusNet customers can view their Data Rate here.
SNR /SNR Margin
The Signal to Noise Ratio on the max product is more flexible than on traditional adsl. On the older fixed line speed products an SNR Margin of less than 6dB suggested that there was a problem with the line.
With Max a target SNR margin is set on the DSLAM and its your router and the DSLAM that agree the best way of meeting this target margin. The target margin range is between 3dB and 15dB and rises in 3dB increments - although it is normal for it to fluctuate either side during the training period. The default is 6dB without interleaving.
Dynamic Line Management (DLM)
When the user logs on they send information (line data) to the DSLAM including details of any errors on the line.
The information is collated by the Data Collector which in turn sends it to the Dynamic Line Management system. Its the job of the DLM to analyse the data from the DSLAM and RAMBO to then decide if there is a stable line. If not if any changes to the SNR should be made and/or Interleaving should be used. The constant management ensures that the circuit remains within the set threshold.
If any changes need to be made the DLM sends the information via the flow stream to NCAS.
NCAS then reports to the DSLAM which then makes the relevant changes to the individual users line card. This process will be repeated to ensure the correct changes have been made.
If necessary this process will be continually repeated changing the SNR and/or interleaving until the line is deemed stable.
The DLM process is carried out every time you are connected and not just within the first 10 days.
Configurable attributes of the DLM are SNR and Interleaving.
April 2006
The bRAS profile (data rate) is based on your lowest sync speed, and jumps up in 0.5Mb stages.
So although you may get higher sync speed, your bRAS profile will limit you to what throughput speed you are likely to acheive.
Sync speed (incr 32kb stages) IP profile Max Throughput speed
From To
288 kbps 544 kbps 250 Up to 0.25 Mbps
576 kbps 1120 kbps 500 Up to 0.5 Mbps
1152 kbps 1696 kbps 1000 Up to 1 Mbps
1728 kbps 2240 kbps 1500 Up to 1.5 Mbps
2272 kbps 2816 kbps 2000 Up to 2 Mbps
2848 kbps 3392 kbps 2500 Up to 2.5 Mbps
3424 kbps 3968 kbps 3000 Up to 3 Mbps
4000 kbps 4512 kbps 3500 Up to 3.5 Mbps
4544 kbps 5088 kbps 4000 Up to 4 Mbps
5120 kbps 5664 kbps 4500 Up to 4.5 Mbps
5696 kbps 6208 kbps 5000 Up to 5 Mbps
6240 kbps 6784 kbps 5500 Up to 5.5 Mbps
6816 kbps 7360 kbps 6000 Up to 6 Mbps
7392 kbps 7936 kbps 6500 Up to 6.5 Mbps
7968 kbps 8096 kbps 7000 Up to 7 Mbps
8128 kbps 7150 Up to 7.15 Mbps
Although I understand why BTw have implemented bRAS profiles (to stop too much data flowing across the backhauls and on to the DSLAM), IMHO it may perhaps have been more sensible to round up the bRAS profile rather than the current system of rounding down, particulary in view that the stages are in rather large jumps of 500.
Under the current system, if you sync at say 5088 kbps, your IP profile will be set at 4000 - which means that the maximum throughput speed you are ever going to see is going to be around 4Mbps. :/
Good news is that 8mg upgrade has taken place again and I can still connect to the internet!
Latest stats:
ADSL firmware version : A2pBT009c1.d17d
Connection mode : G.DMT
Type : Interleave
Noise margin (dB) : 11.2
Attenuation (dB) : 24.0
Attainable download rate (kbps) : 10208
ADSL status : Connected [0]
Downstream Upstream
Rate (kbps) 8096 448
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