- Has my exchange been upgraded for MAX service?
-
The ADSLMAX service was launched on 31st March 2006 with 99.9% of BT
exchanges enabled to provide the higher bandwidth services.
Please use the broadband availability checker to check the status for your line.
- What sort of speed might I expect?
-
For many users ADSL Max will provide an increase in line speed.
However, users should note that MAX is a rate adaptive service and the
actual speed that a user will experience will be dependent on the line
length, line quality and other factors. It is quite possible for users
in close geographical proximity to receive services with different
speeds.
MAX provides download service at up to 8Mb/s. Although some users may
experience line (sync) speeds at or close to this rate, the majority
are likely to receive line rates around 6.5Mb/s
Actual data throughput speeds will also depend on contention in the
external networks and the performance of the remote server etc. Many
users report actual throughput at around 50% of downstream line rate.
Please note that it is highly likely that different speed tester
servers/applications will report widely differing results and at
different times.
BT do advise that IPstream MAX is delivered over a 'best efforts'
network and that no guarantee is given that the line rate seen by End
Users will result in throughput above that of the IPstream Home/Office
fixed rate services (IPstream Home/Office 2000). Outside of busy
periods, services may take advantage of any reduction in the core
bandwidth utilisation which may be seen by End Users as an increase in
throughput. Under network congestion conditions, a BT IPstream Office
or BT IPstream Max Premium product will receive a higher downstream
throughput than an equivalent BT IPstream Home or BT IPstream Max
product.
BT IPstream Max provides a downstream line rate of between 288 kbit/s and 8128 kbit/s (rate adaptive)
Downstream TCP/IP throughput rates will be below the line sync rate -
if line sync is shown at 8128 Kb/s then the absolute maximum payload
rate will be 7150 Kb/s. Users with a sync rate of 4000 Kb/s will see a
maximum throughput rate of 3500 Kb/s. Practical usage is likely to be
below these values.
-
Will there be an immediate increase in speed?
-
Note: Regrades will take up to 5 working days from order to provision.
There will then be a minimum 10 day period whilst the maximum line rate
is determined.
When a user upgrades to ADSL Max the system will attempt to synchronise
the user modem/router and the BT exchange DSLAM to determine the
maximum stable rate (MSR). ADSL Max is rate adaptive - the BT system
will record upper and lower line rates. Data will be collected for a
MINIMUM of 10 DAYS before the lower line rate is rounded down and to
become the MSR. The Fault Threshold Rate (FTR) will be set at a level
30% below MSR. There is likely to be some alteration to the line speed
whilst the BT system undergoes 'training' to find the MSR. Once the MSR
is set this will be the benchmark level for the lifetime of the
connection.
- Once the MSR has been set will the line always run at this speed?
-
The actual line speed will vary but should remain within a tolerance
limit between the MSR and the FTR. ADSL Max is a more sensitive system
than earlier ADSL and Random Electrical Impulse Noise (REIN) and third
part interference may affect the line speed.
If the line rate becomes unstable the user modem/router will establish
a new line rate. This will require re-training of the connection.
Stability does depend on the quality of the users own internal wiring
and on the physical line conditions. It is essential to ensure that all
telephone sockets on the ADSL line are equipped with approved
microfilters to reduce the impact of interference etc.
- What is 'Training' ?
-
When the MAX circuit is first connected the BT DSLAM (in the local
exchange) will communicate with the customer equipment (modem/router)
and will attempt to determine the optimum line synchronisation speed.
This will be dependent, amongst other things, on line length and line
quality.
The BT DSLAM will pass details of the line characteristics to a central
BT system and will set the line profile (initially this is likely to be
within 75 minutes but may take 3 days). The line profile (also known as
the BRAS setting) will determine the download speed of the circuit.
ADSL MAX provides digital line management (DLM) which will continually
monitor the line characteristics and will make adjustments if required.
If the line synchronisation falls below the previously set rate (below
the noise threshold set for the rate) automatic re-training will take
place to try to detemine new characteristics for the line. Automatic
re-training will not take place when the line improves and can support
a higher line rate. In tihs case it will be necessary to attempt a
manual re-synch.
Manual re-training can be initiated by disconnecting the modem/router
from the ADSL service for at least 60 seconds. When re-connected the
equipment will re-establish a link with the DSLAM - if this is
different to the previous synchronisation speed then re-training will
occur and a change in the line profile will follow. When initiating a
manual re-train there will always be a possibility that a line will
re-sync at a lower speed than previously.
Note: Line sync rates can be affected by external interference
(thunderstorms, 'noisy' electrical equipment (fridges, freezers,
washing machines etc.) and may re-sync at a lower rate during or after
periods of interference. Line profiles will fall within 75 minutes of a
lower synchronisation event and will only increase when higher line
rates have been recorded for 3 consecutive days.
When migrating from one provider to another there may be a loss of
synchronisation. If this occurs then there is a possibility of
re-training when migration is completed. This is not implemented by
NewNet and is a function of the BT IPStream MAX circuit.
- If the speed can vary, how will I know if there is a fault?
-
If the line (sync) speed should fall below the fault threshold - set at
30% of the maximum stable rate then there may be a fault with the line
circuit. NewNet Customer Support will be able to refer faults to BT
where the line speed (sync rate) has fallen below the FTR.
Where the line speed falls below the FTR, investigations will be
initiated by BT to determine the reasons for the fall.
- What is Digital Line Management (DLM)?
-
Digital Line Management is provided for ALL ADSL Max services and
offers automatic tuning of line performance to improve stability and
service performance. The performance of the line is determined by
counting the errors and re-trains each day. This will result in a
performance score with a set of rules based on the line performance
history then used to make an automated decision for re-profiling.
Re-profiling will typically cause a loss of service (20-60 seconds)
but, as this will typically only be applied to lines with a poor
performance record, the user is unlikely to experience substantial
service deterioration. Interleaving may be recommended to improve line
stability.
- What is INTERLEAVING?
-
Noise on a line can cause interruptions to data packets. Interleaving
is a process that spreads data over a series of packets so that any
noise or other factor causing packet loss has less of an overall effect
on the data traffic.
Interleaving will be set to AUTO by default. This will permit BT to
adopt interleaving as a DLM tool to resolve issues with a line.
Interleaving can be set to ON or OFF on an individual line basis.
Please note that Interleaving will increase latency within the circuit
- typically between 20 and 40ms. For many users this will not be
significant but for some applications it may be important (games
playing etc.) Individual users will be able to request interleaving to
be set to OFF for their line - although this may impact on line
stability.
Where a fault condition occurs it may be necessary to switch line
interleaving to ON to try to resolve the problem. It may be necessary
to advise a customer that this should be left ON for improved
performance - if the customer requires this to be left OFF then the
original fault state may return.
- How do I change the Interleaving option?
-
New ADSL max circuits (and those regrading from an earlier ADSL
package) will be set to AUTO be default. Customers will be offered the
option to set Interleaving to ON or OFF as part of the order process.
Customers will be able to request a change to their Interleaving status
via the online order form process. Log in and then select the ADSL
Service Change option and then follow the instructions to request a
change to Interleaf status.
Please note that a charge of £6 (£6.90 inc VAT) will be
applied to all requests to change interleaf status (including from Auto
to ON or OFF as part of initial order).
- How do I regrade my existing ADSL service to ADSL Max?
-
Log in to the NewNet online order area and select the ADSL Service
Change option. Click the button to 'Regrade' and follow the on-screen
instructions. A charge of £6.00 (£6.90 inc VAT) will be
made for all upgrade requests.
- Will my existing ADSL equipment work with ADSL Max?
-
Most ADSL equipment (modems and routers) is likely to work with ADSL
Max. Users with routers are likely to find fewer problems when
regrading to Max services than users with USB modems.
Many broadband (USB) modems may be expected to support maximum line
speeds of up to 4 Mb/s but may not support higher speeds. Users of USB
modems should ensure that the latest drivers are installed (refer to
equipment manufacturer's website). Some older USB modems may not be
suitable for Max services - check the manufacturers specifications to
check whether your equipment is able to work at speeds above 2Mb/s.
Users with USB modems connected to USB1 ports are unlikely to see any
benefit from a Max service.
USB modems are likely to require manual re-connection following any
break or interruption to broadband service and require the computer to
be switched on at all times.
NewNet recommends that users upgrade to a router and ethernet
connection in order to experience the optimal ADSL MAX experience. <
- What level of priority does NewNet ADSL Max deliver?
-
Home and Business up to 8Mbps services are delivered with BT IPStream Max level of priority.
Office Broadband up to 8Mbps is delivered with BT IPStream Max Premium
level of priority. Under network congestion conditions, an IPstream Max
Premium product will receive a higher downstream throughput than an
equivalent IPstream Max product
- Can I run VPNs over ADSL MAX?
-
VPNs can be created to run across MAX circuits - and many users will
find the increased upstream speeds to be a benefit. IPStream MAX
Premium products (Office 8000) will be particularly suited to VPN use,
offering upstream speeds to 832 Kb/s and prioritisation of traffic flow
during busy network periods.
