The saga of establishing a stable rate with BT.

My alteration to MAX DSL came as a pleasant surprise about a month ago. My
line started syncing at around 4200 and was stable at this rate. It then
dropped to about 3800 for no obvious reason and remained rock solid for 24
hours or more at a time. Unfortunately BT used a very conservative rate to
prevent downloads being sent to fast and overwhelming things. This started
off at 2000 and only increased to 2500 after nearly a fortnight. Even though
the syncing was quite steady I rebooted every day to try and train the
system. After nearly a month the stable rate has risen to 3000 but is still
below the rate that the line demonstrably supports. Suggestions that the
rate is established over ten days just don't seem to be true because the
actual time seems much longer. From this I can only conclude that the
algorithm BT use to set the stable rate is seriously flawed and needs
changing. I would have hoped that the trial period would have enabled BT to
resolve this sort of issue before they launched the product. Constructive
comments welcome.

Peter Crosland

Peter Crosland wrote:
> My alteration to MAX DSL came as a pleasant surprise about a month ago. My
> line started syncing at around 4200 and was stable at this rate. It then
> dropped to about 3800 for no obvious reason and remained rock solid for 24
> hours or more at a time. Unfortunately BT used a very conservative rate to
> prevent downloads being sent to fast and overwhelming things. This started
> off at 2000 and only increased to 2500 after nearly a fortnight. Even though
> the syncing was quite steady I rebooted every day to try and train the
> system. After nearly a month the stable rate has risen to 3000 but is still
> below the rate that the line demonstrably supports. Suggestions that the
> rate is established over ten days just don't seem to be true because the
> actual time seems much longer. From this I can only conclude that the
> algorithm BT use to set the stable rate is seriously flawed and needs
> changing. I would have hoped that the trial period would have enabled BT to
> resolve this sort of issue before they launched the product. Constructive
> comments welcome.
>
> Peter Crosland
>
>

As a comparison Peter, mine started with a sync rate over 6000. This
quickly dropped to about 5000 and my throughput was initially set to
4500. After a month or so things are now pretty steady. I see a sync
rate of 4000 - 4500 and my throughput fluctuates between 3000-4000.

Regards,

--
|Bob Pullen Broadband Solutions for
|Training & Project Liaison Home & Business @
|PlusNet plc www.plus.net
+ ----- PlusNet - The smarter way to broadband ------

"Peter Crosland" <(E-Mail Removed)> wrote in message
news:4469f387$0$10772$(E-Mail Removed)...
| My alteration to MAX DSL came as a pleasant surprise about a month ago. My
| line started syncing at around 4200 and was stable at this rate. It then
| dropped to about 3800 for no obvious reason and remained rock solid for 24
| hours or more at a time. Unfortunately BT used a very conservative rate to
| prevent downloads being sent to fast and overwhelming things. This started
| off at 2000 and only increased to 2500 after nearly a fortnight. Even though
| the syncing was quite steady I rebooted every day to try and train the
| system. After nearly a month the stable rate has risen to 3000 but is still
| below the rate that the line demonstrably supports. Suggestions that the
| rate is established over ten days just don't seem to be true because the
| actual time seems much longer. From this I can only conclude that the
| algorithm BT use to set the stable rate is seriously flawed and needs
| changing. I would have hoped that the trial period would have enabled BT to
| resolve this sort of issue before they launched the product. Constructive
| comments welcome.
|
| Peter Crosland
|
|
"From this I can only conclude that the algorithm BT use to set the stable rate
is seriously flawed"

Why? Because you don't like the figure it has arrived at? - Can you be sure that
you know better?
How can you tell exactly what the exchange DSLAM monitoring equipment is seeing
on your line?

I am curious because this seems to be a typical rant about BT. You cannot be
sure what the line was doing at 4200. You also have to consider that line and
noise conditions are a variable factor. I appreciate it may frustrate you but it
must be done for a reason, be it for fiscal, technical or conservative reasons.

> "From this I can only conclude that the algorithm BT use to set the stable
> rate
> is seriously flawed"
>
> Why? Because you don't like the figure it has arrived at? - Can you be
> sure that
> you know better?

What I was saying is that the BT system seems to be far slower in responding
to what would by most standards be regarded as stable. Even thought the
router/modem was staying connected for at least twenty four hours at around
3800 and was rebooted day after day the BT system did not alter the stable
rate for a fortnight.

> How can you tell exactly what the exchange DSLAM monitoring equipment is
> seeing
> on your line?

Of course I cannot. What I can see is my router/modem running for hour after
hour with negligible errors reported by its own monitoring.

> I am curious because this seems to be a typical rant about BT.

Reasoned criticism is not ranting. If you think what I wrote was a rant then
perhaps you need to consult dictionary as to the real meaning of the word.

>You cannot be
> sure what the line was doing at 4200. You also have to consider that line
> and
> noise conditions are a variable factor. I appreciate it may frustrate you
> but it
> must be done for a reason, be it for fiscal, technical or conservative
> reasons.

Perhaps you would like to explain just what you mean by that statement? As
it stands it does not make much sense in the context of what is under
discussion.

I mentioned that the router/modem synced at around 4200 and then dropped
back to 3800 or so. That suggests to me that the syncing at 4200 anomalous
and it should have been evident from what I wrote. I also made it abundantly
clear that I was no finding fault with the sync rate but with the stable
rate set by BT which seems to be set at a very low value and the mechanism
for altering it is slow.

Peter Crosland

"Peter Crosland" <(E-Mail Removed)> wrote in message
news:4469f387$0$10772$(E-Mail Removed)...
> My alteration to MAX DSL came as a pleasant surprise about a month ago. My
> line started syncing at around 4200 and was stable at this rate. It then
> dropped to about 3800 for no obvious reason and remained rock solid for 24
> hours or more at a time. Unfortunately BT used a very conservative rate to
> prevent downloads being sent to fast and overwhelming things. This started
> off at 2000 and only increased to 2500 after nearly a fortnight. Even
though
> the syncing was quite steady I rebooted every day to try and train the
> system. After nearly a month the stable rate has risen to 3000 but is
still
> below the rate that the line demonstrably supports. Suggestions that the
> rate is established over ten days just don't seem to be true because the
> actual time seems much longer. From this I can only conclude that the
> algorithm BT use to set the stable rate is seriously flawed and needs
> changing. I would have hoped that the trial period would have enabled BT
to
> resolve this sort of issue before they launched the product. Constructive
> comments welcome.

Does the BRAS have an impact on this issue, because if it does, your not out
of the woods yet. I can feel it in my bones that BT have a problem with BRAS
that will take more time to fix.

>> My alteration to MAX DSL came as a pleasant surprise about a month ago.
>> My
>> line started syncing at around 4200 and was stable at this rate. It then
>> dropped to about 3800 for no obvious reason and remained rock solid for
>> 24
>> hours or more at a time. Unfortunately BT used a very conservative rate
>> to
>> prevent downloads being sent to fast and overwhelming things. This
>> started
>> off at 2000 and only increased to 2500 after nearly a fortnight. Even
> though
>> the syncing was quite steady I rebooted every day to try and train the
>> system. After nearly a month the stable rate has risen to 3000 but is
> still
>> below the rate that the line demonstrably supports. Suggestions that the
>> rate is established over ten days just don't seem to be true because the
>> actual time seems much longer. From this I can only conclude that the
>> algorithm BT use to set the stable rate is seriously flawed and needs
>> changing. I would have hoped that the trial period would have enabled BT
> to
>> resolve this sort of issue before they launched the product. Constructive
>> comments welcome.
>
> Does the BRAS have an impact on this issue, because if it does, your not
> out
> of the woods yet. I can feel it in my bones that BT have a problem with
> BRAS
> that will take more time to fix.


Well AIUI bRAS is the technical term for the stable rate BT notify ISPs
about. The ISP then limits the download speed to a maximum of that figure.
Mine has crept up to 3000 but has taken almost a month to do so.

Peter Crosland

Peter Crosland wrote:

> Well AIUI bRAS is the technical term for the stable rate BT notify ISPs
> about.

nope, that would be the MSR. The BRAS data rate profile limits the rate
at which data is pushed at your line card. The MSR is a record of the
slowest speed the line synced at during its initial training /
monitoring period. The BRAS data rate continues to track your actual
sync speed for ever.

Plusnet managed to mix the two terms up, repeating previous linguistic
triumphs like the "2M exchange upgrade program" :-)

>The ISP then limits the download speed to a maximum of that figure.
> Mine has crept up to 3000 but has taken almost a month to do so.

it "creeps" in 0.5M steps. 3M is the correct rate for sync speeds of
3424-3999 which seems to bracket your stable condition.

Phil

>> Well AIUI bRAS is the technical term for the stable rate BT notify ISPs
>> about.
>
> nope, that would be the MSR. The BRAS data rate profile limits the rate
> at which data is pushed at your line card. The MSR is a record of the
> slowest speed the line synced at during its initial training /
> monitoring period. The BRAS data rate continues to track your actual
> sync speed for ever.
>
> Plusnet managed to mix the two terms up, repeating previous linguistic
> triumphs like the "2M exchange upgrade program" :-)

Thanks for enlightening me. I stand corrected!

>
>>The ISP then limits the download speed to a maximum of that figure.
>> Mine has crept up to 3000 but has taken almost a month to do so.
>
> it "creeps" in 0.5M steps. 3M is the correct rate for sync speeds of
> 3424-3999 which seems to bracket your stable condition.

Interesting. I wonder why they do it in such crude steps. Anyway it does
seem quite stable and once Plusnet start using the new rate I presume I
shall see a little more download speed.

Peter Crosland

In article <446a1530$0$10770$(E-Mail Removed)>,
(E-Mail Removed) says...
> Well AIUI bRAS is the technical term for the stable rate BT notify ISPs
> about.
>

BRAS stands for Broadband Remote Access Server. It refers to the servers
which connect the DSLAM's in the exchange to the Colossus backbone.

It is the BRAS that sets the MSR (most stable rate) and, iirc, does the
capping.

--
Alan LeHun

PhilT wrote:
> Peter Crosland wrote:
>
>> Well AIUI bRAS is the technical term for the stable rate BT notify ISPs
>> about.
>
> nope, that would be the MSR. The BRAS data rate profile limits the rate
> at which data is pushed at your line card. The MSR is a record of the
> slowest speed the line synced at during its initial training /
> monitoring period. The BRAS data rate continues to track your actual
> sync speed for ever.

Whilst the definition of MSR and bRAS are correct here, the Delta
reports we receive are lifted from BT's bRAS rates. There would be no
point in receiving ongoing reports for the MSR as it is static and never
changes. We do get told what it is but we receive ongoing reports as the
bRAS profile fluctuates. This is indeed what we use to throttle the
speed as per Peter's comments. BT also throttle throughput though, we
just mirror what they do so as not to 'push' too much down the line so
to speak (can lead to packet loss for time sensitive apps).

> Plusnet managed to mix the two terms up, repeating previous linguistic
> triumphs like the "2M exchange upgrade program" :-)
>
>> The ISP then limits the download speed to a maximum of that figure.
>> Mine has crept up to 3000 but has taken almost a month to do so.
>
> it "creeps" in 0.5M steps. 3M is the correct rate for sync speeds of
> 3424-3999 which seems to bracket your stable condition.

bRAS profiles do not step in 0.5M steps. We profile accounts in 0.5M
steps but the actual bRAS profile uses smaller increments.

For example, the last few delta reports for my line were:-
5696
4544
4000
4544
5120
4000

I've seen some with 160kbps set as their bRAS profile

Regards,

--
|Bob Pullen Broadband Solutions for
|Support Home & Business @
|PlusNet plc. www.plus.net
+------ PlusNet - The smarter way to Internet! -----