BT announcement re synchronisation

BT have issued the following announcement to ISPs.

"'BLIP LOGIC' FIX To improve the experience for end user customers we have
introduced a fix which takes account of the historical stability of the line
when encountering a one off low synchronization event. This is known as the
'Blip logic' fix. The Blip Logic fix introduces the ability for stable BT
IPstream Max (or BT IPstream Max Premium) line not to wait 3 days to move to
a higher BRAS profile after a single isolated event of low line rate
synchronization. A stable line will be classed by the blip logic as a BT
IPstream Max line that over the previous 14 days has not had a line rate
change that has instigated a downward change in their BRAS profile.
Therefore, if a stable line has a single, isolated low synchronization event
that instigates a downward change of BRAS profile then as long as the next
line rate synchronization event is higher the BRAS will be reset to the
appropriate level for this higher line rate within 75 minutes. This bypasses
the normal wait for 3 days of a constant higher line rate. If the line rate
increases on subsequent synchronization events, further upward BRAS profile
changes will also be allowed within 75 minutes as long as there is not
another downward move in the BRAS rate in the mean time. If another downward
move of BRAS profile does occur within 14 days of the first one then the
line will not be classed as stable by the Blip logic and the 3 days of a
constant higher line rate will need to elapse before the BRAS profile is
changed upwards. Before the line is once again classed as stable by the Blip
logic another 14 days will need to elapse during which time the line must
not have had a downward move of BRAS profile. Please note that BT systems
generate a "heartbeat" synchronization event every night. This will be
registered by our systems as standard synchronization event. If the line has
a modem or router that is constantly switched on it may prevent the line
from synchronizing at a higher line rate before the 'heartbeat' event is
generated. Therefore, the 'heartbeat' event may be detected by the Blip
logic as a second low synchronization event and the 3 day rule for changing
the BRAS profile will apply."



Does the expression putting a sticking plaster on a broken leg come to mind?


Peter Crosland

On 26-Jun-2006, "Peter Crosland" <(E-Mail Removed)> wrote:

> If another downward
> move of BRAS profile does occur within 14 days of the first one then the
> line will not be classed as stable

Does that mean they will come out and fix the line, and be on the job
before you get round to contacting your ISP?

In article <449fdf52$0$950$(E-Mail Removed)>,
(E-Mail Removed) says...
> If the line has
> a modem or router that is constantly switched on it may prevent the line
> from synchronizing at a higher line rate before the 'heartbeat' event is
> generated.
>
Are they trying to say that if you use a router in the normal way that
(i.e. on 24/7), you may suffer?

In article <(E-Mail Removed)>,
(E-Mail Removed) says...


> Are they trying to say that if you use a router in the normal way that
> (i.e. on 24/7), you may suffer?
>

That's how I read it, started turning it off at night now.
--
Regards
James

>> Are they trying to say that if you use a router in the normal way
>> that (i.e. on 24/7), you may suffer?
>>
>
> That's how I read it, started turning it off at night now.

It looks like that to me. It is what the Americans call a crock!

Peter Crosland

On Mon, 26 Jun 2006, Martyn Williams wrote:

> (E-Mail Removed) says...
> > If the line has a modem or router that is constantly switched on
> > it may prevent the line from synchronizing at a higher line rate
> > before the 'heartbeat' event is generated.
> >
> Are they trying to say that if you use a router in the normal way that
> (i.e. on 24/7), you may suffer?

They can't please everybody. If I restarted my router, then it would
often sync at nearly 7Mbit down rate, a speed which I *know* from
experience it can't support throughout the 24hrs. Then, as evening
came on and the SNR margin dwindled, sync would fail and it would
re-sync at, let's say 6.5M. Then later, sync would fail again and it
would re-sync at a lower speed. In the end it would pick a speed
(usually a bit under 6M) that it could sustain around the clock, as
long as I left it running. I just had to be careful not to restart
it, and especially not at times when I had a good SNR, otherwise it
would kick off another series of over-optimistic sync / loss of sync /
try again / lose sync again / etc. before finally settling down.

Finally I discovered that I could set a maxdnrate parameter in the
router, which would stop it from sync-ing at an over-enthusiastic
speed. Now I can restart it whenever I please, and it'll use my more
conservative sync speed setting, even at times when it has plenty of
SNR in hand. However, this option apparently doesn't exist in every
router - I just struck lucky.

Plusnet have a page at the misleadingly-named URL
https://portal.plus.net/my.html?action=stable_rate , which as I
understand it reflects the BRAS rate reported to them by BT (*NOT* the
so-called "stable rate", which is not shown to the user).

A consequence of reconfiguring my router to a more conservative sync
speed was that this reported figure fell from 5500 to 5000, but I
would rather have stability than the last ounce of download speed.

A week or so back, the figure suddenly changed to 3000, for no reason
that I was aware of (presumably it had been one of these short-term
one-off resync-ing at an abnormally low speed, with BT's BRAS setting
responding quickly to the change). I checked it daily, and re-started
the router at least once a day, but it was about 4 days before the
reported figure changed to 4000 and, soon after, to 5000, which, as I
say, is its usual value for me nowadays.

But the connection was otherwise stable, and did the job that I
wanted, so I'm not really complaining, just commenting on what can
happen. But it'll obviously be an advantage if this kind of
short-term glitch can clear more quickly, which is I think what
they're saying, even if it's rather contorted.

h t h

(E-Mail Removed) wrote in
news:(E-Mail Removed):

> Does that mean they will come out and fix the line, and be on the job
> before you get round to contacting your ISP?

No, it should read "Will not be classed as stable at the higher rate". The
profile will be shifted down to a rate which it does classify as
stable..that's about it.

--
Colin
*Drop DEAD from the email address to reply*

Martyn Williams <(E-Mail Removed)> wrote in
news:(E-Mail Removed):

>> If the line has
>> a modem or router that is constantly switched on it may prevent the
>> line from synchronizing at a higher line rate before the 'heartbeat'
>> event is generated.
>>
> Are they trying to say that if you use a router in the normal way that
> (i.e. on 24/7), you may suffer?
>

No, again it is bad wording but I read it as basically stating the
obvious.
If your router is constantly synching at a high rate, then you reboot and
leave it synced at a lower rate then the systems will not update. You
have to force the router/modem to disconnect and resync to get the higher
rate.
However, regardless of this the heartbeat overnight will boot you and
force a resync so if you've left it synched at a low speed it will resync
at the higher speed then.

Theoretically seen as the heartbeat event happens at midnight on my line
and does not cause a disconnection on my line it just kills data transfer
(or makes it do weird things) for anywhere up to 5 minutes. That is
possibly because my line has never synched below the maximum possible
though..

--
Colin
*Drop DEAD from the email address to reply*

Alan J. Flavell wrote:

> Finally I discovered that I could set a maxdnrate parameter in the
> router, which would stop it from sync-ing at an over-enthusiastic
> speed. Now I can restart it whenever I please ...

Which router is this?

On Tue, 27 Jun 2006, pzboyz wrote:

> Alan J. Flavell wrote:
>
> > Finally I discovered that I could set a maxdnrate parameter in the
> > router, which would stop it from sync-ing at an over-enthusiastic
> > speed. Now I can restart it whenever I please ...
>
> Which router is this?

BT Voyager 205 / rebadged virata viking. firmware version 1.8 in my
case.

If you do a goo-groups search you'll find a posting of mine on this
group earlier this month, with more detail.