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BT Voyager 205, MaxDSL, "regular" outage ~ 21:00, long story
[I originally raised this on an internal plusnet n.g, but it seems
it might be of wider interest, and not specific to plusnet, so
here's a potted history of what went before, and an update since.]
I'm connected in the usual way via BT/w to Plusnet, but I was Max-ed
early (in January, at Plusnet's instigation, not mine) as part of a
trial. The results have been mostly beneficial, don't get me wrong.
A few weeks back, it occurred to me that sporadic failures on my
MaxADSL line were following some kind of pattern. The ADSL connection
was failing, once each evening, and was staying failed, until I
manually restarted it. On manual restart, it usually recovered OK,
and all was then well. I began to log the situation (by telnet to the
'205, and keeping the console log), and at first it seemed as if the
failure was occurring every working day (i.e not weekends and bank
holidays!) within about half an hour of 21:15, i.e usually somewhere
between 20:45 and 21:45.
Although there was just the occasional outage that didn't fit this
pattern, the majority of them did so.
(However, I'll present these symptoms in different terms later, and
ask a question...)
Well, thanks to the console log I was able to see a bit better what
was happening. Here's a sample:
Fri Apr 28 21:33:10 2006 : MAJOR ALARM : ATM Interface Down :
Interface - atm-0
Fri Apr 28 21:33:10 2006 : WARNING : PPP Interface Down : Interface -
Fri Apr 28 21:33:10 2006 : WARNING : ATM VC Down : Interface - aal5-0,
PortId=7, Vpi=0, Vci=38
Fri Apr 28 21:33:10 2006 : MAJOR ALARM : DSL Interface Down
Fri Apr 28 21:33:31 2006 : STATUS ALARM : ATM Interface Up : Interface
Fri Apr 28 21:33:31 2006 : STATUS ALARM : ATM VC Up : Interface -
aal5-0, PortId=7, Vpi=0, Vci=38
Fri Apr 28 21:33:31 2006 : STATUS ALARM : DSL Interface Up
Fri Apr 28 21:33:38 2006 : WARNING : PPP Authorization Failed :
Interface - ppp-0
Fri Apr 28 21:33:38 2006 : WARNING : PPP Interface Down : Interface -
The key features of this seemed to be that:
1. The first logged evidence of a problem was "ATM interface down".
This surely wasn't plusnet's fault...?
2. However, the router was making an attempt to re-establish
the connection, but was getting "PPP Authorization Failed"
I started to look into the second problem, and discovered that the
'205 had a parameter setting called "maxauthtries", which was set to
a value of 1 (presumably, its default?).
So, I tried changing this value to something else, as e.g:
modify ppp global maxauthtries 3
and indeed this worked. After subsequent failures, I was able to
observe (in the router's console log) how the connection was
re-established - the auth. was attempted - occasionally it succeeded
first time, but mostly it failed - but, at the second attempt, it was
almost always successful.
So, now at least the break was repaired automatically, but this didn't
explain why the break was happening in the first place.
Now I started to look more closely at the pattern of failures, and
realised that on workdays I usually powered-off the router when I went
to the office, and powered it up again when I got home. Whereas on
weekends (and bank holidays!) I didn't do that. Typically, on work
days I'd get home around 19:00 (give or take half an hour or so), and
would power-up the router when I got in.
So I tried leaving the router powered up occasionally on work days -
and then, the "21:00 break" didn't seem to occur. Which maybe showed
the problem in a different light.
So, now here's a possible alternative hypothesis of what I've been
seeing. After the router has been powered off for a few hours, and
then is powered up again - then, about 2 hours later (give or take
half an hour or so), the connection is broken. Just once.
Is that a possible explanation?
If I power the router off for 10mins or so, and then carry on working,
I don't get a break 2 hours later. So if that really *is* the
explanation, then there's some minimum interval that it has to be
powered off before the effect kicks-in.
Oh, just a final detail, nothing directly to do with the above, but
relevant to interpreting console logs from the '205. When the '205 is
initially powered-up, its hardware clock is showing nowhere near the
right time - I suspect it's showing the last clock time that was
committed to the configuration. The first thing it does is to
re-establish the ADSL line - only afterwards does it seem to contact a
time-server and set its realtime clock.
So, any logging of the ADSL-up which appears on its console log
directly after power-up shows a completely irrelevant timestamp. One
has to query the '205 a minute or two later (e.g with "get system") if
one wants a meaningful timestamp in the log.
So that's two main points:
1. by default, it omits to re-try after first auth. failure -resolved
2. fails mysteriously on workdays at 21:15 +/- 0:30 *OR*
about 2 hours after being powered-up. -still mystery
and this minor point:
3. realtime clock, bad timestamps in the console log when powered-up.
I've read in various places that BT/w would reset the profile, some
time after powering-up. But the discussion suggested half an hour -
not two hours - and there was no mention that resetting the profile
would break the connection to the ISP.
I hope that's (a) useful to someone and (b) any suggestions about the
outstanding mystery please?
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