Recurring unexplained PPP drops on 21CN and subsequent issues reconnecting

[#1]

I appear to be seeing a seemingly unreasonable number of PPP connection drops for no apparently good reason since PN decided that my line *really* needed upgrading to 21CN and therefore did so without even notifying me let alone asking first or taking any notice of the many previous times that I've declined any upgrades and been assured that none will be made.  Prior to this recent surprise "upgrade" to 21CN, PPP connections of  several 100 hours were very much the norm and generally speaking they would have been even longer than that had I not terminated them myself for reasons various.  Any random and very occasional PPP connection drops that did occur were always automatically re-established without any problem.  I have not noticed any problems of this nature at any time over the last ~10 years (except during periods of a confirmed BT line fault) until the line was "upgraded" to 21CN.
Without going into any more specific gory details just now (unless someone wants to ask about something that might be relevant of course !) I'm interested to know:
(1) What are the likely or potential causes of dropped PPP connections when there are no apparent line issues whatsoever ?
(2) What is the relevance of "interleaving" to a PPP connection and should it be on/off/auto for best stability/reliability given the fact that I'm not into gaming and don't use VoIP etc. ?
(3) How frequently is reasonable ? 1/day, 1/week, 1/hour or whatever given stable and very good line stats (8064K/448K, SNR 14/15dB stable to 0.5dB and attenuation 23dB), no loss of synch, no reduction in SNR and no automatic change (e.g. reduction) of IP Profile etc. when these PPP drops occur.
(4) Why should some equipment somewhere between me and the rest of the world so to speak suddenly decide to stop responding to routine control packets in any case and then sometimes apparently refuse to accept/acknowledge any subsequent attempts to re-establish a connection ?
(5) Is anyone else seeing any strange problems at all since being "upgraded" to 21CN ?
Mucho thanks in advance for any responses that may come along

[#2]

I have experienced some thing similar twice in the last few days. The I find my internet connection is non functioning. I check my modem - still synced at the same speed/profile. I check my router - still thinks it's connected, still have  valid IP, PPPoE session is up. The connection can be restored by terminating the ppp session and starting a new one. No power cycling required.
It's a bit odd, like the computer at the other end forgot to give me a new lease. I put it down to weekend maintenance.
Steve

[#3]

I've not seen anything like that this weekend or even very recently TBH but I have kinda seen it before on a few occasions some weeks ago and got tracerts that were suddenly consistently something like this:
1 0 ms 192.168.1.1 Router-adsl
2 32 ms 195.166.128.203 lo0-central2.ptn-ag01.plus.net
3 * * no response * - - -
4 * * no response * - - -
5 * * no response * - - -
6 * * no response * - - -
7 * * no response * - - -
8 * * no response * - - -
at the time until I rebooted or dropped PPP and obtained a different gateway.  Needless to say it was very much a case of "the lights are on but there's no one at home" no matter where you tried to go.

[#4]

HI mikeb,
How often are they happening? The disconnections may be happening too fast for the DLM to pick them up. We're certainly not seeing an awful lot of disconnections at our end, but that can happen.
Jojo

[#5]

Quote from: mikeb

(5) Is anyone else seeing any strange problems at all since being "upgraded" to 21CN ?

I have been experiencing frequent disconnectons and hence the speed drops for some time.  I have got an open ticket since 12th March and I am still waiting for the satisfacotry outcome.  I have had 2 visits from Openreach engineers and both found their tests to be okay including my BT installed fixed extension socket where my router resides.
My exchange had been upgratded to 21Cn when I joined PN from my previous ISP who had my service capped at 1Mbps as my usage was limited at the time to purely surfing and emails.  Ever since joining PN, I have been on ADSL2+ and I have had constant disconnections.  Please note that I am 3.7Km away (by road) from my exchange, so I do not expect great speeds and I accept that.
Both the Openreach engineers have found the loop tests from the test socket to exchange to be good and from test socket to BT installed extended socket to the router to be good.  So, this can only leave the gremlins at the exchange, which I tend to suspect.  But I wonder who can really ask BT to check their equipement/s at the exchange in order to stop the frequent disconnecions I have been experiencing.
For example, today I was down loading my mail and in the middle of the download I had a disconnect and this happened twice within half an hour.  I say this, because I was actually present at the router and Pc when it happened.  But on previous occassions it has happened when I haven't been physically there.
These frequent disconnections definitely not helping my IP profile as I am told the DLM automatically adjusts speeds to find the most stable connections.  How long do we wait for finding stable connections?  
I hope this helps you and gets PN to do something about ADSL2+ instability, which I suspect to be at the exchange.
Many regards,
Chandu.
P.S. By the way my router is on 24/7.
dick:green Quote tags fixed.

[#6]

Quote from: Joanne

How often are they happening?

Well ... when compared to a PPP connection that generally stays up for periods of several hundred hours without any problems whatsoever, anything somewhat less than that kinda figure quite obviously becomes "unusual" to say the very least not to mention "suspicious" and ultimately "seemingly unreasonable" of course    This is especially so when it coincides with some other very significant changes.
In reality, the frequency of these disconnects varies considerably. It ranges from 1 in several days to periods of on the hour every hour.  HOWEVER, it is not the frequency of disconnects that's the problem here. Disconnects can and do happen for 1001 reasons be they good or otherwise. The real problem is the reason that these disconnects are actually happening and the other more serious issues that arise as a direct result.

I have one further question:
(6) When negotiating and establishing a PPP connection, what is the name of the piece of equipment you are negotiating with, where exactly is it located and who exactly is responsible for it ?

[#7]

Hi Mike,
There's not really a single bit of kit involved in the auth process, so not really a simple answer - though none of the authentication equipment is responsible for sync as far as I know. The RAS at the exchange (BTs responsibility) forwards the username and password to the BT RADIUS/ISP RADIUS server based on the realm. The BT RADIUS server then proxies this to the ISP RADIUS, which performs the authentication based on the username and password sent.
As I said though this isn't anything to do with the line sync, which is entirely between exchange and end user dependent on wiring and the power output from the exchange kit - not sure which but I suspect it's the DSLAM.

[#8]

Thanks for the reply  We're not talking about line synch here purely about PPP. Line synch is apparently NEVER lost it's only PPP that is being dropped and sometimes something is also getting very screwed up along the way.  As I've already said, sych rate, SNR and ATT etc. are generally all rock solid and well above the minimum levels required for satisfactory operation. Also, IP Profile or whatever doesn't appear to be affected either.  
I really wish that I knew more about the physical connections between all the kit at the other end of my wires, had a definitive diagram of some sort to confirm things and fully understood exactly how it all fits together and should work in practice rather than knowing very little and having to guess ... but from what you've said, it rather seems to me like Mr.Finger should be pointing at the RAS (or whatever it is that actually handles LCP packets anyway) and Mr.BT should be having a *very* good look at RFC1661 and then be resolving non-compliance issues as a matter of urgency.  Whether the apparent non-compliance is by (bad) design, due to some external intermittent fault, a firmware bug, an overload situation, packet loss, response time issues or anything similar is anyone's guess but the bottom line at this end of the wires certainly appears to be non-compliance with RFC1661 and things subsequently getting very confused or screwed up that is the root cause of the problems being experienced.  I cannot 100% rule out making a similar accusation against my router but many years of previously unblemished performance would tend to suggest that it would be somewhat unwarranted at this particular point in time.
I definitely think that someone somewhere needs to comparing reality to the requirements of the RFC anyway if they're not doing so already and someone somewhere probably also needs to come clean about issues that they are most likely fully aware of and quite possibly have been for some considerable period of time as well.

[#9]

Quote from: mikeb

I really wish that I knew more about the physical connections between all the kit at the other end of my wires, had a definitive diagram of some sort to confirm things and fully understood exactly how it all fits together and should work in practice rather than knowing very little and having to guess

Have a look here and here for a bit more information.
Jojo

[#10]

I can understand why you are wondering about RFC compliance there - especially as the only change appears to be that you're now connecting to 21CN.
Don't forget that the problem could equally be within you modem/router - it is just that you are exercising it in a different way now. Certainly there are routers out there which had rock-solid behaviour under ADSL, that turn out to be a little more flaky with ADSL2+.
In a totally different problem, my parents had a rock-solid setup with ADSL. When KC changed their exchange over to ADSL2+, the modem couldn't keep the sync up between 5PM and 9PM. Part of the solution was to upgrade firmware, but in the end things worked best when I configured the router to stick with ADSL anyway. Obviously a different problem - but it helps show that a change to 2+ isn't always trouble-free.
What router are you using, and are there any firmware updates available? Can you configure it to stick to ADSL (or ADSL2), and if so, does it do any better?
One thing is to make sure that the router isn't configured to drop the connection after 5 minutes, or somesuch. It doesn't look like you are suffering this, but worth checking.

[#11]

I have been having similar issues for the past 6 to 8 weeks sync always remains but ppp drops. I have had both eand d sides changed and am booked tomorrow for a tie pair swap? I have a few threads on the forums lokking for help and some suggestions from PN too.
Maybe if there are a few of us with pp drops but sync remaining it may help Pn and openreach to narrow down the cause. I too have to renew ppp to get back on.
I have tried 4 routers and all have the same issues. inc 2 from PN.
podman

[#12]

@mikeb
have you managed to have you ppp issues resolved? what router are you using?
@chandu
are your troubles resolved?
podman