Increasing consistent small packet loss

[Gary]

I have more work on the 19th now  Same thing Mervl was on about Start:    19/03/2014 02:00
Cleared:    19/03/2014 06:00
Duration:    4 Hours
Message:    total outage while line cards reload new code. Upgrade is designed to minimise down time by upgrading seperately the SRP cards. See staged plan.
Area Codes:    01243 01273 01293 01342 01403 01444 01730 01737 01883 02392

[Technical Ben]

Clear tonight, but had spikes last night. Ever so slight loss every 15 mins to half hour (varies) through out the day, which is strange.

[mervl]

I have more work on the 19th now  Same thing Mervl was on about Start:    19/03/2014 02:00
Cleared:    19/03/2014 06:00
Duration:    4 Hours
Message:    total outage while line cards reload new code. Upgrade is designed to minimise down time by upgrading seperately the SRP cards. See staged plan.
Area Codes:    01243 01273 01293 01342 01403 01444 01730 01737 01883 02392

Yep we had it over 4 nights but only lost service for a couple of minutes one night so it's obviously done in sequence.

[Simon_idnet]

BT have at last admitted to us that they are seeing congestion in parts of their network. They say that they have a dedicated team tasked with investigating reports. Which all rather confirms our suspision that this seems to be a reactive process rather than an automated proactive alert-driven (by monitoring systems) process.

The problems mostly appear to be in saturated SVLANs which link a cabinet to an Exchange. There may be one or more fibre cards in a cabinet that are grouped together into an SVLAN which then links back to the Exchange. So, the symptoms may affect some customers on a single cabinet but no others (on the same cabinet). BT will not give us visibility as to which customers are on which SVLAN

[Bill]

Thanks Simon

There may be one or more fibre cards in a cabinet that are grouped together into an SVLAN which then links back to the Exchange. So, the symptoms may affect some customers on a single cabinet but no others (on the same cabinet).

That would suggest that a planned multiple "lift and shift" at the cabinet level, to spread those affected between the groups, could at least ameliorate it?

Whether BT will bother is a different matter of course.

[Steve]

What happens though if the fibre optics from the cabinets are congested perhaps that does that not happen, if it does that sounds expensive.

[Bill]

What happens though if the fibre optics from the cabinets are congested perhaps that does that not happen, if it does that sounds expensive.

I'd have thought that was one of the easier problems to solve- all the ducting and pipework is in place to blow another fibre through. OK, it may need another box in the cabinet to feed the new fibre but they shouldn't be inordinately expensive.

[Steve]

Thanks Bill , I did wonder whether that was a very time consuming job involving multiple vans, multiple road side conferences and of course tea breaks.

[Bill]

It would still probably involve all that anyway

[Technical Ben]

Thanks Simon.

The problems mostly appear to be in saturated SVLANs which link a cabinet to an Exchange.

As you say, that makes a lot more sense. Hence why those on FTTC (no idea if it effects us on ASDL) were seeing very varied results, that did not seem to correlate to the info we (and you) have at hand.

Wonderful how BT cloak and dagger all the important stuff, while saying "all is good". 

As I've said before, and I'll say again, I left BT when they "upgraded and improved" our connection to "not show you your bandwidth use" and "manage it automatically". With a download limit, that's asking for miss communication purely to get away with charging extra/providing less. I don't care if they now allow users to see bandwidth use, if they have not changed their internal behaviour, that's dreadful.

[Baz]

Well at least they've  said something I guess.

I had two drops about 7pm last night and that has knocked my latency back up and speed down a tad    just when it had improved a bit too

[Tacitus]

BT have at last admitted to us that they are seeing congestion in parts of their network.

Which is pretty much what Adrian Kennard was saying.  IOW, the problem was not with iDNet's network.

[Baz]

I had two drops about 7pm last night and that has knocked my latency back up and speed down a tad    just when it had improved a bit too

  another two drops tonight within 10mins of each other and latency gone up some more and speed down

[Bill]

I think I might print out today's BQM and frame it... I daren't run a speed test

[Bill]

  another two drops tonight within 10mins of each other and latency gone up some more and speed down

Someone please correct me if I'm being thicker than usual, but I don't see why congestion should cause a sync drop (if that's what you're referring to), and it would only cause a drop in PPP if it got so bad the router couldn't communicate with the authentication server. Wouldn't it?

And that wouldn't affect speed or latency. Sounds more like interference from something switching on (or off) at the same time each day.

[Baz]

well someone just tell me something as ive totally lost track of whats going on now.I dont know what it is.Did I say it was congestion? is that what it is, how can you tell if your exchange is congested.Do BT tell your ISP who then tell you?

Its not the same time each day or every day.

[Steve]

I agree Bill loss of sync is not a congestion issue. So Baz if you want to start a new thread with routers stats etc please do so.

[zappaDPJ]

I think I might print out today's BQM and frame it... I daren't run a speed test

I certainly can't compete with that!

[Baz]

I agree Bill loss of sync is not a congestion issue. So Baz if you want to start a new thread with routers stats etc please do so.

OK if you think it needs a new thread but what is the difference between loss of sync and small packet loss...this thread...which do I have and how do you know.Thats all Im asking.

I could also start a thread about ducting,pipework,multiple vans,roadside conferences and lots of tea breaks eh 

[joe]

If it is exchange congestion wouldn't that be the same whichever ISP you were with?

Having now left iDNet I don't see the same packet loss/speed drop with the new provider. Is that coincidental? BT have been doing some card upgrading on my exchange (01277) in recent days.

[Baz]

Good points Joe.It will of been mentioned already somewhere in this thread, I dont know the answer though,wish I did.my latest graph.

[Gary]

If it is exchange congestion wouldn't that be the same whichever ISP you were with?

Having now left iDNet I don't see the same packet loss/speed drop with the new provider. Is that coincidental? BT have been doing some card upgrading on my exchange (01277) in recent days.

Monday and Tuesday is the line card work and also work on a congested svlan in my village's exchange for more capacity, if this cr@p continues after that I think something else is going on, and I really doubt its congestion at the cab in my village.

[Bill]

If it is exchange congestion wouldn't that be the same whichever ISP you were with?

Yes, unless the new ISP were LLU of course, but that's not currently an option with FTTC.

If the congestion is at the cabinet (see Simon's post) then I'm not sure, I don't know how SVLANs are organised. I suspect it's still true.

Then there's the situation where the fibre from a cabinet doesn't go back the the same exchange as the copper (a sort of fibre LLU within BT), so it would be possible to have congestion at one but not the other, and switching between ADSL and VDSL (in either direction) could either introduce or clear congestion... or have no effect.

It's impossible to predict without details of the SVLANs and what goes where, and BT aren't parting with that information

[Gary]

Yes, unless the new ISP were LLU of course, but that's not currently an option with FTTC.

If the congestion is at the cabinet (see Simon's post) then I'm not sure, I don't know how SVLANs are organised. I suspect it's still true.

Then there's the situation where the fibre from a cabinet doesn't go back the the same exchange as the copper (a sort of fibre LLU within BT), so it would be possible to have congestion at one but not the other, and switching between ADSL and VDSL (in either direction) could either introduce or clear congestion...

It's impossible to predict without details of the SVLANs and what goes where, and BT aren't parting with that information

Im not sure about congestion at the cab, Bill. As I see it that's unlikely, you cant fit more connections into a line card than its designed to take, when BTOR are out of room no more capacity is available and BTW stop showing FTTC as available, and at a later point they may install a new cab for more connections, but for congestion at the cab everyone would have to be using a hell of a lot of data all at once and I cant see that as likely tbh. Exchanges get congested, line cards fail and they can run out of ports but to have congestion at a cab seems to me unlikely since they don't typically install capacity for 100% of the lines connected to a PCP anyway. They tend to install a cabinet to supply approximately 50% of the lines available.

[Bill]

Im not sure about congestion at the cab, Bill. As I see it that's unlikely, you cant fit more connections into a line card than its designed to take

The line cards may not be saturated, but the SVLANs they're part of may be:

The problems mostly appear to be in saturated SVLANs which link a cabinet to an Exchange. There may be one or more fibre cards in a cabinet that are grouped together into an SVLAN which then links back to the Exchange.