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I'm in the process of a major revamp of my computing equipment, including the re-siting of my ADSL router to a place in the house where it'll no longer be anywhere near my UPS (uninterruptible power supply) and main computing kit. I usually keep the router, the PC and the monitor on the UPS, to keep things going for a while when electricity dropouts in the precinct occur. Brownouts and blackouts occur more frequently than in the past around here.
The local exchange is now FTTC-enabled and a number of new street cabinets have been installed in the neighbourhood. I understand that my particular line will be transferable to FTTC in July.
One thing that's occurred to me is that these new street cabinets for FTTC require power (since they'll incorporate at least one DSLAM and the means to convert from fibre to copper transmission and vice versa). But does this mean that if local power is lost, eg. a local substation goes down or there's a knock-on effect from the Grid, the power at the street cabinet will also be lost?
The reason I'm asking is that the answer may well determine whether or not it'll be worth my while investing in a second UPS to use at home, for 'powering' the VDSL modem and separate router. Clearly, if the street cabinets aren't equipped with backup power, there's no point in me or anyone else putting their VDSL modem and router on a UPS at home.
So, do these new street cabinets have their own UPSs? It'd be feasible for the cabinets to incorporate battery backup, but any such UPS would need to be especially environmentally robust, it seems to me.
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There are batteries located in the base of the cabinets (not visible when the doors are opened). Openreach routine check each cabinet every quater which includes checking the system switches to backup power when the mains supply is tripped.
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Crikey, I never saw that when I posted.
Reading it all, it seems that the kit in the cabinet is indeed battery-backed, though we should not expect the backup period to be very long.
Knowing that now, I think I will eventually put the VDSL modem and router on a UPS. There'll be a couple of other low-power devices on the same UPS also. It'll then mean that, for short power outages, the line will not have to resync and spend a number of days getting back to its normal speed.
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Crikey, I never saw that when I posted.
Reading it all, it seems that the kit in the cabinet is indeed battery-backed, though we should not expect the backup period to be very long.
Knowing that now, I think I will eventually put the VDSL modem and router on a UPS. There'll be a couple of other low-power devices on the same UPS also. It'll then mean that, for short power outages, the line will not have to resync and spend a number of days getting back to its normal speed. The DLM on FTTC is an Openreach one and seems to do profile changes very soon after a speed rise. BillFord is a case in point.
I read somewhere how it works - it's a totally different way of propagating the sync speed change to the BRAS.
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I doubt if they do have bateries that it is anymore then to cleanly shut the cabinet down and possible log the fault data back to the Engineering centre
The power consumption required would exceed any sensible battery back up. The DSLAM's consume quite a bit of power and the cabinets are environmentaly hostile so would need a fair bit of cooling so lots of power there
Edited by deleted (Fri 25-Mar-11 17:33:49)
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BT will still have to ensure that an analogue line is capable of making & sustaining a 999 call, even in the event of a power outage.
In the FTTP cases, this makes for battery backup in both home & network.
In the FTTC case, it means that the physical copper path (which goes via the MSAN/DSLAM in the FTTC cabinet) needs to be kept whole. The cabinet is going to have to do *something* in a power outage. That something may, or may not, require battery power.
If batteries are present, they may only be there for these emergency requirements - so it is possible that the DSL components are switched off/out. That may ensure they last longer, and can be smaller and more robust.
Of course, the solution might be the use of some NC relay contacts, held open while the cabinet has power, but springing shut once power is lost. That wouldn't necessarily need batteries.
Either way, the rapid appearance of Openreach engineers during a power outage might just be to check that the cabinet has swapped over to a power-outage-mode correctly. I could see that being an Ofcom requirement.
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With FTTC the PSTN service should continue regardless of power at the cabinet as bypass relays will provide a DC path back to the exchange.
No doubt in the event of mains power loss, Openreach will respond to a remote alarm and despatch someone to investigate the cause and possibley arrange replacements of the batteries if its likely to be prolonged.
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The splitter cards in most DSLAMs are passive (unpowered) so no need for any springing relays to maintain the PSTN path in case of a power outage,
This certainly goes for the exchange based Huawei DSLAMs, presume it is the same for the FTTC ones.
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The PSTN line is seperate and does not use the Fibre. It is powerered from the exchange which will have at least a few hours bateery back up enabling engineersd to fix the power issue or move a mobbile generator set in.
It is possible a few cabintts supplying companies where continuity of service is critical may have battery back up. I would suspect though if that is the case subscribers on that cabinett would have a class of service allocated and only those deisgnated as critical users would have continity of supply if the power failed.
Edited by deleted (Sun 27-Mar-11 09:21:03)
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The battery backup will run the whole cabinet, apparently for a minimum of 4 hours
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Bob will know better 
Dave
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When we had a 36 hour power failure recently - fire in substation - VirginMedia did the rounds of their cabinets with a small Honda generator topping up the batteries until United Utilities connected a monster generator on a truck at the substation..
AFAIK VirginMedia have no copper path back to the exchange.
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They have no copper back to the exchange as VM don't have exchanges.
Dave
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"It is powerered from the exchange which will have at least a few hours bateery back up enabling engineersd to fix the power issue "
No, the exchanges have their own diesel powered generators.
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/me whispers in Bob_s2's ear
with electric starter motors.
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Very few exhchanges have generator sets nowadays. The batteries should keep the exchange going for several hours untill the can fix the power fault or move in aa mobile generator. Another last ressort is each subscriber wil have a class of service so they can use that to conserve the batteries. Ordinary subscribers would get cut of first then businesses and less critical users such as OAP homes etc
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Since System X & AXE10 exchanges came in (years ago), I haven't seen an exchange without a standby generator.
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ROFL, you do like to spout bovine dung to people who know.
Dave
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The first bit is wrong, but you take the biscuit with .....
"Another last ressort is each subscriber wil have a class of service so they can use that to conserve the batteries. Ordinary subscribers would get cut of first then businesses and less critical users such as OAP homes etc"
Utter tosh.
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... and less critical users such as OAP homes etc"
Utter tosh. Indeed.
I'm an OAP and can be extreeemely critical!
Or does he mean it's OK if I die because I can't phone an ambulance, or a centre with fifteen like me catches fire, in which case I wonder what his priority list for survival rights looks like and where he would be on it?
You have to admit, Zarjaz & MadMan, he is quite hilarious at times.
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I would imagine that a system x had it's own yellow battery packs behind the mysterious grey panels plus a generator. The 999 service responsibility was taken very seriously back in the days of system x install.
Edited by deleted (Sun 27-Mar-11 21:04:47)
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Yep, they have battery packs which are only designed to run for an hour or so, as the standby generator should be up to speed within a minuite.
In the good old days of clockwork, the batteries had to last a day or so as often there was no standby generator.
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LOL. as you say, utter tosh.
It went out when clockwork was replaced with system x/axe10.
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It may be something to do with the name Bob. I seem to remember another Bob a few years ago, who also talked a load of tosh (as Zarjaz says)
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[cough]
http://forums.thinkbroadband.com/showprofile.php?Use...
And - this laptop, being my second Toshiba, has the network name Tosh2 in Windows, and because of the way our cat walks his nickname is Tosh.
What else do you know about me MadMan?
Ah - perhaps there has been a leak  . My brother was at one time in his life a GPO telecoms engineer. Took me ito an exchange once to show me the Strowger serried ranks clattering away to each other. Triffids have nothing on them.
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The first bit is wrong, but you take the biscuit with .....
"Another last ressort is each subscriber wil have a class of service so they can use that to conserve the batteries. Ordinary subscribers would get cut of first then businesses and less critical users such as OAP homes etc"
Utter tosh.
Now, I may only be a software engineer, and worked on AXE-10 systems for mobile rather than fixed-line installations, but I did get a good grounding in the overall system design in my years at Ericsson.
In all that time, I never came across any way that the system could shed power load gradually. Yes there were ways to reduce traffic load, but not power.
Knowing the way that the system is designed, there isn't a way to reduce power to the group switch, or to any of the central or regional processors, or to any of the trunk hardware. The only way to reduce power to certain subscribers would be to concentrate critical subscribers onto certain hardware, and cut power to the remainder; but (a) I haven't seen that capability, and (b) that goes against the principle of spreading your critical subscribers over different hardware in case of other failures.
At the software level, on the mobile side, there was a lot of effort put into certain robustness & recovery features, to cope with failures etc. But I can say for a fact that extending operation time when on battery was not one of them.
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-----------------
What else do you know about me MadMan?
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Ahh, that would be telling
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Ah - perhaps there has been a leak . My brother was at one time in his life a GPO telecoms engineer. Took me ito an exchange once to show me the Strowger serried ranks clattering away to each other. Triffids have nothing on them.
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I remember many an day spent bank cleaning & oil dagging Strowger selectors when I was a lad
The worst noise was in the STD routing unit. The normal selector units weren't too bad.
Much better than modern exchanges. In those days you were an engineer, but nowadays they need trained monkeys (bit unkind ain't I)
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Post deleted by Andrue
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"The worst noise was in the STD routing unit."
i bet it was ! LOL
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I wonder who's manufacturing Openreach's equipment. It sounds to me as if some FTTC providers are considering supporting the power requirements by using some of the existing twisted pair between the cabinet and the exchange.
See http://connectedplanetonline.com/mag/telecom_solving...
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Article is dated July 1998.
Dave
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FTTC is engine backed, on essential supply. So if power goes off, things keep working E-side.
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Learn to spell much?
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Article is dated July 1998. I couldn't be bothered replying to that last night when I read it, (and missed the date!), but it isn't FTTC as we know it as we get pure fibre. It is also the US?
Wrapping copper round fibre after installation could be a tad interesting. Installation with it would have cost a few years delay here.
I think one of the FTTP trials has it though?
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - IDNet Home Starter Fibre. Live BQM.
"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
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Your an idiot! They ALL have generators! Ranging from 20A for the small radio stations and village exchanges, upto 1.5Mw generators in Derby and Birmingham.
Your idea of having a 1st, 2nd and 3rd class system is proposterous.
Mobile generators only come into play when they're upgrading existing engines to a higher spec.
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Indeed, every exchange I have ever passed has had a generator and I have seen numerous "battery" rooms which I assume kick in instantly on failure awaiting a power tech to fire up the genny. I have seen a decommissioned genny (a frightening black iron monster looked line a steam train engine) in an exchange - across the building was a modern genny waiting to serve..
back ot - the fibre cabs do indeed have battery backup which will last around 4 hours - enough time for OR to deploy their mobile generators (the cabs are monitored for everything). The vdsl modem even has a sticker over a BBU port (battery back up?) have not had a play with that yet to see what voltage it takes but a UPS to the original adaptor and router etc is more sensible anyway.
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