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Standard User meditator
(fountain of knowledge) Thu 24-Mar-11 16:24:57
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Are there maintained supplies in the FTTC cabinets?


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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.
Standard User GeeTee
(member) Thu 24-Mar-11 17:25:18
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Re: Are there maintained supplies in the FTTC cabinets?


[re: meditator] [link to this post]
 
Already discussed here:
http://forums.thinkbroadband.com/fibre/3920901-fttc-...
Anonymous
(Unregistered)Thu 24-Mar-11 17:36:13
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Re: Are there maintained supplies in the FTTC cabinets?


[re: GeeTee] [link to this post]
 
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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Standard User meditator
(fountain of knowledge) Fri 25-Mar-11 09:14:11
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Re: Are there maintained supplies in the FTTC cabinets?


[re: GeeTee] [link to this post]
 
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.
Standard User RobertoS
(sensei) Fri 25-Mar-11 09:22:10
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Re: Are there maintained supplies in the FTTC cabinets?


[re: meditator] [link to this post]
 
In reply to a post by meditator:
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.

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.
Standard User Bob_s2
(regular) Fri 25-Mar-11 17:32:41
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Re: Are there maintained supplies in the FTTC cabinets?


[re: meditator] [link to this post]
 
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 Bob_s2 (Fri 25-Mar-11 17:33:49)

Standard User WWWombat
(regular) Sat 26-Mar-11 12:55:33
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Re: Are there maintained supplies in the FTTC cabinets?


[re: Bob_s2] [link to this post]
 
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.
Standard User Ribble
(regular) Sat 26-Mar-11 13:26:22
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Re: Are there maintained supplies in the FTTC cabinets?


[re: WWWombat] [link to this post]
 
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.
Standard User GeeTee
(member) Sat 26-Mar-11 15:09:30
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Re: Are there maintained supplies in the FTTC cabinets?


[re: WWWombat] [link to this post]
 
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.
Standard User Bob_s2
(regular) Sun 27-Mar-11 09:15:34
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Re: Are there maintained supplies in the FTTC cabinets?


[re: WWWombat] [link to this post]
 
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 Bob_s2 (Sun 27-Mar-11 09:21:03)

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