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Standard User iand
(fountain of knowledge) Mon 16-Sep-13 20:00:29
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BT Exchange failure points


[link to this post]
 
In the company I work for we use BT MPLS wan lines and then have BT adsl lines as a backup.

If both of these services are being served from the same exchange, what parts are common that may then have an issue if something breaks. I am just attempting to understand what the risk is using primary and backup lines from the same exchange

I know some of this is good, some is bad, but for one site its what it is:

* Using 2 cisco routers. One for the Primary and one for the secondary line into site
* Both housed in the same computer room, in the same rack.
* Looks to use different connection points on the wall
* Using the same under road duct for the cables into the site
* Street to the exchange same???
* In the exchange (black hole) what's common and what is not? The question

IanD
Standard User yarwell
(sensei) Mon 16-Sep-13 20:33:47
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Re: BT Exchange failure points


[re: iand] [link to this post]
 
air con, power supply to exchange and physical ducting to / from exchange likely to be same. In the same physical building, so same risk of terrorist attack / aircrash etc if you're looking that wide at scenario planning.

Route from you to exchange likely to be same too.

--

Phil

MaxDSL - goes as fast as it can and doesn't read the line checker first.

MaxDSL diagnostics
Standard User somerset
(committed) Mon 16-Sep-13 21:15:47
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Re: BT Exchange failure points


[re: yarwell] [link to this post]
 
Suggest you look at your building as well. Do you have a UPS and generator, separate supplies to each router etc.?


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Standard User mr_mojo
(knowledge is power) Mon 16-Sep-13 22:40:47
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Re: BT Exchange failure points


[re: yarwell] [link to this post]
 
There's also likely to be some crossover in the backhaul back from the exhange - while will be quite different, it may be going over the same physical fibre at the end of the day, or going through the same routers at some point.

Depending on your availability, you should look at adding one or more of these to the mix:

LLU fibre broadband, which would be more likely to have a different backhaul arrangement (though far from guaranteed)
Virgin Media cable
3G/LTE mobile broadband

In the event of a total failure of BT stuff at your exchange, the latter two are likely to provide more redundancy.
Standard User iand
(fountain of knowledge) Tue 17-Sep-13 18:33:47
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Re: BT Exchange failure points


[re: somerset] [link to this post]
 
I did the physical walk around with the onsite expert today. Its not very separate. Well its just not separate at all for most things on site. A bit of a re-gig needed....

IanD
Standard User iand
(fountain of knowledge) Tue 17-Sep-13 18:36:10
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Re: BT Exchange failure points


[re: mr_mojo] [link to this post]
 
thank you, will look at these options...

IanD
Standard User iand
(fountain of knowledge) Tue 17-Sep-13 18:39:23
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Re: BT Exchange failure points


[re: yarwell] [link to this post]
 
so the physical infrastructure is the same (building, power, air-con, street ducting) and possibly some of the back hall from the exchange to the larger 'cloud'.

Do all BT exchanges have a UPS / generator, or do we not know this type of information at all... so its pot luck.

IanD
Standard User Ribble
(experienced) Tue 17-Sep-13 18:43:36
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Re: BT Exchange failure points


[re: iand] [link to this post]
 
Battery backup, most have standby generators but not all.
Standard User Ignitionnet
(knowledge is power) Tue 17-Sep-13 18:54:38
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Re: BT Exchange failure points


[re: Ribble] [link to this post]
 
Are they still running the generators in the winter and selling it into the grid?

Remember that being the bane of my life working for an OLO - slightly dodgy rectifiers / UPS so when the exchange cut from mains to generator all the colo'd DSLAMs would bounce, then again when the generator run was done.
Standard User eckiedoo
(member) Tue 17-Sep-13 19:30:14
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Re: BT Exchange failure points


[re: iand] [link to this post]
 
If the second "backup" line only comes in to operation when the first fails, have you tested such "failure"?

We also had a two line set-up, one working; and the second only supposed to come in to operation automatically if the first failed.

I requested that this be tested - refused.

So one week-end, I "pulled the plug" on the first line - catastrophe!

It came to light that the other end, at the control centre, had not been set up properly.
Standard User btbert
(member) Tue 17-Sep-13 19:40:54
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Re: BT Exchange failure points


[re: Ignitionnet] [link to this post]
 
In reply to a post by Ignitionnet:
Are they still running the generators in the winter and selling it into the grid?

Remember that being the bane of my life working for an OLO - slightly dodgy rectifiers / UPS so when the exchange cut from mains to generator all the colo'd DSLAMs would bounce, then again when the generator run was done.


" Are they still running the generators in the winter and selling it into the grid?"

Never heard that one , they do run them up now and then to make sure all is ok with them years ago that was a mates job.

these comments are my own and in no way represent any company that i may or may not be linked too.

http://www.speedtest.net/result/2420497773.png
Standard User partial
(member) Tue 17-Sep-13 20:38:04
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Re: BT Exchange failure points


[re: btbert] [link to this post]
 
Bout seven or eight years ago all the exchange generators were firing up a bang on 4pm. Ignition is right. The country was short of power and BT had a generator in every town and village...
Standard User Ignitionnet
(knowledge is power) Tue 17-Sep-13 21:21:41
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Re: BT Exchange failure points


[re: partial] [link to this post]
 
Yes, 4 o'clock. Remember well it getting to 3:55 and counting down before the monitoring lit up with red.
Standard User iand
(fountain of knowledge) Wed 18-Sep-13 18:03:23
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Re: BT Exchange failure points


[re: eckiedoo] [link to this post]
 
Yes the 2nd backup line does need to be tested. They go out of service, are decommissioned and are never commissioned.

If I get the response that you had then I just say, ok, you are so confident that it works lets go to the computer room and YOU pull the main cable. Lets see if this works. That normally gets someone to think about if this service is working or not. It also means they are not confident about the overall 'backup contingency' and I then attempt to implement 3 mth tests until they are just happy to test on request. Its all a confidence thing.

IanD
Standard User IamQ
(experienced) Sat 21-Sep-13 13:51:35
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Re: BT Exchange failure points


[re: Ignitionnet] [link to this post]
 
Yes they still do at some places. Thames Water also do the same thing.

Its not all just about selling power back out it also cuts there electric bill on some large sites. Google electrical triad periods and that should explain how it all works and why its done.
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