BT and leased lines.

Hi guys.

Do you know if BT's using singlemode fibers or multimode?
I thought they are using singlemode, but I saw a MM fiber connected to my
equipment.
Then in goes via cupler to some white fiber, but it doesn't say whether or
not it's singlemode...

Just wondering.
Anyone knows?

Martin

On Fri, 21 Apr 2006 17:42:15 +0100, "Martin Lukasik"
<(E-Mail Removed)> wrote:

>Hi guys.
>
>Do you know if BT's using singlemode fibers or multimode?
>I thought they are using singlemode, but I saw a MM fiber connected to my
>equipment.
>Then in goes via cupler to some white fiber, but it doesn't say whether or
>not it's singlemode...
>
>Just wondering.
>Anyone knows?
>
>Martin
>

What's "fiber" and "cupler" ?

(E-Mail Removed) wrote in news(E-Mail Removed):

> What's "fiber" and "cupler" ?

Easily overlooked typos except to grammar and spelling nazis...

--
Colin
*Drop DEAD from the email address to reply*

<(E-Mail Removed)> wrote in message
news(E-Mail Removed)...
> On Fri, 21 Apr 2006 17:42:15 +0100, "Martin Lukasik"
> <(E-Mail Removed)> wrote:
>
>>Hi guys.
>>
>>Do you know if BT's using singlemode fibers or multimode?
>>I thought they are using singlemode, but I saw a MM fiber connected to my
>>equipment.
>>Then in goes via cupler to some white fiber, but it doesn't say whether or
>>not it's singlemode...
>>
>>Just wondering.
>>Anyone knows?
>>
>>Martin
>>
>
> What's "fiber" and "cupler" ?


A firm of solicitors ;o)
--
Keith Willcocks
(If you can't laugh at life, it ain't worth living!)

On 21-Apr-2006, (E-Mail Removed) wrote:

> >Do you know if BT's using singlemode fibers or multimode?

Generally BT uses monomode to deliver corporate services
(5/125 is common, nowdays it may be blown fibre)
and they charge an arm and a leg for
their NTU with battery backup - UNLESS - they are quoting
against C&W or Telewest. With blown they can add extra fibres
and services and repairs are easier that trying to splice
in a manhole with water lapping over your wellies.
Their presentation to the user may be multimode or monomode,
depending on what the customer requests and can accomodate.
BT's customers premises NTU usually provides BT with
monitoring capability so that if you report a fault their
network control center can check the circuit out from
their end, and create a loopback for end to end testing
if necessary.
It is not unusual for the customers fibre transceiver to
go marginal, the source diodes are run fairly hard.
There is generally some terminating equipment, like
a rack card, or box, between BT's fibre and the users
connection.

> What's "fiber" and "cupler" ?

Sorry master. Coupler and "fibre". It's not my fault I'm not British and not
my fault that english we learnt at school was something between British and
American.

m.

[..]
> There is generally some terminating equipment, like
> a rack card, or box, between BT's fibre and the users
> connection.

I was wondering, because somebody cut our fibre outside, and as I've noticed
it was a singlemode fibre (or monomode -- however you call it). But in the
building we've got multimode fibre.
I've spoken to BT guy and he told me they're using singlemode and he said it
only goes to the patch panel at exchange and it doesn't go to any equipment.
It's just a purely dedicated line.
So what if I connect my 1000Base-ZX GBIC module, which can do 100kms? Would
it work?
I haven't tried in the UK yet, but I tried in few other countries and it did
work.

Martin

Martin Lukasik wrote:
>> What's "fiber" and "cupler" ?
>
> Sorry master. Coupler and "fibre". It's not my fault I'm not British and not
> my fault that english we learnt at school was something between British and
> American.

Don't worry, only Jimmy doesn't understand you.

On 24-Apr-2006, "Martin Lukasik" <(E-Mail Removed)> wrote:

> > There is generally some terminating equipment, like
> > a rack card, or box, between BT's fibre and the users
> > connection.
>
> I was wondering, because somebody cut our fibre outside, and as I've noticed
> it was a singlemode fibre (or monomode -- however you call it). But in the
> building we've got multimode fibre.
> I've spoken to BT guy and he told me they're using singlemode and he said it
> only goes to the patch panel at exchange and it doesn't go to any equipment.
> It's just a purely dedicated line.

Without knowing what's BT's presentation at your end it's hard to be
specific. It would be unusual for BT to splice monomode onto multimode.
It might work ok from them to you (with losses going from monomode to
single mode) but you would need to launch sufficient optical power to
overcome the losses going from multimode to monomode, which is
why it might just work, but is not a preferred solution. A lot depends
on range. At the exchange the monomode terminates on a patch panel,
what he didn't say was what the other side of the panel feeds, most
likely a card, speculatively it could be one of a set of cards that link
to a multiplexed higher rate circuit.
BT can bring in monomode and offer you a dedicated circuit to anywhere
in the world, like your back office in Hong Kong, at a price.
Or you can split a circuit between voice and data, n by 64k channels
for the PABX and the rest of the bandwidth for Ethernet.

> It's just a purely dedicated line.

There has to be a from/to, how far and does the from/to cross one
or more exchange boundries? They could just give you dark fibre,
like the old wires only circuits that you could lease from BT, but
it would be unusual.

> but you would need to launch sufficient optical power to
> overcome the losses going from multimode to monomode, which is
> why it might just work, but is not a preferred solution. A lot depends
> on range. At the exchange the monomode terminates on a patch panel,
> what he didn't say was what the other side of the panel feeds, most
> likely a card, speculatively it could be one of a set of cards that link
> to a multiplexed higher rate circuit.

He came with a funny laser pointer (1mW) and the guy on the other end could
see the light. Distance in straight line is about 8 miles.
But I'm not quite sure whether or not they tried to see the light on the
exchange or the other end.
Anyway, I've got 1000Base-ZX converters, which can do 100km on a singlemode
fibre.


>> It's just a purely dedicated line.
>
> There has to be a from/to, how far and does the from/to cross one
> or more exchange boundries?

It's about 8 miles in straight line; at least two exchanges, but as I'm
calculating it will be about 5.

> They could just give you dark fibre,
> like the old wires only circuits that you could lease from BT, but
> it would be unusual.

Can I ask you a stupid question? What is a "dark fibre"?


Thanks,
Martin