100m line length

I need to get a network point to a seperate building, which is approx
150m from the switch.

The line length of 100m that's specified, ive never tried running
anything beyond 100m - is t a fairly fixed limit, unlikely to run to 50%
beyond ... ?

I think the only other option is wireless, probably a couple of external
wifi points in bridge mode, maybe.

 

Is there anywhere midpoint that you could stick another small switch?
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.uk www.ebayfaq.co.uk

 

There can be trouble (regardless of the distance) if the buildings have
different mains supplies. It is not clear to me why this is a problem
(presumably different phases is part of the reason), but but it has been
mentioned before so I think it is worth pointing out. Maybe someone else can
elaborate.

There is a limit on the maximum propagation time in a collision domain; this
is a hard limit and breaking it will cause major trouble. If you are
exclusively using switches (rather than hubs) then everything should be full
duplex which means no collision domains. I think you will be OK unless you
have hubs at both ends of the run.

The only remaining issue is signal degradation. I think it is likely that
you will find the link only works reliably at 10Mbit/s.

You could do that. Using Yagi antennas would probably be a good idea.

If possible, Dr Zoidberg's suggestion of a hub (or switch) somewhere in the
middle would be preferable.

Another option is to acquire a pair of 10BASE2/10BASE-T bridges and join
them using 50ohm co-ax cable (using a couple of T-pieces and 50ohm
terminators). You may be able to pick up the bridges second-hand quite
cheaply - devices with a single 10BASE2 port and a few 10BASE-T ports were
common when 10BASE-T was coming in, to ease transition. This avoids the
potential security issues of a wireless link and is within the specified
cable length limit for 10BASE2 (185m according to Wikipedia, which sounds
familiar).

Alex

 

To be accurate there is another option which completely eliminates the
problem with earthing differences that can cause problems between two
buildings. This could cause equipment damage in electrical storms.. It is
probably more expensive but guaranteed to work - Fibre Optics.

Fibre converters at either end cost around £50 each for 100 Mbps.
http://www.netshop.co.uk/productcategorydetail.aspx?categoryid=51930

I am not sure how much a fibre cable would be but probably about the same.
You can buy this pre-terminated. Netshop do not have long lengths listed but
they are helpful and could probably quote you. It should work at any speed
you are likely to want up to 1 Gbit at 250-500 metres over the cheaper
multimode fibre (I don't have the actual distance specifications to hand).

 

260 m for "old good quality" 62.5/125 micron core cable. 550m on 50/125, or
various more modern 62 types

limit isnt fibre loss for GigE on m/mode, but smearing of the pulses, so
lower data rates can go much further.

100 Mbps is good for 400m in 1/2 duplex (limit of the collision domain
without a repeater), 2 Km full duplex (AFAIR).

make sure you get the same connector types on kit and cable - lots of
different F/O connectors, and if you need patch leads they will up the cost
significantly.

 

No, its basically going from a construction site office to the security
gate office across the yard in a pre laid duct.

They've run a couple cat5e cables which ive used 1 of for the telephone
extension which works fine but knowing the 100m limit for networks didnt
even try the data side ... I might just patch it up and see if it works
at all just for the sake of trying.

The mentions in the thread of the fibre converters sound ideal - one of
those each end of a fibre run would work great. Only problem of pre
terminated is knowing the length as I wouldnt want too much cable coming
out either end, trying to keep things tidy as there's 450+ network
points on this one.

Is fibre difficult to terminate or just a matter of having the right kit
and its straight forward?

Im going to have to provide wireless of some description to this site
anyway so I might put in a full coverage wds wireless solution which
would cover this building and a fair bit of the site around the main
office building.

 

The issue is that if the two endpoints are at a different ground
potentials, the entire gubbins of two buildings and the ground in
between looks and behaves like a battery - and you have just strung your
data wire between the terminals so you get a flow of current through the
data cable. Best case, this screws data transmission, worse case you
damage stuff with the voltage difference.

I once measured the voltage difference between a buidling's earth point
and some coax that they'd strung to an outbuilding - it came to 70-80v.

Fibre or wireless would be best

 

It won't do any harm to try it certainly.

Pass. We always get people to do it for us at work :0)

--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.uk www.ebayfaq.co.uk

 

Also when you order fibre let them know what you are doing with it as you
may get different types - e.g in a duct it is likely to be in water for most
of its life, or if you want to just bury it you probably want an armoured
type, or yet another flavour if it is going to be on poles with a suspension
wire.

you need the right kit - but the kit isnt all that cheap, and some skill is
required to terminate on conventional connectors.

tthe connectors also are not cheap. If you end up with a damaged end of the
connector or grit, then it may damage "stuff" you plug into it, so this is
one of those areas that can be unforgiving if you go DIY.

there are a few specialised splicing systems which just need a special tool.

i suggest you see if you can find a local supplier who can install and hand
over a working link - at least for your 1st one....

 

I haven't personally built one but there are a couple of open projects
with details of how to build optical data links, probably the most
promising is here: http://ronja.twibright.com/
You have to make some electronics and hardware construction but it would
be a very interesting project to try building if you're into electronics.
Anyway probably not what you're after but might be of interest.

Tony