Linking 2 Buildings..

[Grommit]

We have just aquired a building approx 600m from the main site.. the new building is not on the grounds but across the road..

 

What would the best, easiest and cheapest way of linking the buiding to the School Network..

 

There is no line of sight..

[Gatt]

We have 2 buildings linked by overhead fibre (8 and 16 channel)

Though, we dont need to cross a road like you do...

[localzuk]

You have a couple of options really.

 

1 would be to get a couple of SDSL lines, one at each building and then run a VPN over that. This is going to be the slower solution.

 

The other would be to contact someone like BT or NTL and see what they can offer in terms of installing a fibre. Yes, it'll likely require digging up the road, but you'll then have a proper link. This solution could be quote expensive though.

[Grommit]

You have a couple of options really.

 

1 would be to get a couple of SDSL lines, one at each building and then run a VPN over that. This is going to be the slower solution.

 

The other would be to contact someone like BT or NTL and see what they can offer in terms of installing a fibre. Yes, it'll likely require digging up the road, but you'll then have a proper link. This solution could be quote expensive though.

 

It's not just a road... its 2 blocks of 3 floor flats and a couple of houses in the way as well.. :-(

 

All we want to run in the new building is about 5 PC's

[PEO]

have the kids do it for you perfect project for them me thinks. They could then cover some of the units from maths, ICT, DT and science.

[rhyds]

We used a wireless solution for our music block, but that was only a sub 200m line-of-sight job. I believe my uni used directional high-gain antennas and some specialist cisco kit to connect the accomodation block in town to the uni over about 1/2 a mile, but I see serious £££ in that

[plexer]

What do you want to use those 5 machines for is it absolutely vital they have a network connection?

 

How about an adsl line and some kind of vpn back to your main site?

 

Ben

[dhicks]

For 5 machines, I should think the bandwidth provided by a directional wireless link should (just about) be okay. You don't have to use specialist kit - many standard wireless cards have detachable antennas that you can replace with directional antennas. You can buy point-to-point wireless/wired ethernet converters for about £50 each (you'll need two, obviously). For the ultimate in DIY cheapness you can find instructions on the Internet to build your own antenna from an old Pringles packet, but these days you can buy them ready-made off eBay (search for "cantenna" or "yagi").

 

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David Hicks

[torledo]

We have just aquired a building approx 600m from the main site.. the new building is not on the grounds but across the road..

 

What would the best, easiest and cheapest way of linking the buiding to the School Network..

 

There is no line of sight..

 

I certainly think installing a fibre run isn't going to be the cheapest but would be the most effective solution. They should be able to route through existing underground facilities without digging any holes but it would probably be costly. You don't have line of site so that would rule out a cheap solution such as free space optics.

 

Wireless mesh could be a possibility but I think that would require an intermediate hop (to overcome line of sight)

 

How about PTP WiMax ? Cisco don't do WiMax but there are plenty of vendors whose equipment doesn't require Line of sight so long as you've got NLOS.

 

Or an outdoor 802.11 point-to-point bridged wireless solution. Again would need some line of sight.

 

If you really are that obstrcuted between sited then the SDSL VPN option could well be your best bet, but don't forget depending on distance from the exchange you might not be able to exceed 512kbps up and down. Which probably isn't a problem for 5 pc's but is a lot to pay for not a lot of bandwidth.

[localzuk]

As he said, he doesn't have line of sight, this means any wireless solution will be unreliable at best.

 

For that few a number of machines, I would go with an SDSL line and a VPN.

[torledo]

For 5 machines, I should think the bandwidth provided by a directional wireless link should (just about) be okay. You don't have to use specialist kit - many standard wireless cards have detachable antennas that you can replace with directional antennas. You can buy point-to-point wireless/wired ethernet converters for about £50 each (you'll need two, obviously). For the ultimate in DIY cheapness you can find instructions on the Internet to build your own antenna from an old Pringles packet, but these days you can buy them ready-made off eBay (search for "cantenna" or "yagi").

 

--

David Hicks

 

For just a few hundred pounds he can get a dedicated outdoor bridge/antenna or an indoor AP with an external Yagi or directional antenna for less. He is trying to link two buildings!!! afterall so I'm sure he can find the cost justification without having to go DIY or the cheap as chips route particularly as most schools have spent small fortunes on costly fiber backbones. Plus, it's likely once a suitable link is in place there'll be more than 5 PC's wanting to connect back to the main site He should look at future capacity. A Cisco bridge/AP solution is cheap by comparison with such projects.

[PEO]

how big is the building, how many machines do you think would/could be used in the building? If you are going to be using more than 5 machines in the future then i would just try go for fiber.

[localzuk]

For 5 machines, I should think the bandwidth provided by a directional wireless link should (just about) be okay. You don't have to use specialist kit - many standard wireless cards have detachable antennas that you can replace with directional antennas. You can buy point-to-point wireless/wired ethernet converters for about £50 each (you'll need two, obviously). For the ultimate in DIY cheapness you can find instructions on the Internet to build your own antenna from an old Pringles packet, but these days you can buy them ready-made off eBay (search for "cantenna" or "yagi").

 

--

David Hicks

 

For just a few hundred pounds he can get a dedicated outdoor bridge/antenna or an indoor AP with an external Yagi or directional antenna for less. He is trying to link two buildings!!! afterall so I'm sure he can find the cost justification without having to go DIY or the cheap as chips route particularly as most schools have spent small fortunes on costly fiber backbones. Plus, it's likely once a suitable link is in place there'll be more than 5 PC's wanting to connect back to the main site He should look at future capacity. A Cisco bridge/AP solution is cheap by comparison with such projects.

 

Can I ask why people are suggesting wireless when he stated there is no line of sight? This is simply a poor solution if line of sight is not available as he would need to get agreements with buildings in between in order to mount repeaters - which adds to latency.

[steveg]

How far away from the phone exchange are you? BT will let you rent a direct piece of copper between the 2 buildings (via the phone exchange) that you can then connect your own SDSL equipment too at both ends, creating a private circuit. Data speeds aren't guaranteed, but provided your not miles from the exchange it should be fine. - Last place i worked for had a 2mb line running over it reliably for 2 years. Rental was around £700 a year I believe.

 

Steve

[PEO]

For 5 machines, I should think the bandwidth provided by a directional wireless link should (just about) be okay. You don't have to use specialist kit - many standard wireless cards have detachable antennas that you can replace with directional antennas. You can buy point-to-point wireless/wired ethernet converters for about £50 each (you'll need two, obviously). For the ultimate in DIY cheapness you can find instructions on the Internet to build your own antenna from an old Pringles packet, but these days you can buy them ready-made off eBay (search for "cantenna" or "yagi").

 

--

David Hicks

 

For just a few hundred pounds he can get a dedicated outdoor bridge/antenna or an indoor AP with an external Yagi or directional antenna for less. He is trying to link two buildings!!! afterall so I'm sure he can find the cost justification without having to go DIY or the cheap as chips route particularly as most schools have spent small fortunes on costly fiber backbones. Plus, it's likely once a suitable link is in place there'll be more than 5 PC's wanting to connect back to the main site He should look at future capacity. A Cisco bridge/AP solution is cheap by comparison with such projects.

 

Can I ask why people are suggesting wireless when he stated there is no line of sight? This is simply a poor solution if line of sight is not available as he would need to get agreements with buildings in between in order to mount repeaters - which adds to latency.

 

pluss wireless is not the most securable form of transmitting data.

[Geoff]

Plus directional antennas are illegal.

[dhicks]

> Can I ask why people are suggesting wireless when he stated there is

> no line of sight?

 

I thought the new 802.11n standard had a snazzy facility for dealing with signals bouncing off walls and suchlike. Quickly checking the information on Wikipedia, though, I get the impression that this is due to using a three-part antenna - replacing that with a single directional antenna is going to stop that facility from working. Bother.

 

Hmm - didn't realise a private SDSL line was only £700 a year, might almost be worth looking at that for our sixth form centre...

 

--

David Hicks

[dhicks]

> Plus directional antennas are illegal.

 

I thought legal restrictions on computer wireless kit were regarding the output power of your transmitting antenna? I thought you could legally use antennas up to around 14DBi - is that only for omni-directional antennas?

 

--

David Hicks

[DMcCoy]

BT lan extension? http://www.btglobalservices.com/business/ie/en/products/lan_san/index.html

[greenfieldsupport]

lol geoff you better inform durhamnet, they run hundreds of them!!!!, high gain ones tew.

 

I imagine more than 14dbi.

 

plus thats silly

 

having a gain limit i mean.

 

id rather have a larger antenna with a higher gain, like a small sat dish. then have a small antenna which is leagal that transmits at 16,000watts to get the signal accross

 

higher gain = lower signal power = less cancer

[localzuk]

The gain limit can be increased if you have a license I believe? It also depends on the frequencies used.

[dhicks]

Ah - a little more Googling suggests a legal limit of 100mW power output for wireless devices.

 

--

David Hicks

[torledo]

The gain limit can be increased if you have a license I believe? It also depends on the frequencies used.

 

Bringing the thread back on topic for a moment, the previous poster was correct when he mentioned the line rental for a P2P sdsl circuit between buildings using the same exchange, I remembered a janet document that I read some time ago describing this scenario;

 

http://www.ja.net/services/network-services/mcas/documents/foxes-academy.doc

 

From the document....

 

BT Baseband Private Circuits (EPS 8/9)

 

Originally marketed and used for voice traffic between sites, BT “Baseband” private circuits can also support digital traffic between two site LANs (Local Area Networks) by using DSL modem-routers at each end.

By using SHDSL units, “upstream” and “downstream” data rates are the same, so a link driven by such units would most closely resemble a traditional PDH circuit (like MegaStream) supported by conventional routers. The limitations on using a Baseband circuit as a digital traffic pathway are that the buildings to be connected must share the same BT exchange and ideally the same MDF (Main Distribution Frame) at the exchange and also that the total circuit length must be below certain maxima. This is because digital traffic is sensitive to signal attenuation and line noise.

 

Baseband circuits can either be four wire (EPS 8) or two wire (EPS 9). The four wire circuit can support speeds of up to 4.6Mbit/s while the two wire circuit can support up to 2.3Mbit/s, both dependant on distance and the quality of the copper wire circuit. Although quality of service is not guaranteed by BT and there is no contractual commitment to fix problems within a certain time limit, the cost of these circuits makes them an attractive possibility.

 

So he was spot on about price and the distance limitations.

 

I also remeber the BT learningstream product that provides very cost effective leased lines for education between sites, but overkill in this situation.

[Geoff]

Ah - a little more Googling suggests a legal limit of 100mW power output for wireless devices.

 

Indeed. If you simply replace the omni-directional antenna in a WiFi device with a yagi or similar directional antenna without adjusting the output power of the transmitter then you will likely go over this legal limit in the particular direction you are transmitting.

 

You must either adjust the output power of the device (which you can't in most low budget devices) so that it transmits at a limit of 100mW (thus making the whole reason you added a directional antenna rather moot) you will also need (expensive) radio diagnostic equipment to calibrate and test this and optionaly an (expensive) radio engineer to operate said equipment. Alternatively you can buy (an expensive) radio license.

 

I expect by this point you would of found laying fibre or using a VPN via the Internet to be a cheaper option.

[gwendes]

Can you get cable in your area? We have 20Mb connections available in Portsmouth - if the other site was more than a standard wireless AP could handle I'd have a cable or ADSL line just for VLAN...

 

Cheap and I reckon up to the job for only 5 computers - if it was another full site then you'd be best off renting a cable.