Wireless Networks Thread, External telephony and data at an external site. in Technical; Dear All
I hoping if someone could provide some advice for me for the following setup.
Our school has just ...
13th March 2008, 06:27 PM #1
External telephony and data at an external site.
I hoping if someone could provide some advice for me for the following setup.
Our school has just leased an office block which we are hoping to provide data and telephone access. This office block is about a quarter of a mile from the school so its not very far. From the roof of our building we can see the office block.
I just wanted to know what options we have if require data and telephone points which link into our existing network or would we be better looking at an alternative solution or even having it as a separate entity.
A few ways we have looked at this, as the distance is small we maybe could do a wireless link across both of the sites (wireless Point to point bridge) which will do both our data and telephony or we could extend our leased line provided by link2ict/service birmingham across the second site but i think this would be the more expensive option.
Just wanted to get an independent opinion really on how best we could do this and what would be the most cost effective way. Some staff who use our network would require full access to our network there so I am thinking the best option would be to extend this across using this bridge link or something similar. A cheap and possible horrible way of doing this could be to use our VPN which could work as well but the issue with that is if our vpn server fails, they would lose connection to network on that site and for large data I'm not sure VPN would be adequate and that would fufill our network requirements.
On the telephony side as a school we have a centrex system and if we require further telephone ports around school i usually have this patched via a patch panel rather than an individual socket so as and when staff move offices we can patch in the correct telephone number to the correct port. Staff do move around a lot with regards to office moves so need a flexible solution rather than paying a telecommunication company every time we require a socket moved. I am happy with doing this at the other site but not sure what this involves. Ideally we would like it linked into our existing infrastructure as we qualify for free local numbers but then it would give us the opportunity to maybe look at voip in the near future.
Or as its a new building would I be better off looking at a whole WIFI voip phone system if we go with a wireless bridge option?
I would be interested in knowing what peoples thoughts are about this. I just a bit worried if we put in a centrex system at this new site and a fibre leased line it would be of a high cost and in terms of building i think we would be going backwards rather than forwards.
Any advice on this is much appreciated.:-)
IDG Tech News
13th March 2008, 06:59 PM #2
A wireless PTP link will crawl, and if you want voice over it as well it's a definite no-no. You're probably looking at VPN (cheap) or leased circuit (silly money) for that kind of distance.
You could have a look at laser PTPs, but they're expensive and I've never used one.
Out of nosiness, why has your school taken out an office block?
13th March 2008, 07:42 PM #3
One of the options which has been mentioned a couple of times for this type of problem in previous threads is private-wire SDSL.....basically if both sites connect to the same exchange you can have a ptp link over sdsl between the two....it's a simple case of patching across for bt. The fact the other office is only a quarter of a mile away makes this a distinct possibility. It's also comparatively cheap to do the only trouble is you'll be restricted speedwise by sdsl line limits.
Alternatively get the LEA to provide a line to the new site and site-to-site vpn between the two. If you go this route you'll have to ask the LEA if they can setup a tunnel directly between the sites. Let us know how you get on if you choose this option.
Can't really comment on the speed aspects of a wireless solution, but if a 802.11a/g bridged solution can't cut it....maybe worth looking into other niche wireless solutions such as microwave link (although typicaly that's over longer distances) and FSO.
13th March 2008, 08:05 PM #4
Never heard of that, that's handy to know. Wonder if school will wire my house up
Originally Posted by torledo
13th March 2008, 08:38 PM #5
- Rep Power
We have a couple of 133mb Wireless Bridges at our site provided by a local company... well, they were, (Piping Hot / Orthogon Systems... which became Motorola) they work well and are NLoS. I guess having a Wireless Bridge ultimately depends how much you plan on running off it.
We've got several access points, several IP phones, several computers and several laptops hanging off the end of it and nobody has really made any big complaints about it...
not sure why in the cab that it links to, there's a full 24 port switch and an 8 port switch... but still.
Run a fibre through the sewers between the two buildings?
14th March 2008, 09:57 AM #6
You existing telephony setup using your cat5 structured cabling Is just using the copper to link into your schools pbx.
So I presume that in the cabs where the telephone lines terminate there is a voice patch panel and you just patch from that to your normal cat5 one or something similar.
This means that you can't just provide a telephone service in this new block as easily as you do now.
You could possibly provice some voip functionality at the remote site and patch that into your pbx but it depends on the exact setup, I'd suggest talking to your telecoms provider about that.
14th March 2008, 10:20 AM #7
I could be wrong 'cos i know there are different flavours but he mentioned a centrex system which i belive is a manged pbx, so no onsite pbx hardware. For his school i'd imagine he's got a 24 pair cable coming into the building and connected into his voice patch panel but no pbx. Maybe TS could elaborate on current voice setup in the main building.
Originally Posted by plexer
If he did have an existing on-site pbx, dpending on the type and model, he could implement a voip system at the new office and have it link back to a local voice gateway at the main site that connected into the pbx using analog E&M connections. It's in the cisco docs as a Tie line trunk.
If it is a managed system he'd half to contact the centrex provider to get advise.
14th March 2008, 10:22 AM #8
Ok but in essence what I said is still true he can't just hookup something like he does now to provide telephony.
14th March 2008, 03:22 PM #9
- Rep Power
If you have a line of sight you could use the infrared option for data
14th March 2008, 04:30 PM #10
- Rep Power
The wireless point to point bridge seems like the best idea in my opinion. This will be more economical in the long run as you won't have to pay for the running costs of another centrex setup or additional internet connectivity, you are also able to upgrade the speed of the link as your requirements change.
You may also wish to consider the set-up times for all of these systems; in my experience of working with centrex I have found that a new site installation normally takes about 12 weeks if there is no existing 24 pair cabling in the office block.
To achieve your desired functionality I believe you could put a VOIP server into your patch cabinet allowing up to 48 of your existing POTS copper telephone lines to be patched into the VOIP system, this could then be sent across the wireless bridge to VOIP phones at the desks of your office staff. It would seem pointless to convert the lines back to analogue phones at the other end considering the price of VOIP hardware. Whether the VOIP phones are wireless or not is completely up to you.
Overall link speed is surprisingly not so much of a problem, your key consideration should be the latency of the link hardware; if you have a low latency link you will be able to send your phones over using VOIP. You have two main options in terms of low latency link hardware, these are microwave transmitters and line of sight lasers. It would be very ambitions to try and use a standard 802.11g access point for this type of link even with external directional aerials.
Lasers are the best technology for high bandwidth and low latency, we tend to use 'LaserBit' equipment at 1Gbps with no issues; they do however have the obvious disadvantage of only working through line of sight. This may not be a concern immediately, however over time I have seen problems with trees, and insects / birds interrupting the signal transmission.
I would personally use a wireless microwave link; these are expensive, but they can go reliably for several miles without direct line of sight. I would again recommend the Motorola units as they are very reliable, easy to install and use power over Ethernet. A great feature of these units is the fact that the Tx / Rx hardware is the same for all current models, the speed is simply controlled by a firmware upgrade - this means that you can purchase an upgrade to your wireless link if/when you need it without having the boxes on your roof replaced. The Motorola units are available from these guys:
Advertising removed but rest left as it is good advice - Ben
Last edited by plexer; 14th March 2008 at 04:48 PM.
14th March 2008, 06:18 PM #11
Originally Posted by Raj
i'm no wireless ptp expert, but my understanding is that there is a distinction between the 'wireless' ptp products and the microwave solutions. The motorola ptp products in you're link don't appear to be
microwave products. Correct me if my thinking is muddled :-)
Also, the disadvantage of microwave products is the requirement for licensed usage. Add to that expense there's the additional cost of installation....
Some of the motorola products operate in the unlicensed frequency, but can they be diy installed. 3500 for 21mbps is a bargain.
14th March 2008, 07:15 PM #12
- Rep Power
My apologies, should have read what I wrote before I posted it. The Motorola p2p kits are in fact RF kits rather han microwave; there is a licenced and unlicenced version depending on your preferred frequency. I believe you are right, you do need a licence for microwave transmitters. Although the motorola wireless transmitters are RF they are not the same as 802.11a bridge kits.
To clarify, I think the wireless RF kits I linked to in my last post are definately much better value than a licenced microwave bridge for this scenario.
14th March 2008, 07:26 PM #13
See if your LEA/BBC can connect you up to the MPLS first.
It should be well subsidised and easier to manage.
A BT uncontended 2mb on a 2mb bearer will cost about £7000 pa and should be good enough for what you need with a 99% uptime SLA.
Depending on how far you are from the nearest POP the install should cost from £0 - 3k. As you are nearby anyway I guess it will cost £0.
Business SDSL is a contended service and has no guarantees.
If you want to DIY then I would suggest a Gigabit Laserlink with a wifi backup.
Do get a proper survey done including a Sun Track forecast.
I have seen the best designed Laser systems knocked out for up to an hour every day due to the sun striking the Laser Reciever!
A Wifi bridge using traditional A/B/G/N is only going to be suitable as a backup route or light network/voice for one or two users.
Use a proprietory Wifi bridge using true Microwave or see if there is a local Mesh provider in the area, these are becoming increasingly common and used by LA's and the Police to connect CCTV and "other" systems connected.
If I tell you any more about the "other" systems I will have to kill you...
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