Wireless Network Solutions for a Metropolitan Area?

An anonymous reader asks: "I work for a company that is expanding into multiple buildings within the same office park. We have line-of-sight between the buildings and are looking into wireless alternatives. Does anyone have experience with products such as Proxim's Tsunami or Bridgewave's GE60 Gigabit wireless link? The point-to-point links will need to support the usual LAN traffic (SMB, HTTP, SMTP, etc.) as well as VOIP. The buildings are not large--up to 140 users, whose main network use would be e-mail, printing, and saving Excel documents to file servers, as well as the aforementioned VOIP). Are these connections any more secure and reliable than using something in the 802.11 family of protocols?"

Comments

The US's oldest metro-area mesh

[Baldrson]

I designed and deployed the first metro area mesh network in the US using Locustworld's MeshAP software. It wasn't and isn't big (small tourist town) and it required a lot of babysitting for the first year, but its a pretty mature technology now and the price is right (the software is free unless you start getting into the WISP stuff they sell).

At this level - pay the money

[ejoe_mac]

If its all in one complex see about the options to having fiber pulled inside existing conduits. Otherwise it's time to justify the cost over a number of years, and allow for a redundant pathing setup & better hardware. Do 3 links and run OSPF on the back side - that way you're safe in the event of one link failure. Also consider CanoBeam (Canon) free air optics http://www.usa.canon.com/html/industrial_canobeam/ canobeam/canobeam130.html which may also work better for you, depending on needs.

Keep in mind that fog and tall buildings can impact performance on laser based systems, but compare this to everyone 's wifi APs as background noise. Just make sure to go to either licenses bands or the 5.8ghz range if you go the radio path.

Re:Laser Link

[HavokDevNull]

Saw this at a trade show this year (see boss I do learn from these things) http://www.lightpointe.com/home.cfm and from what I saw they have the technology and the bandwidth to handle most LAN's today. I did ask the rep if fog, rain, and snow etc... plays a part in the reliability of the connection. He said yes it does but you have to have major conditions (hurricane) for the connection to drop completely. If you go this route I would ask for a demo of it and research more QOS issues.

Not really a metro question, it is point to point

[jwkane]

Good question. What you are looking for is a point to point bridge. At short range with good line of sight there are only three relevant factors. Price, Speed and Quality.

If price is irrelivent, a free space optic (like gigabeam) with an RF backup (like a Tsunami) will give you massive amounts of bandwidth, low latencies and lots of 9s for uptime/reliability.

Price is rarely irrelivent. A more economical option would be to skip the FSO and just use something like a Proxim QuickBridge. Another alternative which hits a nice price/performance/reliability is a Trango Atlas (45Mbps, about $3k). Most inexpensive (ala 10k) and the licence may be an annual recurring cost. Licence costs depend on location (city/county/state).

So for rough ballparks...

FSO w/RF backup, 1Gbps, $25k +
Licenced P2P RF, 100Mb, $12k + Licence
Unlicenced P2P RF, 54Mb, $3k (Trango)
Unlicenced P2P RF on-the-cheap, 54Mb, $1500 (Microtik, other 802.11x based systems)
Unlicenced P2P RF ultra-cheap, 54Mb, $400 (WRT54Gx2 w/Sveasoft firmware, external antennas)

Some answers to common questions

[cloricus]

One thing I hear a lot from people interested in doing this sort of thing is worries about fog and buildings. So here are my observations on these two topics, I hope they are helpful if they are in the back of your mind. Though I have no real idea about laser as it tends to be rather expensive (I'd love to know about some home brew solutions if any one knows some) I have had dealings in fibre through the company that I work for and personally I'd rather wireless for simple tasks (like the ones you listed) and fibre for that intersite LAN feeling (at work all of the sites are effectively on the one LAN which can be handy as they all use centralised DBs and content systems.

Fog has little to no effect on short range and long range wireless links. I have rarely used extreme short range (standard 6dbi antenna that you get with your home dsl router) wireless and have no idea what fog does to its already pathetic range. Though I have done extensive testing with one to eight km range gear (15 to 36dbi austar standard, grey sat, omni 180/360 wave guide, omni sticksomethings, and many more) transferring large files during fog periods and during sunny normal days and at most (you can't see five feet in front of you fog) the difference is a drop of around 20kb/s (sustained speeds of around 600kb/s) max to deal with the slightly contorted packet noise from the bounces. Over long range links (using 4watt Austraian max on the old 3 foot grey sat dishes to similar and to 24dbi austar) from 25km to 61km fog has had at most a 40-50kb/s (sustained-ish speeds of 550kb/s) effect which is nothing compared to lite dust which just kills the connection with a loss of around 430kb/s. So in my extensive experience in home brew/city wide community wireless projects (specifically Brismesh, Ipsmesh, and DDwireless in Queensland Australia) I can happily say fog is not some thing to worry about and rain may even give you small boosts in speed on short range links.

Large buildings in your way however will almost completely kill off any chances you have of getting a stable connection. And even if you can some how pull off enough of an angle to get a connection to your other site you may get a problem we often noticed where the noise causes a stable 600kb/s connection to drop to around 80kb/s after 20 minutes to around 12-13kb/s after 35 minutes or just drop out while moving large files. Remember that in Australia we have a 4watt limit so blasting our way through objects other than trees is a lot more illegal and a lot harder than it is in the US so it may be possible, I'm not sure. So as a rule of thumb...If you can't see it don't bother.

If you need to know more details or have other worries I am happy to answer and link you to wiki write ups on testing and projects we've done.

Rain fade on 38 GHz microwave

[billstewart]

I work for a carrier, and we occasionally use 18GHz or 38GHz equipment to provide access or access diversity. It'll carry up to an OC3 or so depending on exactly which equipment you use, requires line of sight, etc. The limiting factor for us as a carrier is that we're expected to offer a service level agreement, and the amount of heavy rain an area gets determines how long a distance we can go before we drop below 99.99% uptime. So Phoenix can get up to 10 miles or so - Seattle's a lot lower (though not as low as you'd expect, because they get lots of light rain. Houston's worse.) Most of the US older-48 states get 2-3 miles.

Then there's backhoe fade. Guys named Bubba driving heavy equipment are not your friends....