Cheap Wireless 802.11b Bridging

eggboard writes "You can bridge two wired networks using two cheap Linksys 802.11b access points. This isn't exactly new, but the article I wrote, which just went up on Friday, describes in excruciating detail how to configure the units. The big news is really price: the WAP11 described is about $185 with a manfacturer's rebate. Using higher-gain antennas than the ones shipped with the WAP11 and/or tuning line-of-sight access, you've either figured out how to hook up a neighborhood of separate wired networks, or how to link multiple offices cheaply."

Comments

Legal issues

[mwillems]

Careful though.

a) By modifying equipment you may be breaking FCC rules (USA) or your local rules.

Additionally, in the UK, 802.11b is NOT apprived for commercial use. I spoke at length with the UK government Radio Agency last week to establish this (my company use 802.11b to connect remote advertising screens, but not in the UK where this is forbidden.)

Michael

Re:Detalils?

[oldave]

Reverse TNC Male

And you can use any antenna that's built for 2.4 GHz. Unity gain, 5.5 dBi (what I'm using to link 2 condo complexes), etc.

Use LMR-400 (or better - better is left as an exercise for the reader) cable, reverse TNC Male connector for the back of the Linksys... N-type female (usually) on the antenna end of the cable.

Calculate your system gains/losses at this site:

http://www.dct.com/~multiplx/wireless/wireless.mai n.cgi?GoButton=Go+Now%21

A word of caution - don't mess with the connectors yourself unless you know what you're doing. A stray strand of braid touching the center conductor will blow you out of the water. Also, to minimize loss (we're only talking 50 milliwatts here - not much power), be sure you use quality, solder-type connectors, and only the ones at each end... "measure twice, cut once" is an invaluable piece of advice when installing your transmission cable.

Also be careful of short coax runs and 24 dBi gain antennae - don't want to run afoul of the FCC.

One other comment - don't use channel 6 (the default in the WAP 11).

$199 Cheap? Make it yourself.

[steevo.com]

Why not turn bridging on in the kernel and bridge to an internally connected 802.11b card.

I used to work for (company unnamed, but you have heard of them) a place that developed a stand-alone product where the "bridged mode" is done exactly this way. (It was still in development when I left, and I don't believe it is yet on the market.) Bridging performance was about the same as other 802.11b access point devices.

While the platform was a bit differant (StongARM and mini-PCI cards) there is no reason you couldn't do the same with a P166 sitting in the closet, a card bus controller and a cheap 802.11 card.

Mobil Ad-Hoc NETworks: Re:next, forward packets

[voop]

You're right - and it exists. Routing protocols that would make such things work exists for so-called MANETS (Mobile Ad-hoc NETworks), being developed by the IETF.

Working in this area myself, I'd like to point to
http://www.ietf.org/html.charters/manet-charter. ht ml, which is the IETF-working group dealing with MANET's.

Now, for the shameless plug: A link to the OLSR routing protocol for MANET's, which is showing promising results. Implementations (downloadable, with sourcecode etc. of the routing deamon) are available (drop voop@cs.auc.dk an email if interrested in the code - the www-server is currently not responding).