Karl Herrick

A technologist and web developer

Budget Wireless Distribution

Working for a non-profit organization requires a special type of ingenuity at times. In this case it was due to the requirement of setting up easy to use systems that are sustainable, yet affordable. Below are some pictures that show a wireless distribution system that I helped setup that serves the needs of 10 families, 4 guest apartments, and 2 work shops.

The Internet access is being provided via a business DSL modem in the lower level of the building with a red star on it. From there, a multi-purpose wireless router (RT-N16) is configured with DD-WRT and acts as the LAN’s gateway and firewall. Other common services it provides to the LAN include ones like local DNS, static DHCP, DynDNS client, SSH client/server, and OpenVPN client/server. It also has real time traffic monitoring, traffic graphs over time, QOS capabilities, and other exciting features. Nobody actually uses the wireless from the RT-N16 though, as it is being used only as a powerful, yet inexpensive wired appliance.

From there the only wired client connected is the main AP, a Bullet M2 HP. This little piece of equipment is quite exciting. A tough 600 mW self contained outdoor router built on Linux. It has already survived through the year long seasonal variations and is rated to operate at temperatures between -40C to 80C. Along with a 9dBi outdoor omnidirectional antenna mounted to it, they provide over 600,000 square ft. of network coverage through trees, hills and buildings with users reliably connecting in their homes over 250 feet away (though with the right antenna and conditions, the Bullet M2 HP is rated to perform at distances of over 50km away).

The 35.5m and 75.7m links act as “wireless repeater bridges” (http://www.dd-wrt.com/wiki/index.php/Repeater_Bridge) while the 134.7m link doesn’t repeat any network traffic wirelessly. It acts as a wireless client bridge (http://www.dd-wrt.com/wiki/index.php/Client_Bridged). The 35.5m and 75.7m links use Bufallo WHR-HP-G300N routers (with DD-WRT already installed at the time of purchase) and only required a few configuration changes to make them clients of the main SSID and re-broadcasters of another unique SSID (providing wireless to other clients). The 134.7m link on the other hand has a second Bullet M2 HP as a client bridge. This brings the wireless to the most remote location in the setup, where clients then receive signal from a WRT-54GL being utilized as an AP.

Can you spot the D-Link AP in the mix? Towards the end of the 75.7m link, people were unable to reliable reach the Bufallo WHR-HP-G300N signal (building materials) so one last inexpensive piece of equipment was thrown at the problem. Networks of this type are agile in nature. 🙂

The setup was completed in the beginning of Q1 2011. Parts used were a variety of new and existing equipment with recent prices listed next to the items below:

Total after shipping, taxes and a variety of screws and fasteners: around $900 – $1000 USD.

WDS Bridging Experiences

At the moment, our best solution for network coverage to multiple buildings is wireless. I have been planning out various solutions to improve our system (fiber optics, dslam, or a better wireless setup) but wanted to share what we have now and how well it has worked in this particular area of our property.

WDS Repeating Map

The image above shows the main buildings that are being linked. The main router sits in an upstairs window and is a:

Linksys WRT300N

  • Runs DD-WRT V24 – SP2 (Beta)
  • Has original antennas
  • Has the following properties set (among others, these are the interesting ones)
    • Wireless – Basic Settings
      • Mode: AP
      • Network Mode: BG-Mixed
      • Channel: 11 – 2.462 GHz
      • SSID Brodcast: Enable
    • Wireless – Advanced Settings
      • TX Power: 71
    • Wireless – Security
      • Security Mode: WEP (I haven’t tested WPA2 with WDS yet, and I understand that WEP can be cracked easily)
    • Wireless – WDS
      • The three router’s MAC addresses are filled in, and are set to “LAN”

The three client WDS routers are also sitting in windows, and are on the first level of the buildings that they are in. They repeat the same SSID, and run on channel 11.

Buffalo WLI-TX4-G54HP

  • Originally purchased as an ethernet bridge, it is now running DD-WRT V24 – SP2 (Beta)
  • Replaced the stock antenna with a 9 dBi omni-directional
  • Is on the 72.6m link

(2) Belkin F5D7230-4 routers

  • WDS on the stock firmware works with DD-WRT, sweet!
  • These are unmodified, running with their tiny fixed (two) omni-directional antennas
  • One is on the 35.4m link, and the other on the 88.5m link

This setup has been going for weeks without an issue, and has served upwards of six families, a two person office, a fifteen to twenty person office, and a classroom with sixteen students.

We have other areas on the same property that have wireless access between buildings, but are nowhere near as complete as this arrangement. If we do end up using wireless to unify the property’s networks, then I will start looking into site to site links, multiple gateways, OLSR, and other mesh technologies. I have my doubts as to how well WDS scales. Has anyone had positive results with professional mesh solutions built on DD-WRT and Linksys hardware?

Wireless keyboard

I am happy to report that I am typing this blog entry from my first wireless keyboard… it was free and it even had two rechargeable AAA batteries inside! The only issue I have with it, is that it is infrared… meaning it has to be pointed directly at the receiver, and also, I can’t read the monitor from this far away. 🙂

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