Also see OldNodeHowTo for out of date info.
Contents
Introduction
What This Document Will Teach You
This HOWTO is intended to be a complete step by step guide to setting up a basic node on a community wireless network. Certain aspects of individual set-ups may not be included here. Please use common sense in reading this document and building your node. If you find mistakes or feel something should be added please do so.
What Is A Node?
A node is one location on a network. When we're talking about a city-wide ("Metropolitan Area Network", in traditional networking lingo) network, like SeattleWireless, a node could span a house, business, appartment, school, or any other building. Note that a given node is usually itself a sub-network, or "Local Area Network". People often create LANs to connect the different computers in a house together in order to share files, printers, and Internet connections. The goal of the SeattleWireless network is to interconnect many such small networks around the city into one, larger, network of networks.
When we talk below about nodes having this and that piece of equipment, we mean that the equipment is all in the same place - either in the same computer ("router"), or in different devices close together and connected by traditional, wired Ethernet systems. ((TODO: make a diagram, anyone?)) The parts of a node important to our discussion here are
- Antennas, which provide the physical link to another node;
- Radios, each of which operates a particular antenna;
AccessPoints (or APs), which are typically small computers that house radio(s) and connect them to other parts of a node; and
- Routers, which direct traffic between the parts of a node, and provide some level of security.
When we say that a node or AP has an antenna, we imply that the antenna is plugged into a radio, which is inside an AccessPoint. Also, most radios come with built-in antennas, but we often attach new antennas to them to suit our particular needs.
Kinds of nodes
We classify nodes based on their role in the larger network. (see individual node's pages for detailed descriptions).
A DxNode is not really connected to the SeattleWireless network at all. Instead, it has one antenna providing wireless access to the local network. A laptop user might use a DxNode to access resources local to that node - for example, an Internet connection.
A CxNode is like a DxNode, but it has an additional antenna pointed at another node on the SeattleWireless network. This allows people connecting to the node access to any other part of the SeattleWireless network.
A BxNode is a computer with atleast three radios. One radio provides client access and the other two radios provide redundant upstream links to two other nodes. If one connection goes down, the node is not stranded from the network. Furthermore, a BxNode is contributing to the structure of the network by allowing transit from one part of the network to another.
An AxNode consists of three or more radios, each connected via DirectionalAntenna to other Cx or Bx nodes. AxNodes form the backbone of the network, and are not concerned with providing local access to users.
What Node Is Right For Me?
You probably want to start off with a DxNode. This will require you to set up an AccessPoint, connect it to your local network, and figure out how you want to regulate access to your private network. Once you are comfortable with the technology involved, then you can work on upgrading to a CxNode by connecting to someone else's node.
If you are already comfortable with the technology, the node you create will be defined by how many other SeattleWireless nodes you can find to connect to, and by whether or not you want to be able to connect wirelessly to your own node.
Knowledge Pre-Requisites
Although you do not need to be a technical guru to run a node, It helps to have a little bit of UNIX knowledge. If nothing else, you should understand routing concepts and OSI layers.
Hardware Pre-Requisites
There are many many ways to set up node hardware, and many of them are scattered throughout the wiki. If you want to have something on your roof with a minimal amount of effort, you may want to look at MetrixCommunication.
Planning Your Node
Finding Other Nodes In Your Area
Checking Your Line Of Sight
In order to create a link to another node you will need to be able to see it (i.e. there are not any trees or buildings between the two nodes). What you can see from your node's location is what we call Line of Sight (LoS). Checking your line of sight involves making sure that you can see any node you plan to link to.
Take some pictures of your LoS and place them on the WebSite so others can see what you see. If it turns out others can see their nodes from your images then they can contact you about making a link.
Link Scoping
Before you get to far down the road, it can be very helpful to 'scope' the site for a point to point link with a second node. This can be as easy as a notebook & some luck, but often requires a directional antenna pointed at an existing or planned link. There are several people here who can help you with this phase of your install. It's a good idea to bring most of the following: binoculars, compass, small antenna tripod, functional notebook with a fresh charge, sunlight, various directional antennas, digital camera, paper to take notes, spotter, cellphone.
I would suggest a good quality topographical map of the area you are in. Plot your location and examine the local area, hills, trees and tall buildings are all problems for line of sight but are handy landmarks when aligning an antenna ( ever tried to balance on a roof with a compass, map, screwdriver and antenna? ) If possible get in touch with local node owners, with their location know you can derive a compass bearing to align to.
The above physical approach might be replaced with the use of topographical map charting software. Some of the consumer-grade mapping software will provide a LoS evaluation between two points on a topographical map. Various members use this software and it may be possible for a topographical LoS evaluation to be performed if you discuss this with one of the members at a SeattleWireless meeting.
Links And Potential Links
When planning your node you should estimate how many links you will have. You may already know who you are linking to but many will not. 802.11b provides only three non-overlapping channels, 1, 6, and 11. This will limit the number of radios you can use at your location.
Wires (Wait! I thought this was wireLESS?!?!)
If you are not placing your router on your roof you will need wires connecting your radios to your router. Many find that it is easiest to combine their power cable and ethernet cables by setting up Power over Ethernet (PoE).
An alternative to the ethernet-based radio is that of USB. Some 802.11b devices make use of USB for both communication and power. Various USB repeaters are available that support wire runs of as much as 60 feet, so it might be technically feasible to try this approach for a lower-grade node. A USB repeater that supports runs of 35-feet sells for $45 at Supertronix. More info on using USB to reach your rooftop is located at RoofTopAdHoc.
Software
Nothing here yet. If you are at a monthly meeting, you might ask other members about LoS topographic software though.
Other Helpful Notes
See some tidbits over at the bottom of the Link1 page.
Node Set-Up
Safety
Some notes on mounting antennas on your roof.
Roofs are dangerous places to work, most construction accidents result from falls so working off the ground is not to be taken lightly. Think about your roof and the shape it is in. Flat roofs are the safest, but beware of rotting boards (i have had that sinking feeling, not fun!). Thus, walking on your roof might damage it to the point where you need repairs. Sloped roofs are more difficult; always use ladders and properly secured crawl boards, not only does it help to stop you slipping and going into freefall, it spreads your body weight and prevents cracking of the tiles or slates on the roof (take it from me this is a good thing). The safest time to go up on to a sloped roof is in the afternoon, when the sun has been on it awhile and dried the tiles. In the UK we use slate roofs almost exclusively, and wet slate is very slippery. If you have trees that overhang the roof, BE VERY CAREFUL, most trees coat the tiles in a moss / slime that is like grease!
- Natural hazards: well, being on the roof in a rain storm isn't a good idea, and thunderstorms are a no-no... you do get an excellent view of the lightning though! Wind is also a problem as there is no natural shelter up on the roof.
- Ultraviolet radiation can also degrade anything you use, so be sure that the items you use are rated for continuous outdoor use.
Hardware Set-Up
TV yagi antennas are everywhere, they also provide handy parts for mounting WLAN gear. Poles, clamping straps, wall mounts etc are all commercially available. There are also antenna rotation kits ( basically a worm drive motor that turns the pole). Of course you can make your own, but why waste time fabricating a mount when you can go buy one for under $20?
Software Set-Up
Pebble Linux is a full-featured linux distribution that fits on a 64MB flash. It comes with all the updated wireless drivers, routing software and tools you will need (including NoCatAuth) to set up a node. It runs on MetrixCommunication Gear as well as PCs, Single Board Computers and Industrial PCs. Check it out at the Pebble Homepage
If you are looking for a linux distro that is easy to set up and run via webmin, check out Clark Connect. at www.clarkconnect.com. It's a stripped-down linux that sets up as a firewall/ftp/webserver box. (AndyReilly)
Another piece of software will let you setup an old PC to be used as an access point. The Unwired AP Project is made simple such that it will fit on a single floppy disc.
