GalwayWAN FAQs

Version 1.4, © Copyright 2004-2008 by Stephen Mulcahy

Comments, additional questions, corrections and enhancements are most welcome. Please send them to stephen@skynet.ie.

• What is the IrishWAN?
• What do I need to get started on the network?
  • Full Member Node #1
  • Simple Client Node #1
  • Simple Client Node #2
• What kind of power does that equipment use?
• Where can I learn more about wireless networking?
• Where can I learn more about the IrishWAN?
• Is this legal?
• Will I get free internet access?
• How do I access the internet from the Wan?
• Who can I connect to on the network?
• What does it cost?
• Why would I want to join?
• Can businesses use the network?
• What losses are caused by cables and connectors?
• Where can I buy wireless equipment?
• What kind of performance can I expect to get?
• What about lightning?
• Can you help me with a problem with my wireless connection?
• How do I know if I have a good signal?
• How should I configure the network connections on my node?
• How big is the GalwayWAN?
• StarOS specific questions
  • What is StarOS?
  • What do the signal quality values in the Association list mean?
  • How can I calculate what signal quality I should be seeing?

What is the IrishWAN?

The IrishWAN started as a loosely connected group of people who were developing wireless networks across Ireland. WAN stands for wide area network (or maybe wireless area network these days). Since the founding of the IrishWAN, various groups have created their own separate WANs. The main not-for-profit wireless networks in the West of Ireland include IrishWAN and TheWAN. Both WANs have websites which include web-based forums for discussing wireless network and problems experenced in getting going. The aims and motivations of members of the WANs are pretty varied - some people are simply interested in getting a decent broadband-class connection to a remote countryside location where traditional DSL will probably never be available. Others are interested in experimenting with either wireless equipment or the technologies which are used to network computers. As a general rule, parts of the IrishWAN are operated on a voluntary, non-profit basis although some parts of the WAN are being organised around the co-operative societies and all parts of the WAN welcome dontations of equipment, money or expertise in everything from climbing roofs, to wireless networking.

The IrishWAN is loosely organised geographically with groups based in either counties or regions of Ireland. The GalwayWAN is a group of people based in and around Galway and Clare.

What do I need to get started on the network?

The short answer (as always) is that it depends. It depends on whether you want to simply connect to the network (what we'll call a simple client node) or whether you want to participate as a full member of the network (what we'll call a full member node). The following lists 2 sample configurations with prices correct as of 14-Sep-2005. You may be able to build something for less using components from other supplies or by constructing some components yourself rather than buying off of the shelf. The following configurations work and have been found to be reliable. Other configurations and prices are welcome.

Note: I'd strongly encourage you to build a full member node rather than a simple client node. Without full member nodes the network can't grow - while you will have full access to the network with a simple client node, we'd never have a network if everyone adopted this approach. Also, note that some AP nodes look for a donation toward network backbone costs from client only nodes.

Full Member Node #1

Simple Client Node #1

Simple Client Node #2

A potential complete off-the shelf solution for a simple client node is the Wi-Pipe Outdoor Wireless Client. The unit includes all components needed to connect to the WAN including a wireless bridge device, an antenna, a waterproof box and a power over ethernet unit. I have installed one of these units for a 3-4 km link and it works quite well. Installation and setup are completely painless. The Wi-Pipe retails at approximately 285 EUR.

What kind of power does that equipment use?

The power demands vary a lot depending on which board you're using what cards are in it and how busy the board is but the following are some numbers sourced from measurements and information from the web. You can calculate power usage if you know the current and voltage a unit uses (power = voltage x current). Soekris net4521s use about 5W with 2 PCMCIA installed (each cards uses about 100mW). The WRAP boards use about 6W with 2 MiniPCI cards installed (the CM9 cards use a maximum of about 400mW when active).

Where can I learn more about wireless networking?

• The excellent Wireless Networking in the Developing World book.
• seattle wireless (including a hardware comparison and a node hardware recipe).
• solwise
• Tom's Networking Need to Knows.

Where can I learn more about the Irish WANs?

• www.irishwan.ie
• www.thewan.net

Is this legal?

Yes. The wireless frequencies we use for the Irish WANs are part of the unlicensed spectrum. The law allows their use for purposes such as ours as long as your equipment doesn't output a signal in excess of the legal power limit. The legal power limit in Ireland for 802.11b wireless cards is 100mW or 20dbM. 802.11g is subject to different limits. The Irish telecommunications regulator provides guidelines on these regulations.

Will I get free internet access?

No. This is a common misconception with newcomers to the IrishWAN. Unfortunately in Ireland (and most other countries that I'm familiar with) - you have to pay for Internet access. You may be able to use someone elses Internet connection via the wan for free, but this is entirely at the discretion of the person with the Internet connection and is not a feature of the Wan itself. It helps to think of the Wan as an entirely separate network from the Internet. Some people on the Wan do happen to be connected to the Internet also, but there are no guaranteed connections from the Internet to the Wan and vice-versa. Some people on the Wan also provide copies of information such as Linux distributions and Shareware on the Wan from the Internet as a service to the Wan.

So, if you want Internet access through the Wan - you need to get in touch with someone that wishes to share their internet connection and make some arrangement with them. What the Wan will allow us to do is to purchase better internet access than we could purchase individually and share the resulting connection between a number of people - but this will still need to be paid for.

Will I get free internet access?

If you do have someone willing to offer you internet access, you both have to figure out what kind of access you require (and your provider is willing to give you). If you just want to browse the web, your provider needs to setup a web proxy (such as Squid) and give you access to that proxy. You then need to update the settings in your web browser to use this proxy.

Using a web proxy will only give you access to websites on the Internet. It will not normally give you access to game servers, instant messaging servers, irc servers or p2p filesharing systems.

To have full access to the internet and services such as those listed above requires your internet provider to do one of a number of things:

1. They can just allow traffic from your IP address(es) to be routed through their firewall and onto the internet. You can then set your default gateway to the address of his firewall. This is relatively insecure since there is nothing stop someone else using your IP address to avail of your providers internet connection.
2. A more secure option is for your provider to set up a PPTP server on their firewall/proxy box. If the firewall/proxy system is running Linux, poptop (http://www.poptop.org/) is one such server. You can then create a VPN connection in Windows Network Settings and route your internet traffic through the VPN connection (Windows automatically configures the routing when you setup a new VPN connection although you may need to explicitly add a new route to stop all WAN traffic going over the VPN connection by default).
3. Various experts in the internet security community believe the PPTP protocol to be insecure ( http://www.jacco2.dds.nl/SANE2004_PPTP_Must_Die.pdf) so it only offers you a marginal improvement over plain old routing. Your other options include using a full blown IPSEC tunnel which are apparently reasonably difficult to configure or OpenVPN (http://www.openvpn.org/) which is alleged to be easy to configure and secure ( http://www.cs.auckland.ac.nz/~pgut001/pubs/linux_vpn.txt).

Who can I connect to on the network?

Generally, with the equipment we're using - you need to have Line of Sight (LOS) to someone on the network already and they probably need to be within a few miles of you even with a clear LOS. Once you connect to them - you're on the network and should be able to connect to anyone else on the network regardless of how far away from you they are. This is the simple answer - there are a lot of variables that can affect radio signal and there are lots of other devices using the same frequencies as the wireless gear we use so if you're unlucky - there may be a lot of interference in your area which degrades your signal.

What does it cost?

The only costs involved are those outlined in What do I need to get started on the network? - the IrishWAN and its members don't charge people to connect to the network (although some AP nodes may request a donation from client only nodes to cover the some of the costs of the network backbone equipment). Of course, if you want internet access you will have to pay for that.

Why would I want to join?

• You want to learn about wireless networking - a lot of the work being done on the IrishWAN is experimental - its a good learning environment and current wan members are a helpful bunch.
• You want to learn about wide area networking - joining the wan provides good opportunities for learning about how to manage a wide area network. Areas such as routing, address allocation and naming policies are still under design (and redesign), so you get an opportunity to learn about these in real environment.
• You live somewhere that will never have conventional DSL - for those living in country areas, it seems unlikely that DSL will ever be available directly. A connection to the wireless network could provide a broadband class internet connection via a DSL connection somewhere else on the network (but see, Will I get free internet access?). There are other alternatives for people in the countryside such as satellite internet access, but these may not be acceptable depending on your planned use of it (satellite broadband in particular is subject to high latency which makes it unsuitable for network gaming or interactive services such as ssh or telnet).
• You're unhappy with the current broadband infrastructure - aren't we all? Some people on the wan see a lot of potential in having a few hundred people interconnected via an essentially free network. This situation (which we haven't achieved yet) would create some interesting possibilities for obtaining alternative internet connections at bulk rates. We need more people on the network before this becomes feasible though, so its a bit of a chicken and egg situation.
• You like network gaming - good, we do too :) The wan works pretty well for network gaming and there are between 10 and 20 regular gamers at the moment who get together on Wednesday nights for some multiplayer gaming.

Can businesses use the network?

Yes and no. Maybe. Businesses are certainly welcome to connect but the nature of the network (a loosely connected network consisting of nodes run and provided on a volunteer basis) makes it impossible to offer any guarantees on quality of service. The network tends to be reasonably reliable but its not out of the question for parts of the network to go down for weeks at a time depending on individuals available time and other committments - this certainly precludes it from being useful as a primary source of an internet connection for a business. A scenario where businesses might find the wan beneficial would be where they wanted to provide out of hours access to their employees (as an alternative to providing dial-ins). Employees could connect in to their business via a vpn connection of some sort. There are people on the wan atm using this approach quite successfully.

What losses are caused by cables and connectors?

The following are the typical losses incurred by typical equipment we use on the IrishWAN - additional numbers welcome. Solwise provides useful information on a number of wireless topics including losses.

• pigtails 1-2db
• LMR-400 0.2dB/m at 2.4 GHz

Where can I buy wireless equipment?

All Wireless Components

• Wireless Connect - a wireless consulting company who also have an online shop which sells lots of good quality wireless gear including Routerboards.
• Wi-Pipe - a company in Waterford that sell an all-in-one weatherproof wireless box. They also supply antennae and other components.

Embedded boxes

• Soekris Corp - embedded boxes from California.
• PC Engines - embedded boxes from Switzerland.
• Routerboard - single board computers from Latvia.

Wireless cards (and general PC components)

• Elara - Irish vendor for components such as Linksys WET11 and Buffalo WLI-PCM-L11GP.
• Komplett - Irish vendor for PC components. Also stock a range of wireless gear (although not Linksys or Buffalo gear at the time of writing this document).

What kind of performance can I expect to get?

This depends entirely on the quality of link you have to your neighbouring nodes. Factors which influence the quality of your link include:

• The distance to the next node.
• Whether or not you have good line of sight (LOS) to nodes.
• Whether there is any interference in your area (the 2.4Ghz frequencies in particular are unlicensed and lots of other equipment shares the same frequences including wireless video senders, microwaves and other common household bits).
• The quality of your equipment - for cards receiver sensitivity is important. You should also be wary of turning up the power of your equipment unneccesarily - more power won't neccesarily give you a better signal (and may interfere with others around you).

802.11b has a theoretical maximum bandwidth of 11 Mbps (Megabits per per second). I would emphasise the theoretical part of that. The general opinion is that in practice, 4-6 Mbps is the most you're going to see on a good 802.11b wireless connection due to signalling overhead and so on. I tend to measure bandwidth in MBps (MegaBytes per second) or KBps (KiloBytes per second) since thats what most tools report. In fact, the only people that seem to use Mbps and Kbps are the hardware manufacturers (I wonder why?).

In a nutshell, the absolute maximum you can expect to see on an 802.11b connection would be 768 KBps (6 Mbps). In practice, the best links we have running in Galway have topped out at 558 KBps (4.4 Mbps). As mentioned above, this decreases as the quality of the link goes down so don't expect anything near 558 KBps unless you have excellent line of sight, no interference, good equipment and a reasonable distance.

In terms of latency - the best links on the GalwayWAN have latencies down around 3-5 ms. From one side of the GalwayWAN to the other latencies are more in the region of 30 ms. Some of the longer, multi-hop links we have with networks in other parts of the country have higher latencies (in the region of 10-100 ms).

What about lightning?

Nasty stuff around electronics. Best enjoyed from a distance. There are devices you can obtain for protecting wireless equipment from lightning but I don't have much experience with them. Opinions vary on how well it works and what the impact is on your radio signal. Without some protection, you will undoubtedly fry some or all of your wireless equipment and any devices attached to the network. The following are some examples of lightning protection for wireless equipment but I haven't any direct experience with them so I can't comment on how effective they are.

• Datavilla Surge Suppressor.
• HyperLink CAT-5 Lightning Protector.
• WiMo
• Fleeman Anderson & Bird's range of lightning protection.

Can you help me with a problem with my wireless connection?

Maybe. The best chance of getting someone to help you diagnose and fix a problem with your wireless connection (or indeed with your computer) is to provide enough information for someone to have a chance of figuring out what is up. Some of the information you may wish to supply include,

• Details of any changes you made immediately before things stopped working.
• Details of the equipment you are using (wireless and the computers connected to it).
• Details of the operating system you are using (including details of any firewalls you may have configured).
• Details from your operating system - in the case of Linux this could include iwconfig, ifconfig and route output at a minimum. On windows, ipconfig/all and route print would be a good start.

How do I know if I have a good signal?

Most equipment reports connection quality in dBm. Some kit uses their own quality measurement which can be a percentage or the manufacturers own arbitrary scale. If your equipment returns readings in dBm, it should usually report 3 things - signal, noise and signal-to-noise (the signal - the noise). As a general rule of thumb, a signal to noise (snr) of 10 dBm is marginal and will give you an erratic connection (if you get any). An snr of 13 dBm is good enough for a reasonable connection (but possibly not at the higher speeds that 802.11b is capable of) and anything above 18 dBm is pretty good.

How should I configure the network connections on my node?

This depends on what kind of equipment you have and where your node is located on the network (on the backbone, on the fringes). A typical sample configuration for a full member node is available at http://www.skynet.ie/~stephen/wireless/soekris-config.pdf.

How big is the GalwayWAN?

The GalwayWAN network diagram gives a rough idea of the size and layout of the network.

StarOS specific questions

This section answers some FAQs about StarOS.

What is StarOS?

StarOS is a commercial operating system intended for us on Wireless networking devices such as WRAP and Soekris boards. It is developed by a company called Valemount Networks (http://www.star-os.com). It features binary wireless device drivers which should perform better than the standard Linux drivers. It also provides a very user-friendly curses based interface to the system rather than the traditional Linux console.

What do the signal quality values in the Association list mean?

StarOS displays information about associated clients under one of its menus. The signal for each client is reported as xxx/yyy. The meaning of xxx and yyy depends on the type of wireless cards in use in the StarOS system. If the cards are Prism or Orinoco based, xxx is the signal strength that the StarOS Access Point sees and yyy is the signal strength that the client node sees. If the cards are Atheros based, xxx is the ACK packet value and YYY is the DATA packet value.

Note also that noise data is not reported at all for Atheros cards and not reported accurately for Prism cards. It is reported accurately for Orinoco based cards.

How can I calculate what signal quality I should be seeing?

The signal reported by StarOS for a particular connection can be calculated by adding up the following values (all units in dB):

• Power output of the wireless card.
• Losses incurred by pigtail, cable and connector on 1st end of link.
• Gain of antenna on 1st end of link.
• Free space loss (loss incurred by signal travelling from one antenna to the other - an approximation can be calculated using the formula 20 * Log10 (frequency in MHz) + 20 * Log10 (Distance in Miles) + 36.6).
• Losses incurred by pigtail, cable and connector on other end of link.
• Gain of antenna on other end of link.

• Power output of wireless card = +15 dB
• Losses due to pigtail, cable and connector = -3 dB
• Antenna Gain = +23 dB
• Free space loss from 10 mile link = -124 dB
• Antenna Gain = +23 dB
• Losses due to pigtail, cable and connector = -3 dB

In this example we should see a signal quality of about -69 dB reported for the link. Note that this may be off by a few dB due to inaccuracies in the reported power output of both the card and the antennae. The free space loss may also be higher in unusual weather conditions or over rough ground.