Understanding Wireless Networks

IT Services

Understanding Wireless Networks

Contents

1. Introduction
2. Hardware
3. Operating Systems
4. Client Software
5. Security Considerations

1. Introduction

The following is a guide for users of OWL-partnered wireless services that are perhaps unsure of what is required of them, or how they might benefit from connecting to the Oxford Wireless LAN.

2. Hardware

To make use of this service you will need a

wireless network client
adaptor

. This component may take a number of forms depending on the age and type of your computing device. Typically it will be one of the following:

If you have a new laptop computer, there is a good chance it came supplied with a wireless adaptor fitted within the body. Look for an Intel® Centrino sticker or consult your hardware documentation.
Older or more compact or inexpensive laptops may require a wireless adaptor card that is purchased separately and plugs into an available PCMCIA card slot.
Some PDA's have a Compact Flash (CF) slot to which a wireless adaptor card may be connected.
Newer PDA's may also come with wireless adaptors fitted within their bodies.

To help guide your purchase there may be some logos or codes on poduct packaging that identify supported standards. The following table indicates those supported by our service together with a brief explanation:

Identifier	Meaning
Figure ../images/logo_wifi.gif []	The `WiFi Alliance` is a consortium of vendors that guarantee hardware compatibilty. We recommend that you purchase a product with this logo
`802.11b`	The most common standard for wireless, providing data speeds of upto 11Mbits per second
`802.11g`	A newer standard that uses the same radio frequencies as 802.11b but provides faster data rates of upto 54Mbits per second (compared to, say, half a Mbit for domestic broadband or 100Mbits at your desktop)
`802.11a`	A less common standard that also runs at 54Mbits but using less crowded radio frequencies

We have tested the following client adaptors, and found them each to work successfully:

Logo	Manufacturer
Figure ../images/logo_centrino.gif []	Intel Centrino
Figure ../images/logo_cisco.gif []	Cisco Aironet
Figure ../images/logo_airport.gif []	Apple Airport
Figure ../images/logo_symbol.jpg []	Symbol Wireless Networker

We have also tested the following hardware platforms, and found them each to work successfully:

Toshiba Satellite Pro Intel Pentium 4 (laptop)
Apple G3 iBook (laptop)
Apple G4 iBook (laptop)
Sharp Zaurus SL-5500 (PDA)

It must be said that wireless networking is a technology with many competing standards from different vendors, and is not guaranteed that a service will be supported across all devices and operating systems. We have tried to make the Oxford service as widely accessible as possible. Please see the next section for further software advice.

3. Operating Systems

Our service design is intended to permit network access as widely as possible to University members and guests. We have therefore selected infrastructure hardware that should allow any standards-compliant client adaptors to be used.

As long as the adaptor you use is supported on your operating system, and you have the tools available to associate with a wireless network (included with most modern operating systems), you should be able to use our service. We do not anticipate any problems in this respect that are particular to our own network - in other words if you cannot use this wireless network it is unlikely you would be able to use any other.

We have tested the following operating systems, and found them all to work successfully:

Microsoft Windows XP
Mac OS X
Embeddix GNU/Linux

4. Client Software

Your operating system should provide all the tools you need in order to associate with our network. However, for reasons of security we do not allow users directly onto the University network without first proving who they are. We also provide services that require some form of data encryption, as your radio signals (that contain the network traffic) are easily intercepted by malicious users. Technical details of the individual wireless network services are available elsewhere, but there follows a brief summary of the software requirements.

The basic service that is actively advertised by our access points is based upon the University VPN Service. For this you will need to have the Cisco VPN Client software installed, configured and working. We highly recommend that you test this with a regular wired connection if at all possible, and then use the wireless network; the Cisco client will work in the same way regardless of the method of network connection.

5. Security Considerations

Security is a major concern with wireless networks, because many more users are able to view your network traffic than would be possible with wired networks. This is because the radio waves that are transmitted between your client adaptor and our access points are available to other radio receivers at the same time. You can imagine it being like shouting across a crowded room to another person - the conversation is available to eavesdroppers in the vicinity, as long as they understand your language.

We therefore strongly recommend that you encrypt all your network traffic, which will not prevent reception by third parties, but should stop them from understanding the contents of that traffic (for example your passwords and emails).

Using the OWL-VPN service is secure, because your Cisco VPN connection to our central server is encrypted, and all your traffic is sent over that connection. There is also an unencrypted service for visitors to the University, where we cannot enforce or expect that they will have the Cisco VPN client. This latter service is not intended for University members, and will provide limited network connectivity compared to the preferred VPN service.