Wireless Overview

Conventional network topology uses cables, patch panels, and hubs to connect the nodes or users to the resources on the network (servers).  These connection devices are defined in the OSI Model Layer One: the Physical layer.  Wireless devices fulfill the function of the Physical layer without the need for cabling to the nodes or end users.  This is accomplished with the following devices:  wireless network interface card (NIC), access points, and point-to-point microwave trunks.

Components of a Wireless Network

The wireless NIC works like a conventional NIC but instead of having a cable connection the wireless NIC has a built in radio frequency (RF) transceiver.  The wireless NIC handles all in-bound and out-bound network transmission like the wired NIC.  The wireless NIC connects via a PCI slot in a workstation, or a PC card in a laptop.  Drivers are loaded for the PCI card, and the PC card is self-configuring.  The wireless NIC communicates to the network through an access point.

The access point is necessary in a wireless environment for network communication to a server, much like a hub or switch is necessary for network communication to a server in a wired network.  These access points are strategically placed to offer the maximize number of nodes and insure free mobility of these users.  Access points are wired to the network using conventional EIA-586 Category 5 cables and switches. 

All wireless NICs are installed with a software configuration tool.  This software allows the user to verify connectivity to an access point and check signal strength from the access point.  The configuration software also allows the user to define some settings.  Signal throughput and encryption levels are examples of user specified options.

Wireless backbone technology is accomplished using point-to-point wireless transmissions.  Point-to-point devices need a clear line of sight to function.  The RF is compressed to a tight beam transmitting from a rod then collected by a small, usually flat surfaced antenna.  The devices are often place on masts, towers, or existing geographical high points (water towers, mountains, etc.).  A high point installation establishes a continuous line of sight, insures security, and diminishes the risk of tampering.

Wireless Local Area Networks (WLANS)

WLANS can be used to either replace the LAN or as an extension of an existing LAN.  On a basic level, the wireless nodes will communicate with each other to form a peer-to-peer network.  Once there is the addition of an access point that is wired into an existing LAN the nodes no longer function as a peer-to-peer network.  Authentication and network security follows the rules of what ever network operating system (NOS) that the access point is wired to.

Access points are strategically placed so that there is an overlap of coverage.  In this manner, a wireless node may move from place to place in the covered area without a noticeable interruption of service.  This is called roaming.  The authors of the 802.11 wrote the specifications to allow for integration with the IEEE 802.3 Ethernet LANs.  They adopted the 48-bit addressing scheme, thereby maintaining address compatibility with the entire family of IEEE 802 standards.  Therefore, the logical addressing for the wireless media, distribution system, and wired network will usually be identical.

Security

IEEE 802.11 uses two types of security: authentication and encryption.  The definition of authentication is having one station verified to have communication with another station, the same as in any 802 network.  In a WLAN attached to a Windows Domain, authentication is between the PDC and the workstation via the access point.  WLAN nodes may use any existing NOS authentication scheme.

Encryption is intended to provide a level of security equal to a wired network.  Wired Equivalent Privacy (WEP) is the industry standard.  WEP employs RF frequency hops following the RC4 PRNG algorithm from RSA Data Security Inc.  Entry-level 802.11b access points do not necessarily support WEP.  All business class wireless access points support WEP.  Without it, casual hackers may gain unfettered access to a peer-to-peer network or may ‘see’ a Windows Domain.

WEP uses signal-hopping technology developed in WW II.  The wireless signal hops from frequency to frequency on a predefined scheme called an algorithm.  Signal hopping is no longer considered secure, as there is a finite amount of algorithms. The industry answered with layering algorithm hopping on top of signal hopping.  These wireless signals are not as easily compromised. 

There are wireless security appliances that take security to a much higher level.  These appliances, such as the BlueSocket device, drop an encryption and identification key into the client during the logon process.  In this manner the wireless access points become invisible to wireless sniffers.

There has been a dramatic increase in the use of home wireless network access points.  These may become an unwitting entry point to the most secure network.  These access points are easily compromised by hackers using tools readily available on the Internet.  A determined hacker can gain access to a network via unauthorized use of an authorized user’s logon information.  IT administrators in charge of remote access rights need to formulate policies and conduct user education to limit this access.

Commonly Asked Questions

1. What commercially available technologies exist to provide wireless web capabilities to complex and distributed customer bases?

   There are two IEEE protocols governing the use of Ethernet 802.11b, and 802.11a.  The main differences are: speed of throughput, availability, and price.  IEEE 802.11b has been commercially available for over two years.  These products operate in the 2.4-2.4835 GigaHertz (GHz) range.  About 130 manufacturers have complete 802.11b product lines.  The reported throughput speeds for 802.11b vary.  There may be a vast difference between the theoretical maximum throughput and the actual network connection speed.  Eleven megabits per second (11Mbps) is the highest possible connection for 802.11b.  The ranges of connection speeds are 1, 2, 5.5, and 11 Mbps.
   IEEE 802.11a is the newly defined specification.  There are ever-increasing numbers of companies providing 802.11a equipment.  In April 2002 there was only one manufacturer shipping these products, at this writing there are four.  New products are available at the speed we have come to expect from the technology sector.  Operating in the 5.150-5.350 GHz range these products have connection speeds of 6, 9, 12, 18, 24, 36, 48, 54, and 72 Mbps.  Many of the manufacturers are developing 802.11a equipment that is backwardly compatible with 802.11b.  IEEE 802.11g is in the final stages of being defined. 
   

2. What is the scope of a deployment effort of such a commercially available product in various environments?

   A network design is essential for any wireless deployment.  Once a product line is approved, a site survey needs to be performed.  The site survey will determine: the feasibility of a wireless solution, the placement of the access points, and strategies to connect to the existing network.  Using this information, a project plan can be formulated.  The project plan covers wireless network design, equipment needed, and installation schedule. 
   

3. What performance and acceptance measures are commonly employed in these technologies?

   As stated earlier, there is a wide variety of 802.11b equipment and a growing number of 802.11a products to choose from; there are wide varieties of prices as well.  Performance considerations are actual speed of connections, dropped connection rate, durability of the equipment, manufacturer’s stability and commitment to wireless technologies, and price.  A wireless network connection should be completely transparent to the end user.  Nothing less than that is acceptable.
   

4. What customers currently use the suggested technology?

   This is a partial list of uses in the marketplace:

   	TechData computer equipment distributors have wireless laptops installed on each forklift. This allows inventory management to be uploaded into a real time database.
   	Novell corporation uses wireless Internet for all of their office-based employees. This allows them to access the i. Portal solution from any where in the building, then use all of the e.Directory features in Netware 6.
   	Schools throughout the nation have wireless laptop carts. By connection an access point to an existing data line drop, up to 25 students may work in a networked environment, access network resources, or browse the Internet. No extra cabling is necessary. The carts may be moved from one classroom to any other room with a wired data line drop and a different group of 25 students may use this resource.
   	Historical buildings and constructions with other cabling challenges have embraced wireless technologies for their LAN’s. Wireless needs minimal cabling eliminating the need for structural integrity changes or breaches.
   	Companies who do not wish to invest in their existing building infrastructure use wireless networks due to the ease of moving from one site to another.

   Wireless network uses are only limited by the imagination of engineers and planners who employ these solutions.

5. What improvements in service/response are other organizations realizing as a result of using these types of technologies?

   The main feature that a wireless environment provides is the right of entry of a workstation to the network resources at any location in a covered area.  The modern professional sees their laptop as an essential tool.  A wireless environment allows all of this professionals network resources (e-mail, database, archived records, the Internet) to be available with the same ease as wall current.  This professional can only work with increased efficiency. 

   The buildings that house wireless networks do not need to be physically altered to accommodate the wireless technology.  This completely satisfies the concerns of the historical building preservationists. 

To find out how Daly can help you implement a wireless solution, please contact Daly Technical Services at (888) DALY-TEC or visit www.daly.com.