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Issue of July 2002 
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Buying Tips - WLAN
Setting up a wireless LAN?

A Wireless LAN is ideal for certain work environments and can boost work efficiency levels in most cases. Here's what you'll require to go wireless. by Mahesh Rathod

Cabling is the least expensive building block of your network, yet it is highly significant for performance and reliability. Bad cabling can result in frequent network breakdowns. Sometimes there's a situation where laying wires or physically connecting network nodes is impractical. Here are three instances when an organization would require a wireless LAN. A marketing person needs anytime, anywhere communications capability in order to access e-mail and Internet-based applications, from any room in the office. A corporate executive needs network access for his notebook as he moves from his desk to the conference room to the boss's cabin. Desktops need to be instantly connected to the LAN. In all three cases, network connectivity can be established instantly using WLAN (Wireless LAN) technology.

WLAN, a complement to wired LAN, uses radio frequencies to transmit and receive data over the air. WLAN is represented by the 802.11 standard that forms an efficient data communications system.

BUILDING BLOCKS
WLAN consist of two main components: an Access Point and wireless adapters. A bridge and an antenna can also be used when required.

Access point: An access point looks like an external modem with two small antennae. This radio-based receiver-transmitter is connected to your wired LAN using network cables. It performs the same function as a switch, i.e. receiving, buffering, and transmitting data between wired and wireless networks. Access points can be placed at different locations around the office called 'Hot spots'.

Radio cards: These are also called WLAN cards, and are similar to NIC's (Network Interface Cards) in function. Two flavours of WLAN cards are available. One is the PCMCIA radio card for notebooks and the ISA or PCI WLAN card for desktop PCs.

Antenna: The range of an 802.11b WLAN is typically 100 feet and can be extended to several hundred feet by using an antenna.

An omni-directional antenna enhances radio frequency coverage. This antenna is connected to the access point and is mounted at a certain height for the required coverage.

Wireless bridges: These are similar to the wired bridges and are used to connect two WLANs. Bridges can provide point-to-point wireless connection between two LANs that may be on two different floors or in separate buildings.

In addition, you'll also need appropriate network management software and drivers for the network cards.

BEFORE YOU DEPLOY
An enterprise needs to understand first and foremost, the applications that it plans to deploy on the wireless LAN network, irrespective of the decision of replacement or complementing the existing network. It makes little sense to deploy WLAN if applications like CAD/CAM are to be deployed/accessed, as these are bandwidth hungry.

One also needs to understand the usage pattern of the person who will access the WLAN. If all users are to access the WLAN at the same time, then the issue clearly becomes one of what the total bandwidth requirement of the enterprise is, and whether the solution helps achieve this. This becomes relevant in the context of a replacement decision.

Deployment considerations also include the location of wireless access points. Since they use radio waves, which are fundamentally hard to control, if the location is not proper, the solution may not be optimal.

BENEFITS
WLANs have proved to be highly efficient when it comes to sharing data and resources. The equipment is easy to deploy and its prices have fallen to affordable levels. Here are some benefits over wired networks:

  • Installation of a WLAN is quick and simple, and prevents the need to break walls to install cabling.
  • WLAN provides the flexibility of extending the LAN to places where cables cannot be deployed.
  • The initial investment for WLAN hardware can be more than that of wired LAN hardware, but the overall installation costs and operational costs can be much lower. Cost benefits are greatest in dynamic environments requiring frequent moves and changes.
  • WLAN presents the flexibility and mobility that LAN users need to access real-time information anywhere in their organization.
  • The 802.11x standard makes WLAN more secure than the wired LAN. Complex 64-bit and 128-bit encryption techniques make unauthorized access and eavesdropping difficult.
Company Access Point
(Indicative pricng in Rupees)
WLAN Desktop Card
(Indicative pricng in Rupees)
WLAN PCMCIA Card
(Indicative pricng in Rupees)

Krone Communications Ltd

Rs 25,000

Rs 18,000

Rs 14,000

US Robotics

Rs 25,500

Rs 14,000

Rs 13,000

3 Com

Rs 30,000

Rs 12,000

Rs 8,500

Cisco Systems

Rs 90,000 - 1,30,000

NA

NA

Avaya Communciations

Rs 93,000 - 1,04,000

Rs 14,750 - 23,000

NA

D-Link India Ltd

Rs 16,500 - 17,000

Rs 11,500 - 13,500

Rs 8,500

Intel

Rs 47,000 - 67,000

Rs 8,800 - 14,000

NA

Enterasys Networks

Rs 79,000

Rs 17,200

Rs 10,800

Surecom

Rs 29,800

Rs 15,000

Rs 12,400

Accton Technology

Rs 24,000

Rs 19,000

Rs 12,500

Compex

Rs 13,000

Rs 6,500

NA

CONCERNS
While WLANs provide installation and configuration flexibility, and the freedom inherent in network mobility, customers may have some concerns when considering WLAN systems. These include throughput, security, ease-of-use, and power source issues.

Throughput, reliability, and integrity depend on a variety of factors like number of users/nodes. More users can cause air-wave congestion, which can lead to slower throughput. Throughput improves whenever there is less interference, whether from internal or external sources. Throughput also improves when mobile users are closer to the access points, hence range is also important.

The type of WLAN technology also determines throughput. For example throughput and speed for Infrared wireless systems is different from Spread Spectrum. Latency and bottlenecks are issues for both wired and WLANs. These have to be addressed by using appropriate management tools to improve throughput.

The actual data transfer rates for most WLANs is in the 1-10 Mbps range. This is generally sufficient for most LAN-based office applications. Like wired Ethernet, actual throughput will always be less than the maximum specified transmission rate. Signal degradation or interference can happen through radio waves, microwave ovens, and other wireless devices operating in the same frequency spectrum.

Security has been one of the hottest concerns for users planning to implement wireless networks. In terms of wireless security, 802.11x support in networking technology is being incorporated by leading wireless vendors. It is vital that wireless networks are capable of supporting various operating systems from legacy Windows and Unix to new operating systems like Windows XP and the latest distributions of Linux.

Various WLAN vendors are now able to offer a range of capabilities that can be customized to suit customer applications requirement. These range from simple MAC address-based access control, to stronger 128-bit encryption. There are also solutions with better key management and dynamically generated session-based keys, scalable authentication with RADIUS and 802.11x, and enhanced layer 3 security. So look out for products that support these security algorithms and standards.

Mahesh Rathod can be reached at rathodmp@hotmail.com

 
     
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