Comparing WLAN and LAN
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Wireless networks (WLAN) have become common in organisations and home use. The price of the wireless equipment is no longer a problem for home users. But even though the prices have gone down there are still things which have to be taken into consideration when deciding whether to obtain a wireless or a wired network. How good and reliable is the wireless network compared to a traditional wired one? Which choice is the better one? This article describes some advantages and disadvantages of wireless networks.
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[edit] Advantages
[edit] Flexibility and wirelessness
Wireless networks have many advantages compared to wired networks. One of the advantages of wireless network is its flexibility. The radio waves go through the walls (or wooden floors, typically max 2) and the wireless computer can be anywhere within range of an access point (up to 100 feet for 802.11b with few obstructions). There is no need to install new network cables when a workstation is moved or deal with a tangle of cables to give everyone network access in a conference room.
[edit] Easy to use
The wireless networks are superficially very easy to set-up and use. Just plug-in a base station and equip your laptops with wireless LAN cards (or purchase new Laptops with built in WLAN capability). This is seen as a big advantage, however ignoring the need to configure the Wireless LAN with the same care as a wired network is one of the main reasons that a company's biggest security 'hole' is often its Wireless LAN. It is also a myth that wireless networks do not need the same kind of control and maintenance that wired networks do. In fact, the need to enable IPsec (or change WEP keys on a daily basis) and restrict access to specific computers (usually to those with specified MAC address) often means that a wireless network requires more attention (per user).
[edit] Planning
Wireless networks have some advantages related to planning. Both types of network must be carefully planned (especially with respect to capacity) and of course the Wireless base-stations still have to be plugged into the wired LAN at some point. The physical components of wired networks (cables, hubs, switches, etc.) have to be planned carefully while wireless networks are much easier in that sense. It is a mistake not to plan a wireless network for actual usage patterns - many offices quickly find that their carefully sited base-stations may give good general coverage but one becomes totally overloaded when workers move from the desks to concentrate in one area (for example, to attend a meeting).
[edit] Setting of equipment
A Wireless LAN can be almost invisible. Equipment can be placed in roof cavities or behind screens. A Wireless LAN is especially suited to sites where a wired network could be very awkward (or expensive) to implement, such as large open spaces (including temporary sites and open plan offices), museums (and other old buildings) and 'one-off' usage (such as an exhibition or fair)
[edit] Robustness
Wireless networks can be robust. If one base station goes down, users may be able to physically move their PCs to be in range of another. It is also possible to site base stations with overlapping ranges so that users can remain connected if one base station goes down, although this is more expensive and requires careful planning. However wireless networks can suffer from radio-interference from other devices (like microwave ovens), and performance can collapse when too many users attempt to use the same access point.
[edit] Application transparency
One thing related to easy use of wireless networks is called application transparency. This means that applications which function in wired networks are made to function also in wireless networks. But there are longer delays and a narrower bandwidth which can cause problems when using the same applications in wireless networks.
[edit] Prices
The price of wireless products were once quite high for home users. PCI cards for wireless network cost 100 euros in 2000. At the end of 2004 the same card cost only 30 euros. Prices are not high anymore and wireless LAN is a common choice for home networks.
[edit] Disadvantages
[edit] Safety and security
Security is a major concern. The fact that someone can sit in the car park (or building next door), pick-up and store all of a business's wireless traffic, and crack the most common implementation of wireless encryption (WEP) in less than a week (and then read all the stored traffic) has to be a concern to any business operation (see Wardriving). Changing the wireless LAN encryption key on a daily or weekly basis, and then 'rolling it out' (by some means other than 'plain text' emails) is an extra overhead that many Companies never manage to achieve. IPsec is often used by larger businesses that have the infrastructure to support it. Wi-Fi Protected Access (WPA) is now available in most access points and provides adequate security for most purposes.
The transmission frequencies and powers used are such that wireless networks are safe to use in most environments, however (especially in the USA) many may decide that the potential risk (or liability) is just not worth the reward. Use (for example) in hospitals may be impossible to obtain liability insurance against. Most airlines also prohibit the use of any type of wireless system during flight.
[edit] Limitations related to radio waves
Users need 'line of sight' to a base station. Typical 802.11b base stations have a range of approx 300 feet (further in an open plan office). However the more walls (or floors) that are in the 'line of sight' the more the transmissions will be degraded (and the slower the network will run). Too many base-stations will result in overlapping areas of coverage and cross-interference - the base stations will adjust their frequency bands in an attempt to avoid clashing, however in 802.11b and 802.11g there are only 3 complete bands that do not overlap at least in some frequencies.
Often the unauthorized user in the car park will get better reception (as the radio waves go straight through the glass windows) than the company workers in the meeting rooms (where foil insulated partition walls block radio transmission).
[edit] Data Transfer speed
Data transfer speeds will typically not be as good as in a wired network. All users of the same base station have to share the bandwidth (typically 11Mb/s or 54Mb/s) while those wired to a hub or switch typically get almost the full bandwidth (typically 10 Mb/s or 100Mb/s) as long as transfer is not bottlenecked by the uplink of the hub/switch. Also, wireless data rates degrade rapidly with signal strength/interference.
[edit] Data transfer protocols
The use of wireless adds some overhead to each 'packet' of information exchanged. The TCP/IP control protocol requires many small packets to be exchanged (to establish a link) and even after the link is established data is transferred in packets. The overhead added by wireless may cause problems with 'latency' that could lead to other equipment in the network assuming a packet has been 'dropped' and thus requesting a retransmit. This can result in a much slower connection than expected as bandwidth becomes overloaded by retransmissions.
[edit] Standards and limitations
There are also limitations concerning the wireless networks. All the wireless products have to support international standards. The international institutions introduce practices and also limit the frequencies used in wireless equipment. Publishing and implementation of regulations of this kind takes time. For this reason some companies are producing products to which they have applied patents. This means that the products of two separate companies may not work together at all. In this situation the products should be ordered only from one company if those products are used in a same wireless network. The Wi-Fi Alliance was formed to test and certify compliance with standards and promote interoperability, but standards are still being developed and vendors include their own proprietary features so interoperability is often difficult to achieve.
[edit] Global operations
There is also a disadvantage related to global operation. In theory, wireless equipment that conforms to the common standard has to function all over the world. A device which is bought in Finland has to function also in the USA. However changing the Wireless adaptor settings to operate at the radio frequencies permitted in another country may well require re-installing the drivers (or re-running the Wireless installation software) which may be beyond the capabilities of many users.
On arrival at your overseas branch office, plugging your PC into an Ethernet socket (with its world-wide standard physical layout) and using the (world-wide standard) DHCP and TCP/IP protocols is more likely to get you a 'connection' back to your home office's server than any amount of playing around with a Wireless LAN.
[edit] Conclusions
Wired networks are more secure, more reliable and offer a higher data transfer speed. Wireless networks are more convenient when mobility is required, and are sometimes the only feasible choice (like in old buildings where installing cables is difficult or impossible). Wireless networks can also pose a significant security risk when not properly installed and maintained. The location and intended use must both be considered when deciding between wired and wireless networks. Many companies provide both wired connections for fixed offices and wireless connections for the convenience of users who need to roam around the site.
