Wireless LAN & Wired (Ethernet) LAN
There are different network infrastructures (wired LAN, Service Provider Networks) that allows mobility, but in a business environment, the most important is the wireless LAN (WLAN). Most modern business networks rely on switch-based LANs for day-to-day operation inside the office.
Productivity is no longer restricted to a fixed work location or a defined time period. People now expect to be connected at any time and place, (you are in when you are out...) from the office to the airport or even the home.
Traveling employees used to be restricted to pay phones for checking messages and returning a few phone calls between flights. Now employees can check e-mail, voice mail, and the status of products on personal digital assistants (PDAs) while at many temporary locations.
Wireless LAN and Wired (Ethernet) LAN
Wireless LANs share a similar origin with Ethernet LANs. The IEEE has adopted the 802 LAN/MAN portfolio of computer network architecture standards. The two dominant 802 working groups are 802.3 Ethernet and 802.11 wireless LAN. However, there are important differences between the two.
WLANs use radio frequencies (RF) instead of cables at the Physical layer and MAC sub-layer of the Data Link layer. In comparison to cable, RF has the following characteristics:
i. RF does not have boundaries, such as the limits of a wire in a sheath. The lack of such a boundary allows data frames traveling over the RF media to be available to anyone that can receive the RF signal.
ii. RF is unprotected from outside signals, whereas cable is in an insulating sheath. Radios operating independently in the same geographic area but using the same or a similar RF can interfere with each other.
iii. RF transmission is subject to the same challenges inherent in any wave-based technology, such as consumer radio. For example, as you get further away from the source, you may hear stations playing over each other or hear static in the transmission. Eventually you may lose the signal all together. Wired LANs have cables that are of an appropriate length to maintain signal strength.
iv. RF bands are regulated differently in various countries. The use of WLANs is subject to additional regulations and sets of standards that are not applied to wired LANs.
WLANs connect clients to the network through a wireless access point (AP) instead of an Ethernet switch.
WLANs connect mobile devices that are often battery powered, as opposed to plugged-in LAN devices. Wireless network interface cards (NICs) tend to reduce the battery life of a mobile device.
WLANs support hosts that contend for access on the RF media (frequency bands). 802.11 prescribe collision-avoidance instead of collision-detection for media access to proactively avoid collisions within the media.
WLANs use a different frame format than wired Ethernet LANs. WLANs require additional information in the Layer 2 header of the frame.
WLANs raise more privacy issues because radio frequencies can reach outside the facility.
802.11 wireless LANs extend the 802.3 Ethernet LAN infrastructures to provide additional connectivity options. However, additional components and protocols are used to complete wireless connections.
In an 802.3 Ethernet LAN, each client has a cable that connects the client NIC to a switch. The switch is the point where the client gains access to the network.
In a wireless LAN, each client uses a wireless adapter to gain access to the network through a wireless device such as a wireless router or access point.