Networking Guide

Introduction The OSI Reference Model
Physical Media Cat 5 Wiring Scheme
Network Components Network Topologies
Network Architectures Network Types

Networking Guide : Network Components

Access Point

Access point in wireless LAN (Wi-Fi) functions like a hub or a switch in wired network. It connects computers or devices together to create a wireless network. Most wireless access points also function as a network bridge that connects the Wi-Fi network to a wired network such as Ethernet. An access point has an interface to a broadband modem or a router that is used when the Wi-Fi network connects to the Internet. Some access points come as a multi-function device that incorporates the functions of switch, bridge, router, or broadband modem. You may have heard about wireless router which is an access point that has a built-in router.
Access point is also known as base station.

Access Point
Picture: Wireless (Wi-Fi) Access Point.
The Access Point creates a wireless network and connects it to the Internet.

Data transfer rate decreases as the distance from a computer or a device to the access point increases. A Wi-Fi access point provides wireless network coverage within an area of up to about 100 meters outdoor. In typical indoor application, an access point can cover an area of up to about 50 meters. The exact coverage depends on the access point transceiver and antenna design. Physical obstacles and interference from other wireless networks can reduce the wireless signal range.

An area that is within a Wi-Fi network coverage is popularly known as hotspot. Many public places such as airports, hotels, and cafs provide public Wi-Fi hotspots that have broadband connection to the Internet. Such hotspots can be accessed by the public for free or with a fee. To connect to a Wi-Fi hotspot, your wireless network adapter must be compatible with the hotspot's access point.

Below are things that you need to consider if you want to connect your computer to a hotspot:
- most existing hotspots are served by 802.11b or 802.11g access points. You can use either 802.11b or 802.11g adapter. But, you can't expect the best performance of your Wireless G adapter if it is connected to a Wireless B access point.
- 802.11g is backward compatible with 802.11b. You can use either 802.11b or 802.11g adapter to connect to 802.11g access point.
- 802.11a is not compatible with 802.11b/g. 802.11a network card can only work with 802.11a access point. But fortunately, 802.11a is rarely used in public hotspot. It is mostly used in corporate networks that have high user density.
- most public hotspots only support the legacy WEP encryption that was proven susceptible to eavesdropping by hackers with specialized tools. And the fact that some public hotspots even don't turn on the encryption increases the vulnerability of your data. Do some precautionary actions, such as never exchanging sensitive personal or corporate data over such public network, turning off file sharing, using strong password, turning on firewall, and having a regularly updated OS, anti-virus, and anti-spyware.
- if you don't want to risk your password or other personal information when accessing the Internet from a public hotspot then you must make sure you only input such sensitive data to secure websites (i.e. those with https://) and use only Web-based e-mail client when reading and sending e-mails.
- if you want to connect to your office network or even your home network from a public hotspot, use VPN to put your data in a secure tunnel.
- WPA/WPA2 encryption is stronger than WEP. To apply WPA/WPA2, the access point and your Wi-Fi adapter must support WPA/WPA2. But in most installed public Wi-Fi networks, you can't expect to meet a WPA-enabled access point.

If you want to use your Wi-Fi network to make a good quality VoIP call or run other real-time and multimedia applications, you'd better choose an access point and network adapters that support QoS and have passed the new WMM certification.

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