Wireless Distribution System (WDS) is a system that enables the wireless interconnection of access points in an IEEE 802.11 network. It allows a wireless network to be expanded using multiple access points without the need for a wired backbone to link them, as is traditionally required. The notable advantage of WDS over other solutions is that it preserves the MAC addresses of client frames across links between access points.
An access point can be either a main, relay or remote base station. A main base station is typically connected to the wired Ethernet. A relay base station relays data between remote base stations, wireless clients or other relay stations to either a main or another relay base station. A remote base station accepts connections from wireless clients and passes them on to relay or main stations. Connections between "clients" are made using MAC addresses rather than by specifying IP assignments.
All base stations in a Wireless Distribution System must be configured to use the same radio channel, method of encryption (none, WEP, or WPA) and encryption keys. They can be configured to different service set identifiers. WDS also requires that every base station be configured to forward to others in the system.
WDS may also be referred to as repeater mode because it appears to bridge and accept wireless clients at the same time (unlike traditional bridging). It should be noted, however, that throughput in this method is halved for all clients connected wirelessly.
WDS may be incompatible between different products (even occasionally from
the same vendor) as it is not certified by the Wi-Fi Alliance.
WDS can be used to provide two modes of wireless AP-to-AP connectivity:
* Wireless Bridging in which WDS APs communicate only with each other and don't allow wireless clients or Stations (STA) to access them
* Wireless Repeating in which APs communicate with each other and with wireless STAs
Two disadvantages to using WDS are:
* The maximum wireless effective throughput is halved after the first retransmission (hop) that is made. For example, in the case of two routers connected via WDS, and communication is made between a computer that is plugged into router A and a laptop that is connected wirelessly using router B's access point, the throughput is halved, because router B has to retransmit the information during the communication of the two sides.
However, in the case of communications between a computer that is plugged into router A and a computer that is plugged into router B, the throughput is not halved since there is no need to retransmit the information.
* Dynamically assigned and rotated encryption keys are usually not supported in a WDS connection. This means that dynamic Wi-Fi Protected Access (WPA) and other dynamic key assignment technology in most cases can not be used, though WPA using pre-shared keys is possible. This is due to the lack of standardization in this field, which may be resolved with the upcoming 802.11s standard. As a result only static WEP or WPA keys may be used in a WDS connection, including any STAs that associate to a WDS repeating AP.
Recent Apple base stations allow WDS with WPA, though in some cases firmware updates are required. Firmware for the Renasis SAP36g Super Access Point and most third party firmware for the Linksys WRT54G(S)/GL support AES encryption using WPA2-PSK Mixed Mode security, and TKIP encryption using WPA-PSK, while operating in WDS mode. However, this mode may not be compatible with other units running stock or alternate firmware.
dikutip dari http://en.wikipedia.org/wiki/Wireless_Distribution_System
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