Wireless Distribution System

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A 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 packets across links between access points. [1]

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 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, and share WEP keys or WPA keys if they are used. 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.

Contents

[edit] Implementations

WDS may be incompatible between different products (even occasionally from the same vendor) as it is not certified by the Wi-Fi Alliance

  • Deliberant have 'Transparent Bridge' in their current range. They previously used Zinwell radio cards which had an excellent implementation of WDS. The two are incompatible.
  • ZINWELL Cost effective range of Indoor and Outdoor Units.
  • Firepro Wireless n series AP
  • AVM FRITZ!Box WLAN 7xxx FRITZ!Box
  • Apple Inc's Time Capsule, Airport Extreme and Airport Express are all able to use WDS.
  • Secure Computing's SnapGear SG565 supports WDS
  • All FreeWRT supported hardware should theoretically support WDS when FreeWRT is installed.
  • All OpenWRT supported hardware should theoretically support WDS when OpenWRT is installed.
  • All DD-WRT supported hardware should theoretically support WDS when DD-WRT is installed.
  • Some Buffalo routers support WDS. All of the Nfniti routers plus the WHR-HP-AG108 do not support WDS.
  • All NETGEAR ProSafe access points (WG102, WAG102, WG302, WAG302) natively support the full implementation of the Wireless Distribution System. Several of their SOHO devices do also, whether with full implementations like the WG602v2/v3 or partial implementations like the WPN802. With firmware version V1.02.08, the Netgear DG834N.WNR834B offers native repeater mode.
  • All Tomato Firmware [1]
  • U.S. Robotics Professional Access Point (5453), MAXg (5432, 5441, 5451, 5455, 5461, 5465, 9108) and Ndx (5454, 5464, 9113) wireless products support WDS.
  • All Comtrend wireless 802.11g products support WDS.
  • MSI's RG54SE and probably other routers support WDS, while providing both wireless and ethernet connection to the router.
  • Renasis SAP36g 820 mW Super Access Point supports WDS.
  • Zoom X6 (Firmware Version 2.0.4) supports WDS
  • Siemens Gigaset SE515 (Firmware Version 2.14.02.16_BA09b6e), SE551, SE 366, SX763 WLAN supports WDS.
  • CNet Wireless-G MIMO Router (CWR-903)
  • SMC EZ Connect G Wireless Access Point (SMCWEBT-G), SMC7908VoWBRA support WDS.
  • SMC Barricade SMCWBR14T-G, SMCWBR14-G2 and SMC7908A-ISP support WDS
  • Edimax Access Point EW-7206APg and Router Broadband BR-6304WG support WDS
  • E-Tech WGRT04, WGRT05, WMRT01, ADWG05, ADWG06 support WDS.
  • Eminent EM4032, EM4114, EM4115, EM4030, EM4040, EM4050, EM4214, EM4216, EM4217, EM4050 and EM4550 support WDS
  • Thomson's SpeedTouch 780 WL & 585 support WDSs
  • D-Link DGL-4300 (Firmware 1.8 and later), DWL-2100AP (Firmware 2.40eu - also supports WDS with AP), DAP-1160 (WDS with AP)
  • Draytek Vigor 2100, 2200, 2700, 2800, 29xx series routers and some 2600 series (Wireless hardware v2) support WDS.
  • Canyon CN-WF514M MIMO Wireless Broadband Router supports WDS
  • 3COM OfficeConnect ADSL Wireless 11g Firewall Router Version 1.00.00.T13 supports WDS
  • 3Com Wireless 7760 11a/b/g PoE Access Point supports WDS
  • ProCurve AP 530
  • Allied Telesis AT-WA7400, AT-WA1104G, AT-WR4561 & AT-WR4562 are supporting WDS
  • Alcatel SpeedTouch 716 and 780 supports WDS
  • Some ValuePoint products including the 700g MultiSSID AP support WDS, sometimes with a firmware upgrade.
  • Motorola WR850G and WR850GS with firmware 6.14.
  • Zonet ZSR1134WE
  • Acer W422g product supports WDS
  • BEWAN SYSTEMS BWIFI-AP54T
  • Trendnet TEW-450APB Supports Access Point, AP Client, Repeater and Bridge (PTP & PTMP) Modes
  • Airlink101 AP431W Multi-function Access Point supports WDS.
  • PLANET wireless AP & Router, WAP-4000A, WAP-4033, WAP-4035, WAP-4036, WAP-4060PE, WRT-414, WRT-416, WNRT-620, support WDS.
  • EnGenius 3220 series (EOC and ECB) Not compatible with the 8610 & 3610 series due to different chipsets. The 3220 currently uses the Realtek chipset while the 8610 & 3610 uses Atheros chipset.
  • ENGENIUS TECHNOLOGIES ESR-9710 can be used as a WDS.
  • Cisco wireless AP (such as aironet)
  • BT Home Hub can support WDS. No direct support from BT is available.
  • Asus WL-500g, WL-500W ,WL-520gC, WL520gU
  • LinoWave LW1000 series
  • Mikrotik RouterBoard OS
  • Belkin F5D7230-4 (v7001/v1000)Configuration on hidden page <routerip>/wireless_wds.stm
  • TP-Link TL-WA601G
  • NEXXT router NW230NXT14 also supports WDS.
  • SWEEX LW055 supports WDS but unfortunately without WPA-support (no encryption or WEP only)
  • Billion BiPAC 7402(G)X(L) series support WDS and plugged in 3G USB modems

Note: Wireless Distribution System is distinct from the WDS implementation by Cisco, which stands for Wireless Domain Services.

[edit] Technical

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 firmwares 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 firmwares.

[edit] See also

[edit] References

  1. ^ Wireless Distribution System Linked Router Network DD-WRT Wiki. Retrieved December 31, 2006.

[edit] External links

Retrieved from "http://en.wikipedia.org/wiki/Wireless_Distribution_System"
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