http://wiki.openwrt.org/doc/howto/clientmode
Un WDS és un sistema que permet la interconnexió de punts d'accés en una xarxa WI-FI (IEEE 802.11). Permet doncs expandir una xarxa wireless utilitzant múltiples punts d'accés sense l'ús de xarxes amb fil (sense l'ús de cables).
Un dels avantatges de WDS es que manté les MAC dels clients de la xarxa distribuïda amb independència del punt d'accés de la xarxa. [1]
Quan es va dissenyar l'estàndard 802.11, es va pensar en dos tipus de serveis:
El sistema de distribució wireless no està definit completament a l'estàndard 802.11 (secció 5.2.2(9)) ja que no interessab definir-lo completament, per què conceptualment és molt senzill però pot ser força complicat d'implementar. De fet el sistema de distribució està definit per separat ja que el medi pot ser diferent de 802.11 (p. ex. 802.3 Ethernet).
DS és simplement una forma d'interconnectar punts d'accés per permetre ampliar una xarxa wireless. També pot ser la base per a sistemes més sofisticats com NoCatAuth, Roaming con IAPP, Mobility IP, etc.
Consulteu també l'article sobre WIFI.
Dos modes:
TODO:
WDS Explained
WDS, which stands for Wireless Distribution System, is a feature that enables single-radio APs to be wirelessly inconnected instead of using a wired Ethernet connection.
WDS connections are MAC address-based and employ a special data frame type that uses all four of the (MAC) address fields allowed in the 802.11 standard, instead of the three addresses used in normal AP <-> STA (client) traffic. (In the 802.11 frame header, address 1 is the destination address, address 2 is the source address, address 3 is the BSSID of the network and address 4 is used for WDS, to indicate the transmitter address.)
The provision for four MAC addresses in a frame is about the only thing covered by the 802.11 standards. But it was enough to allow bridging features to first be added to enterprise-grade, i.e. expensive, 802.11b products in the late 1990's. Many of these implementations were based around a medium access control (MAC) layer design originated by a long-defunct company called Choice Microsystems.
APs with wireless bridging features remained as high-priced items until fall 2002 when wireless bridging moved into consumer priced wireless products. D-Link first broke the artificially high wireless bridging price barrier by releasing a free upgrade to its DWL-900AP+ Access Point [reviewed]. This upgrade created the first consumer-priced WLAN product to support bridging and repeating. Other companies soon followed with similar upgrades, and also introduced dedicated Wireless Bridges, such as Linksys' WET11 [reviewed here].
Though these products were actually making use of the WDS feature, they didn't refer to it as such. It wasn't until products based on Broadcom's 802.11g chipset started to hit the market at the beginning of 2003 that the WDS term started to be commonly used. (Broadcom apparently included WDS support in its AP reference design code.)
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
Incovenients:
Two disadvantages to using WDS are:
NOTA: La perdua de throughput no pasa en el mode Wireless Bridging només Wireless repeating
WDS isn't the only way to bridge and repeat, however. Some products don't use WDS at all and instead act like wireless client adapters. But instead of connecting via USB, Cardbus or other computery interfaces, they connect via Ethernet. So they can be used to wirelessly connect devices like media players, game systems or any other networkable device that has an Ethernet connector. I'll cover these devices in another part of this series.
Recursos:
Un punt d'accés d'una xarxa WDS pot ser:
Les connexions entre clients es fan per MAC en comptes de IP ????
Imatge:
http://mrncciew.files.wordpress.com/2013/03/802-11-frames-02.png?w=529&h=140
Vegeu també:
Els nodes configurats per a funcionar amb WDS no apareixen als scans (no es mostra el SSID). Al menys em passa això amb un supernode de guifi.net amb RouterBoard 600A. Si està el WDS i faig scanners amb una loco5 (i la loco no té la MAC del altre punt de l'enllaç WDS) no els detecta. Si trec el WDS sí.
Consulteu el mode wireless a:
http://wiki.mikrotik.com/wiki/Manual:Wireless_Station_Modes#Mode_station-bridge
Vegeu Ubiquiti WDS.
Nota: és important l'opció de l'apartat Advanced anomenada "Allow Multicast All" per tal que funcioni WDS de forma transparent (per exemple per que funcioni OSPF)
Acacha Wiki
