Wireless Distribution System (Wds) - THOMSON Gateway Configuration Manual

Chapter 5

Wireless Distribution System (WDS)

5 Wireless Distribution System (WDS)
What is WDS?
WDS is the acronym for Wireless Distribution System. WDS functionality enables the interconnection of
several access points (AP) wirelessly and can thus be used to extend the range of wireless service coverage.
WDS includes:
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Wireless bridging in which WDS APs communicate only with each other and don't allow wireless stations
to access them.
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Wireless repeating in which APs communicate with each other and with wireless stations.
WDS is described in IEEE 802.11. An AP can be either a main, relay or remote AP:
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A main AP is typically connected to the wired Ethernet.
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A relay AP relays data between remote APs, wireless stations or other relay APs and either a main or
another relay AP.
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A remote AP
All APs in a Wireless Distribution System must be configured to use the same radio channel, and share WEP
keys if used. They can be configured to different service set identifiers. The following illustration shows two
WDS-enabled devices communicating via WDS.
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WDS may be incompatible between different products as it is not certified by the Wi-Fi Alliance.
How does it work?
Traffic between 802.11 compatible devices requires four MAC addresses. When a station is associated to an
AP, it will direct its traffic to the AP with the MAC address of the AP as its destination address. The MAC
address of the end station to which the frame has to be sent, is also included in the frame header. The AP
determines where to relay the frame to. Finally the sending station's own MAC address is also included in the
frame as the source address. So a total of three addresses is used. When a WDS link is set up between two
APs, all four available address fields in the MAC header are used:
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The MAC address of the sending station
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The MAC address of the destination station
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The MAC address of the sending AP
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The MAC address of the destination AP
E-DOC-CTC-20060609-0001 v2.0
accepts connections from wireless stations and passes them to relay or main APs.
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