Wireless Distribution System (WDS)
The majority of wireless large sized LAN like campus wireless network requires more than one access point to supply adequate radio frequency (RF) signal coverage throughout a facility. To enable roaming between multiple access points and connections to wired network resources, the 802.11 standard specifies a wireless distribution system, which provides wired interconnections between access points.
There are two possible configuration – using wired backbone or a fully wireless distribution system where wireless is use as its backbone. In the wire backbone, the switch or hub connects access points together. Most access points accommodate connection to a switch or hub via an RJ-45 connector and twisted pair (Category 5) wiring. The Cat5 cable can be up to 100 meters (roughly 300 feet) long. As a result, you need to plan the installation of hubs or switches to avoid exceeding this distance. If distances exceed the 100 meters, you can interconnect switches via optical fiber and place switches close enough to access points in various parts of the facility.
In Fully Wireless Distribution System (WDS) the features allow you to build a completely wireless infrastructure because the network equipment no longer has to be connected to a wired LAN. WDS features allow you tocreate large wireless networks bylinking several wireless access pointswith WDS links. WDS is normallyused in large, open areas where pulling wires is cost prohibitive, restricted or physically impossible.
The area covered by the several APs is larger than the coverage area of a single AP. This can negatively impact the defer mechanism of the radios. (i.e. the APs maybe to far away from each other so that they cannot “hear” each others transmissions, which can result in excessive collisions and retransmissions).
Major drawback of WDS is its performance. As the traffic flow example shows the frame goes through the air three times, and because of the CSMA/CA technology used and the fact that a single PC Card (and a single channel) is used, the end-to-end throughput will be about one third of the maximum attainable value.
Reference: Wi-Fi Handbook : Building 802.11b Wireless Networks.
A WDS link is defined as the MAC address pair of the connected APs. In order for WDS APs to work they must set to the same (radio) channel. WDS only support only WEP mode security.
Wireless Bridge Configuration
This is sometimes call the Point-to-Point WDS Link. This configuration connects two LANs at the link layer. The 2 APs behaves as a standard brdige that forwards traffic between WDS links. Even if a wireless station is with the range of AP1 or AP2, it will not be allowed to connect into the network.
Wireless Repeater Configuration
AP2 extend the range of the infrastructure by forwarding traffic between associated wireless stations and other repeater. If Sta3 is to connect to Sta5, it has to first link to AP2 and then over WDS to AP1 and then on to Sta5.
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