
www.cooperbussmann.com/BussmannWirelessResources
Cooper Bussmann Wireless Ethernet & Device Server BU-945U-E 802.11 DSSS User Manual
35
3A1582Rev1.6
Example - Roaming with WDS Access Points
Another common use for WDS is extending the range across a large wireless network but allowing roaming connections between access points or
being able to switch to the next Access Point when out of range of the previous Access Point.
The diagram above shows a bridging network with a number of Access Points all with the same SSID, network structure, etc. (so as the Stations
can freely roam between Access Points)
Each Access Point then needs a separate connection to the next Access Point, which is done using the WDS Virtual Access Points and Stations
Site B is acting as a Virtual AP for Site A, which in turn is acting as a Virtual Station. At the same time Site B is also acting as a Virtual Station for
Site C which in turn is acting as a Virtual AP.
This setup can be replicated to extend the range and will allow any Roaming Stations full connectivity across the network
Site B WDS Configuration 2
Example – Adding Redundancy
In the example below, 4 x Access Points (A, B, C, & D) form a mesh network using only WDS bridge interfaces. Each of the Access Points may
also have its own clients associated. Each Access Point is configured with a different SSID, meaning the clients associated with each Access Point
are fixed.
Sites A, B, C, and D can all exchange data with each other (as can all of their Stations) as if they were all on the same wired segment. It can be
seen that there are redundant paths and therefore the possibility for loops to occur, so the bridge Spanning Tree Protocol should be enabled and
depending on the size of the mesh possibly configuring a Bridge Priority.
Bridge Priority is used to determine the connection priority when selecting an interface to put into the forwarding state. You can assign higher
priority values to interfaces that you want spanning tree to select first and lower priority values to interfaces that you want spanning tree to select
last. If all interfaces have the same priority value, the MAC address is used to work out the priority.
To illustrate the redundancy, consider that if Site A needs to send data to Site D it has redundant paths through both B and C. However, due to the
spanning tree protocol only one of B or C will relay the data, with the other taking over in the event of a failure.