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are four WDS Access points each with the possibility of having their own client/stations
associated. In both examples A, B, C, and D can all exchange data with each other. The
bridged example has the advantage of redundancy but at the expense of extra overhead.
The routed example below cannot provide the redundancy of the bridged example, and
requires more configuration effort, but does not have the overhead of using the bridge
Spanning Tree Protocol, so is suited to fixed installations that do not require redundancy.
As mentioned previously, configuration of the WDS router example is more complex
than the bridged example given earlier. In this case, all Access Points have different SSID’s
and none of them have SSID broadcast disabled so that WDS configurations can be made
without knowledge of Access Point MAC addresses. If SSID broadcasts were disabled,
each configuration entry would require an SSID
and
a MAC address (this is because
both SSID
and
MAC addresses are required to establish a link – but the MAC address is
always broadcast in beacons whereas the SSID broadcast is configurable).
Unit B in the WDS router example above has three WDS links – to units A, C, and D;
we show unit B’s configuration below. It can be seen that there are 3 entries in the WDS
Connections list. The first entry specifies a connection to the Access Point whose SSID is
“A”, and that it is to be a WDS router interface with Router IP address 169.254.0.3 (this
is the address that unit B adopts for the router interface link to unit A). Note that this
IP Address specifies a different network than that of the default interface for unit B (i.e.
default interface network 192.168.0.x compared to WDS interface network 169.254.0.x).
It is a requirement that the interfaces at each end-point of a WDS link have the same
network address, so by using a different network address to that of the default interface
we ensure that each end point has a different
network
address than its default interface.
This ensures that the WDS links at either end point are not bridged with their default
interface, since in this example we wish to eliminate the overhead associated with a
bridged interface.
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