[MLB-WIRELESS] Multiple APs

Simon J Mudd sjmudd at pobox.com
Mon Aug 19 17:10:39 EST 2002


r.venning at telstra.com (Roger Venning) writes:

> > With an AP in the mix, all traffic must be relayed through the
> > AP. This
> > means packets between clients must be transmitted twice, once to the AP, and
> > again to the destination client. Now unless AP's negotiate some sort of
> > collision avoidance, you still have 1/2 total available bandwidth from
> > collisions, and then you halve it again because of the double transmits,
> > giving you only 1/4 total available bandwidth. The only use I can see for an
> > AP is relaying between two clients that are in range of the AP but not each
> > other.

> I'm not certain that the A/P will *always* relay the frame. Also
> remember though, that in a typical enterprise situation that this
> isn't a really bad thing if it does becuase most traffic is destined
> somewhere else and not locally anyway.

I think that this is the major difference between adhoc and AP
mode. In AP mode everything talks to the access point thus it acts as
a "router" when the source and destination packets are for different
clients on the same subnet.  This obviously does reduce the available
bandwidth, but avoids problems like hidden transmitter syndrome
because normally the AP is expected to be situated in the most
favourable location and thus should hear everyone.  The clients may
not hear each other.

Simon
--
Simon J Mudd,   Tel: +34-91-408 4878,  Mobile: +34-605-085 219
Madrid, Spain.  email: sjmudd at pobox.com,  Postfix RPM Packager

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