Re: Host AP support 'repeater' mode?

From: Jim Thompson (
Date: 2002-07-27 03:38:36 UTC

On Friday, July 26, 2002, at 09:54 PM, Jason Boxman wrote:

> Does HostAP support something like this:
> Basically, point to point with simultaneous access point
> functionality? The
> hardware APs I have do PtP or AP mode, but not both. There's an Intel
> 2011
> that does do both, but it's $350. :(

Yes.. something like it.

>> 7/8/2002
>> Well some time has gone on and this driver does some pretty neat
>> things.
>> WDS aka WirelessDistributionSystem... allows access points to talk to
>> other access points. The Prism chipsets are actually broken in this
>> regard as they cannot send 4-address frames in HostAP mode. So,
>> following on the original extensions done to the driver by the
>> Instant802 OpenAP project, Jouni implemented a workaround by which
>> 3-address frames are sent with a 4th address in an footer portion.
>> So essentially now HostAP access points can talk to each other. The
>> interface works such that when WDS is enabled and another HostAP AP is
>> in range, an interface of form wlanNwdsM appears for use. This is an
>> altogether logically different ethernet that only these two APs share.
>> These interfaces can be added to a Linux bridge group and STP run such
>> that a mesh of HostAP APs can have and offer to their client STAs
>> seamless layer 2 connectivity. Or, these interfaces can be routed
>> between in a somewhat more efficient though harder to configure
>> scheme. It is not abundantly clear what the best automated routing
>> protocol for this arrangement would be.
>> Remember that fundamentally the card is only on one RF channel at a
>> time so in a group of HostAP APs all links are dependent on the
>> openness of a single radio channel. Of note is that within a WDS mesh
>> there is no resolution of any HiddenNode issues... it's the same
>> topology as pure ad-hoc between the HostAP APs. One tip is to decrease
>> the beacon intervals of the HostAP APs such that less radio time is
>> monopolized such. Changing to 1s intervals from 1/100s allowed
>> approximately 15% faster transfer rates between a two-node WDS test
>> system.

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