Re: frame capture, DWL900AP Point to Point link

From: Jason Boxman (
Date: 2002-09-06 05:25:16 UTC

On Thursday 05 September 2002 09:59 am, Jouni Malinen wrote:
> On Wed, Sep 04, 2002 at 10:31:48PM -0400, Jason Boxman wrote:
> > A while ago someone mentioned support could be added for talking to a
> > D-Link DWL900AP running in Point to Point mode if captures were provided,
> > so here some are. If someone could tell me what's going on between these
> > two APs, that would be educational as well.
> Hmm.. Unfortunately that capture did not include very much information.
> There seems to be one AP with hwaddr 00:06:25:76:83:61 that is sending
> beacons. It transmitted few broadcast and multicast frames (NB name
> query and HTTP over multicast UDP) to its own BSSID. In addition to
> this, another device (hwaddr 00:05:5d:25:74:ce), maybe the other AP,
> seemed to send some ARP requests to wireless distribution system--I
> would guess that these would be destined to the other APs.

As it turns out, the requests from 00:05:* are from someone who just bought an AP down the street (with default essid of "linksys" and all) that I can't pick up 2 ft from my hostap box, but conveniently it can just barely get a signal from where it is. It took me a while to figure out just where that AP which wasn't mine was coming from. I thought I was losing it for a minute.

(The 00:06:25:76:83:61 addr doesn't match any of my hardware, either. That must also belong to my new wireless neighbor. My WPC11v3 has a different 00:06 addr, as does the WMP11 used for captures, and the two DWL900APs have 00:05 addrs.)

> The ARP who-has requests were sent with four address frame. However,
> even though this was a point-to-point mode, these frames were sent to
> broadcast address. This might be to limit the number of broadcast
> packets needed with multiple APs. I don't see any problem in
> transmitting similar frames with Host AP driver.
> I would like to see a capture of some unicast packets sent between those
> APs. For example couple of ICMP echo request/replies (i.e., ping)
> between two hosts behind the APs. This should give enough information to
> check addr1 (immediate destination) of the WDS frames. In addition, it
> would be useful to check whether the APs complete some kind of
> registeration with eachother (e.g., by resetting them while capturing
> all the sent packets).

I was thinking the same thing. I had started the capture, unplugged them both, then plugged them back in during the course of the capture. Perhaps nothing special goes on between them during that phase? I'm going to do another capture with both APs in point to point mode again with some ICMP echos and see what happens.


Jason Boxman
Administrator TrekWeb.COM - Linux Pages

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