wireless-to-wired bridging

Reid Linnemann lreid at cs.okstate.edu
Thu Feb 10 14:12:36 PST 2005

I have a question that is more of a networking question than a BSD
question, but I am hoping someone out there has faced this same dilemma
before and has some advice:

I have a FreeBSD machine running -current that servers as a router for my
home LAN, using nat. I recently tossed in a DLink DWL-G520 wireless card
(ath0), and bridged that interface to the internal LAN interface on the
machine (rl1). After a bit of configurating, I had the ath interface in
hostap mode, and everything was working great - except the wired clients
cannot route to eachother.

I am suspicious that, since the wired network is in AP mode, if a
wireless client wants to send a packet to another wireless client, it
must be sent to the AP, which should theoretically redirect the packet
to the appropriate host on the wireless net. In the wired network, a
switch handles this automagically on the datalink layer without those
messages hitting the rl1 interface of the BSD router. I've looked at
the bridge code, and it seems that unless a packet is multicast or
broadcast it will be copied to the other bridge interfaces but not
returned to the original caller. Since the packets being sent between
wireless clients are not broadcast, I think they are getting dumped into
the black hole of the wired LAN, and not being processed and pumped back
out through the ath interface. Is this a correct assumption? Are there
ways I can overcome this problem?


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