Problem with if_bridge?

[Dan Swartzendruber]

This has got to be something silly I'm doing, but the man pages don't 
tell me what.  I've googled a fair amount and likewise nothing.  Anyway...

I've got a box running 6.0-RELEASE-p3.  Two network cards present, an 
intel pro/100 (fxp0) and a cisco aironet card (ath0).  I want to 
bridge the wireless users onto the LAN, but can't get it to work.  I 
was told to use if_bridge instead of bridge.  Recommended steps:

ifconfig bridge0 create
ifconfig addm fxp0
ifconfig addm ath0

***

The first steps works fine.  After doing the second, I completely 
lose ethernet connectivity.  The odd thing is that I can ping hosts 
on the LAN, but no TCP or UDP traffic will flow.  I'm not running pf 
or ipfw.  I also this this:

ifconfig addm fxp0 addm ath0

(in fact the above was the original rec I found on google, but that 
didn't work either, so I tried eliminating the ath interface from the 
equation by doing the wired nic first...)

There has GOT to be something obvious and/or stupid here, but I'm stumped :(