> smd@ab.use.net

Love that domain name. :-)

>> Presumeably, if packets are getting corrupted, that TCP checksumming
>> should really be catching this, unless the bridge is "fixing" them
>> in some way...
> It sure looks like that...  However, I haven't figured out why local
> traffic through the bridge works OK but non-local doesn't.

Do you have a station-c machine available?  My next inclination for
debugging this would be to try

Router ---- hub --- NetBSDbridge --- switch --- station-b
             |                        |
           station-a                station-c

and then have station-a and station-c simultaneously sniff a failing
attempt between station-b and the outside world, keeping full packet
contents for comparison...and then compare them and see where it goes
awry.  I've seen data-dependent bugs in network infrastructure before,
not often, but I've seen 'em.

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