Dennis -

  Thanks for the pointers; unfortunately I can't move wires
around until Sunday (travel's principal disadvantage, after
adjusting to sleeping on someone's floor).

  I wasn't seeing huge numbers IP or TCP or UDP checksums, or
interface ierr counts, so I don't think it's that there's
so many errors that randomness kicked in.   I also didn't
get very far on doing a proper ethernet-level capture on
both sides of the bridge, before having to run along.

  I'm still not sure whether it's the bridge itself, or
whether somehow the router knows there's a bridge and
is doing something toxic.   (I can't really imagine how it would
detect a simple learning bridge though, particularly if
there's a hub or switch in the way).

  You don't have to sell me on the evils of ATM :) but I don't
see how it can be blamed, since on the "outside" of the bridge an
scp2 file transfer through the router will complete fine, and on
the "inside" it will fail.  I didn't see anything in the code walk
I did that distinguishes between local-to-this-LAN traffic
and delivered-beyond-this-LAN stuff, although I didn't get to
look for arp magic and the like.

| (I know this is stretching a bit).

  Well, I'm relieved you're stumped too. :-)

  More on Sunday...

	Sean.