mad mad interrupts(bridging)

[Jake Luck <openbsd@10k.org>]

trying to bridge...

on sparc4 running Dec1's -current. with a sbus quad-fast-ethernet board.
here is the layout

                                               -+---to internet--
                                                |
          +--------------------------+    +----++---+
          |   openbsd-current sparc  |    |router   |
          |     +------------------+ |    +--+------+
          +--+--+-  quadfast ether +-+       |
          le0|  +------------+-----+
             |          hme2 |   |hme3       |
             |               |   |           |
             |               |   +----+------+
             |               |
             |               |
             |               |         LAN
  +----------+---------------+------------------------------------+


the bridge is composed of hme2 and hme3. le0 has a real IP(so I can reach
the box over the network from the internal LAN). the openbsd box has a
default route to the router(i also tried without it). however as soon as I
bind the 2 hme interface to the bridge, the box slows to a grinding halt.
the first 10 seconds it seems to pass packets(was able to ping the router
from another box on the LAN. but after that, network traffic goes
berserk(i can see it on the hubs). check the openbsd box: it has a load of
1.4 and the cpu is loaded 99% with system interrupts(from top). I check
the wire via arp, and all 4 interfaces from the quad card seems to get
unique mac addresses.

would the wise here please shed some light on this? is my topology asking
for trouble? what would be a better way? 

thanks.
Jake