Gigabit Ethernet w/Jumbo Frames

[george+freebsd at m5p.com]

I'm having poor luck trying to use NFS over a gigabit ethernet using
jumbo frames.  By all indications, my switch (Netgear GS608) forwards
jumbo frames with no difficulty, but my Realtek 8169-based cards seem
unreceptive to the idea, giving many watchdog timeouts and other
obscure log messages.  One server is amd64 and my clients are i386,
but I think I've ruled that out as the problem because I see errors
evern with an i386 server.  So I strongly suspect my network cards at
the moment.  What gigabit ethernet cards do you use for reliable
performance with jumbo frames?                -- George Mitchell