On a netbsd-3 branch, amd64 system with kern.sbmax set to 2000000, I see
this:

# ttcp -s -t -b 1677722 -l 16384 backup.netbsd.org
ttcp-t: buflen=16384, nbuf=2048, align=16384/0, port=5001, sockbufsize=1677722
tcp  -> backup.netbsd.org
ttcp-t: socket
ttcp-t: setsockopt: sndbuf: No buffer space available
errno=55
# ttcp -s -t -b 1677721 -l 16384 backup.netbsd.org
ttcp-t: buflen=16384, nbuf=2048, align=16384/0, port=5001, sockbufsize=1677721
tcp  -> backup.netbsd.org
ttcp-t: socket
ttcp-t: sndbuf
ttcp-t: connect: Connection refused
errno=61

Can anyone explain it?  On the system on the other end, an older 3-branch
kernel -- but on an i386 -- I can set the socket buffer size as large as
I want, up to just a little below kern.sbmax.

-- 
  Thor Lancelot Simon	                                     tls@rek.tjls.com

  "We cannot usually in social life pursue a single value or a single moral
   aim, untroubled by the need to compromise with others."      - H.L.A. Hart