TSO and pf(4) reply-to/route-to combination problem

[Yoshiaki Kasahara]

Hello,

Could anyone who knows the TCP/IP stack well please review kern/144311?

In summary, on a multi-homed server I have a trouble when using pf(4)
'reply-to' to return reply packets of incoming TCP connections to the
incoming interface.  When TSO is enabled on the interface which is
used for the default route, redirecting packets to other interfaces
using 'reply-to'(or 'route-to') causes massive 'ICMP unreachable -
need to frag' storm on lo0 (up to 10Mbytes/sec on my server).  The
problem doesn't happen when TSO is disabled on the default NIC.  I
reproduced the problem on msk(4) and em(4), so I guess it is not
device specific.

http://www.freebsd.org/cgi/query-pr.cgi?pr=144311

Regards,
-- 
Yoshiaki Kasahara
Research Institute for Information Technology, Kyushu University
kasahara at nc.kyushu-u.ac.jp