cvs commit: src/sys/netinet tcp.h

Tue Feb 1 10:09:27 PST 2005

On Sat, Jan 29, 2005 at 02:46:45PM +0100, Joerg Sonnenberger wrote:
> On Sat, Jan 29, 2005 at 12:02:16PM +0900, YONETANI Tomokazu wrote:
> > The DragonFly box in question is in my office and talking to computers
> > in another office over an IPSEC tunnel, and I think the link MTU on the
> > routers talking IPSEC is already set as such.
> 
> The tunnel mtu as to be small enough to allow IPsec to prepend it's
> headers.  Also check if any strange / stupid DF bit appear.

That should not be the problem because another machine running
FreeBSD 4.9-RELEASE in my office is not suffering the stall
even if I set net.inet.tcp.mssdflt to 1460 and do the same test.
Looking at the output from tcpdump though, the DragonFly_Stable box
keeps receiving "need to frag" ICMP messages from the router until
the TCP session is closed, while the FreeBSD machine receives only
several of them at the beginning. Is this something related to
the "strange / stupid DF bit"?