Date: Sun, 21 Apr 2002 17:22:04 +0200 From: "Richie B." <richie@NO-SPAM-HERE.com> To: freebsd-net@freebsd.org Subject: Path MTU Discovery and missing DF bit Message-ID: <3CC2D91C.2010308@NO-SPAM-HERE.com>
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[-- Attachment #1 --]
When using Path MTU Discovery, according to RFC 1191, all TCP datagrams
must have the Don't Fragment (DF) bit set. It seems that FreeBSD does
not obey this rule. On "SYN ACK" packets, the DF bit is not set. It is
set on all other packets though (including SYN packets). See attached
dumps (use ethereal to view them). The versions of the systems are:
$ uname -a
SunOS mort 5.9 s81_57 sun4u sparc SUNW,Sun-Blade-100
$ uname -a
FreeBSD trantor.xs4all.nl 5.0-CURRENT FreeBSD 5.0-CURRENT #6: Mon Apr 15
20:16:39 MET DST 2002
paulz@trantor.xs4all.nl:/usr/obj/usr/source/src/sys/trantor i386
Can anyone explain this behaviour?
Thanks to paulz for providing the dumps.
Please respond to me directly (as well), since I am not a member of this
list.
Richie
--
Yes that *is* my E-mail address
[-- Attachment #2 --]
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