Date: Tue, 09 Feb 2010 14:12:47 +0100 From: Harald Schmalzbauer <h.schmalzbauer@omnilan.de> To: Ilya Zhuravlev <i.a.zhuravlev@cbtnet.ru> Cc: freebsd-questions@freebsd.org Subject: Re: MTU, fragmentation and Jumbo Frames question Message-ID: <4B715F4F.4030401@omnilan.de> In-Reply-To: <4B7153A3.3000002@cbtnet.ru> References: <4B715125.8070809@omnilan.de> <4B7153A3.3000002@cbtnet.ru>
next in thread | previous in thread | raw e-mail | index | archive | help
This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig93B013FAA4CF5CEAD811FAF6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Ilya Zhuravlev schrieb am 09.02.2010 13:22 (localtime): > On 09.02.2010 20:12, Harald Schmalzbauer wrote: >> Hello all, >> >> I have 3 machines connected to an JumboFrame enabled switch. >> One FreeBSD 8-stable and two windows machines. >> I can send echo requests with payload of 8972 between the windows >> machines, but I don't get an answer from the FreeBSD machine. At the >> edge of 8130 bytes, the FreeBSD machine eats the packets without any >> error notification. A payload <=3D 8130 bytes works! >> All MTUs are set to 9000, interfaces are all intel em. >> Like mentioned, the ping between the two windows machines work like >> expected, beyond 8972 bytes payload the OS is fragmenting (resp. tells= >> me that DF bit was set but fragmentation was needed) >> FreeBSD seems to never fragment packets, since I don't get an answer i= f >> I define payload greater than MTU. But this should work, shouldn't it >> (`ping -s 10000 host`) >> >> Does anybody have any explanation why pings are working up to 8130 byt= es >> payload and are silently droped beyond that even my MTU ist set to 900= 0 >> (and route get confirms the MTU 9000)? >=20 > kern/143285 > but "ifconfig em0 -rxcsum" is enough for me. Thanks, but disabling any sum offloading doesn't change anything. Still, I wonder why FreeBSD doesn't fragment packets if they're too large= =2E Thanks, -Harry --------------enig93B013FAA4CF5CEAD811FAF6 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) iEYEARECAAYFAktxX08ACgkQLDqVQ9VXb8iL1QCfQn2JsFyIagKXkCgpHdbx0uT0 Ge4AoLZJuwo4YJQqngaeKxo5hViD2Fud =OO5W -----END PGP SIGNATURE----- --------------enig93B013FAA4CF5CEAD811FAF6--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4B715F4F.4030401>