Date: Sun, 27 Dec 2009 06:33:28 +0900 From: Hideki Yamamoto <hyama99@gmail.com> To: freebsd-net@freebsd.org Subject: GIF MTU parmeter is needed Message-ID: <90dbee150912261333l602c4161nccaf1995dc83699a@mail.gmail.com>
next in thread | raw e-mail | index | archive | help
Hi,
I often use FreeBSD for developing the gateway. For example, I use gif for the
tunnel protocol when using IPv6 over IPv4 and use an application for changing
packet address for special purpose. When we were using old FreeBSD, such as
FreeBSD 4.11, the MTU of the tunnel packets or forwarded packets
was not limited into 1280. However, FreeBSD 6,7, and 8 fragments packets
by 1280 when using tunnel.
I know that this behavior is based on the RFC specification. However
it is not useful when using AV application that use around 1400B RTP packet.
AV packets will be fragmented into long packets (1280) and short
packets (1400-1280)
when using tunnel, and short packet will sometimes be lost by network.
I hope new parameter by sysctl to control MTU of tunnel will be implemented.
The following is an example of new paramter to control MTU size.
net.inet6.use_mmtu :1 --- is the same as current versions, it means
minimum MTU 1280
will be used when gateway node.
:0--- is the same as the
old versions. It means
OS uses
as long MTU size as possible
( I hope "1" will be default)
Are there any comment on this matter?
Best regards,
Hideki Yamamoto
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?90dbee150912261333l602c4161nccaf1995dc83699a>