Date: Sat, 26 Dec 2009 14:45:19 -0800 From: Julian Elischer <julian@elischer.org> To: Hideki Yamamoto <hyama99@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: GIF MTU parmeter is needed Message-ID: <4B3691FF.3050402@elischer.org> In-Reply-To: <90dbee150912261333l602c4161nccaf1995dc83699a@mail.gmail.com> References: <90dbee150912261333l602c4161nccaf1995dc83699a@mail.gmail.com>
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Hideki Yamamoto wrote: > 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. ?? huh? it is defined by the MTU of the gif interface as set with ifconfig > > 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 > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
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