Date: Mon, 08 Mar 2021 23:14:32 +0100 From: Lars Schotte <lars@gustik.eu> To: freebsd-current@freebsd.org Subject: Re: FreeBSD 13.0-RC1 ethertype IPv6 (0x86dd), length 2942 on 1500 MTU Message-ID: <bbb859d09244a26963ffba11b2dfa630c093913e.camel@gustik.eu> In-Reply-To: <2a8d7089955ca70cd4e0e644aef988ca4a9019e3.camel@gustik.eu> References: <2a8d7089955ca70cd4e0e644aef988ca4a9019e3.camel@gustik.eu>
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It looks like vtnet driver ignored MTU setting on 13.0-RC1. I see this on both, IPv4 and IPv6 ... however IPv4 works maybe because DigitalOcean and Vultr do split those frames on KVM virt host, but don't do this for IPv6 (I suppose). Everything about this is strange but so far I have been able to reproduce this problem only with vtnet driver. On Mon, 2021-03-08 at 20:18 +0100, Lars Schotte wrote: > Hey friends, > > I am running this FreeBSD 13.0-RC1 and I am experiencing strange > Ethernet frame sizes, TCP sizes well above 2500 on an MTU of 1500. > Somehow it seems that this problem only applies on IPv6, > IPv4 works fine. > > I have seen some strange network behaviour with TCP connections > randomly dropping under load, and now I see that they are too big. > MSS-MAX on PF also does not help. It seems to ignore my 1440 setting. > > Something is broken here and I do not know what. > > Is anyone else experiencing this on IPv6? > -- Lars Schotte Mudroňova 13 92101 Piešťany
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