Re: [PATCH 0/2] net: Set maximum receive packet size on veth interfaces

From	Cong Wang <xiyou.wangcong@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/2] net: Set maximum receive packet size on veth interfaces
Date	2017-05-12 05:30 +0200
Message-ID	<tG9rb-6Vk-9@gated-at.bofh.it> (permalink)
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On Tue, May 9, 2017 at 5:42 PM, Fredrik Markström
<fredrik.markstrom@gmail.com> wrote:
>
> Maybe I was unclear, the veth implementation drops all packers larger then the
> configured MTU (on the receiving interface).
> Most ethernet drivers accepts packets up to the ethernet MTU no matter the
> configured MTU. As far as I can tell from the RFC:s that is ok.

This is because IP layer does the fragmentation for you. But some drivers,
for example tg3, drop packet larger than its dev->mtu very early too.

>
> A simpler solution would be to only drop packets larger then ethernet MTU (like
> most network drivers), but I guess that will break existing stuff
> already out there.

I wonder why did we introduce that mtu check for veth when IP layer
could either fragment or reject with ICMP?

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[PATCH 0/2] net: Set maximum receive packet size on veth interfaces Fredrik Markstrom <fredrik.markstrom@gmail.com> - 2017-05-09 14:50 +0200
  [PATCH 1/2] net: Added mtu parameter to dev_forward_skb calls Fredrik Markstrom <fredrik.markstrom@gmail.com> - 2017-05-09 14:50 +0200
  Support for VETH_MRU in libnl Fredrik Markstrom <fredrik.markstrom@gmail.com> - 2017-05-09 14:50 +0200
  [PATCH 2/2] veth: Added attribute to set maximum receive size on veth interfaces Fredrik Markstrom <fredrik.markstrom@gmail.com> - 2017-05-09 14:50 +0200
  Re: [PATCH 0/2] net: Set maximum receive packet size on veth  interfaces Stephen Hemminger <stephen@networkplumber.org> - 2017-05-09 17:50 +0200
  Re: [PATCH 0/2] net: Set maximum receive packet size on veth  interfaces David Miller <davem@davemloft.net> - 2017-05-09 19:50 +0200
    Re: [PATCH 0/2] net: Set maximum receive packet size on veth interfaces Fredrik Markström <fredrik.markstrom@gmail.com> - 2017-05-10 02:50 +0200
      Re: [PATCH 0/2] net: Set maximum receive packet size on veth interfaces Cong Wang <xiyou.wangcong@gmail.com> - 2017-05-12 05:30 +0200

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