From: Stephen Hemminger <stephen@networkplumber.org>
To: Fredrik Markstrom <fredrik.markstrom@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
bridge@lists.linux-foundation.org
Subject: Re: [PATCH v2 1/2] net: Added mtu parameter to dev_forward_skb calls
Date: Thu, 11 May 2017 09:01:32 -0700 [thread overview]
Message-ID: <20170511090132.79fdbf12@xeon-e3> (raw)
In-Reply-To: <20170511134629.139528-2-fredrik.markstrom@gmail.com>
On Thu, 11 May 2017 15:46:27 +0200
Fredrik Markstrom <fredrik.markstrom@gmail.com> wrote:
> From: Fredrik Markström <fredrik.markstrom@gmail.com>
>
> is_skb_forwardable() currently checks if the packet size is <= mtu of
> the receiving interface. This is not consistent with most of the hardware
> ethernet drivers that happily receives packets larger then MTU.
Wrong.
Hardware interfaces are free to drop any packet greater than MTU (actually MTU + VLAN).
The actual limit is a function of the hardware. Some hardware can only limit by
power of 2; some can only limit frames larger than 1500; some have no limiting at all.
Any application that should:
* not expect packets larger than MTU to be received
* not send packets larger than MTU
* check actual receive size. IP protocols will do truncation of padded packets
next prev parent reply other threads:[~2017-05-11 16:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-11 13:46 [PATCH v2 0/2] net: Set maximum receive packet size on veth interfaces Fredrik Markstrom
2017-05-11 13:46 ` [PATCH v2 1/2] net: Added mtu parameter to dev_forward_skb calls Fredrik Markstrom
2017-05-11 16:01 ` Stephen Hemminger [this message]
2017-05-11 19:10 ` Fredrik Markström
2017-05-11 19:44 ` Stephen Hemminger
2017-05-12 14:35 ` Fredrik Markström
2017-05-12 8:05 ` [Bridge] " Teco Boot
2017-05-12 12:48 ` Fredrik Markström
2017-05-11 13:46 ` [PATCH v2 2/2] veth: Added attribute to set maximum receive size on veth interfaces Fredrik Markstrom
2017-05-11 13:46 ` Support for VETH_MRU in libnl Fredrik Markstrom
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