From: Pravin Shelar <pshelar@nicira.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>,
netdev@vger.kernel.org, jesse@nicira.com, davem@davemloft.net
Subject: Re: [PATCH net] gre: Fix MTU sizing check for gretap tunnels
Date: Thu, 11 Jul 2013 16:19:17 -0700 [thread overview]
Message-ID: <CALnjE+oXbT+J01A-9GRxAAVuANaVA6ifF5_oc6ZSWRY2TTVUBw@mail.gmail.com> (raw)
In-Reply-To: <1373582702.4600.85.camel@edumazet-glaptop>
On Thu, Jul 11, 2013 at 3:45 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Thu, 2013-07-11 at 15:24 -0700, Pravin Shelar wrote:
>> On Thu, Jul 11, 2013 at 1:12 PM, Alexander Duyck
>> <alexander.h.duyck@intel.com> wrote:
>> > This change fixes an MTU sizing issue seen with gretap tunnels when non-gso
>> > packets are sent from the interface.
>> >
>> > In my case I was able to reproduce the issue by simply sending a ping of
>> > 1421 bytes with the gretap interface created on a device with a standard
>> > 1500 mtu.
>> >
>> > This fix is based on the fact that the tunnel mtu is already adjusted by
>> > dev->hard_header_len so it would make sense that any packets being compared
>> > against that mtu should also be adjusted by hard_header_len and the tunnel
>> > header instead of just the tunnel header.
>> >
>> we can simplify code by not doing dev->hard_header_len adjustment to tunnel-mtu.
>>
>> And right thing would be adjusting tunnel-mtu according to rt->dst.dev
>> header-len so that we get mtu for out going path.
>
> What's the mtu value we want to put in the ICMP message ?
>
>
I think it should be max payload that tunnel-device can take for that
route. Something like (route_mtu - (tunnel_header_len + iph_len +
route_dev->header_len))
gre is been using dev->hard_header_len rather than
rt_dev->hard_header_len for long time which does not look right.
next prev parent reply other threads:[~2013-07-11 23:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-11 20:12 [PATCH net] gre: Fix MTU sizing check for gretap tunnels Alexander Duyck
2013-07-11 21:52 ` Eric Dumazet
2013-07-11 23:30 ` David Miller
2013-07-11 22:24 ` Pravin Shelar
2013-07-11 22:45 ` Eric Dumazet
2013-07-11 23:19 ` Pravin Shelar [this message]
2013-07-11 23:30 ` David Miller
2013-07-11 23:36 ` Jesse Gross
2013-07-12 0:13 ` Alexander Duyck
2013-07-12 1:11 ` Cong Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CALnjE+oXbT+J01A-9GRxAAVuANaVA6ifF5_oc6ZSWRY2TTVUBw@mail.gmail.com \
--to=pshelar@nicira.com \
--cc=alexander.h.duyck@intel.com \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=jesse@nicira.com \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).