From: Stephen Hemminger <shemminger@vyatta•com>
To: Joseph Glanville <joseph.glanville@orionvm•com.au>
Cc: David Miller <davem@davemloft•net>,
alexander.h.duyck@intel•com, netdev@vger•kernel.org
Subject: Re: [PATCH] vxlan: Fix error that was resulting in VXLAN MTU size being 10 bytes too large
Date: Mon, 19 Nov 2012 08:03:51 -0800 [thread overview]
Message-ID: <20121119080351.477525b3@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <CAOzFzEiuhqiNiiij9P+sh8_ypyXN4zABeRB6tzH2TQqVsNHjCA@mail.gmail.com>
On Mon, 19 Nov 2012 22:33:50 +1100
Joseph Glanville <joseph.glanville@orionvm•com.au> wrote:
> On 14 November 2012 08:33, Stephen Hemminger <shemminger@vyatta•com> wrote:
> > On Tue, 13 Nov 2012 14:37:19 -0500 (EST)
> > David Miller <davem@davemloft•net> wrote:
> >
> >> From: Alexander Duyck <alexander.h.duyck@intel•com>
> >> Date: Fri, 09 Nov 2012 15:35:24 -0800
> >>
> >> > This change fixes an issue I found where VXLAN frames were fragmented when
> >> > they were up to the VXLAN MTU size. I root caused the issue to the fact that
> >> > the headroom was 4 + 20 + 8 + 8. This math doesn't appear to be correct
> >> > because we are not inserting a VLAN header, but instead a 2nd Ethernet header.
> >> > As such the math for the overhead should be 20 + 8 + 8 + 14 to account for the
> >> > extra headers that are inserted for VXLAN.
> >> >
> >> > Signed-off-by: Alexander Duyck <alexander.h.duyck@intel•com>
> >>
> >> Applied, thanks for the detailed commit message.
> >
> > Probably need smarter code there to look at header length requirement
> > of underlying device as well, maybe someone will be perverse and runn
> > vxlan over a tunnel or IPoIB.
>
> Forgive my ignorance but why would running VXLAN on IPoIB require
> special header handling? (and would it work or behave strangely?)
>
> I was planning on giving this a go when 3.7 is released but I might do
> that sooner if problems are anticipated.
>
> > --
> > To unsubscribe from this list: send the line "unsubscribe netdev" in
> > the body of a message to majordomo@vger•kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>
> Joseph.
>
Some lower layers require bigger (or smaller headers). As it was, vxlan
was only allocating skb with a fixed amount of headroom. This would lead to
lower layers having to copy the skb.
My suggestion has already been addressed by a later patch.
next prev parent reply other threads:[~2012-11-19 16:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-09 23:35 [PATCH] vxlan: Fix error that was resulting in VXLAN MTU size being 10 bytes too large Alexander Duyck
2012-11-13 19:37 ` David Miller
2012-11-13 21:33 ` Stephen Hemminger
2012-11-13 23:10 ` [PATCH] vxlan: Update hard_header_len based on lowerdev when instantiating VXLAN Alexander Duyck
2012-11-13 23:12 ` Stephen Hemminger
2012-11-13 23:20 ` David Miller
2012-11-19 11:33 ` [PATCH] vxlan: Fix error that was resulting in VXLAN MTU size being 10 bytes too large Joseph Glanville
2012-11-19 16:03 ` Stephen Hemminger [this message]
2012-11-19 23:37 ` Joseph Glanville
2012-12-03 15:26 ` Joseph Glanville
2012-12-04 0:48 ` Re[2]: " Naoto MATSUMOTO
2012-12-04 17:12 ` Alexander Duyck
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