Subject: Re: [Bugme-new] [Bug 12327] New: Intermittent TCP issues with => 2.6.27

From: Stephen Hemminger <[email-masked]>
Date: Thu, 8 Jan 2009 11:54:51 -0800

On Thu, 8 Jan 2009 21:39:30 +0200 (EET)
"Ilpo Järvinen" <[email-masked]> wrote:

> On Thu, 8 Jan 2009, Stephen Hemminger wrote:
> 
> > On Fri, 09 Jan 2009 00:04:42 +0900
> > Speedster <[email-masked]> wrote:
> > 
> > > Herbert Xu wrote:
> > > > 
> > > > Can you please take a look at /proc/net/snmp on the host and the
> > > > guest to see if IP InDiscards is non-zero?
> > > 
> > > Both are 0
> > > 
> > > > Also now that we know the problem is definitely in the host/guest
> > > > please take another set of dumps on the interfaces leading to and
> > > > within the guest to see exactly which path of the system is dropping
> > > > the reply.
> > > 
> > > Attached (all are the exact same attempted connection), and reveal some 
> > > interesting information.
> > > 
> > > The path the inbound traffic should take is
> > > 1. vlan50 (host)
> > > 2. tap interface vnet3 (host) / eth0 (guest)
> > > 3. ppp0 (guest)
> > > 
> > > It looks as though when it is sent out the tap interface the payload 
> > > length is incorrect in the PPPoE section of the frame. When it arrives 
> > > via vlan50 it appears fine. Or at least that's what wireshark highlights 
> > > for me :)
> > 
> > Maybe there is an issue that GRO receive isn't handling padding
> > properly?
> 
> Hmm, is gro supposed to have something to do with 2.6.27??? Or are you 
> talking something else than Herbert's recent GRO stuff?

Trying to find a common thread of why splice and TCP is having
issues in some cases.