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From: "Gray, Mark D" <mark.d.gray@intel.com>
To: "Xie, Huawei" <huawei.xie@intel.com>,
	Thomas Monjalon <thomas.monjalon@6wind.com>,
	Franck BAUDIN <Franck.BAUDIN@qosmos.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"dpdk-ovs@lists.01.org" <dpdk-ovs@lists.01.org>
Subject: Re: [dpdk-dev] Wrong TCP checksum of packets sent by Linux guest	(virtIO/vhost)
Date: Wed, 3 Sep 2014 16:15:04 +0000
Message-ID: <738D45BC1F695740A983F43CFE1B7EA92D72362F@IRSMSX102.ger.corp.intel.com> (raw)
In-Reply-To: <C37D651A908B024F974696C65296B57B0F284EE2@SHSMSX101.ccr.corp.intel.com>

> > >
> > > Hi Franck,
> > >
> > > 2014-09-02 13:20, Franck BAUDIN:
> > > > I am using dpdk-ovs 1.1.0 (latest release) as follow :
> > > >
> > > > linux-guest (no DPKD) <---  virtIO ---> OVDK 1.1.0 (with latest
> > > > DPDK [*]) < --
> > > - Niantic --- > linux-native
> > > >
> > > [...]
> > > > UDP/ICMP connectivity is fine, but TCP checksum of packet sent by
> > > > the
> > > guest are incorrect, as showed with tcpdump on linux-native.
> > >
> > > Thanks for reporting.
> > > Could you try virtio without vhost?
> > >
> > >
> >
> > Looping in the dpdk-ovs list.
> >
> > * Does the new vhost API allow a user to know if all the relevant
> > offloads have been turned on/off for that interface? It seems that
> > this is possible through the virtio_net structure but it would be good
> > to get some feedback from the relevant person working on DPDK
> > (Huawei?).
> >
> > * If this is the case, then it is probably in the realm of the vswitch
> > do the actual checksum (for VM-VM) or correctly configure the NIC when
> > sending out through the physical interface.
> >
> > Comments?
> 
> 
> Mark:
> So far not supported. This is important as well in VxLan case. For the packet

Ok 

> flow Guest A->  virtio -> ..->OVDK->.. -> Guest B.
> 1) If guest A and B are on different host machines, say A and B respectively,
> and if the nic on A supports vxlan checksum offload, then both guest and
> host needn't generate checksum, the nic will generate checksum for both
> inner and outer packet.

The vswitch would need to support this

> 2) In VM2VM case, as it is trusted communication channel, could we
> negotiate with the guest tcp stack not to verify checksum for received
> packet?

Perhaps

> 
> >
> > Mark

      parent reply	other threads:[~2014-09-03 16:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-02 13:20 Franck BAUDIN
2014-09-02 13:29 ` Thomas Monjalon
2014-09-02 14:37   ` Franck Baudin
2014-09-03 10:00   ` Gray, Mark D
2014-09-03 11:13     ` Xie, Huawei
2014-09-03 14:12       ` Franck Baudin
2014-09-03 16:07         ` Gray, Mark D
2014-09-04  2:54         ` Xie, Huawei
2014-09-04  9:24           ` Franck Baudin
2014-09-04 10:35             ` Xie, Huawei
2014-09-03 16:15       ` Gray, Mark D [this message]

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