Re: [Xen-devel] pv_ops routing problem?

[Michael D Labriola <mlabriol@xxxxxxxx>]

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 04/27/2010 06:02:12 PM:

> Jeremy Fitzhardinge <jeremy@xxxxxxxx> 
> Sent by: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> 
> 04/27/2010 06:02 PM
> 
> To
> 
> Michael D Labriola <mlabriol@xxxxxxxx>
> 
> cc
> 
> Jayson A Dyke <jdyke@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
> 
> Subject
> 
> Re: [Xen-devel] pv_ops routing problem?
> 
> On 04/27/2010 02:22 PM, Michael D Labriola wrote:
> > Ok, I've got a problem.  My current setup is as follows:
> >
> > I have a pv_ops dom0 (xen/master from a few weeks ago) running 3 
domUs. 
> > Each domU has an eth0 interface and one or more VLAN interfaces.
> >
> > vm1, vm2, and vm3 are all domUs running with the same pv_ops kernel as 

> > dom0.  vm1's eth0.107 interface routes through vm3 to get to vm2's 
> > eth0.1020 interface.
> >
> > dom0:
> >   eth0:     192.168.1.20/24
> >
> > vm1:
> >   eth0:     192.168.1.10/24
> >   eth0.107: 10.7.1.1/16
> >   gateway:  10.7.0.1
> >
> > vm2:
> >   eth0:      192.168.1.11/24
> >   eth0.1020: 10.20.1.1/16
> >   gateway:   10.20.0.1
> >
> > vm3:
> >   eth0:      192.168.1.12/24
> >   eth0.107:  10.7.0.1/16
> >   eth0.1020: 10.20.0.1/16
> >
> >
> > >From vm1, I can ping the gateway (10.7.0.1) and vm3's 1020 interface 
> > (10.20.0.1), but get no response if I try to ping vm2's 10.20.1.1.
> >
> > vm3 can ping both 10.7.1.1 and 10.20.1.1.
> >
> > Should be a pretty simple packet forwarding example, and it used to 
work 
> > using the old xen-linux 2.6.18 kernel we were using on our deployed 
> > systems.  But now it's broken...
> >
> > I have verified that the exact same setup running on 3 physical PCs 
> > bare-metal works w/out any problems.  I had the problem initially on 
Xen 
> > 3.4.2, but just upgraded to 4.0.0 and have the exact same symptoms.
> > 
> 
> Have you tried turning off tx checksum offload?  (ethtool -K <dev> tx 
off)
> 
> Though for me that just fixes network access between dom0 and domU;
> external traffic normally works fine.

Jeremy, I haven't tried that yet.  I'll try it this morning, although I 
don't really expect that to fix the problem.  I'm also going to pull from 
the xen/master branch again to see if that makes a difference.  My last 
2.6.31.12 kernel was pulled from your tree a few weeks ago.

By the way, the packet forwarding is definitely happening on my router 
domU.  If I look at vm3's eth0 w/ wireshark, I can see the VLAN 
encapsulated ICMP echo request coming in on the 107 VLAN and I can see 
that vm3 is forwarding it out over its 1020 VLAN interface.  However, if I 
look at my dom0's vif3.0 interface with wireshark I only see the VLAN 107 
traffic...  no sign of the 1020 forwarded packet anywhere.  It's as if 
forwarded packets aren't finding their way onto dom0's vif3.0.  I've never 
seen this before, and was under the impression that dom0's vif interfaces 
_WERE_ the domU's interfaces just with a different name... 

-Mike

---
Michael D Labriola
Electric Boat
mlabriol@xxxxxxxx
401-848-8871 (desk)
401-848-8513 (lab)
401-316-9844 (cell)



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