problem with network in domU

problem with network in domU

[Maciej Browarski]

Hello,
I'm using xen-3.1.2 downloaded today from repository.
As dom0 I have linux-kernel 2.6.18 and Debian distro.
As domU I install OpenSolaris Nevada 75a.
My config file looks:
name = 'osdev'
memory = '1024'
vcpus = 2
disk = [ 'file:/mnt/xen/osdev/disk.raw,0,w',  
'file:/mnt/xen/osdev/disk1.raw,1,w' ]
vif = [ '' ]
on_shutdown = 'destroy'
on_reboot = 'destroy'
on_crash = 'destroy'

After xm create I see new devices in dom0: peth0, xenbr0 and etc.
bash# brctl show
xenbr0          8000.feffffffffff       no              vif0.0
                                                        peth0
                                                        vif3.0
So, on dom0 outside network works fine, but on domU I have strange 
behavior ( dom0 and domU has addresses from DHCP).
 From domU I catch good address. I can also ping outside gateway but 
connect with any TCP/UDP ports outside my machine is incorrect (there 
are only SYN and SYN/ACK nothing more and timeout).
All connection between dom0 and domU works good.
Have you any idea what's wrong ?

Regards
Maciej

Re: problem with network in domU

[michael schuster]

Maciej Browarski wrote:
> Hello,
> I'm using xen-3.1.2 downloaded today from repository.
> As dom0 I have linux-kernel 2.6.18 and Debian distro.
> As domU I install OpenSolaris Nevada 75a.
> My config file looks:
> name = 'osdev'
> memory = '1024'
> vcpus = 2
> disk = [ 'file:/mnt/xen/osdev/disk.raw,0,w',  
> 'file:/mnt/xen/osdev/disk1.raw,1,w' ]
> vif = [ '' ]
> on_shutdown = 'destroy'
> on_reboot = 'destroy'
> on_crash = 'destroy'
> 
> After xm create I see new devices in dom0: peth0, xenbr0 and etc.
> bash# brctl show
> xenbr0          8000.feffffffffff       no              vif0.0
>                                                         peth0
>                                                         vif3.0
> So, on dom0 outside network works fine, but on domU I have strange 
> behavior ( dom0 and domU has addresses from DHCP).
>  From domU I catch good address. I can also ping outside gateway but 
> connect with any TCP/UDP ports outside my machine is incorrect (there 
> are only SYN and SYN/ACK nothing more and timeout).
> All connection between dom0 and domU works good.
> Have you any idea what's wrong ?

sounds a bit like you're having difficulty with checksums.

the following is a way to disable ip checksums *in dom0*; I don't know 
whether the same works in domU, but you could give it a try:

Set "ip:dohwcksum" to 0 in /etc/system. Reboot, retest, report results.

(btw: that means you need to add a line looking like this:
	set ip:dohwcksum = 0
to /etc/system in your domU)

hth
-- 
Michael Schuster	Sun Microsystems, Inc.
recursion, n: see 'recursion'

Re: Re: [xen-discuss] problem with network in domU

[Maciej Browarski]

michael schuster wrote:
> Maciej Browarski wrote:
>> Hello,
>> I'm using xen-3.1.2 downloaded today from repository.
>> As dom0 I have linux-kernel 2.6.18 and Debian distro.
>> As domU I install OpenSolaris Nevada 75a.
>> My config file looks:
>> name = 'osdev'
>> memory = '1024'
>> vcpus = 2
>> disk = [ 'file:/mnt/xen/osdev/disk.raw,0,w',  
>> 'file:/mnt/xen/osdev/disk1.raw,1,w' ]
>> vif = [ '' ]
>> on_shutdown = 'destroy'
>> on_reboot = 'destroy'
>> on_crash = 'destroy'
>>
>> After xm create I see new devices in dom0: peth0, xenbr0 and etc.
>> bash# brctl show
>> xenbr0          8000.feffffffffff       no              vif0.0
>>                                                         peth0
>>                                                         vif3.0
>> So, on dom0 outside network works fine, but on domU I have strange 
>> behavior ( dom0 and domU has addresses from DHCP).
>>  From domU I catch good address. I can also ping outside gateway but 
>> connect with any TCP/UDP ports outside my machine is incorrect (there 
>> are only SYN and SYN/ACK nothing more and timeout).
>> All connection between dom0 and domU works good.
>> Have you any idea what's wrong ?
>
> sounds a bit like you're having difficulty with checksums.
>
> the following is a way to disable ip checksums *in dom0*; I don't know 
> whether the same works in domU, but you could give it a try:
>
> Set "ip:dohwcksum" to 0 in /etc/system. Reboot, retest, report results.
>
> (btw: that means you need to add a line looking like this:
>     set ip:dohwcksum = 0
> to /etc/system in your domU)
>
> hth
Thanks :) it's works :)

Best Regards,
Maciej

Re: problem with network in domU

[Juergen Keil]

> Maciej Browarski wrote:
> > Hello,
> > I'm using xen-3.1.2 downloaded today from repository.
> > As dom0 I have linux-kernel 2.6.18 and Debian distro.
> > As domU I install OpenSolaris Nevada 75a.
> > My config file looks:
> > name = 'osdev'
> > memory = '1024'
> > vcpus = 2
> > disk = [ 'file:/mnt/xen/osdev/disk.raw,0,w',  
> > 'file:/mnt/xen/osdev/disk1.raw,1,w' ]
> > vif = [ '' ]
> > on_shutdown = 'destroy'
> > on_reboot = 'destroy'
> > on_crash = 'destroy'
> > 
> > After xm create I see new devices in dom0: peth0, xenbr0 and etc.
> > bash# brctl show
> > xenbr0          8000.feffffffffff       no              vif0.0
> >                                                         peth0
> >                                                         vif3.0
> > So, on dom0 outside network works fine, but on domU I have strange 
> > behavior ( dom0 and domU has addresses from DHCP).
> >  From domU I catch good address. I can also ping outside gateway but 
> > connect with any TCP/UDP ports outside my machine is incorrect (there 
> > are only SYN and SYN/ACK nothing more and timeout).
> > All connection between dom0 and domU works good.
> > Have you any idea what's wrong ?
> 
> sounds a bit like you're having difficulty with checksums.

Yep, see also: 
http://www.opensolaris.org/os/community/xen/docs/linux-dom0/#Networking_failures

Maciej probably has to set the kernel variable "xnf_cksum_offload = 0"
in the solaris domU, so that the linux dom0 network backend driver sends
packets with correct checksums for the solaris domU.


Apparently there are issues with OpenSolaris's xen network frontend driver
checksum offload support, which does not get along with a linux dom0
backend driver.