[Users] Routing problems using SMP kernel

[Kir Kolyshkin]

I guess it makes much sense to diagnose the hardware at this point. Some
info is available at http://wiki.openvz.org/Hardware_testing

Steve Hodges wrote:
> On 27/08/2007 10:57 PM, Kirill Korotaev wrote:
>> Steve,
>>
>> Sure, SMP shouldn't affect your routing and it is very strange. I
>> guess >90% of people
>> are running SMP kernels.
>>
>> >From your report it is totally unclear what OVZ kernel version is
>> (e.g. something like 028stab039)
>> and where this kernel was got from. Have you built it yourself?
>> Can you please provide a bit more details on what is working and what
>> not?
>> Why have you decided that it is rounting to blame to?
>>   
>
> it's 2.6.18-028stab035.1-ovz-smp obtained from deb
> http://debian.systs.org/ stable openvz
>
> when I use the normal kernel I can ping from the VE to the HN and to
> other VE's on this HN, to my other HN and to an external site
> (google.com)
>
> when I use the smp kernel (no other change) I can ping from the VE to
> the NH and to other VEs on this HN, but not the other HN or to
> external sites
>
> in all cases pinging from the HN is ok.
>
> from the VE, if I try to to a traceroute to the HN it shows the HN as
> the first hop (with either smp or normal kernel).  If I traceroute to
> my other HN, I just get endless * * * lines with the smp kernel (it
> doesn't even show the HN as the first hop).  With the normal kernel it
> shows the HN, then the destination of the ping (the other HN in this
> case).
>
> Is that a routing issue?  dunno?  but it looks like it might be.  I
> was actually leaning toward it being a hardware fault until I noticed
> the anomaly in the traceroute.
>
> I'm not sure if having 2 nics in the box has any bearing on it.
>
> with the smp kernel I also note checksum errors when I do a ping -R. I
> don't get those errors using the non-smp kernel.
>
> OK, this gets extremely weird. I just checked the kernel I'm running
> and it is still the smp version.  and that is after I executed:
>
> aptitude install ovzkernel-2.6.18
> aptitude remove ovzkernel-2.6.18-smp
> shutdown -r now
>
> I am now concerned that this problem will recurr if I am forced to
> reboot.  It can't be as simple as the reboot fixing it as I rebooted
> several times while I was having the problem and it didn't go away.
>
> I wonder if I have just entered the twighlight zone?