[ovs-discuss] DNS?

David Erickson derickso at stanford.edu
Wed Jul 29 21:04:44 UTC 2009


David Erickson wrote:
> Ben Pfaff wrote:
>> David Erickson <derickso at stanford.edu> writes:
>>
>>> Does ovs have any bearing on the dns servers set for dom0 in Xen? For
>>> some reason I cannot get them to persist through a reboot by setting
>>> in console or /etc/resolv.conf. The only reason I ask is I grepped
>>> /etc and the nameserver ips showed up in ovs-vswitch.dbcache (could be
>>> entirely coincidental).
>>
>> OVS does change the DNS settings (via
>> /opt/xensource/libexec/interface-reconfigure) but its behavior
>> there doesn't differ from stock Citrix XenServer (or ought not
>> to; let me know if we goof somehow).
>>
>> The DNS servers used are taken from the xapi management PIF
>> settings.  You can see this with e.g. "xe pif-list
>> management=true params=all" and update them with "xe
>> pif-reconfigure-ip".
> 
> Setting it at the command line using xe did work. I verified on two of 
> my machines that setting it through the actual physical console 
> configuration app on the machine does not persist through reboot with 
> vswitch running, I don't have a machine handy without it to compare if 
> this is intended behavior or not.

I should also add, whatever was causing me not to be able to persist 
name servers through reboots was also causing vswitch to behave very 
strangely. After booting I would go to the console and add the name 
servers, verify they were in /etc/resolv.conf, and the box seemed to 
have ip connectivity fine. The switch would connect to the controller 
fine, but the VMs connectivity out through vswitch was very problematic, 
it seemed that only packet-ins and packet-outs would work, anything that 
matched via a set flow-mod would fail and never be delivered. I did the 
xe pif-reconfigure-ip and included name servers and rebooted to verify 
they were preserved, then tested openflow and everything worked fine.. 
very odd.

-David






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