[Openstack-operators] Neutron DHCP failover bug

Kris G. Lindgren klindgren at godaddy.com
Thu Oct 1 02:02:42 UTC 2015

We run nova-metadata on all the compute nodes, then bind to lo on each HV.  This usually works with the standard iptables rule that nova-metadata add's.  Worse case you just add it to the the default rules set for the compute node.  Inside the images I think all you need to do is make sure that zeroconfig is turned off.  So that the default route for out eth0 is still there.  I suppose you could also add a route via dhcp to always point out the 169.254.169254 out eth0.  Worst case if the arp entry for makes it out of the HV, you get automatic HA with all the other HV's on the same network who will respond to the ARP request for that vm.  IE for us we typically have 43 other servers running metadata on the same network, so its a active, active, active, active config.

Kris Lindgren
Senior Linux Systems Engineer

From: Sam Morrison
Date: Wednesday, September 30, 2015 at 7:24 PM
To: Assaf Muller
Cc: "openstack-operators at lists.openstack.org<mailto:openstack-operators at lists.openstack.org>"
Subject: Re: [Openstack-operators] Neutron DHCP failover bug

On 1 Oct 2015, at 10:52 am, Assaf Muller <amuller at redhat.com<mailto:amuller at redhat.com>> wrote:

That's interesting. Looks like DHCP A/A only works if you use your (HA) routers to provide metadata, then.

Yes that’s true, we’re not doing any L3 stuff in neutron yet. These are just shared external provider networks.


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