[Openstack] Multiple nova-compute hosts, single-host nova-network, and a guest unreachable via its floating IP

Adam Gandelman adamg at canonical.com
Tue Jun 19 22:34:15 UTC 2012


On 06/19/2012 10:52 AM, Florian Haas wrote:
> Hi everyone,
>
> perhaps someone can shed some light on a floating IP issue.
>
> I have 2 nova-compute nodes (call them alice and bob), one of them
> (alice) is also running nova-network. bob uses alice as its
> --metadata_host and --network_host.
>
> I assign a floating IP to a guest running on bob. Expectedly, that IP
> is bound to the NIC specified as the --public_interface on alice (my
> nova-network host).
>
> However, since alice has a route into the --fixed_range network over
> its local bridge, the incoming traffic for the floating IP is routed
> there, where there's no guest to answer it -- because the guest is,
> after all, running on bob.
>
> Now, this seems fairly logical to me in the combination of
>
> 1. a nova-network host also running nova-compute;
> 2. other nova-compute hosts being around;
> 3. those other nova-compute hosts _not_ also running nova-network (and
> hence there being no multi-host networking).

Florian-

I was helping someone debug a similar setup a while back and found that 
nova was not putting the interface into promiscuous mode and it was 
dropping packets bound for the other compute node on the floor.  This 
came to me after noticing everything seemed to work fine as soon as I 
started debugging with tcpdump on nova-network. :)

HTH,
Adam





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