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Re: Multiple nova-compute hosts, single-host nova-network, and a guest unreachable via its floating IP

 

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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