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> On 03/07/2015 01:10 PM, Leo Y wrote:
> What happens when neutron DB is updated to change network settings (e.g.
> via Dashboard or manually) when there are communication sessions opened
> in compute nodes. Does it influence those sessions? When the update is
> propagated to compute nodes?

Hi Leo,

when you say "change network settings" I think you mean a change in the
security group, is my assumption correct? In that case the Neutron
server will notify all the L2 agent (they reside on each compute node)
about the change. There are different kind of messages that the Neutron
server sends depending on the type of the update,
security_groups_rule_updated, security_groups_member_updated,
security_groups_provider_updated. Each L2 agent will process the message
and apply the required modification on the host. In the default
implementation we use iptables to implement security group, so the
update consists in some modifications of the iptables rules. Regarding
the existing connections in the compute nodes they might not be affected
by the change, which is a problem already discussed in this mail thread
[1] and there's a patch in review to fix that [2].
Hope that answers your question.

cheers,

Rossella

[1]
http://lists.openstack.org/pipermail/openstack-dev/2014-October/049055.html
[2] https://review.openstack.org/#/c/147713/

On 03/13/2015 04:10 AM, Kevin Benton wrote:
> Yeah, I was making a bad assumption for the l2 and l3. Sorry about that.
> It sounds like we don't have any protection against servers failing to
> send notifications.
> 
> On Mar 12, 2015 7:41 PM, "Assaf Muller" <amuller at redhat.com
> <mailto:amuller at redhat.com>> wrote:
> 
> 
> 
>     ----- Original Message -----
>     > > However, I briefly looked through the L2 agent code and didn't see a
>     > > periodic task to resync the port information to protect from a
>     neutron
>     > > server that failed to send a notification because it crashed or
>     lost its
>     > > amqp connection. The L3 agent has a period sync routers task
>     that helps in
>     > > this regard.
> 
>     The L3 agent periodic sync is only if the full_sync flag was turned
>     on, which
>     is a result of an error.
> 
>     > > Maybe another neutron developer more familiar with the L2
>     > > agent can chime in here if I'm missing anything.
>     >
>     > i don't think you are missing anything.
>     > periodic sync would be a good improvement.
>     >
>     > YAMAMAOTO Takashi
>     >
>     >
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