On 03/23/2018 07:05 AM, Ramon Orru wrote:
Hi Brian,
yes, you're right, that's the point, libvirt is sending gARPs too
early.... am I misconfiguring something? Seems to me a really strange
behaviour...
Hi Ramon,
Sorry, don't know much about the libvirt side of things, maybe someone
more familiar with the Nova side of the migration would know?
-Brian
Il 21/03/18 22:35, Brian Haley ha scritto:
On 03/20/2018 12:40 PM, Ramon Orru wrote:
Hello everybody, I'm running a fresh queens cluster. I'm using
bridges to support networking. I'm facing an issue when an instance
is live migrated.
Suppose we have an instance running with an interface on vlan XXX,
and we want to migrate it to compute host YYY. We'll call that
instance ZZZ.
If no other instance is already running on YYY using vlan XXX, no
bridge called 'br-vlan.XXX@br-vlan' exists yet on YYY.
Now, if I migrate ZZZ on YYY host, a new bridge 'br-vlan.XXX@br-vlan'
will be created.
During the migration process, ZZZ become unreachable while interfaces
are going up on YYY (from 10 seconds to about 2 minutes).
After some troubleshooting, we spotted the problem: bridge
'br-vlan.XXX@br-vlan' is being created after gratuitous ARP packets
are sent from migrating machines to advise other devices about new
position.
The result is: no other device can reach the fresh migrated machine
until ARP table becomes stale.
This does not happen when an instance with an interface on same vlan
is already runnning on destination host ('br-vlan.XXX@br-vlan' is
already up and running, and ARPs can be sent flawlessly).
Any idea of how to get rid of this? I think it's very unlikely that
I'm the first to face this problem, but i didn't manage to find
additional info on this strange behaviour.
Thanks in advance.
Just to clarify - are you talking about connectivity to the floating
IP or just on the VLAN itself, i.e. the instance is directly connected
to the VLAN. I'm thinking it's the latter, which would mean it's
libvirt(?) sending the gARPs before the bridge is up?
-Brian
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