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Re: Auto Assigned Floating IPs take a long time to associate

 

Are you sure that its Nova that is taking the time to associate the IP, and not an ARP issue in your network ?

I've seen this behaviour when quickly reusing floating IP addresses - Nova does the assignment and sends out an unsolicited ARP response (assuming you have the "send_arp_for_ha" flag set) - this is in network/linux_net.bind_floating_ip().   However  sometimes an unsolicited APR response can get dropped in the network, ad so if the switch doesn't see this message and it already has a previous ARP mapping in its cache then it will continue to try and send traffic to the previous user of that address until the cache times out.

Note that some network failover systems send multiple requests to get more certainty around this (for example I've seen a VPN solution use 6 messages).

There are a couple of things you could try:


-          Add a flag to be able to increase the number of arp_responses sent

-          Change the allocation of floating_ips so that instead of picking the first free one in the DB you pick the one which has been unused for the longest time (reduces the risk of reusing an address before the switch times out the entry in its cache).

Phil

From: openstack-bounces+philip.day=hp.com@xxxxxxxxxxxxxxxxxxx [mailto:openstack-bounces+philip.day=hp.com@xxxxxxxxxxxxxxxxxxx] On Behalf Of Kevin Jackson
Sent: 28 March 2012 12:49
To: openstack@xxxxxxxxxxxxxxxxxxx
Subject: [Openstack] Auto Assigned Floating IPs take a long time to associate

Hi all,
I've got the following set in my nova.conf:

--auto_assign_floating_ip

and I fire up an instance.
Everything works, a private IP is assigned... the instance is running... but it can take an inordinate amount of time (anywhere upwards of 2 mins, sometimes a lot longer) to associate a floating IP automatically.

Anybody else experienced this?  Any clues on what I can do to troubleshoot this?  What is the condition when a Floating IP is assigned?  I've seen it assign Floating IPs very quickly when it is still Booting, not Active, say.
Is it dependent on anything within the Instance itself?

Cheers,

Kev
--
Kevin Jackson
@itarchitectkev

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