[Openstack] [OpenStack] Second Public IP for VM on Another Public Network does not work properly

Brian Haley brian.haley at hpe.com
Wed Aug 17 18:34:11 UTC 2016

On 08/17/2016 01:54 PM, Piotr Baranowski wrote:
> ----- Oryginalna wiadomość -----
>> Od: "Brian Haley" <brian.haley at hpe.com>
>> Do: openstack at lists.openstack.org
>> Wysłane: środa, 17 sierpnia, 2016 18:53:47
>> Temat: Re: [Openstack] [OpenStack] Second Public IP for VM on Another Public Network does not work properly
>> On 08/17/2016 05:08 AM, Ludwig Tirazona wrote:
>>> Hello,
>>> Has anybody had this experience/problem as well?
>> I'm not sure I'd expect this to work, here is just one reason.
> Brian,
> Ever heard of policy based routing?
> You can have multiple outbound links and use them when your traffic meets some particular criteria.

Yes, and that was what I was alluding to in order to make packets go out the 
correct interface based on the source IP in the packets.

> One simple example:
> You have an expensive low latency link and a high latency cheap one.
> You may use policy routing to automatically select which route to use.

Is a cloud datacenter going to have multiple link types?  I doubt it.  And 
having two VMs would be easier anyways as there are probably other things you're 
going to tune.

 > TL;DR It makes sense to have multiple uplinks.

A cloud provider is probably going to have multiple links to the Internet, and 
they'll be able to deal with one being down without any action on the part of a 

I can only guess the OP wants to do this because their existing architecture is 
doing something like it, but I don't know.


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