[Openstack] transfer of IP address between ports

공용준 sstrato.kong at gmail.com
Wed Aug 23 14:47:19 UTC 2017

Hi Volodymyr

From my understanding, Do you need to maintain same IP address between port(and Mac will be changed)?
If that, it will be hard because there’s some cool down time(something like reuse ip timeout)  in the neutron IPAM db. If my memory is right, it was ten or five sec.  

Actually, I’m using the same kind of scenario here( same ip address to different neutron port)
I changed neutron db schema so it can assign same ip address to different port ( I also changed the neutron policy. only admin can use this function)
In this scenario, 
If i need to have a new port with the previous IP, 
I just create new port with the same IP. and I use this function to achieve the ECMP in our cloud. 


> 2017. 8. 23. 오후 11:30, Volodymyr Litovka <doka.ua at gmx.com> 작성:
> Hi Andrew,
> thanks for the prompt reply.
> I'm using fixed ip addresses, not floating IPs. In terms of Heat it looks like there:
> n1-wan:
>   type: OS::Neutron::Port
>   properties:
>     name: n1-wan
>     network: e-net
>     fixed_ips: [ { subnet: e-subnet, ip_address: X.X.X.X } ]
> n1:
>   type: OS::Nova::Server
>   properties:
>     name: n1
>     networks:
>       - port: { get_resource: n1-wan }
> and there are some constraints in my installation:
> I can't move ports between VMs (in order to support predictable naming according to port roles, their MAC addresses are stored in udev rules inside VM and if I will change port, rules/roles will fail)
> I don't want to use floating ip due to possible performance degradation when using massive NAT
> Another idea I have is to move ports between VMs, changing their MACs accordingly and will try it if no other ways will be found :)
> Thanks again.
> On 8/23/17 5:17 PM, 공용준 wrote:
>> Hi
>> You can use fixed ip port for this. 
>> create neutron port and attach it to the one vm. 
>> or 
>> you can use floating ip for this purpose as well 
>> Regards, 
>> Andrew
>>> 2017. 8. 23. 오후 10:58, Volodymyr Litovka <doka.ua at gmx.com <mailto:doka.ua at gmx.com>> 작성:
>>> Hi colleagues,
>>> imagine, somebody (e.g. me :-) ) needs to transfer IP address between two ports. The straight way is: release IP address and then assign it to another port.
>>> The possible problem with this way is time between release and assignment - during this time, this IP address is in DHCP pool and can be automatically assigned to some another port upon request.
>>> Any ideas how to prevent leasing this IP address during this time?
>>> Thank you.
>>> -- 
>>> Volodymyr Litovka
>>>   "Vision without Execution is Hallucination." -- Thomas Edison
>>> _______________________________________________
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> -- 
> Volodymyr Litovka
>   "Vision without Execution is Hallucination." -- Thomas Edison

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