2

Has anyone had an idea of what are the possible configuration design of a network infrastructure in an OpenStack environment to enable instances to have a public IP as a floating IP? An example below is a simple topology that I wish to accomplish, how would you integrate the public IP directly assign to instances in the topology? Thanks in advance.

enter image description here

@Dohnal, thanks for the reply, and sorry for the lack of information in the original question and had to edit it but I really appreciate your answer.

  • What is the router model and configuration? We cannot help with configuration if we don't know what the device is. Please edit your question to provide the necessary information. – Ron Maupin Feb 25 '18 at 4:13
  • Removed the off-topic request for resources. – Ron Maupin Feb 25 '18 at 4:14
  • Hi Ron, sorry about that. Is it possible to change the question title and the body entirely, or would it be better to delete this and have a new one. Thanks – reynold Feb 26 '18 at 4:35
  • That depends on if you want to preserve the answer (it would be bad form to orphan an answer that someone took the time to give you). A completely different question deserves a new question, but it is also possible to edit this one. When you edit a question that was placed on hold, it automatically comes up for a reopen vote. – Ron Maupin Feb 26 '18 at 4:38
  • What is the router model and configuration? We need to know as much as possible. – Ron Maupin Feb 26 '18 at 15:06
1

The problem is that a packet incoming on the local interface of the router/firewall with the public address e.g. 100.0.0.27 cannot be routed by the router/firewall in NAT mode.

You have assigned the 100.0.0.0/24 subnet to the public interface of the router and thus you cannot use the same subnet for internal network, which comes on another physical interface. Assigning the same subnet (100.0.0.0/24) to two distinct physical interfaces of one router simply cannot work unless the router is set up as a bridge.

You do not have to define static NAT mappings for all the internal addresses, you can use NAT masquerade.

You can also use bridged mode as opposite to NAT mode on the router/firewall which allows you to have public IP adresses behing the firewall. See also this answer.

| improve this answer | |
  • Hi Dohnal, thanks for the reply, I edited my post and sorry for lack of information – reynold Feb 25 '18 at 4:10
  • @reynold I think that IPv4 public address should remain public and should be translated to local addresses, so your present configuration is OK. But in bridged mode it should be possible. Check this: serverfault.com/a/153418/229754 – Vojtěch Dohnal Feb 26 '18 at 12:55
  • 1
    @Dohnal I search on bridge mode and I think this is a possible solution I am looking for. And now I am searching a way on how to integrate the bridge interfaces on the router in a leaf-spine topology up to the OpenStack hosts. Thank you so much. – reynold Feb 27 '18 at 6:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.