How to re-use Onpremise Public IPs in Azure VMware Solution

Question

Dear Experts,

Scenario -

There is a requirement to migrate VM workloads from Onpremise VMware environment to Azure VMware solution. If apps in these VM workloads are exposed to Internet either through Onpremise FW or through Reverse Proxy and if same Public IPs needs to be retained in Azure environment using third party NVA or Azure Firewall

I have following queries

1. First of all whether it is feasible to retain similar public IPs in Azure ( is there any concept of bring your own public IPs in Azure and what is the process to advertise from Azure) so that there will not be any changes in Public DNS service for Customer
2. When VMs are getting migrated from Onprem to AVS then what is the best practice for how to configure & advertise these Public IPs from Azure. If there is a scenario that Onprem environment has public IP pool of /26, however not all VMs or segments will be migrated to Azure in 'one go' but there migration will happen in batches then whether it is feasible to advertise /32 public IP out of that IP pool from Azure

Answer 1

@Raviraj Velankar

I believe what you are looking for is Custom IP address prefix (BYOIP). Please review the limitations and requirements. The process is outlined here:

I believe the answer for your second question can be found here: "When the command to update the custom IP prefix to the Commissioned state is executed, the IPs advertise from Microsoft's network. Any advertisement of this same range from a location other than Microsoft could potentially create BGP routing instability or traffic loss. For example, a customer on-premises building. The advertisement should be disabled once the Azure infrastructure has been verified as operational."

If you have multiple /24 prefixes then you can keep one for on-premise. Otherwise you need to migrate the whole prefix.

Hope this helps! Let me know if you still have questions.

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