Layer 2 azure site recovery

Question

Layer 2 azure site recovery

Tyler Saville 431

Greetings! Does anyone know of a way that I could connect an on-prem network to azure site recovery when both networks are the same on each side? I was seeing if there was a layer 2 option (the least expensive). I would like to avoid NAT as well. Open to any ideas, thank you.

SadiqhAhmed-MSFT 49,331 Reputation points Microsoft Employee Moderator

2023-05-26T17:14:18.0866667+00:00

Hello @Tyler Saville Thank you for posting this question on the Microsoft Q&A platform. Happy to answer any questions you may have!

In general, its recommend to use this approach Keep IP addresses after Azure VM failover with Azure Site Recovery - Azure Site Recovery | Microsoft Learn

Considering your scenario - Retaining IP address while having source and target networks with the same address space/same IP addr/subnet and connected (ER or S2S VPN) is not possible as they overlap, subnets must be unique:

https://learn.microsoft.com/en-us/azure/site-recovery/concepts-on-premises-to-azure-networking#retain-ip-addresses

Note: If the target Azure VM uses the same IP address/subnet as your on-premises site, you can't connect between them using a site-to-site VPN connection or ExpressRoute, because of the address overlap. Subnets must be unique.”

If your objective is to retain IP addresses on failover with unique subnet address space, then this approach will work for you. However, in your question you mention that the source and target networks are the same implying conflict (as in the note above), this approach will not be possible. Hence the suggestion to address this question with the VNET team for other possible alternatives.
SadiqhAhmed-MSFT 49,331 Reputation points Microsoft Employee Moderator

2023-05-29T09:35:24.61+00:00

@Tyler Saville Have you had a chance to see the previous response? If the suggestions were helpful, click “Accept Answer” and Up-Vote. Feel free to reach out to us if you've additional questions in this regard.
SadiqhAhmed-MSFT 49,331 Reputation points Microsoft Employee Moderator

2023-05-30T10:57:10.7366667+00:00

@Tyler Saville We haven't heard back from you. Please reply if you have any questions in this matter and we will gladly continue the discussion.

Accepted answer

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SadiqhAhmed-MSFT 49,331 Reputation points Microsoft Employee Moderator

2023-05-26T17:14:18.0866667+00:00

Hello @Tyler Saville Thank you for posting this question on the Microsoft Q&A platform. Happy to answer any questions you may have!

In general, its recommend to use this approach Keep IP addresses after Azure VM failover with Azure Site Recovery - Azure Site Recovery | Microsoft Learn

Considering your scenario - Retaining IP address while having source and target networks with the same address space/same IP addr/subnet and connected (ER or S2S VPN) is not possible as they overlap, subnets must be unique:

https://learn.microsoft.com/en-us/azure/site-recovery/concepts-on-premises-to-azure-networking#retain-ip-addresses

Note: If the target Azure VM uses the same IP address/subnet as your on-premises site, you can't connect between them using a site-to-site VPN connection or ExpressRoute, because of the address overlap. Subnets must be unique.”

If your objective is to retain IP addresses on failover with unique subnet address space, then this approach will work for you. However, in your question you mention that the source and target networks are the same implying conflict (as in the note above), this approach will not be possible. Hence the suggestion to address this question with the VNET team for other possible alternatives.
SadiqhAhmed-MSFT 49,331 Reputation points Microsoft Employee Moderator

2023-05-29T09:35:24.61+00:00

@Tyler Saville Have you had a chance to see the previous response? If the suggestions were helpful, click “Accept Answer” and Up-Vote. Feel free to reach out to us if you've additional questions in this regard.
SadiqhAhmed-MSFT 49,331 Reputation points Microsoft Employee Moderator

2023-05-30T10:57:10.7366667+00:00

@Tyler Saville We haven't heard back from you. Please reply if you have any questions in this matter and we will gladly continue the discussion.

Answer 1

Hi @Tyler Saville

Welcome to Microsoft Q&A community forum!

Extended network for Azure enables you to stretch an on-premises subnet into Azure to let on-premises virtual machines keep their original on-premises private IP addresses when migrating to Azure.

The network is extended using a bidirectional VXLAN tunnel between two Windows Server 2019 VMs acting as virtual appliances, one running on-premises and the other running in Azure, each also connected to the subnet to be extended. Each subnet that you are going to extend requires one pair of appliances. Multiple subnets can be extended using multiple pairs.

Note

Extended network for Azure should only be used for machines that cannot have their IP address changed when migrating to Azure. It is always better to change the IP address and connect it to a subnet that wholly exists in Azure, if that is an option.

there are also other solutions that you can take into consideration, I am attaching links to better evaluate if they can do for your case

https://docs.aviatrix.com/documentation/latest/planning-secure-networks/overlapping-network-connectivity-solutions.html?expand=true

https://www.italtel.com/fast-shift-an-innovative-solution-to-migrate-applications-to-cloud-azure/

Hope this helps

Cheers

Luca

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Layer 2 azure site recovery

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