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Local/Virtual Networks Overlapping RRS feed

  • Question

  • Referencing Azure's FAQ documentation, it states local networks (on-prem) and virtual networks (Azure) cannot overlap. Does that indicate NetCFG will become corrupt if I include 10.0.0.0/8 in the local networks address space with an existing subnet in that range configured within the joining Virtual Network (Azure)? With some forethought, I want to think of Azure an extension of my internal network and control connectivity using firewall rules instead of maintaining "routing rules" in Azure.
    Wednesday, February 4, 2015 2:43 PM

Answers

  • Hi,

    As the document said,

    overlapping address spaces will cause the NETCFG upload or creating virtual network to fail

    The azure virtual network configuraion include element AddressPrefix (LocalNetworkSite), it specifies the address space that is used for the local network site. This is the address space of the on-premises network. The IP address ranges that you specify must not overlap with the IP address ranges of any other local network sites or virtual network sites.

    So i think we need to avoid the ip address overlap.

    Regards.


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com

    • Marked as answer by rdanzberger Thursday, February 5, 2015 4:20 PM
    Thursday, February 5, 2015 8:53 AM
    Moderator

All replies

  • Hi,

    As the document said,

    overlapping address spaces will cause the NETCFG upload or creating virtual network to fail

    The azure virtual network configuraion include element AddressPrefix (LocalNetworkSite), it specifies the address space that is used for the local network site. This is the address space of the on-premises network. The IP address ranges that you specify must not overlap with the IP address ranges of any other local network sites or virtual network sites.

    So i think we need to avoid the ip address overlap.

    Regards.


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com

    • Marked as answer by rdanzberger Thursday, February 5, 2015 4:20 PM
    Thursday, February 5, 2015 8:53 AM
    Moderator
  • Hi,

    As Vivian said, the address spaces cannot overlap. If you have a connection with overlapping address spaces, it will fail to connect properly. Sorry for any inconvenience this causes you.

    Thanks,

    Phillip
    Thursday, February 5, 2015 1:19 PM
  • The address space for a vNET to overlap with an address space in on-prem is a common scenario that we sometimes have to implement. In some cases the on-prem space cannot be changed and you may need to migrate those servers to Azure. In that scenario we put a firewall in Azure and NAT those addresses.

    This configuration is not supported but is sometimes necessary.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Steve D. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Tuesday, June 6, 2017 7:46 PM