azureip-addressazure-virtual-networkvnet

One Azure vNET peering with multiple vnets that are using the same address space

I am a beginner with azure vnet peering, so please indulge me if this is such an obvious question. I would like to vnet peer one vnet to multiple vnets. All those vnets however uses the same address space. Let me explain more with examples. Let's say vnet_source is the one that will peer with some existing vnets.

vnet_source > 192.168.0.0/16 for example
vnet1> 10.0.0.0/16
vnet2> 10.0.0.0/16
vnet3> 10.0.0.0/16

Would this be possible? For one vnet (vnet_source) to peer with other vnets that are using the same address space, in this case (vnet 1,2, and 3)? and if so is there a routing trick that can identify, that in this case 10.0.1.81 for example ip address belongs to vnet1 and not. Any help would be highly appreciated! Thank you so much.

I am still in the planning phase, so have not tested yet.

Solution

  • Unfortunately it is not possible to implement vnet peering between vnets with same address space.

    enter image description here

    There are likely to be address conflicts (same IP address used in both locations) and Azure Route tables won't be able to decide where to send the traffic.(VM with IP 10.0.0.10 from vnet1, vnet2 or vnet3?)

    https://community.cisco.com/t5/other-collaboration-subjects/the-best-way-to-connect-2-lan-s-with-the-same-ip-addresses/td-p/2724403

    It is important to use unique IP address spaces for each virtual network used in Azure so that routing can occur between virtual networks. If virtual networks have the same IP address space it would not be possible to route traffic between resources from different vnets.

    https://superuser.com/questions/1661852/can-two-networks-connected-to-a-router-both-have-a-host-with-the-same-ip-address

    L2 forwarding can solve this problem but Azure does not support it for peering. enter image description here https://blog.ipspace.net/2019/11/stretched-layer-2-subnets-in-azure.html