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EnterpriseArchitect asked Vicky-2996 commented

Overlapping Subnet in VNET-Peering and ExpressRoute?

Folks,

In Azure, how can we detect or know if the Subnet1 in VNET1 is overlapping with Subnet2 in VNET2?

also what would be the implication if any of the Subnets in Azure that we peered, is overlapping or the same as the onPremise Subnet after establishing ExpressRoute or VPN Gateway?

Thank you in advance.

azure-virtual-networkazure-virtual-machines-networkingazure-expressrouteazure-virtual-wan
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learn2skills answered Vicky-2996 commented

@EnterpriseArchitect

It starts giving the warning for overlap To detect if the subnet is overlapping and overlapping subnet can't be peered 57675-capture1.jpgas per attached screenshot.

Do not overlap networks of each VNet.

Ensure non-overlapping address spaces. Make sure your VNet address space (CIDR block) does not overlap with your organization's other network ranges



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What happened if it is overlapping with the OnPremise network?

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If it is overlapping network, VM's from on-prem can't connect to peered vm's no traffic flow.

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Is there any outage or issue when the Overlapping network address has been configured accidentally between OnPremise and Azure ?

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Hi,

Please let me know whether it's possible or not to make a connection like below,

VNET1(10.0.0.0/16) Connected with VNG1
VNET2(10.0.2.0/23) Connected with VNG2

1) Now both VNG1 & VNG2 need to connect with same Expressroute - (All part of Same subscription).

2) VNG1(Sub1) & VNG2(Sub2) need to connect with same Expressroute(Sub1). (VNG1 & ER part of Subscription1 and VNG2 part of Subscription 2).

3) VNG1(Sub2) & VNG2(Sub2) need to connect with same Expressroute(Sub1). (ER part of Subscription1 and VNG1 &2 part of Subscription 2).


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