Adding a Virtual Network Gateway to an existing vNet

Question

Hi,

I am curently working on a client environment. The tenant currently has 2 CSP Subscriptions (Prod and Dev) and 2 MCA Subscriptions (Prod and Dev). The CSP subscriptions were taken out when the client started their Azure journey. Each subscription has their vNets configured as /16 vNets.

The CSP Prod subscription currently has a Virtual Network Gateway with ExpressRoute and is the Hub of the environment. I have got peering configured between all the vNets.

We need to collapse the CSP subscriptions soon and are planning to migrate all the resources to the MCA subscriptions. As part of this we need to recreate the ExpressRoute in the MCA Prod Subscription. I attempted this by trying to create the Virtual Network Gateway however when selecting the vNet in the subscription I get an errors stating that it is in use already.

I couldn't understand why this is the case and I realized the peering.

Can someone please confirm my suspicion that the peering could be causing this? Would this mean I would have to break the peering first, build the gateway and enable the ExpressRoute?

Regards
Dhillan

Answer 1

Hi @Dhillan Kalyan ,

the vNet you want to create the new VNGW in is peered with another vNet? If so: Please verify the setting in the peering Use the remote virtual networks's gateway is unchecked and set to none (default).

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Regards
Andreas Baumgarten

Answer 2

Thanks for the feedback. Thought as much as I was typing this question out. I guess I am going to have to ask for some down time to get everything configured again.