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Recommendations for Extending VNET or Creating New VNET for Azure Resources

InfraSolutions 646 Reputation points
2025-04-29T18:43:17.8233333+00:00

When adding a new subnet for Azure resources in an existing VNET that lacks sufficient capacity and with all subnets already allocated to resources such as VMs, Application Gateway, and VNet peering, what are Microsoft's recommendations?

Is it advisable to extend the existing VNET to accommodate the additional subnet, or should a new VNET be created and link both VNETs?

Guidance on the best approach is requested.

Azure Virtual Network
Azure Virtual Network
An Azure networking service that is used to provision private networks and optionally to connect to on-premises datacenters.
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  1. Rohith Vinnakota 4,010 Reputation points Microsoft External Staff
    2025-04-29T20:05:30.03+00:00

    Hi @InfraSolutions,

    I understand that you're trying to find the best way to deal with a situation where your existing VNET is running out of subnet capacity. Here are some considerations and recommendations to help you decide between extending your current VNET or creating a new one:

    1. Extending Existing VNET:
      • This is a suitable option if your current VNET has available address space that can be expanded without overlapping with other existing subnets. Microsoft allows you to update your virtual network's address space, but keep in mind that if your VNET is peered with others, you'll need to sync those changes, which may temporarily disable peering.
      • If your resources are operating satisfactorily within the existing VNET, extending it could maintain simpler management without needing to integrate a new network.
    2. Creating a New VNET:
      • If extending the existing VNET isn't feasible due to address space restrictions or if you want to segment resources for security or performance reasons, creating a new VNET could be a good approach.
      • You can establish VNET peering between the new and existing VNETs, allowing resources across both networks to communicate while keeping them logically separate. This is particularly useful if you foresee different security, scaling, or policy requirements for the resources.
    3. Considerations:
      • Address Space: Always ensure that the address ranges of any new subnets you create do not overlap with existing ones or other connected networks.
      • Future Scaling: Think about possible growth. If you anticipate needing more subnets or higher capacity in the future, plan your address space accordingly.
      • Service Requirements: Some Azure services require dedicated subnets (like Azure Firewall and VPN Gateway), so if you plan to use those, make sure your subnet sizing accommodates for them.

    Kindly let us know if the above helps or you need further assistance on this issue.

    Please do not forget to "Accept the answer” and “Yes” wherever the information provided helps you, this can be beneficial to other community members.

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