Hello @Song, John (MTO) ,
Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.
I understand that you would like to know how many VPN gateways can be deployed in a Virtual Network.
You can create only one Azure VPN gateway per virtual network.
But if we talk about virtual network gateway, one of the settings that you specify when creating a virtual network gateway is the "gateway type". The gateway type determines how the virtual network gateway will be used and the actions that the gateway takes. A virtual network can have two virtual network gateways; one VPN gateway and one ExpressRoute gateway.
Refer: https://learn.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-about-vpngateways#vpn
https://learn.microsoft.com/en-us/azure/expressroute/how-to-configure-coexisting-gateway-portal
But the limit for Azure VPN gateway in a Vnet remains the same - only one.
Now, talking about active-active, it is a Connection resiliency setting for an Azure VPN gateway.
Refer: https://learn.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-about-vpngateways#planningtable
Every Azure VPN gateway consists of two instances in an active-standby configuration. But you can create a VPN gateway in an active-active configuration, where both instances of the gateway VMs establish S2S VPN tunnels to your on-premises VPN device.
Active-active is nothing but a setting/option in the VPN gateway creation template/UI, that you can set to enable/disable according to your requirement.
Even when you enable this setting, the Azure VPN gateway remains a single resource. The only difference here is - both the backend instances of the VPN gateway become active-active instead of the default active-standby.
Refer: https://learn.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-highlyavailable
https://learn.microsoft.com/en-us/azure/vpn-gateway/active-active-portal#gateway
Kindly let us know if the above helps or you need further assistance on this issue.
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