Configure a VNet-to-VNet VPN gateway connection using PowerShell

Article
10/08/2024

This article helps you connect virtual networks by using the VNet-to-VNet connection type. The virtual networks can be in the same or different regions, and from the same or different subscriptions. When you connect virtual networks from different subscriptions, the subscriptions don't need to be associated with the same tenant. If you already have VNets that you want to connect and they're in the same subscription, you might want to use the Azure portal steps instead because the process is less complicated. Note that you can't connect VNets from different subscriptions using the Azure portal.

In this exercise, you create the required virtual networks (VNets) and VPN gateways. We have steps to connect VNets within the same subscription, as well as steps and commands for the more complicated scenario to connect VNets in different subscriptions. The PowerShell cmdlet to create a connection is New-AzVirtualNetworkGatewayConnection. The -ConnectionType is Vnet2Vnet.

About connecting VNets

There are multiple ways to connect VNets. The following sections describe different ways to connect virtual networks.

VNet-to-VNet

Configuring a VNet-to-VNet connection is a good way to easily connect VNets. Connecting a virtual network to another virtual network using the VNet-to-VNet connection type (VNet2VNet) is similar to creating a Site-to-Site IPsec connection to an on-premises location. Both connectivity types use a VPN gateway to provide a secure tunnel using IPsec/IKE, and both function the same way when communicating. The difference between the connection types is the way the local network gateway is configured. When you create a VNet-to-VNet connection, you don't see the local network gateway address space. It's automatically created and populated. If you update the address space for one VNet, the other VNet automatically knows to route to the updated address space. Creating a VNet-to-VNet connection is typically faster and easier than creating a Site-to-Site connection between VNets.

Site-to-Site (IPsec)

If you're working with a complicated network configuration, you might prefer to connect your VNets using the Site-to-Site steps, instead the VNet-to-VNet steps. When you use the Site-to-Site steps, you create and configure the local network gateways manually. The local network gateway for each VNet treats the other VNet as a local site. This lets you specify additional address space for the local network gateway in order to route traffic. If the address space for a VNet changes, you need to update the corresponding local network gateway to reflect the change. It doesn't automatically update.

VNet peering

You might want to consider connecting your VNets using VNet Peering. VNet peering doesn't use a VPN gateway and has different constraints. Additionally, VNet peering pricing is calculated differently than VNet-to-VNet VPN Gateway pricing. For more information, see VNet peering.

Why create a VNet-to-VNet connection?

You might want to connect virtual networks using a VNet-to-VNet connection for the following reasons:

Cross region geo-redundancy and geo-presence
- You can set up your own geo-replication or synchronization with secure connectivity without going over Internet-facing endpoints.
- With Azure Traffic Manager and Load Balancer, you can set up highly available workload with geo-redundancy across multiple Azure regions. One important example is to set up SQL Always On with Availability Groups spreading across multiple Azure regions.
Regional multi-tier applications with isolation or administrative boundary
- Within the same region, you can set up multi-tier applications with multiple virtual networks connected together due to isolation or administrative requirements.

VNet-to-VNet communication can be combined with multi-site configurations. This lets you establish network topologies that combine cross-premises connectivity with inter-virtual network connectivity.

Which VNet-to-VNet steps should I use?

In this article, you see two different sets of steps. One set of steps for VNets that reside in the same subscription and one for VNets that reside in different subscriptions. The key difference between the sets is that you must use separate PowerShell sessions when configuring the connections for VNets that reside in different subscriptions.

For this exercise, you can combine configurations, or just choose the one that you want to work with. All of the configurations use the VNet-to-VNet connection type. Network traffic flows between the VNets that are directly connected to each other. In this exercise, traffic from TestVNet4 doesn't route to TestVNet5.

VNets that reside in the same subscription: The steps for this configuration use TestVNet1 and TestVNet4.
VNets that reside in different subscriptions: The steps for this configuration use TestVNet1 and TestVNet5.

How to connect VNets that are in the same subscription

You can complete the following steps using latest version of the Azure PowerShell module locally, see How to install and configure Azure PowerShell.

Step 1 - Plan your IP address ranges

In the following steps, you create two virtual networks along with their respective gateway subnets and configurations. You then create a VPN connection between the two VNets. It's important to plan the IP address ranges for your network configuration. Keep in mind that you must make sure that none of your VNet ranges or local network ranges overlap in any way. In these examples, we don't include a DNS server. If you want name resolution for your virtual networks, see Name resolution.

We use the following values in the examples:

Values for TestVNet1:

VNet Name: TestVNet1
Resource Group: TestRG1
Location: China East
TestVNet1: 10.1.0.0/16
FrontEnd: 10.1.0.0/24
GatewaySubnet: 10.1.255.0/27
GatewayName: VNet1GW
Public IP: VNet1GWIP
VPNType: RouteBased
Connection(1to4): VNet1toVNet4
Connection(1to5): VNet1toVNet5 (For VNets in different subscriptions)
ConnectionType: VNet2VNet

Values for TestVNet4:

VNet Name: TestVNet4
TestVNet2: 10.41.0.0/16
FrontEnd: 10.41.0.0/24
GatewaySubnet: 10.41.255.0/27
Resource Group: TestRG4
Location: China North
GatewayName: VNet4GW
Public IP: VNet4GWIP
VPNType: RouteBased
Connection: VNet4toVNet1
ConnectionType: VNet2VNet

Step 2 - Create and configure TestVNet1

For the following steps, you can run PowerShell locally. For more information, see How to install and configure Azure PowerShell.

Note

You might see warnings saying "The output object type of this cmdlet will be modified in a future release". This is expected behavior and you can safely ignore these warnings.

Declare your variables. This example declares the variables using the values for this exercise. In most cases, you should replace the values with your own. However, you can use these variables if you're running through the steps to become familiar with this type of configuration. Modify the variables if needed, then copy and paste them into your PowerShell console.
```
$RG1 = "TestRG1"
$Location1 = "China East"
$VNetName1 = "TestVNet1"
$FESubName1 = "FrontEnd"
$VNetPrefix1 = "10.1.0.0/16"
$FESubPrefix1 = "10.1.0.0/24"
$GWSubPrefix1 = "10.1.255.0/27"
$GWName1 = "VNet1GW"
$GWIPName1 = "VNet1GWIP"
$GWIPconfName1 = "gwipconf1"
$Connection14 = "VNet1toVNet4"
$Connection15 = "VNet1toVNet5"
```

Create a resource group.

New-AzResourceGroup -Name $RG1 -Location $Location1

Create the subnet configurations for TestVNet1. This example creates a virtual network named TestVNet1 and two subnets, one called GatewaySubnet, and one called FrontEnd. When substituting values, it's important that you always name your gateway subnet specifically GatewaySubnet. If you name it something else, your gateway creation fails. For this reason, it isn't assigned via variable in the example.

The following example uses the variables that you set earlier. In this example, the gateway subnet is using a /27. While it's possible to create a gateway subnet using /28 for this configuration, we recommend that you create a larger subnet that includes more addresses by selecting at least /27. This will allow for enough addresses to accommodate possible additional configurations that you might want in the future.
```
$fesub1 = New-AzVirtualNetworkSubnetConfig -Name $FESubName1 -AddressPrefix $FESubPrefix1
$gwsub1 = New-AzVirtualNetworkSubnetConfig -Name "GatewaySubnet" -AddressPrefix $GWSubPrefix1
```

Create TestVNet1.

New-AzVirtualNetwork -Name $VNetName1 -ResourceGroupName $RG1 `
-Location $Location1 -AddressPrefix $VNetPrefix1 -Subnet $fesub1,$gwsub1

A VPN gateway must have an allocated public IP address. When you create a connection to a VPN gateway, this is the IP address that you specify. Use the following example to request a public IP address.
```
$gwpip1 = New-AzPublicIpAddress -Name $GWIPName1 -ResourceGroupName $RG1 `
-Location $Location1 -AllocationMethod Static -Sku Standard
```

Create the gateway configuration. The gateway configuration defines the subnet and the public IP address to use. Use the example to create your gateway configuration.

$vnet1 = Get-AzVirtualNetwork -Name $VNetName1 -ResourceGroupName $RG1
$subnet1 = Get-AzVirtualNetworkSubnetConfig -Name "GatewaySubnet" -VirtualNetwork $vnet1
$gwipconf1 = New-AzVirtualNetworkGatewayIpConfig -Name $GWIPconfName1 `
-Subnet $subnet1 -PublicIpAddress $gwpip1

Create the gateway for TestVNet1. In this step, you create the virtual network gateway for your TestVNet1. VNet-to-VNet configurations require a RouteBased VpnType. Creating a gateway can often take 45 minutes or more, depending on the selected gateway SKU.
```
New-AzVirtualNetworkGateway -Name $GWName1 -ResourceGroupName $RG1 `
-Location $Location1 -IpConfigurations $gwipconf1 -GatewayType Vpn `
-VpnType RouteBased -GatewaySku VpnGw2 -VpnGatewayGeneration "Generation2"
```

After you finish the commands, it will take 45 minutes or more to create this gateway.

Step 3: Create and configure TestVNet4

Create TestVNet4. Use the following steps, replacing the values with your own when needed.

Connect and declare your variables. Be sure to replace the values with the ones that you want to use for your configuration.

$RG4 = "TestRG4"
$Location4 = "China North"
$VnetName4 = "TestVNet4"
$FESubName4 = "FrontEnd"
$VnetPrefix4 = "10.41.0.0/16"
$FESubPrefix4 = "10.41.0.0/24"
$GWSubPrefix4 = "10.41.255.0/27"
$GWName4 = "VNet4GW"
$GWIPName4 = "VNet4GWIP"
$GWIPconfName4 = "gwipconf4"
$Connection41 = "VNet4toVNet1"

Create a resource group.

New-AzResourceGroup -Name $RG4 -Location $Location4

Create the subnet configurations for TestVNet4.

$fesub4 = New-AzVirtualNetworkSubnetConfig -Name $FESubName4 -AddressPrefix $FESubPrefix4
$gwsub4 = New-AzVirtualNetworkSubnetConfig -Name "GatewaySubnet" -AddressPrefix $GWSubPrefix4

Create TestVNet4.

New-AzVirtualNetwork -Name $VnetName4 -ResourceGroupName $RG4 `
-Location $Location4 -AddressPrefix $VnetPrefix4 -Subnet $fesub4,$gwsub4

Request a public IP address.

$gwpip4 = New-AzPublicIpAddress -Name $GWIPName4 -ResourceGroupName $RG4 `
-Location $Location4 -AllocationMethod Static -Sku Standard

Create the gateway configuration.

$vnet4 = Get-AzVirtualNetwork -Name $VnetName4 -ResourceGroupName $RG4
$subnet4 = Get-AzVirtualNetworkSubnetConfig -Name "GatewaySubnet" -VirtualNetwork $vnet4
$gwipconf4 = New-AzVirtualNetworkGatewayIpConfig -Name $GWIPconfName4 -Subnet $subnet4 -PublicIpAddress $gwpip4

Create the TestVNet4 gateway. Creating a gateway can often take 45 minutes or more, depending on the selected gateway SKU.

New-AzVirtualNetworkGateway -Name $GWName4 -ResourceGroupName $RG4 `
-Location $Location4 -IpConfigurations $gwipconf4 -GatewayType Vpn `
-VpnType RouteBased -GatewaySku VpnGw2 -VpnGatewayGeneration "Generation2"

Step 4: Create the connections

Wait until both gateways are completed.

Get both virtual network gateways.

$vnet1gw = Get-AzVirtualNetworkGateway -Name $GWName1 -ResourceGroupName $RG1
$vnet4gw = Get-AzVirtualNetworkGateway -Name $GWName4 -ResourceGroupName $RG4

Create the TestVNet1 to TestVNet4 connection. In this step, you create the connection from TestVNet1 to TestVNet4. You'll see a shared key referenced in the examples. You can use your own values for the shared key. The important thing is that the shared key must match for both connections. Creating a connection can take a short while to complete.
```
New-AzVirtualNetworkGatewayConnection -Name $Connection14 -ResourceGroupName $RG1 `
-VirtualNetworkGateway1 $vnet1gw -VirtualNetworkGateway2 $vnet4gw -Location $Location1 `
-ConnectionType Vnet2Vnet -SharedKey 'AzureA1b2C3'
```
Create the TestVNet4 to TestVNet1 connection. This step is similar to previous step, except you're creating the connection from TestVNet4 to TestVNet1. Make sure the shared keys match. The connection will be established after a few minutes.
```
New-AzVirtualNetworkGatewayConnection -Name $Connection41 -ResourceGroupName $RG4 `
-VirtualNetworkGateway1 $vnet4gw -VirtualNetworkGateway2 $vnet1gw -Location $Location4 `
-ConnectionType Vnet2Vnet -SharedKey 'AzureA1b2C3'
```
Verify your connection. See the section How to verify your connection.

How to connect VNets that are in different subscriptions

In this scenario, you connect TestVNet1 and TestVNet5. TestVNet1 and TestVNet5 reside in different subscriptions. The subscriptions don't need to be associated with the same tenant.

The difference between these steps and the previous set is that some of the configuration steps need to be performed in a separate PowerShell session in the context of the second subscription. Especially when the two subscriptions belong to different organizations.

Step 5: Create and configure TestVNet1

You must complete Step 1 and Step 2 from the previous section to create and configure TestVNet1 and the VPN Gateway for TestVNet1. For this configuration, you aren't required to create TestVNet4 from the previous section, although if you do create it, it won't conflict with these steps. Once you complete Step 1 and Step 2, continue with Step 6 to create TestVNet5.

Step 6: Verify the IP address ranges

It's important to make sure that the IP address space of the new virtual network, TestVNet5, doesn't overlap with any of your VNet ranges or local network gateway ranges. In this example, the virtual networks might belong to different organizations. For this exercise, you can use the following values for the TestVNet5:

Values for TestVNet5:

VNet Name: TestVNet5
Resource Group: TestRG5
Location: China East 2
TestVNet5: 10.51.0.0/16
FrontEnd: 10.51.0.0/24
GatewaySubnet: 10.51.255.0.0/27
GatewayName: VNet5GW
Public IP: VNet5GWIP
VPNType: RouteBased
Connection: VNet5toVNet1
ConnectionType: VNet2VNet

Step 7: Create and configure TestVNet5

This step must be done in the context of the new subscription. This part might be performed by the administrator in a different organization that owns the subscription.

Declare your variables. Be sure to replace the values with the ones that you want to use for your configuration.

$Sub5 = "Replace_With_the_New_Subscription_Name"
$RG5 = "TestRG5"
$Location5 = "China East 2"
$VnetName5 = "TestVNet5"
$FESubName5 = "FrontEnd"
$GWSubName5 = "GatewaySubnet"
$VnetPrefix5 = "10.51.0.0/16"
$FESubPrefix5 = "10.51.0.0/24"
$GWSubPrefix5 = "10.51.255.0/27"
$GWName5 = "VNet5GW"
$GWIPName5 = "VNet5GWIP"
$GWIPconfName5 = "gwipconf5"
$Connection51 = "VNet5toVNet1"

Connect to subscription 5. Open your PowerShell console and connect to your account. Use the following sample to help you connect:
```
Connect-AzAccount -Environment AzureChinaCloud
```
Check the subscriptions for the account.
```
Get-AzSubscription
```
Specify the subscription that you want to use.
```
Select-AzSubscription -SubscriptionName $Sub5
```

Create a new resource group.

New-AzResourceGroup -Name $RG5 -Location $Location5

Create the subnet configurations for TestVNet5.

$fesub5 = New-AzVirtualNetworkSubnetConfig -Name $FESubName5 -AddressPrefix $FESubPrefix5
$gwsub5 = New-AzVirtualNetworkSubnetConfig -Name $GWSubName5 -AddressPrefix $GWSubPrefix5

Create TestVNet5.

New-AzVirtualNetwork -Name $VnetName5 -ResourceGroupName $RG5 -Location $Location5 `
-AddressPrefix $VnetPrefix5 -Subnet $fesub5,$gwsub5

Request a public IP address.

$gwpip5 = New-AzPublicIpAddress -Name $GWIPName5 -ResourceGroupName $RG5 `
-Location $Location5 -AllocationMethod Static -Sku Standard

Create the gateway configuration.

$vnet5 = Get-AzVirtualNetwork -Name $VnetName5 -ResourceGroupName $RG5
$subnet5  = Get-AzVirtualNetworkSubnetConfig -Name "GatewaySubnet" -VirtualNetwork $vnet5
$gwipconf5 = New-AzVirtualNetworkGatewayIpConfig -Name $GWIPconfName5 -Subnet $subnet5 -PublicIpAddress $gwpip5

Create the TestVNet5 gateway.

New-AzVirtualNetworkGateway -Name $GWName5 -ResourceGroupName $RG5 -Location $Location5 `
-IpConfigurations $gwipconf5 -GatewayType Vpn -VpnType RouteBased -GatewaySku VpnGw2 -VpnGatewayGeneration "Generation2"

Step 8: Create the connections

In this example, because the gateways are in the different subscriptions, we've split this step into two PowerShell sessions marked as [Subscription 1] and [Subscription 5].

[Subscription 1] Get the virtual network gateway for Subscription 1. Sign in and connect to Subscription 1 before running the following example:
```
$vnet1gw = Get-AzVirtualNetworkGateway -Name $GWName1 -ResourceGroupName $RG1
```
Copy the output of the following elements and send these to the administrator of Subscription 5 via email or another method.
```
$vnet1gw.Name
$vnet1gw.Id
```
These two elements will have values similar to the following example output:
```
PS D:\> $vnet1gw.Name
VNet1GW
PS D:\> $vnet1gw.Id
/subscriptions/aaaa0a0a-bb1b-cc2c-dd3d-eeeeee4e4e4e/resourceGroupsTestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW
```
[Subscription 5] Get the virtual network gateway for Subscription 5. Sign in and connect to Subscription 5 before running the following example:
```
$vnet5gw = Get-AzVirtualNetworkGateway -Name $GWName5 -ResourceGroupName $RG5
```
Copy the output of the following elements and send these to the administrator of Subscription 1 via email or another method.
```
$vnet5gw.Name
$vnet5gw.Id
```
These two elements will have values similar to the following example output:
```
PS C:\> $vnet5gw.Name
VNet5GW
PS C:\> $vnet5gw.Id
/subscriptions/bbbb1b1b-cc2c-dd3d-ee4e-ffffff5f5f5f/resourceGroups/TestRG5/providers/Microsoft.Network/virtualNetworkGateways/VNet5GW
```
[Subscription 1] Create the TestVNet1 to TestVNet5 connection. In this step, you create the connection from TestVNet1 to TestVNet5. The difference here is that $vnet5gw can't be obtained directly because it is in a different subscription. You'll need to create a new PowerShell object with the values communicated from Subscription 1 in the previous steps. Use the following example. Replace the Name, ID, and shared key with your own values. The important thing is that the shared key must match for both connections. Creating a connection can take a short while to complete.

Connect to Subscription 1 before running the following example:
```
$vnet5gw = New-Object -TypeName Microsoft.Azure.Commands.Network.Models.PSVirtualNetworkGateway
$vnet5gw.Name = "VNet5GW"
$vnet5gw.Id   = "/subscriptions/bbbb1b1b-cc2c-dd3d-ee4e-ffffff5f5f5f/resourceGroups/TestRG5/providers/Microsoft.Network/virtualNetworkGateways/VNet5GW"
$Connection15 = "VNet1toVNet5"
New-AzVirtualNetworkGatewayConnection -Name $Connection15 -ResourceGroupName $RG1 -VirtualNetworkGateway1 $vnet1gw -VirtualNetworkGateway2 $vnet5gw -Location $Location1 -ConnectionType Vnet2Vnet -SharedKey 'AzureA1b2C3'
```

[Subscription 5] Create the TestVNet5 to TestVNet1 connection. This step is similar previous step, except you're creating the connection from TestVNet5 to TestVNet1. The same process of creating a PowerShell object based on the values obtained from Subscription 1 applies here as well. In this step, be sure that the shared keys match.

Connect to Subscription 5 before running the following example:

$vnet1gw = New-Object -TypeName Microsoft.Azure.Commands.Network.Models.PSVirtualNetworkGateway
$vnet1gw.Name = "VNet1GW"
$vnet1gw.Id = "/subscriptions/aaaa0a0a-bb1b-cc2c-dd3d-eeeeee4e4e4e/resourceGroups/TestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW "
$Connection51 = "VNet5toVNet1"
New-AzVirtualNetworkGatewayConnection -Name $Connection51 -ResourceGroupName $RG5 -VirtualNetworkGateway1 $vnet5gw -VirtualNetworkGateway2 $vnet1gw -Location $Location5 -ConnectionType Vnet2Vnet -SharedKey 'AzureA1b2C3'

How to verify a connection

Important

Network security groups (NSGs) on the gateway subnet are not supported. Associating a network security group to this subnet might cause your virtual network gateway (VPN and ExpressRoute gateways) to stop functioning as expected. For more information about network security groups, see What is a network security group?

You can verify that your connection succeeded by using the 'Get-AzVirtualNetworkGatewayConnection' cmdlet, with or without '-Debug'.

Use the following cmdlet example, configuring the values to match your own. If prompted, select 'A' in order to run 'All'. In the example, '-Name' refers to the name of the connection that you want to test.
```
Get-AzVirtualNetworkGatewayConnection -Name VNet1toSite1 -ResourceGroupName TestRG1
```
After the cmdlet has finished, view the values. In the example below, the connection status shows as 'Connected' and you can see ingress and egress bytes.
```
"connectionStatus": "Connected",
"ingressBytesTransferred": 33509044,
"egressBytesTransferred": 4142431
```

VNet-to-VNet FAQ

For more information about VNet-to-VNet connections, see the VPN Gateway FAQ.

Next steps

Once your connection is complete, you can add virtual machines to your virtual networks. See the Virtual Machines documentation for more information.
For information about BGP, see the BGP Overview and How to configure BGP.