Configure a VNet-to-VNet VPN gateway connection using Azure CLI

Article
08/02/2024

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 connecting VNets from different subscriptions, the subscriptions don't need to be associated with the same tenant.

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 Azure CLI command to create a connection is az network vpn-connection. If you're connecting VNets from different subscriptions, use the steps in this article or in the PowerShell article. 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.

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 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, but doesn't provide the same level of flexibility if you want to add another connection because the local network gateway address space isn't available to manually modify.

Connecting VNets using Site-to-Site (IPsec) steps

If you're working with a complicated network configuration, you might prefer to connect your VNets using the Site-to-Site steps, instead of 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 spaces for the local network gateway in order to route traffic. If the address space for a VNet changes, you need to manually 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 VNet-to-VNet connection steps. One set of steps for VNets that reside in the same subscription and one 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.

VNets that reside in the same subscription
VNets that reside in different subscriptions

Connect VNets that are in the same subscription

Before you begin

Before beginning, install the latest version of the CLI commands (2.0 or later). For information about installing the CLI commands, see Install the Azure CLI.

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: 10.11.0.0/16 & 10.12.0.0/16
FrontEnd: 10.11.0.0/24
BackEnd: 10.12.0.0/24
GatewaySubnet: 10.12.255.0/27
GatewayName: VNet1GW
Public IP: VNet1GWIP
VPNType: RouteBased
Connection(1to4): VNet1toVNet4
Connection(1to5): VNet1toVNet5 (For VNets in different subscriptions)

Values for TestVNet4:

VNet Name: TestVNet4
TestVNet2: 10.41.0.0/16 & 10.42.0.0/16
FrontEnd: 10.41.0.0/24
BackEnd: 10.42.0.0/24
GatewaySubnet: 10.42.255.0/27
Resource Group: TestRG4
Location: China North
GatewayName: VNet4GW
Public IP: VNet4GWIP
VPN Type: RouteBased
Connection: VNet4toVNet1

Step 1 - Connect to your subscription

Sign in to your Azure subscription with the az login command and follow the on-screen directions. For more information about signing in, see Get Started with Azure CLI.
```
az cloud set -n AzureChinaCloud
az login
```
If you have more than one Azure subscription, list the subscriptions for the account.
```
az account list --all
```

Specify the subscription that you want to use.

az account set --subscription <replace_with_your_subscription_id>

Step 2 - Create and configure TestVNet1

Create a resource group.

az group create -n TestRG1  -l chinaeast

Create TestVNet1 and the subnets for TestVNet1 using the az network vnet create command. This example creates a virtual network named TestVNet1 and a subnet named FrontEnd.
```
az network vnet create \
  -n TestVNet1 \
  -g TestRG1 \
  -l chinaeast \
  --address-prefix 10.11.0.0/16 \
  --subnet-name Frontend \
  --subnet-prefix 10.11.0.0/24
```
Create an additional address space for the backend subnet. Notice that in this step, we specified both the address space that we created earlier, and the additional address space that we want to add. This is because the az network vnet update command overwrites the previous settings. Make sure to specify all of the address prefixes when using this command.
```
az network vnet update \
   -n TestVNet1 \
   --address-prefixes 10.11.0.0/16 10.12.0.0/16 \
   -g TestRG1
```

Create the backend subnet.

az network vnet subnet create \
   --vnet-name TestVNet1 \
   -n BackEnd \
   -g TestRG1 \
   --address-prefix 10.12.0.0/24

Create the gateway subnet. Notice that the gateway subnet is named 'GatewaySubnet'. This name is required. In this example, the gateway subnet is using a /27. While it's possible to create a gateway subnet as small as /29, we recommend that you create a larger subnet that includes more addresses by selecting at least /28 or /27. This will allow for enough addresses to accommodate possible additional configurations that you might want in the future.
```
az network vnet subnet create \
   --vnet-name TestVNet1 \
   -n GatewaySubnet \
   -g TestRG1 \
   --address-prefix 10.12.255.0/27
```
A VPN gateway must have a public IP address. The public IP address is allocated to the VPN gateway that you create for your virtual network. Use the following example to request a public IP address using the az network public-ip create command:
```
az network public-ip create \
 -g TestRG1 \
 -n VNet1GWIP1 \
 --sku Standard \
 --allocation-method Static \
 --l chinaeast
```
Create the virtual network gateway for TestVNet1 using the az network vnet-gateway create command. If you run this command using the '--no-wait' parameter, you don't see any feedback or output. The '--no-wait' parameter allows the gateway to create in the background. It doesn't mean that the VPN gateway finishes creating immediately. Creating a gateway can often take 45 minutes or more, depending on the gateway SKU that you use.
```
az network vnet-gateway create \
  --name VNet1GW \
  --public-ip-address VNet1GWIP \
  --resource-group TestRG1 \
  --vnet TestVNet1 \
  --gateway-type Vpn \
  --sku VpnGw2 \
  --vpn-gateway-generation Generation2 \
  --no-wait
```

Step 3 - Create and configure TestVNet4

Create a resource group.

az group create -n TestRG4 -l chinanorth

Create TestVNet4.

az network vnet create \
  -n TestVNet4 \
  -g TestRG4 \
  -l chinanorth \
  --address-prefix 10.41.0.0/16 \
  --subnet-name Frontend \
  --subnet-prefix 10.41.0.0/24

Create additional subnets for TestVNet4.

az network vnet update \
   -n TestVNet4 \
   --address-prefixes 10.41.0.0/16 10.42.0.0/16 \
   -g TestRG4 \

az network vnet subnet create \
   --vnet-name TestVNet4 \
   -n BackEnd \
   -g TestRG4 \
   --address-prefix 10.42.0.0/24

Create the gateway subnet.

az network vnet subnet create \
  --vnet-name TestVNet4 \
  -n GatewaySubnet \
  -g TestRG4 \
  --address-prefix 10.42.255.0/27

Request a Public IP address.

az network public-ip create \
 -g TestRG4 \
 --n VNet4GWIP \
 --sku Standard \
 --allocation-method Static \
 --l chinanorth

Create the TestVNet4 virtual network gateway.

az network vnet-gateway create \
  -n VNet4GW \
  -l chinanorth \
  --public-ip-address VNet4GWIP \
  -g TestRG4 \
  --vnet TestVNet4 \
  --gateway-type Vpn \
  --sku VpnGw2 \
  --vpn-gateway-generation Generation2 \
  --no-wait

Step 4 - Create the connections

You now have two VNets with VPN gateways. The next step is to create VPN gateway connections between the virtual network gateways. If you used the preceding examples, your VNet gateways are in different resource groups. When gateways are in different resource groups, you need to identify and specify the resource IDs for each gateway when making a connection. If your VNets are in the same resource group, you can use the second set of instructions because you don't need to specify the resource IDs.

To connect VNets that reside in different resource groups

Get the Resource ID of VNet1GW from the output of the following command:

az network vnet-gateway show -n VNet1GW -g TestRG1

In the output, find the "id:" line. The values within the quotes are needed to create the connection in the next section. Copy these values to a text editor, such as Notepad, so that you can easily paste them when creating your connection.

Example output:

"activeActive": false, 
"bgpSettings": { 
 "asn": 65515, 
 "bgpPeeringAddress": "10.12.255.30", 
 "peerWeight": 0 
}, 
"enableBgp": false, 
"etag": "W/\"ecb42bc5-c176-44e1-802f-b0ce2962ac04\"", 
"gatewayDefaultSite": null, 
"gatewayType": "Vpn", 
"id": "/subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW", 
"ipConfigurations":

Copy the values after "id": within the quotes.

"id": "/subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW"

Get the Resource ID of VNet4GW and copy the values to a text editor.
```
az network vnet-gateway show -n VNet4GW -g TestRG4
```

Create the TestVNet1 to TestVNet4 connection. In this step, you create the connection from TestVNet1 to TestVNet4. There's 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 takes a short while to complete.

az network vpn-connection create \
   -n VNet1ToVNet4 \
   -g TestRG1 \
   --vnet-gateway1 /subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW \
   -l chinaeast \
   --shared-key "aabbcc" \
   --vnet-gateway2 /subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG4/providers/Microsoft.Network/virtualNetworkGateways/VNet4GW

Create the TestVNet4 to TestVNet1 connection. This step is similar to the previous step, except you're creating the connection from TestVNet4 to TestVNet1. Make sure the shared keys match. It takes a few minutes to establish the connection.

az network vpn-connection create \
   -n VNet4ToVNet1 \
   -g TestRG4 \
   --vnet-gateway1 /subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG4/providers/Microsoft.Network/virtualNetworkGateways/VNet4GW \
   -l chinanorth \
   --shared-key "aabbcc" \
   --vnet-gateway2 /subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW

Verify your connections. See Verify your connection.

To connect VNets that reside in the same resource group

Create the TestVNet1 to TestVNet4 connection. In this step, you create the connection from TestVNet1 to TestVNet4. Notice the resource groups are the same in the examples. You also see a shared key referenced in the examples. You can use your own values for the shared key, however, the shared key must match for both connections. Creating a connection takes a short while to complete.
```
az network vpn-connection create \
   -n VNet1ToVNet4 \
   -g TestRG1 \
   --vnet-gateway1 VNet1GW \
   -l chinaeast \
   --shared-key "eeffgg" \
   --vnet-gateway2 VNet4GW
```
Create the TestVNet4 to TestVNet1 connection. This step is similar to the previous step, except you're creating the connection from TestVNet4 to TestVNet1. Make sure the shared keys match. It takes a few minutes to establish the connection.
```
az network vpn-connection create \
   -n VNet4ToVNet1 \
   -g TestRG1 \
   --vnet-gateway1 VNet4GW \
   -l chinaeast \
   --shared-key "eeffgg" \
   --vnet-gateway2 VNet1GW
```
Verify your connections. See Verify your connection.

Connect VNets that are in different subscriptions

In this scenario, you connect TestVNet1 and TestVNet5. The VNets reside different subscriptions. The subscriptions don't need to be associated with the same tenant. The steps for this configuration add an additional VNet-to-VNet connection in order to connect TestVNet1 to TestVNet5.

Step 5 - Create and configure TestVNet1

These instructions continue from the steps in the preceding sections. You must complete Step 1 and Step 2 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: traffic from TestVNet4 doesn't route to TestVNet5. Once you complete Step 1 and Step 2, continue with Step 6.

Step 6 - Verify the IP address ranges

When creating additional connections, it's important to verify that the IP address space of the new virtual network doesn't overlap with any of your other VNet ranges or local network gateway ranges. 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 & 10.52.0.0/16
FrontEnd: 10.51.0.0/24
BackEnd: 10.52.0.0/24
GatewaySubnet: 10.52.255.0/27
GatewayName: VNet5GW
Public IP: VNet5GWIP
VPN Type: RouteBased
Connection: VNet5toVNet1
ConnectionType: VNet2VNet

Step 7 - Create and configure TestVNet5

This step must be done in the context of the new subscription, Subscription 5. This part can be performed by the administrator in a different organization that owns the subscription. To switch between subscriptions use az account list --all to list the subscriptions available to your account, then use az account set --subscription <subscriptionID> to switch to the subscription that you want to use.

Make sure you're connected to Subscription 5, then create a resource group.
```
az group create -n TestRG5  -l chinaeast2
```

Create TestVNet5.

az network vnet create \
   -n TestVNet5 \
   -g TestRG5 \
   --address-prefix 10.51.0.0/16 \
   -l chinaeast2 \
   --subnet-name FrontEnd \
   --subnet-prefix 10.51.0.0/24

Add subnets.

az network vnet update \
   -n TestVNet5 \
   --address-prefixes 10.51.0.0/16 10.52.0.0/16 \
   -g TestRG5 \

az network vnet subnet create \
   --vnet-name TestVNet5 \
   -n BackEnd \
   -g TestRG5 \
   --address-prefix 10.52.0.0/24

Add the gateway subnet.

az network vnet subnet create \
   --vnet-name TestVNet5 \
   -n GatewaySubnet \
   -g TestRG5 \
   --address-prefix 10.52.255.0/27

Request a public IP address.

az network public-ip create \
   -g TestRG5 \
   --n VNet5GWIP \
   --sku Standard \
   --allocation-method Static \
   --l chinaeast2

Create the TestVNet5 gateway

az network vnet-gateway create \
  -n VNet5GW \
  -l chinaeast2 \
  --public-ip-address VNet5GWIP \
  -g TestRG5 \
  --vnet TestVNet5 \
  --gateway-type Vpn \
  --sku VpnGw2 \
  --vpn-gateway-generation Generation2 \
  --no-wait

Step 8 - Create the connections

This step is split into two CLI sessions marked as [Subscription 1], and [Subscription 5] because the gateways are in the different subscriptions. To switch between subscriptions use az account list --all to list the subscriptions available to your account, then use az account set --subscription <subscriptionID> to switch to the subscription that you want to use.

[Subscription 1] Sign in and connect to Subscription 1. Run the following command to get the name and ID of the Gateway from the output:
```
az network vnet-gateway show -n VNet1GW -g TestRG1
```
Copy the output for id:. Send the ID and the name of the VNet gateway (VNet1GW) to the administrator of Subscription 5 via email or another method.

Example output:
```
"id": "/subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW"
```
[Subscription 5] Sign in and connect to Subscription 5. Run the following command to get the name and ID of the Gateway from the output:
```
az network vnet-gateway show -n VNet5GW -g TestRG5
```
Copy the output for id:. Send the ID and the name of the VNet gateway (VNet5GW) to the administrator of Subscription 1 via email or another method.

[Subscription 1] In this step, you create the connection from TestVNet1 to TestVNet5. You can use your own values for the shared key, however, the shared key must match for both connections. Creating a connection can take a short while to complete. Make sure you connect to Subscription 1.

az network vpn-connection create \
   -n VNet1ToVNet5 \
   -g TestRG1 \
   --vnet-gateway1 /subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW \
   -l chinaeast \
   --shared-key "eeffgg" \
   --vnet-gateway2 /subscriptions/e7e33b39-fe28-4822-b65c-a4db8bbff7cb/resourceGroups/TestRG5/providers/Microsoft.Network/virtualNetworkGateways/VNet5GW

[Subscription 5] This step is similar to the preceding step, except you're creating the connection from TestVNet5 to TestVNet1. Make sure that the shared keys match and that you connect to Subscription 5.

az network vpn-connection create \
   -n VNet5ToVNet1 \
   -g TestRG5 \
   --vnet-gateway1 /subscriptions/e7e33b39-fe28-4822-b65c-a4db8bbff7cb/resourceGroups/TestRG5/providers/Microsoft.Network/virtualNetworkGateways/VNet5GW \
   -l chinaeast2 \
   --shared-key "eeffgg" \
   --vnet-gateway2 /subscriptions/d6ff83d6-713d-41f6-a025-5eb76334fda9/resourceGroups/TestRG1/providers/Microsoft.Network/virtualNetworkGateways/VNet1GW

Verify the connections

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 az network vpn-connection show command. In the example, '--name' refers to the name of the connection that you want to test. When the connection is in the process of being established, its connection status shows 'Connecting'. Once the connection is established, the status changes to 'Connected'. Modify the following example with the values for your environment.

az network vpn-connection show --name <connection-name> --resource-group <resource-group-name>

VNet-to-VNet FAQ

See the VPN Gateway FAQ for VNet-to-VNet frequently asked questions.

Next steps

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