When using infrastructure as a service in Microsoft Azure you could earlier only have one virtual network, which would be like it’s own little isolated island. A while back Microsoft enabled for its customers to connect multiple virtual networks together, both in the same datacenter, same region, cross region and cross subscription. This enables a whole lot of new scenarios, for example building your own global datacenter on top of Azure infrastructure.
So how do you go about doing it? Well, you need to start with planning. I know it’s boring but if you don’t you could end up having to tear everything down just to rebuild it, doesn’t sound too much fun either.
What you need before starting:
An ip-plan
A VPN device with a public IPv4 address (not necessary, but will let you enable a hybrid cloud scenario)
PowerShell cmdlets for Azure installed and configured
My ip-plan looks like this:
Local network name |
Subnet |
HomeNet |
10.0.0.0/24 |
AzureNet-Local |
10.0.1.0/24 |
USNet-Local |
10.0.2.0/24 |
JNNet-Local |
10.0.3.0/24 |
Of the networks above HomeNet is my physical network location. The other three networks exists only in Azure. What you must make sure when you plan is that no range overlap anywhere, no matter if it’s in Azure or at any physical locations.
Once you’ve planned that I have a separate table for my topology so I know which networks to connect. When starting off you won’t know your gateway ip, so don’t worry.
Virtual Network |
Subnet |
Gateway |
Local network |
AzureNet |
10.0.1.0/24 |
137.117.227.xxx |
HomeNet 10.0.0.0/24 |
USNet |
10.0.2.0/24 |
168.61.160.xxx |
JNNet 10.0.3.0/24 |
JNNet |
10.0.3.0/24 |
23.97.77.xxx |
USNet 10.0.2.0/24 |
Getting started
Starting off I already have one network called AzureNet (10.0.1.0/24) which is connected to my physical network Homenet (10.0.0.0/24). You can follow this guide even if you don’t have that, just repeat the process.

Let’s create a new virtual network first
In the portal, click New -> Network Services -> Virtual Network -> Custom Create
Name your network and select a location. South Central is in Brazil so I’ve named my network BRnet.

Select (or enter) your DNS servers ip and name for local name resolution.

Enter your address space. Make sure there’s no overlapping subnets anywhere. Very important!

Repeat this process for all the virtual networks you need.
When all your virtual networks are created it’ll look like this. Note the different locations in my setup, placing my networks in Japan, USA and Amsterdam.

Local networks
When the virtual networks are done we’ll create local networks of the virtual networks. This is because to be able to connect the networks they need to be defined as “local” in Azure.

Name your network, and specify 1.2.3.4 as VPN device address.

Specify the address space that you’ve planned beforehand.

Repeat this for each virtual network, re-defining it as local.
When you’re done it’ll look like this

Switch back to your virtual networks in the portal and go into the configure tab. Check the “connect to the local network”-box and select the corresponding “local network” that you planned before. Click save at the bottom. Repeat this process for each virtual network connecting it to the designated “local” network.

Next step is to create the dynamic gateway. You get the message “The gateway was not created” in the portal. At the bottom click “Create gateway” and select “Dynamic”. Do this for all your virtual networks. It’ll take 10-25 minutes to finish for each gateway. Coffee time!

When they’re all done, note the gateway ip address in your table for all your networks/gateways.

Edit your local networks and add the gateway ip address for each network.Click on the network, click Edit and enter your gateway ip.

When all virtual networks and their corresponding local networks are created it’s XML-time. Get some more coffee!
Click the Export-button and save the file.
Open it in Notepad / Notepad++ (if you haven’t tried it you must)
In the XML you’ll find the section <LocalNetworkSites> which contains all the networks defined as local.
<LocalNetworkSites>
<LocalNetworkSite name="AzureNet-Local">
<AddressSpace>
<AddressPrefix>10.0.1.0/24</AddressPrefix>
</AddressSpace>
<VPNGatewayAddress>137.117.227.238</VPNGatewayAddress>
</LocalNetworkSite>
<LocalNetworkSite name="HomeNet">
<AddressSpace>
<AddressPrefix>10.0.0.0/24</AddressPrefix>
</AddressSpace>
<VPNGatewayAddress>178.78.193.167</VPNGatewayAddress>
</LocalNetworkSite>
<LocalNetworkSite name="JNNet-Local">
<AddressSpace>
<AddressPrefix>10.0.3.0/24</AddressPrefix>
</AddressSpace>
<VPNGatewayAddress>23.97.65.15</VPNGatewayAddress>
</LocalNetworkSite>
<LocalNetworkSite name="USNet-Local">
<AddressSpace>
<AddressPrefix>10.0.2.0/24</AddressPrefix>
</AddressSpace>
<VPNGatewayAddress>168.61.160.90</VPNGatewayAddress>
</LocalNetworkSite>
</LocalNetworkSites>
If you look further down in the XML you’ll find the section <VirtualNetworkSites>. This contains subsections for each virtual network site <VirtualNetworkSite>, and in that section in turn you’ll see where to define the connections to each network.
<ConnectionsToLocalNetwork>
<LocalNetworkSiteRef name="HomeNet">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
<LocalNetworkSiteRef name="JNNet-Local">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
<LocalNetworkSiteRef name="USNet-Local">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
</ConnectionsToLocalNetwork>
So for each virtual network you’ll need to copy and paste each local network as above.
If you look at my complete XML I’ve marked those sections in red.
<NetworkConfiguration xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/ServiceHosting/2011/07/NetworkConfiguration">
<VirtualNetworkConfiguration>
<Dns>
<DnsServers>
<DnsServer name="cmdc01" IPAddress="192.168.1.4" />
<DnsServer name="cmdemodc01" IPAddress="192.168.1.10" />
<DnsServer name="DC01" IPAddress="10.0.0.10" />
<DnsServer name="DC02" IPAddress="10.0.1.4" />
</DnsServers>
</Dns>
<LocalNetworkSites>
<LocalNetworkSite name="AzureNet-Local">
<AddressSpace>
<AddressPrefix>10.0.1.0/24</AddressPrefix>
</AddressSpace>
<VPNGatewayAddress>137.117.227.238</VPNGatewayAddress>
</LocalNetworkSite>
<LocalNetworkSite name="HomeNet">
<AddressSpace>
<AddressPrefix>10.0.0.0/24</AddressPrefix>
</AddressSpace>
<VPNGatewayAddress>178.78.193.167</VPNGatewayAddress>
</LocalNetworkSite>
<LocalNetworkSite name="JNNet-Local">
<AddressSpace>
<AddressPrefix>10.0.3.0/24</AddressPrefix>
</AddressSpace>
<VPNGatewayAddress>23.97.65.15</VPNGatewayAddress>
</LocalNetworkSite>
<LocalNetworkSite name="USNet-Local">
<AddressSpace>
<AddressPrefix>10.0.2.0/24</AddressPrefix>
</AddressSpace>
<VPNGatewayAddress>168.61.160.90</VPNGatewayAddress>
</LocalNetworkSite>
</LocalNetworkSites>
<VirtualNetworkSites>
<VirtualNetworkSite name="AzureNet" AffinityGroup="AzureNet">
<AddressSpace>
<AddressPrefix>10.0.1.0/24</AddressPrefix>
</AddressSpace>
<Subnets>
<Subnet name="Subnet-1">
<AddressPrefix>10.0.1.0/27</AddressPrefix>
</Subnet>
<Subnet name="Contoso-Subnet">
<AddressPrefix>10.0.1.200/27</AddressPrefix>
</Subnet>
<Subnet name="GatewaySubnet">
<AddressPrefix>10.0.1.32/29</AddressPrefix>
</Subnet>
</Subnets>
<DnsServersRef>
<DnsServerRef name="DC01" />
<DnsServerRef name="DC02" />
</DnsServersRef>
<Gateway>
<ConnectionsToLocalNetwork>
<LocalNetworkSiteRef name="HomeNet">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
<LocalNetworkSiteRef name="JNNet-Local">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
<LocalNetworkSiteRef name="USNet-Local">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
</ConnectionsToLocalNetwork>
</Gateway>
</VirtualNetworkSite>
<VirtualNetworkSite name="CMDemo" AffinityGroup="CMDemo-AFG">
<AddressSpace>
<AddressPrefix>192.168.1.0/24</AddressPrefix>
</AddressSpace>
<Subnets>
<Subnet name="Infra">
<AddressPrefix>192.168.1.0/26</AddressPrefix>
</Subnet>
<Subnet name="Mgmt">
<AddressPrefix>192.168.1.64/26</AddressPrefix>
</Subnet>
<Subnet name="Clients">
<AddressPrefix>192.168.1.128/27</AddressPrefix>
</Subnet>
</Subnets>
<DnsServersRef>
<DnsServerRef name="cmdc01" />
</DnsServersRef>
</VirtualNetworkSite>
<VirtualNetworkSite name="JnNet" AffinityGroup="JnNet-AFG">
<AddressSpace>
<AddressPrefix>10.0.3.0/24</AddressPrefix>
</AddressSpace>
<Subnets>
<Subnet name="Subnet-1">
<AddressPrefix>10.0.3.0/28</AddressPrefix>
</Subnet>
<Subnet name="Subnet-2">
<AddressPrefix>10.0.3.24/29</AddressPrefix>
</Subnet>
<Subnet name="Subnet-3">
<AddressPrefix>10.0.3.32/27</AddressPrefix>
</Subnet>
<Subnet name="GatewaySubnet">
<AddressPrefix>10.0.3.16/29</AddressPrefix>
</Subnet>
</Subnets>
<DnsServersRef>
<DnsServerRef name="DC01" />
</DnsServersRef>
<Gateway>
<ConnectionsToLocalNetwork>
<LocalNetworkSiteRef name="USNet-Local">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
<LocalNetworkSiteRef name="AzureNet-Local">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
</ConnectionsToLocalNetwork>
</Gateway>
</VirtualNetworkSite>
<VirtualNetworkSite name="UsNet" AffinityGroup="CentralUS-AG">
<AddressSpace>
<AddressPrefix>10.0.2.0/24</AddressPrefix>
</AddressSpace>
<Subnets>
<Subnet name="Subnet-1">
<AddressPrefix>10.0.2.0/28</AddressPrefix>
</Subnet>
<Subnet name="Subnet-2">
<AddressPrefix>10.0.2.24/29</AddressPrefix>
</Subnet>
<Subnet name="GatewaySubnet">
<AddressPrefix>10.0.2.16/29</AddressPrefix>
</Subnet>
</Subnets>
<DnsServersRef>
<DnsServerRef name="DC02" />
</DnsServersRef>
<Gateway>
<ConnectionsToLocalNetwork>
<LocalNetworkSiteRef name="JNNet-Local">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
<LocalNetworkSiteRef name="AzureNet-Local">
<Connection type="IPsec" />
</LocalNetworkSiteRef>
</ConnectionsToLocalNetwork>
</Gateway>
</VirtualNetworkSite>
</VirtualNetworkSites>
</VirtualNetworkConfiguration>
</NetworkConfiguration>
Note that for each network there is a corresponding section of <ConnectionsToLocalNetwork>.
When you’re done save the file and then it’s time to import it!

Wait for your networks to configure. Then it’s PowerShell-time!
Fire up PowerShell with the Azure cmdlets.
Run the cmdlet “Set-AzureVNetGatewayKey -VNetName AzureNet -LocalNetworkSiteName JNNet-Local -SharedKey a1b2c3d4” for each virtual network setting the key for each local network.
So I’d run:
Set-AzureVNetGatewayKey -VNetName AzureNet -LocalNetworkSiteName JNNet-Local -SharedKey a1b2c3d4
Set-AzureVNetGatewayKey -VNetName AzureNet -LocalNetworkSiteName USNet-Local -SharedKey a1b2c3d4
Set-AzureVNetGatewayKey -VNetName AzureNet -LocalNetworkSiteName HomeNet -SharedKey a1b2c3d4
Set-AzureVNetGatewayKey -VNetName JNNet -LocalNetworkSiteName USNet-Local -SharedKey a1b2c3d4
Set-AzureVNetGatewayKey -VNetName JNNet -LocalNetworkSiteName AzureNet-Local -SharedKey a1b2c3d4
And so on, switching the virtual network and the local network according to your topology.
When you’re done with that it’s time to connect your networks:
Set-AzureVNetGateway -VNetName AzureNet -LocalNetworkSiteName JNNet -Connect
And as before, substitute the vnetnames and local network names.
Once done it’ll (hopefully) look like this:

How did you do? Let me know in the comments!