Create a cross-subscription internal load balancer
In this how-to guide, you learn how to create a cross-subscription internal load balancer by connecting a virtual network in a subscription to a load balancer in a different subscription.
A cross-subscription internal load balancer (ILB) can reference a virtual network that resides in a different subscription other than the load balancers. This feature allows you to deploy a load balancer in one subscription and reference a virtual network in another subscription.
Prerequisites
- Two Azure subscriptions.
- An Azure account with active subscriptions. Create an account for free
- An existing Virtual Network. deployed in one of the subscriptions. For this example, the virtual network is in Azure Subscription A.
- Azure PowerShell installed locally or Azure Cloud Shell.
If you choose to install and use PowerShell locally, this article requires the Azure PowerShell module version 5.4.1 or later. Run Get-Module -ListAvailable Az
to find the installed version. If you need to upgrade, see Install Azure PowerShell module. If you're running PowerShell locally, you also need to run Connect-AzAccount
to create a connection with Azure.
Important
All of the code samples will use example names and placeholders. Be sure to replace these with the values from your environment.
The values needing replacement will be enclosed in angle brackets, like this: <example value>
.
Sign in to Azure
With Azure PowerShell, you sign into Azure with Connect-AzAccount
, and change your subscription context with Set-AzContext
to Azure Subscription A. Then get the virtual network information with Get-AzVirtualNetwork
. You need the Azure subscription ID, resource group name, and virtual network name from your environment.
# Sign in to Azure
Connect-AzAccount
# Set the subscription context to Azure Subscription A
Set-AzContext -Subscription '<Azure Subscription A>'
# Get the Virtual Network information with Get-AzVirtualNetwork
$net = @{
Name = '<vnet name>'
ResourceGroupName = '<Resource Group Subscription A>'
}
$vnet = Get-AzVirtualNetwork @net
Create a resource group
In this section, you create a resource group in Azure Subscription B. This resource group is for all of your resources associate with your load balancer.
With Azure PowerShell, you switch the subscription context with Set-AzContext
and create a resource group with New-AzResourceGroup
.
# Set the subscription context to Azure Subscription B
Set-AzContext -Subscription '<Azure Subscription B>'
# Create a resource group
$rg = @{
Name = 'myResourceGroupLB'
Location = 'westus'
}
New-AzResourceGroup @rg
Note
When create the resource group for your load balancer, use the same Azure region as the virtual network in Azure Subscription A.
Create a load balancer
In this section, you create a load balancer in Azure Subscription B that is connected to a virtual network in Azure Subscription A. You create a load balancer with a frontend IP address.
With Azure PowerShell, you'll:
- A load balancer with
New-AzLoadBalancer
- Create a public IP address with
New-AzPublicIpAddress
- Add a frontend IP configuration with
Add-AzLoadBalancerFrontendIpConfig
- Create a backend address pool with
New-AzLoadBalancerBackendAddressPool
.
# Create a load balancer
$tags = @{
'IsRemoteFrontend'= 'true'
}
$loadbalancer = @{
ResourceGroupName = 'myResourceGroupLB'
Name = 'myLoadBalancer'
Location = 'westus'
Sku = 'Standard'
Tags = $tags
}
$LB = New-AzLoadBalancer @loadbalancer
$LBinfo = @{
ResourceGroupName = 'myResourceGroupLB'
Name = 'myLoadBalancer'
}
## Add load balancer frontend configuration and apply to load balancer.
$fip = @{
Name = 'myFrontEnd'
SubnetId = $vnet.subnets[0].Id
}
$LB = $LB | Add-AzLoadBalancerFrontendIpConfig @fip
$LB = $LB | Set-AzLoadBalancer
## Create backend address pool configuration and place in variable.
$be = @{
ResourceGroupName= "myResourceGroupLB"
Name= "myBackEndPool"
LoadBalancerName= "myLoadBalancer"
VirtualNetwork=$vnet.id
SyncMode= "Automatic"
}
# Create the backend pool
$backend = New-AzLoadBalancerBackendAddressPool @be
$LB = Get-AzLoadBalancer @LBinfo
Create a health probe and load balancer rule
Create a health probe that determines the health of the backend VM instances and a load balancer rule that defines the frontend IP configuration for the incoming traffic, the backend IP pool to receive the traffic, and the required source and destination port.
With Azure PowerShell, create a health probe with Add-AzLoadBalancerProbeConfig
that determines the health of the backend VM instances. Then create a load balancer rule with Add-AzLoadBalancerRuleConfig
that defines the frontend IP configuration for the incoming traffic, the backend IP pool to receive the traffic, and the required source and destination port.
## Create the health probe and place in variable. ##
$probe = @{
Name = 'myHealthProbe2'
Protocol = 'tcp'
Port = '80'
IntervalInSeconds = '360'
ProbeCount = '5'
}
## Create the load balancer rule and place in variable. ##
$lbrule = @{
Name = 'myHTTPRule2'
Protocol = 'tcp'
FrontendPort = '80'
BackendPort = '80'
IdleTimeoutInMinutes = '15'
FrontendIpConfiguration = $LB.FrontendIpConfigurations[0]
BackendAddressPool = $backend
}
## Set the load balancer resource. ##
$LB | Add-AzLoadBalancerProbeConfig @probe
$LB | Add-AzLoadBalancerRuleConfig @lbrule
$LB | Set-AzLoadBalancer
Attach network interface cards to the load balancer
In this section, you attach the network interface card (NIC) in Azure Subscription A to the load balancer in Azure Subscription B. You create a network interface with New-AzNetworkInterface
and then create an IP configuration for the network interface card with New-AzNetworkInterfaceIpConfig
.
Note
The network interface card (NIC) must be in the same VNet as the load balancer’s backend pool.
# Set the subscription context to **Azure Subscription A**
Set-AzContext -Subscription 'Sub A'
# Create a network interface card
$IP1 = @{
Name = 'MyIpConfig'
subnetID= $vnet.subnets[0].Id
PrivateIpAddressVersion = 'IPv4'
-LoadBalancerBackendAddressPool $lb-be-info
}
$IP1Config = New-AzNetworkInterfaceIpConfig @IP1 -Primary
$nic = @{
Name = 'MyNic'
ResourceGroupName = '<Resoure Group Subscription A>'
Location = 'eastus'
IpConfiguration = $IP1Config
}
New-AzNetworkInterface @nic
Clean up resources
When no longer needed, you can use the Remove-AzResourceGroup command to remove the resource group you created along with the load balancer, and the remaining resources.
Remove-AzResourceGroup -Name 'myResourceGroupLB'