If you work for a Cloud Service Provider or an Enterprise that needs to provide gateway and routing services to multiple tenants, whether they are your customers or they are departments in your organization, you know that without a multitenant gateway, each tenant needs a dedicated virtual machine (VM) gateway/router. And typically for failover it's wise to deploy two gateways, so you're using two VMs per tenant as gateways.

This technical solution is extremely costly as you add tenants - and therefore gateway VMs - to your configuration.

Deploying the Windows Server 2012 R2 RRAS Multitenant Gateway vastly reduces the cost and complexity of operating a multitenant environment by reducing administrative costs, complexity, and the number of gateway VMs that you need to deploy to support multiple tenants.

The RRAS Multitenant Gateway eliminates the need to deploy two gateway VMs per tenant, because it supports up to 200 tenants. These tenants can be deployed on VM networks using either Hyper-V Network Virtualization or virtual Local Area Networks (VLANs).

As for throughput, when you deploy the gateway with site-to-site VPN connections in a 2 VM failover configuration, the RRAS Multitenant Gateway can handle combined network traffic of 1.5 GB per second.

When you compare the cost of the traditional gateway routing method with two VMs per tenant to using the RRAS Multitenant Gateway instead, the advantages of using the multitenant gateway become clear.

Assuming an hourly cost per gateway VM pair of twelve cents, and a cost per year ($0.12*24*365) of $1,051.20 for one pair of VMs used as a gateway, it becomes clear that as you add tenants using the traditional method, the cost increases rapidly, because you must add two VMs per tenant.

With just 15 tenants, the traditional method using 30 VMs costs $15,750 per year. 

The cost of using the RRAS Multitenant Gateway with 15 tenants is the same as the cost with one tenant - just $1,051.20, providing a cost savings of $14,698.80 per year.

For more information about the RRAS Multitenant Gateway, see http://gallery.technet.microsoft.com/Windows-Server-2012-R2-37eb8e17 (Word format in TechNet Gallery) and http://technet.microsoft.com/en-us/library/dn641937.aspx (HTML format in the TechNet Library).