DirectAccess in Windows Server 2012 R2 supports many different deployment configurations. It can be deployed with a single server, multiple servers in a single location, multiple servers in multiple locations, edge facing, in a perimeter or DMZ network, etc.
There are a number of important DirectAccess settings that are global in scope and apply to all DirectAccess clients, such as certificate authentication, force tunneling, one-time password, and many more. For example, if you configure DirectAccess to use Kerberos Proxy instead of certificates for authentication, Windows 7 clients are not supported. In this scenario it is advantageous to have a second parallel DirectAccess deployment configured specifically for Windows 7 clients. This allows Windows 8 clients to take advantage of the performance gains afforded by Kerberos Proxy, while at the same time providing an avenue of support for Windows 7 clients.
To the surprise of many, it is indeed possible to deploy DirectAccess more than once in an organization. I’ve been helping customers deploy DirectAccess for nearly five years now, and I’ve done this on more than a few occasions. In fact, there are some additional important uses cases that having more than one DirectAccess deployment can address.
Common Use Cases
QA and Testing – Having a separate DirectAccess deployment to perform testing and quality assurance can be quite helpful. Here you can validate configuration changes and verify updates without potential negative impact on the production deployment.
Delegated Administration – DirectAccess provides support for geographic redundancy, allowing administrators to create DirectAccess entry points in many different locations. DirectAccess in Windows Server 2012 R2 lacks support for delegated administration though, and in some cases it may make more sense to have multiple separate deployments as opposed to a single, multisite deployment. For example, many organizations are divided in to different business units internally and may operate autonomously. They may also have different configuration requirements, which can be better addressed using individual DirectAccess implementations.
Migration – If you have currently deployed DirectAccess using Windows Server 2008 R2 with or without Forefront UAG 2010, migrating to Windows Server 2012 R2 can be challenging because a direct, in-place upgrade is not supported. You can, however, deploy DirectAccess using Windows Server 2012 R2 in parallel to your existing deployment and simply migrate users to the new solution by moving the DirectAccess client computer accounts to a new security group assigned to the new deployment.
Major Configuration Changes – This strategy is also useful for scenarios where implementing changes to the DirectAccess configuration would be disruptive for remote users. For example, changing from a single site to a multisite configuration would typically require that all DirectAccess clients be on the LAN or connect remotely out-of-band to receive group policy settings changes after multisite is first configured. In addition, parallel deployments can significantly ease the pain of transitioning to a new root CA if required.
Unique Client Requirements – Having a separate deployment may be required to take advantage of the unique capabilities of each client operating system. For example, Windows 10 clients do not support Microsoft Network Access Protection (NAP) integration. NAP is a global setting in DirectAccess and applies to all clients. If you still require NAP integration and endpoint validation using NAP for Windows 7 and Windows 8.x, another DirectAccess deployment will be required to support Windows 10 clients.
To support multiple Windows Server 2012 R2 DirectAccess deployments in the same organization, the following is required:
Unique IP Addresses – It probably goes without saying, but each DirectAccess deployment must have unique internal and external IPv4 addresses.
Distinct Public Hostname – The public hostname used for each deployment must also be unique. Multi-SAN certificates have limited support for DirectAccess IP-HTTPS (public hostname must be the first entry in the list), so consider using a wildcard certificate or obtain certificates individually for each deployment.
Group Policy Objects – You must use unique Active Directory Group Policy Objects (GPOs) to support multiple DirectAccess deployments in a single organization. You have the option to specify a unique GPO when you configure DirectAccess for the first time by clicking the Change link next to GPO Settings on the Remote Access Review screen.
Enter a distinct name for both the client and server GPOs. Click Ok and then click Apply to apply the DirectAccess settings for this deployment.
Windows 7 DirectAccess Connectivity Assistant (DCA) GPOs – If the DirectAccess Connectivity Assistant (DCA) v2.0 has been deployed for Windows 7 clients, separate GPOs containing the DCA client settings for each individual deployment will have to be configured. Each DirectAccess deployment will have unique Dynamic Tunnel Endpoint (DTE) IPv6 addresses which are used by the DCA to confirm corporate network connectivity. The rest of the DCA settings can be the same, if desired.
The rest of the supporting infrastructure (AD DS, PKI, NLS, etc.) can be shared between the individual DirectAccess deployments without issue. Once you’ve deployed multiple DirectAccess deployments, make sure that DirectAccess clients DO NOT belong to more than one DirectAccess client security group to prevent connectivity issues.
DirectAccess with Windows Server 2012 R2 supports many different deployment models. For a given DirectAccess deployment model, some settings are global in scope and may not provide the flexibility required by some organizations. To address these challenges, consider a parallel deployment of DirectAccess. This will enable you to take advantage of the unique capabilities of each client operating system, or allow you to meet the often disparate configuration requirements that a single deployment cannot support.