IPv6 Recommend Reading for DirectAccess Administrators

IPv6 Recommended ReadingDirectAccess uses IPv6 exclusively for communication between the DirectAccess client and server. The DNS64 and NAT64 services running on the DirectAccess server allow the client to connect to IPv4-only resources on the corporate network. Although no IPv6 knowledge is necessary to implement DirectAccess, it is most certainly required to support it going forward. A fundamental understanding of IPv6 is vital when it comes to troubleshooting DirectAccess connectivity issues, so learning IPv6 is critically important for the DirectAccess administrator.

To help you learn more about IPv6, here are three essential resources I think you will find helpful!

Understanding IPv6 Practical IPv6 for Windows Administrators IPv6 Address Planning

Understanding IPv6
(Joe Davies) – This is an excellent reference for the IPv6 protocol and should be on every DirectAccess administrator’s desk. This book provides detailed documentation and explanations for the IPv6 protocol including IPv6 transition protocols, which are commonly used with DirectAccess.

Practical IPv6 for Windows Administrators (Ed Horley) – Another essential title for learning IPv6. This book focuses on the use of IPv6 for a variety of popular Windows workloads, including DirectAccess.

IPv6 Address Planning (Tom Coffeen) – This book is an optional read for DirectAccess administrators, but a recommended one still. There is no IPv6 address planning required to implement DirectAccess, as most commonly IPv6 addressing happens automatically. However, this book will help you understand IPv6 subnetting, which can be helpful for fully understanding DirectAccess.

If you prefer video training, be sure to check out this great course on Pluralsight from Ed Horley. Don’t be afraid of IPv6. Embrace it! Start learning IPv6 today!

DirectAccess SQL Server High CPU Usage

UPDATE – March 14, 2016: Microsoft has published official guidance for implementing the changes outlined in this article using PowerShell. Details here.


DirectAccess SQL Server High CPU UsageRADIUS and Inbox accounting are the two supported logging options for DirectAccess in Windows Server 2012 R2. When Inbox accounting is selected, a Windows Internal Database (WID) is provisioned. Part of the base operating system, WID is functionally similar to SQL Server Express.

SQL Server Utilization Issues

Over the last few months I’ve had a few customers reach out to me with a peculiar performance issue. For customers with very busy DirectAccess servers, where those servers have also been configured to use Inbox accounting, they’ve reported observing unusually high CPU utilization on the sqlservr.exe process.

DirectAccess SQL Server High CPU Usage
Image courtesy Thomas Vuylsteke. Used with permission. – setspn.blogspot.com

As luck would have it, Thomas Vuylsteke, a Microsoft Platforms Premiere Field Engineer (PFE), had already identified the issue and a workaround. Thomas traced the source of high CPU utilization on the sqlservr.exe process to a missing index on a session state table in the DirectAccess accounting database. If you are interested in learning how he performed the troubleshooting to identify and resolve this problem, you can read his entire blog post here.


To resolve this issue, create an index on the Session Table in the DirectAccess database. Changes to WID must be made locally, as it is not remotely manageable. WID does not include a management interface, which means the SQL Server management tools would normally have to be installed. However, I’m not a fan of installing any extraneous software on the DirectAccess server, so thankfully one of the readers of Thomas’ excellent article on this subject, Fredrik Elmqvist, provided a very helpful alternative. Fredrik suggesting using the HeidiSQL tool, for which a fully portable version exists. This allows for changes to be made to the WID database without having to install any additional software.

Changes to WID

Begin by downloading the portable version of HeidiSQL here. Next, log on to the DirectAccess server as the local administrator. It is crucial that you must be the local administrator, not just a local or domain user with local administrator privileges. Extract the files from the download and copy them to the DirectAccess server, then follow these steps:

  1. Double-click heideisql.exe to launch the management tool.
  2. Click on New and then for the Network Type select Microsoft SQL Server (named pipe).
  3. For the Hostname / IP: enter \\.\pipe\MICROSOFT##WID\tsql\query.
  4. Select the option to Use Windows Authentication.
  5. Click Open to continue.DirectAccess SQL Server High CPU Usage
  6. Click the Query tab in the center console window and enter the following commands:
    Use RaAcctDb
    Create NonClustered Index IdxSessionTblSessionState on SessionTable (SessionState,ConnectionID)
  7. Click the Run icon in the tool bar or press F9. This will execute the code and create the missing index on the Session Table in the DirectAccess database.DirectAccess SQL Server High CPU Usage
  8. Confirm the index was created by clearing the previous query or creating a new query and then entering the following commands:
    select * from sys.indexes
    where name like ‘idx%’
    order by name ascDirectAccess SQL Server High CPU Usage

Once the change has been made, sqlservr.exe CPU utilization should return to normal. If you have multiple DirectAccess servers configured in a load-balanced array or in a multisite configuration, be sure to repeat these steps on each DirectAccess server in the organization.

%d bloggers like this: