DirectAccess and Communications Server 2007 R2

The direct scoop about DirectAccess and Office Communications Server 2007 R2-read on to find out.

Author: Rob Pittfield

Publication date: March 2010

Product version: Office Communications Server 2007 R2

We’ve recently seen some questions on Twitter and a few other sources regarding support for Office Communications Server 2007 R2 working via DirectAccess. (For details about DirectAccess, see DirectAccess works only with IPv6. For details, see the section "Overview of Direct Access" in the Windows Server 2008 R2 Technical Overview at Communications Server 2007 R2 and Communicator 2007 R2 support only IPv4. For details, see Networking Protocols Support at

For Communications Server 2007 R2, we generally recommend the use of an Access Edge Server for remote users. We use TLS and SRTP for encryption of the SIP and media traffic respectively.

Microsoft recommends using an Access Edge Server instead of DirectAccess or other remote VPN-like technologies because of the network traffic overhead and processing latency that these technologies create. Audio/video and other media traffic are incredibly sensitive to any latency, and adding additional encryption (IPSec in DirectAccess) can cause delays in sending and receiving media traffic. There can also be delays due to the additional processing on the client side that is required for encrypting and decrypting the traffic that travels through the DirectAccess network path. For the best possible performance, we recommend that you add as little additional overhead as possible.

For details about IPSec and Communications Server 2007 R2, see the Microsoft Office Communications Server 2007 R2 Troubleshooting guide at

If you are still interested in DirectAccess and Communications Server 2007 R2, see UAG and DirectAccess at This information explains how to extend the DirectAccess functionality to allow the use of IPv4 applications.

To learn more, check out the following:

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