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Enabling DSCP Marking

Communications Server 2007 R2

Topic Last Modified: 2009-10-15

The procedures in this section describe how to configure components to enable Differentiated Services Code Point (DSCP) marking for Office Communications Server 2007 R2. This includes:

  • Enabling QoS.
  • Installing the QoS Packet Scheduler on computers.
  • Verifying Group Policy settings on computers.
Dd441192.note(en-us,office.13).gifNote:
DSCP marking is generally enabled at the time of deployment in a QoS environment. If you add Differentiated Services capability to the Enterprise network after deploying Office Communications Server 2007 R2, you can configure Office Communications Server media traffic to take advantage of this new capability at that time.

To enable DSCP marking for Office Communications Server 2007 R2, you must enable QoS on the following components:

  • Media servers, which are configured via in-band provisioning. These servers include the following:
    • A/V Conferencing Server.
    • Front End Servers or Standard Edition servers running Conferencing Attendant or Response Group Service.
    • Unified Communications Managed API server.
  • Mediation Servers, which are configured using WMI settings.
  • Office Communicator 2007 R2 clients, including Communicator 2007 R2 Attendant, which are configured by creating a registry key.
  • Office Communicator 2007 R2 Phone Edition clients, which are configured using Office Communicator property settings via in-band provisioning.
Dd441192.note(en-us,office.13).gifNote:
After completing these procedures for enabling QoS, you must verify that the QoS Packet Scheduler is running and the Group Policy settings are correct on each client and server, using the procedures provided later in this topic.
To enable QoS on media servers
  1. Log on to the Office Communications Server 2007 R2 server as a member of the RTCUniversalServerAdmins group or an account with equivalent user rights.

  2. Click Start, and then click Run.

  3. In the Open box, type wbemtest, and then click OK.

  4. In the Windows Management Instrumentation Tester dialog box, click Connect.

  5. In the Connect dialog box, in Namespace, specify root\cimv2, and then click Connect.

  6. In the Windows Management Instrumentation Tester dialog box, click Query.

  7. In the Query dialog box, in Enter Query, do one of the following:

    • For Standard Edition Server, specify select * from MSFT_SIPPoolConfigSetting where backend="(local)\\rtc", and then click Apply.
    • For an Enterprise pool, specify select * from MSFT_SIPPoolConfigSetting where backend=”<SQL Server>\\<database instance>", and then click Apply. (RTC is the default database instance name.)
  8. In the Query Result dialog box, double-click the MSFT_SIPPoolConfigSetting instance (which should be the only instance available on this media server).

  9. In the Object editor dialog box, in Properties, click ServerQoSEnabled, and then click Edit Property.

  10. In the Property Editor dialog box, in Value, specify True, and then click Save Property.

  11. Repeat the preceding steps for each Office Communications Server 2007 R2 server that is in a different pool in your environment, including each A/V Conferencing Server, server running the Response Group Service, and Unified Communications Managed API server. Media servers within the same pool will share the settings after they have been set on the Office Communications Server 2007 R2 server for that pool. Mediation Server does not join a pool, so the settings need to be run separately as a WMI setting on that platform.

Dd441192.important(en-us,office.13).gifImportant:
After completing this procedure, ensure that the QoS Packet Scheduler is installed and that Windows Group Policy settings are appropriately configured on each computer.
Policies are propagated via in-band provisioning, so for the policies to become effective, you must do one of the following:
  • Restart the service.
  • Log off of the A/V Conferencing Server, the server running the Response Group Service, and the Unified Communications Managed API server, and then log on again.
  • Wait for an in-band provisioning update (a few minutes) for the policies to become effective.
To enable QoS on Mediation Servers
  1. Log on to the Mediation Server as a member of the RTCUniversalServerAdmins group or an account with equivalent user rights.

  2. Click Start, and then click Run.

  3. In the Open box, type wbemtest, and then click OK.

  4. In the Windows Management Instrumentation Tester dialog box, click Connect.

  5. In the Connect dialog box, in Namespace, type root\cimv2, and then click Connect. and then click Enum Classes.

  6. In the Windows Management Instrumentation Tester dialog box, click Enum Classes.

  7. In the Superclass info dialog box, leave the name blank, and then click OK.

  8. In the Query Result dialog box, double-click the class name MSFT_SIPMediationServerConfigSetting.

  9. In the Object editor for MSFT_SIPMediationServerConfigSetting dialog box, click Instances.

  10. In the Query Result dialog box, double-click the MSFT_SIPMediationServerConfigSettingInstanceID instance (which should be the only instance available on this Mediation Server).

  11. In the Object editor dialog box, in Properties, click QoSEnabled, and then click Edit Property.

  12. In the Property Editor dialog box, in Value, specify True, and then click Save Property.

  13. In the ObjectEditor dialog box, click Save Object.

  14. Restart the Mediation Server service.

  15. Repeat the preceding steps on each Office Communications Server 2007 R2 Mediation Server.

Dd441192.note(en-us,office.13).gifNote:
This procedure only enables DSCP in the WMI settings of the Mediation Server. After completing this procedure, ensure that the QoS Packet Scheduler is installed and that Group Policy settings are appropriately configured on each computer, and then restart the services.
To enable QoS on Communicator clients
  1. Log on to the desktop, laptop, or Attendant client as a member of the Administrator group or an account with equivalent user rights.

  2. Open the Registry Editor.

  3. Create the following registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\RTC\Transport
    "QoSEnabled"=dword:00000001

  4. Restart the Office Communicator 2007 R2 service.

  5. Repeat the preceding steps on each desktop, laptop, and attendant client.

Dd441192.note(en-us,office.13).gifNote:
This procedure only enables DSCP on the client. After completing this procedure, ensure that the QoS Packet Scheduler is installed and that Group Policy settings are appropriately configured on each computer, and then restart the services.
To enable QoS on Office Communications Server 2007 R2 Phone Edition
  1. Log on to a server running Office Communications Server 2007 R2 or a computer on which Office Communications Server 2007 R2 administrative tools are installed, as a member of the RTCUniversalServerAdmins group or an account with equivalent user rights.

  2. Open the Office Communications Server 2007 R2 snap-in.

  3. In the console tree, expand the forest node, and then do one of the following:

    • For an Enterprise pool, expand Enterprise pools, expand the pool, right-click Front Ends, and then click Properties.
    • For a Standard Edition server, expand Standard Edition servers, right-click the pool, click Properties, and then click Front End Properties.
  4. In the Front End Properties dialog box, on the Voice tab, next to Advanced options, click Configure.

  5. Verify the IP QoS value (default is 40) and the 802.1p Voice value (default is 0) For optimum quality of service, we recommend that you use the default values. To turn off DSCP marking, set both values to 0.

  6. For the new settings to take effect, restart the device or log off and log on to the device.

  7. Click OK, twice.

The QoS Packet Scheduler needs to be active and configured properly in order for Office Communications Server 2007 R2 servers and clients in order to make the marking active. For details about the QoS Packet Scheduler service, see Voice Quality of Service (QoS) in the Technical Reference for Office Communications Server 2007 R2 in the Reference documentation.

By default, the QoS Packet Scheduler is installed on computers running Windows XP, Windows Vista, and Windows 2008. By default, the QoS Packet Scheduler is not installed on Windows Server 2003. Use the following procedures to determine whether the QoS Packet Scheduler is installed and, if not, install it.

To install the QoS Packet Scheduler on Windows XP or Windows Server 2003
  1. Log on to the computer as a member of the Administrators group or an account with equivalent user rights.

  2. Click Start, and then click Control Panel.

  3. Click Network Connections.

  4. Right-click the network interface on which you want to enable the QoS Packet Scheduler, and then click Properties.

  5. Click Install.

  6. In Select Network Component Type, click Service.

  7. Click Add.

  8. In Select Network Service, click QoS Packet Scheduler, and then click OK.

To install the QoS Packet Scheduler on Windows Vista or Windows Server 2008
  1. Log on to the computer as a member of the Administrator group or an account with equivalent user rights.

  2. Click Start, and then click Control Panel.

  3. Click Network and Sharing Center.

  4. Right-click the network interface on which you want to enable the QoS Packet Scheduler, and then click Properties.

  5. Click Install.

  6. In Select Network Feature, click Service.

  7. Click Add.

  8. In Select Network Service, click QoS Packet Scheduler, and then click OK.

In order to support DSCP marking on the servers and client computers in your organization, the Group Policy settings for conforming packets for the two service types used by QoS Packet Scheduler must be enabled and cannot be set to zero. This includes the following:

  • SERVICETYPE_GUARANTEED. This setting guarantees that IP datagrams will arrive within the guaranteed delivery time and will not be discarded due to queue overflows, provided the flow's traffic stays within its specified traffic parameters. This service is intended for applications that need a firm guarantee that a datagram will arrive no later than a certain time after it was transmitted by its source.
    The Real Time Media Communications stack marks the RTP/SRTP audio packets (default payload type value equal to 0, 3, 4, 8, 13, 97, 101, 111, 112, 114, 115, 116, or 118) as SERVICETYPE_GUARANTEED. This marking is off by default. To enable QoS on high-definition video, also update the following registry key to set the value to 250000 bytes per sec (2 Mbps):
    HKEY_LOCAL_MACHINE\Software\Microsoft\RTC\Transport\VideoBandwidthDiscardThresholdBytesPerSec
  • The SERVICETYPE_CONTROLLEDLOAD setting provides an end-to-end QoS that closely approximates transmission quality provided by best-effort service, as expected under unloaded conditions from the associated network components along the data path.
    Applications that use SERVICETYPE_CONTROLLEDLOAD may therefore assume the following:
    • The network will deliver a very high percentage of transmitted packets to its intended receivers. In other words, packet loss will closely approximate the basic packet error rate of the transmission medium.
    • Transmission delay for a very high percentage of the delivered packets will not greatly exceed the minimum transit delay experienced by any successfully delivered packet.
    • The Real Time Media Communications stack marks the RTP/SRTP video packets (default payload type value equal to 34 or 121) as SERVICETYPE_CONTROLLEDLOAD. This marking is off by default.

Use the following procedure on each client and server to ensure that the Group Policy settings for the two service types are set correctly.

To verify service type settings on a computer
  1. Log on to the computer as a member of the Administrators group or an account with equivalent user rights.

  2. Click Start, and then click Run.

  3. In the Open box, type gpedit.msc.

  4. In the Group Policy Object Editor dialog box, expand Computer Configuration, expand Administrative Template, expand Network, expand QoS Packet Scheduler, and then click DSCP value of conforming packets.

  5. In DSCP value of conforming packets, verify that Guaranteed service type and Controlled load service each have one of the following settings:

    • Not configured.
    • Enabled with a nonzero value. To see the value, right-click the setting, and then click Properties.
    • Disabled.
    Dd441192.note(en-us,office.13).gifNote:
    To ensure that the policies are applied, you may need to run the gpupdate /target:computer /force command. This command may need to be run each time the computer is restarted. For details, see Knowledge Base article 973779, “Some QoS Group Policy settings are not retained after you restart a client computer that is running Windows Vista or Windows Server 2008” at http://support.microsoft.com/kb/973779 and Knowledge Base article 972878, “The "Guaranteed service type" Group Policy setting returns to the default value after you restart a client computer that is running Windows XP or Windows Server 2003” at http://support.microsoft.com/kb/972878.
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