In the Configuration Manager console, click Administration.

In the Administration workspace, expand Overview, and then select the Distribution Points node.

Select the distribution point that you want to use to multicast the operating system image.

On the Home tab, in the Properties group, click Properties.

Select the Multicast tab, and configure the following options:

• Enable Multicast: You must select this option for the distribution point to support multicast.
  
  
• Multicast service point connection account: Specify an account to connect to the database if you cannot use the computer account of the distribution point.
  
  
• Multicast address settings: Specify the IP addresses to send data to the destination computers. By default, the IP address is obtained from a DHCP server that is enabled to distribute multicast addresses. Depending on the network environment, you can specify a range of IP addresses between 239.0.0.0 and 239.255.255.255.
  
  

  Important
  These IP addresses must be accessible by the destination computers that request the operating system image. This means that routers and firewalls in between the destination computer and the site server must be configured to allow multicast traffic.

• UDP Port Range: Specify the range of UDP ports to send data to the destination computers.
  
  

  Important
  These ports must be accessible by the destination computers that request the operating system image. This means that routers and firewalls in between the destination computer and the site server must be configured to allow multicast traffic.

• Enabled scheduled multicast: Specify how Configuration Manager controls when to start deploying operating systems to destination computers. Click Enabled scheduled multicast, and then select the following options.
  
  In the Session start delay box, specify how many minutes that Configuration Manager waits before it responds to the first deployment request.
  
  In the Minimum session size box, specify how many requests must be received before Configuration Manager starts to deploy the operating system.
  
  
• Transfer rate: Select the transfer rate to download data to the destination computers.
  
  
• Maximum clients: Specify the maximum number of destination computers that can download the operating system from this distribution point.
  
  

Click OK.

In the Configuration Manager console, click Software Library.

In the Software Library workspace, expand Operating Systems, and then click Operating System Images.

Select the operating system image that you want to distribute to the multicast-enabled distribution point.

On the Home tab, in the Properties group, click Properties.

Select the Distribution Settings tab, and configure the following options:

• Allow this package to be transferred via multicast (WinPE only): You must select this option for Configuration Manager to simultaneously deploy operating system images.
  
  
• Encrypt multicast packages: Specify whether the image is encrypted before it is sent to the distribution point. Use this option if the package contains sensitive information. If the image is not encrypted, the contents of the package will be visible in clear text on the network and might be read by an unauthorized user.
  
  
• Transfer this package only via multicast: Specify whether you want the distribution point to deploy the image only during a multicast session.
  
  If you select Transfer this package only via multicast, you must also specify Download content locally when needed by running task sequence as the deployment option for the operating system image. You can specify the deployment options for the image when you deploy the operating system image, or you can specify them later by editing the properties of the deployment. The deployment options are on the Distribution Points tab of the Properties page of the deployment object.
  
  

Click OK.