Multicast is a network optimization method that you can use in your System Center 2012 Configuration Manager environment where multiple clients are likely to download the same operating system image at the same time. When multicast is used, multiple computers simultaneously download the operating system image as it is multicast by the distribution point, rather than having the distribution point send a copy of the data to each client over a separate connection.
Multicast Deployment Process
The following flowchart shows the process that you must follow to deploy operating systems by using multicast.
Multicast and Windows Deployment Services
Windows Deployment Services (WDS) must be installed on the same server as the distribution point that you use to multicast the operating systems image. For more information about WDS and other operating system deployment prerequisites, see Prerequisites For Deploying Operating Systems in Configuration Manager.
Enable a Distribution Point to Support Multicast
To deploy operating system images by using multicast, you must provide a distribution point that supports multicast deployments. There are two ways to configure a distribution point to support multicast deployments. You can set the multicast settings when you install the distribution point by using the Create Site System Server Wizard, or you can configure the multicast settings on an existing distribution point by using the Property page for the distribution point. For more information about how to configure the distribution point and configure the operating system image to support multicast, see How to Manage Multicast in Configuration Manager.
When you create a distribution point there are other configuration issues that need to be considered in addition to configuring the distribution point for multicast support. For more information about the attributes that you can configure for your distribution point, see Planning for Content Management in Configuration Manager.
Specify When the Operating System Image is Available
You can further conserve bandwidth by configuring when the operating system image is deployed from the distribution point. This consolidates the client requests into a specific time frame, which optimizes the benefits of multicast but might require clients to wait before the operating system package is available. The multicast session starts when it replies to a service location request from a client computer. The distribution point can be configured to require a specified number of requests before it begins to multicast, or it can wait a specified number of minutes after the first request before it begins to multicast. The multicast session ends when the maximum number of client requests is reached. Clients can join a multicast session already in progress. When the multicast is complete, the client will then download missing portions of the package.
Deploying Content when Running a Task Sequence
When you deploy the task sequence that multicasts the operating system, the content referenced by the task sequence must be downloaded locally from the distribution point to the destination computers. When you deploy your task sequence you can specify that the content is downloaded locally when it is needed by the task sequence or that all the content is downloaded before the task sequence is run.
These deployment options are specified on the Distribution Points page when you deploy the task sequence. For more information about how to specify that the content is downloaded locally from the distribution point, see the How to Deploy a Task Sequence section in the How to Manage Task Sequences in Configuration Manager topic.