Enable Multicast Transmission of an Image

  • Article

Applies To: Windows Server 2008

This topic contains information about how to implement multicast when you have installed Deployment Server. If you installed Transport Server, see the Transport Server topic for information related to multicast with Transport Server.

  • Overview

  • Requirements

  • Enabling a multicast transmission

    • Using the Windows interface

    • Using a command line

Overview

Multicast allows you to deploy an image to a large number of client computers without overburdening the network. When you create a multicast transmission for an image, the data is sent over the network only once, which can drastically reduce the network bandwidth that is used.

Consider implementing multicast if your organization: Multicast might not optimize your installations if your organization:
  • Has network routers that support multicast.

  • Is a large company that requires many concurrent client installations.

  • Wants to efficiently use network bandwidth. This is because with this feature, images are only sent over the network once, and you can specify limitations (for example, to only use 10% of your bandwidth).

  • Has enough disk space on client computers for the image to be downloaded.

  • Meets the requirements listed below.
  • Has network routers that do not support multicast.

  • Does not have bandwidth overload problems.

  • Deploys images to only a small number of client computers simultaneously.

  • Has disk space limitations on the client computers. (This is because the image is downloaded to client computers instead of being installed from a server.)

Requirements

To implement this feature in your organization, you must have:

  • Routers that support multicast.

  • At least one install image (that you want to transmit) on the server.

  • The boot.wim file from the Windows Server 2008 media (located in the \Sources folder). The boot image from Windows Vista will not work with multicast transmission. If you use a Windows Vista file, you will be able to create the transmission, but people who boot into it will not be able to join a transmission.

Note

If multiple servers are using multicast functionality on a network (through Transport Server, Deployment Server, or another solution), it is important that each server is configured so that the multicast IP addresses do not collide. Otherwise, you may encounter excessive traffic when you enable multicast. Note that each Windows Deployment Services server will have the same default range. To work around this issue, specify static ranges that do not overlap to ensure that each server is using a unique IP address.

Enabling a multicast transmission

There are two types of multicast transmissions:

  • Auto-Cast. This option indicates that as soon as an applicable client requests an install image, a multicast transmission of the selected image begins. Then, as other clients request the same image, they too are joined to the transmission that has already started.

  • Scheduled-Cast. This option sets the start criteria for the transmission, based on the number of clients that are requesting an image and/or a specific day and time. If you do not select day and/or time check boxes, then you must manually start the transmission. In addition to these criteria, you can start a transmission manually at any time by right-clicking the transmission and clicking Start.

Note

Content is transferred over the network only if clients request the data. If no clients are connected (that is, the transmission is idle), then data is not sent over the network.

You can create transmissions using the Windows interface or a command line.

  • Using the Windows interface

  • Using a command line

Using the Windows interface

To enable multicast for an image, you must create a multicast transmission for it. To create a transmission, do either of the following:

  • Right-click the Multicast Transmission node, and then click Create Multicast Transmission.

  • Right-click an image, and then click Create Multicast Transmission.

Configuring transmissions

After a transmission is created, you can do the following:

  • Start the transmission. If the transmission is on a Scheduled-Cast, there is at least one client, and the transmission has not started yet, you can right-click the transmission, and click Start.

  • Delete the transmission. If you right-click the transmission and click Delete, the multicast transmission stops and each client installation reverts to using unicast. That is, the client installations are not deleted or stopped, but they do not use the multicast transmission to complete the installation.

  • Deactivate the transmission. If you right-click and click Deactivate, each client that is currently installing continues, but no new clients are joined to the transmission. After each current client installation is complete, the transmission is deleted. If there are no clients when you click this option, then the transmission is deleted instantly.

  • View properties. To view the properties, right-click the transmission, and click Properties. Note that you cannot edit the properties of a transmission after it is created. To make a change after you have created a transmission, you need to delete and recreate it.

  • Refresh the transmissions and data. To refresh the data, right-click a transmission and click Refresh, or press F5.

Configuring clients in a transmission

After you have created the transmission, client computers join the transmission by selecting the image in the Windows Deployment Services client. Client computers can also join a transmission using Wdsmcast.exe—a command-line tool included in the Windows AIK. When there are clients in a transmission, you can:

  • Viewclients and see progress. To view information about clients that are connected, expand the Multicast Transmissions node, and click the image. The clients are shown in the right pane.

  • Stop a client installation. To stop the installation completely, right-click a client and click Disconnect. You should use this option with caution because the installation will fail and the computer could be left in an unusable state.

  • Disconnect a client from a multicast transmission. To discontinue the transmission for a particular client but continue to transfer the image through unicast, right-click the client, and then click Bypass multicast.

Using a command line

Creating a multicast transmission for an install image

You have two options for transmission type: Auto-Cast and Scheduled-Cast.

  • To create an Auto-Cast transmission, run:

    WDSUTIL /New-MulticastTransmission /Image:<image name> /FriendlyName:<friendly name> /ImageType:Install /ImageGroup:<Image group name> /TransmissionType:AutoCast

  • To create a Scheduled-Cast transmission, run:

    WDSUTIL /New-MulticastTransmission /Image:<image name> /FriendlyName:<friendly name> /ImageType:Install /ImageGroup:<Image group name> /TransmissionType:ScheduledCast [/Time:<yyyy/mm/dd:hh:mm>][/Clients:<no of clients>]

Configuring transmissions

After a transmission is created, you can start it, delete it, deactivate it, and view its properties.

  • To start the transmission, run:

    WDSUTIL /Start-MulticastTransmission /Image:<image name> /ImageType:Install /ImageGroup:<image group name>

Note

You can only start the transmission if it is on a Scheduled-Cast, there is at least one client, and the transmission is not started.

  • To delete the transmission, run:

    WDSUTIL /Remove-MulticastTransmission /Image:<image name> /ImageType:Install /ImageGroup:<image group name> /Force

  • To deactivate the transmission, run:

    WDSUTIL /Remove-MulticastTransmission /Image:<image name> /ImageType:Install /ImageGroup:<image group name>

  • To view properties, run:

    WDSUTIL /Get-MulticastTransmission /Image:<image name> /ImageType:Install /ImageGroup:<image group name>

Configuring clients in a transmission

After you have created the transmission, client computers join the transmission by selecting the image in the Windows Deployment Services client. Client computers can also join a transmission through Wdsmcast.exe—a command-line tool that is included in the Windows AIK. When there are clients in a transmission, you can perform the following actions:

  • To view clients and see progress, run:

    WDSUTIL /Get-MulticastTransmission /Image:<image name> /ImageType:Install /ImageGroup:<image group name> /show:clients

  • To stop a client installation completely, run:

    WDSUTIL /Disconnect-Client /ClientID:<id> /Force.

Note

You should use this option with caution because the installation will fail and the computer could be left in an unusable state.

  • To disconnect a client from a multicast transmission but continue to transfer the image by using unicast, run:

    WDSUTIL /Disconnect-Client /ClientID:<id>

  • To view client <id> for each transmission, run:

    WDSUTIL /Get-MulticastTransmission /Image:<image name> /ImageType:Install /ImageGroup:<image group name> /show:clients

Additional references