Windows Media Encoder 12

Unicast edge server sourcing from a multicast broadcast on an origin server Multicast edge server sourcing from a unicast broadcast on an origin server

In this post, I'll address the first scenario, a unicast edge server sourcing from a multicast broadcast on an origin server, as illustrated by the following diagram.

Multicast is often employed across an enterprise wide-area network (WAN) or content distribution network (CDN) to move broadcast content out to edge servers. Two examples of where this is useful are for distributing:

Executive broadcasts across a multicast-enabled WAN link to a remote enterprise LAN that is not multicast-enabled. IPTV broadcasts across a CDN and then delivering the broadcasts to end users using public-facing edge servers.

The primary advantage of multicast is that no matter how many edge servers you have, you only have one video stream being distributed. In other words, even if you run a large CDN and have two thousand edge servers to which you need to distribute a 500kbps stream, your network will only need to support 500kbps. If you had to use two thousand unicast streams to reach those edge servers, some portions of your network would need to be able to support up to 1Gbps of streaming traffic (2, 000 x 500kbps).

Let me describe how you would you set up this scenario when using WMS 9.0 or above. The following steps assume:

You have Windows Media Service 9 Series running on Windows Server 2003 servers and/or Windows Media Services 2008 running on Windows Server 2008 servers, and Your network hardware (routers, etc.) between the Origin and Edge Servers is multicast-enabled.

Origin Server: Set up a multicast publishing point

First, we need to set up the Origin Server, from which the multicast originates, sourcing from a file, playlist, or live encoder.

On the Origin Server, right-click on Publishing Points in the console tree on the left side of the WMS user interface, as shown below.

Click on Add Publishing Point (Wizard)… to create a new publishing point with the following settings (click Next to move from one dialog box to the next):

Name: A descriptive name (I'll call it GlobalMulticast in this example) Content Type: One file, for testing purposes. (Later, you can source from a live encoder running on a PC, such as the free Windows Media Encoder 9 Series or a free trial version of Microsoft Expression Encoder 2, hooked up to a Webcam or other video camera.) Publishing Point Type: Broadcast publishing point Delivery Options: Multicast; for testing purposes, leave the 'Enable unicast rollover' box unchecked

File Location: Pick any lengthy Windows Media video (.wmv) file that you have

TIP: For testing purposes, you could also source from a WMS Server-Side Playlist that is set to loop Publishing Point Summary: Verify your selections Completing the Publishing Point Wizard: Leave the default choice of creating a .nsc file and click Finish

Multicast Announcement Wizard

Click Next if you see the Welcome dialog Specify Files to Create: Select the second option, Multicast information file (.nsc)

Stream Formats: Click the Add button

Add Stream Formats:

If sourcing from a file, click the Browse button

In the Windows Media Browse dialog box, change the Data Source and Location fields as needed to find your multicast source file Click once on the file name to highlight it Click the Select File button