A few folks have recently had questions about how to do sourcing of a video stream when using multicast with Windows Media Services (WMS). There are two basic scenarios that we often see:
- 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):
Multicast Announcement Wizard
Ensure multicast streaming is enabled
- In the console tree, click the new broadcast publishing point (if the publishing point is started, click Stop)
- In the details pane, click the Properties tab
- In Category, click Multicast streaming
- In Plug-in, click WMS Multicast Data Writer, and then right-click – if Enable is not grayed out, click on it
Edge Server: Set up a unicast broadcast publishing point
Now, let's set up an edge server, which will receive the multicast stream and pass it on to end users via unicast streams.
If all went well, you are now able to source from a multicast broadcast and re-distribute content using unicast streams from the edge.
Coming soon: I'll describe how to set up scenario #2, sourcing a multicast edge server from a unicast origin server.