Managing multicast fragmentation in a typical Windows Media Services (WMS) environment

On occasions you may notice your multicast clients experience unwanted behavior and you note one or more of the following

  • Some packets are lost on the network.
  • Video buffers or frames are dropped in Windows Media Player.
  • Network bandwidth appears to spike when looking at traffic at the sub-second level.
  • Packets are fragmented into multiple 1500 byte packets.

The link below will open a PowerPoint diagram of a typical WMS  multicast configuration, it will display simple traffic flow  and the 2 basic steps that can be accomplished to assist with handling t5he fragmentation. Note however , removing fragmentation for the sake of simply removing fragmentation is not necessary always required , especially  if the network and its structure are robust enough to  handle such fragmentation.  The purpose of  the tweaks are to hopefully assist where the network infrastructure cannot accommodate the fragments.

So basically there are only a couple of actions we can take from a media perspective to address performance when it is not as expected in multicast stream:
          1. Set the UPD/TCP bust limits  on the server 
          2. Modify the content (optimum maximum packet size; bitrate etc.)

If the modifications above do not remedy the issue,  and if you are not using the Microsoft Expression Encoder,  you  will  want to download the encoder and test using the same parameters to see if you get different behavior.  Again,  if that does not help you will want to  troubleshoot the  network and its components to ensure appropriate bandwidth can be achieved for each client

This sample is provided as - is for illustration only, without warranty either expressed or implied.
Open the following link to view the PowerPoint slide:  


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