Cisco Systems 5.2.x manual Limit DMS-CD Disruptions to DMP Performance, 19-10

Chapter 19 Content Distribution and Delivery

Concepts

Limit DMS-CD Disruptions to DMP Performance

Improper scheduling practices and improper WAN bandwidth parameters in your media network might cause DMS-CD to disrupt playback performance temporarily on DMPs. The disruption affects multicast video streams, HD videos, Shockwave Flash animations, and image assets that these DMPs show on their attached presentation systems while simultaneously downloading newly provisioned, large assets. When this disruption occurs:

•Videos might become fragmented (contain artifacts), drop frames, or cut out during playback.

•SWF animations might play slowly.

•Images might redraw slowly.

•DMPs might restart unexpectedly, in rare instances.

You can configure bandwidth restrictions in your WAN that should help to alleviate these symptoms or eliminate them completely, depending on the system load of each DMP.

Best Practices

We recommend that you apply these DMS-CD best practices in your network whenever possible.

•Create and maintain only one deployment package for any DMP group whose constituent DMPs should play assets from local storage. Simply configure its deployment to recur nightly (or whatever other time has the least possible impact on your audience). Then, modify it as necessary, to:

–Include all new or changed assets that member DMPs should obtain or keep for playback.

–Remove obsolete assets that member DMPs should autoclean from local storage.

DMS-CD syncs DMP storage with the current version of the deployment package and applies all changes automatically.

Note	This method is simpler and more scalable than developing and maintaining a new package and
	scheduling a new deployment each time that your needs change. Also, it increases the likelihood that large
	deployments will resume and be completed successfully on a slow connection. Furthermore, it prevents deployments
	from becoming too numerous to manage.

•Even if you have not imposed any bandwidth restrictions upon DMS-CD, avoid scheduling deployments and playback to run in parallel on DMPs. Otherwise, deployments can take longer to finish than you anticipate. (This delay occurs because the load is doubled on DMPs.) For best results, schedule DMS-CD deployments to run when no playback is scheduled. During such times, there is little or no load on DMPs.

•When playback and deployments must overlap, configure an upper threshold for DMS-CD bandwidth consumption. The value that you enter should be less than your network’s maximum transfer rate. Adjust and test values as necessary, until you determine exactly how much bandwidth DMS-CD can use in your WAN without affecting DMP performance.

		Tip	Use the “Enable maximum transfer rate” field (at Digital Media Players > Deployment Manager >
			Deployment Preferences) to limit DMS-CD bandwidth consumption.
		Note	In our tests, we found that using 5 Mbps as the upper threshold provided adequate bandwidth restriction in
			most cases. However, this is not necessarily a value that you should use. Results will vary depending on network
			capacity and the load placed on a DMP.
	User Guide for Cisco Digital Media Manager 5.2.x
19-10			OL-15762-03