DLVR customers completely avoided the catastrophe of a major CDN outage by relying on DLVR’s direct stream measurement and Fallback URL feature.
Video Delivery Optimization Challenge
OCT 22, 2017 — One of the major CDNs rolls out a change that causes content length mismatch errors and client aborts. The issue prevents the CDN from delivering manifests/segments for any of the streams served by that CDN from the affected delivery domains.
Hazard Predicted, Catastrophe Avoided
DLVR customers using this CDN were largely unaffected by the hazard due to DLVR’s Fallback URL feature, avoiding a complete loss of the viewers going through the affected CDN. Looking into the DLVR dashboard, our refined metrics revealed an increase in the percentage of sessions activating Fallback URLs at the time of the failure. In just 20 seconds, 100% of the affected streams failed over midstream to another CDN. As a result of their client-initiated CDN switching, enabled by DLVR Fallback URLs, our customers’ sessions continued streaming when they would have otherwise experienced video playback failure. Videos played continuously and the CDN failure had no impact on the viewing audience.
Best Practices
This incident underscores the necessity for midstream CDN switching as part of a video delivery optimization plan. DLVR’s Responsive Manifest™ designates the primary CDN selected to power the video stream, as well as Fallback URLs that designate the next best CDN. DLVR can add fallback URLs for more than one CDN and up to as many as our customers have in their mix, based upon their preferences.
Client Initiated Stream Switching
In non-outage situations, Fallback URLs are also used by clients for both fallback (due to intermittent connectivity) and player-specific, non-fallback reasons. DLVR’s ability to expose the varying fallback rates seen within and between clients can be used to help inform investigations into true outages versus player-specific fallback behavior.
