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CLIENT REACTION TO CACHE FAILURE OR REDIRECT

IP.com Disclosure Number: IPCOM000247014D
Publication Date: 2016-Jul-26
Document File: 8 page(s) / 141K

Publishing Venue

The IP.com Prior Art Database

Related People

Gareth Bowen: AUTHOR [+2]

Abstract

Presented herein are techniques that minimize the chance of disruption during streaming from a content delivery network (CDN) by alleviating issues associated with edge servers becoming unavailable in the middle of a playback session. The techniques include a header in the HTTP response for media segments that signals that an edge is going to be shut down or taken offline. This proactive signal allows clients to migrate prior to any possible interruptions. The ability to quickly and cleanly move clients away from an edge prior to the edge becoming available is important to provide maximum elasticity in a cloud deployment. Otherwise, scaling down could only be accomplished with an interruption in service or when an edge is completely unused.

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CLIENT REACTION TO CACHE FAILURE OR REDIRECT

AUTHORS:

  Gareth Bowen Francois Le Faucheur

CISCO SYSTEMS, INC.

ABSTRACT

    Presented herein are techniques that minimize the chance of disruption during streaming from a content delivery network (CDN) by alleviating issues associated with edge servers becoming unavailable in the middle of a playback session. The techniques include a header in the HTTP response for media segments that signals that an edge is going to be shut down or taken offline. This proactive signal allows clients to migrate prior to any possible interruptions. The ability to quickly and cleanly move clients away from an edge prior to the edge becoming available is important to provide maximum elasticity in a cloud deployment. Otherwise, scaling down could only be accomplished with an interruption in service or when an edge is completely unused.

DETAILED DESCRIPTION

    In order to scale media playback over a wide area network, a content delivery network (CDN) can be used to hold content on edge servers and reduce the load on the origin (classic caching in Hypertext Transfer Protocol (HTTP)). An example infrastructure is shown in Figure 1. In Figure 1, each edge server maintains a CDN cache.

    However, this infrastructure also creates unique issues with respect to content delivery. For example, if a CDN cache stops serving video content, whether due to a failure or a scheduled shut-down (e.g., for maintenance), the video may be terminated on at least some clients/players and ruin or negatively impact the experience of one or more users. A CDN cache may stop serving video for a number of reasons. For example, an edge server may be taken down to accommodate maintenance (e.g., patching or OS upgrade), changes in demand (as allowed by cloud computing and software-defined

Copyright 2016 Cisco Systems, Inc.

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networking), or active load balancing (e.g., new edge servers may become available and steer clients away from a first edge server, even if it the first edge server is not "going away").

    As a more specific example, if a first CDN cache is serving a video session to an adaptive bit rate (ABR) client and the first CDN cache wants to redirect the session to another cache (e.g., for scheduled maintenance or upon being identified as a cache instance to be terminated as part of a CDN scale down), the first CDN cache may issue a HTTP redirect to the client for a given segment request. In this situation, ABR client implementations generally follow the HTTP redirect for the explicitly redirected segment (e.g., by receiving that segment from a second CDN cache). However, the clients will continue to request subsequent segments from the first CDN cache. In other words, clients do not "apply" the redirect to subsequent segments. Consequently, if the first CDN cache cannot serve the subsequent segments, it still must stay in the HTTP signaling path and redirect each and every segment request until the end of the session. This...