By Mae Kowalke
In my blog last week, I focused on some of the changes and challenges in digital media delivery that vendors likeVelocix (an Alcatel-Lucent company) are developing to help service providers maximize the quality of end user experiences while minimizing network traffic. In that piece I cited the first article in a two part series by Richard Gibbs, Vice President Worldwide Technical and Business Consulting at Velocix’s article in the Alcatel-Lucent e-zine TechZine, “A New Approach to Publishing and Caching Video.” It focused on the architecture and design considerations for a Content Delivery Network (CDN). This post picks up the story with the second Gibbs post, “Optimize Delivery to Meet Demand for “Video Everywhere,” which looks in detail at the delivery, management and control functions needed for efficient CDN operation.
First a little background refresh. A CDN (in the example one architected for a cable TV MSO) is a system of distributed caches containing copies of data, placed within a network to maximize bandwidth for data access. They rely on a series of processes and functions categorized as publishing/storage, caching, delivery, and management and control to assure the delivery of the best quality experiences to end-user devices with the new solutions also ensuring that this is done with minimal strain on network resources. These processes include:
In his second article, Gibbs noted that delivery is the last step in a chain that includes logging/auditing, encryption, request routing, cache selection, geo-configuration and authentication. Simply put, delivery means a consumer request is received, authenticated, and then routed to a relevant device for fulfillment.
All delivery interactions with a CDN follow a three step process:
- The publisher domain name server (DNS) issues a redirect to the request router — critical since CDNs only deliver content a publisher has authorized for distribution.
- The request router issues a redirect to a surrogate, which is a delivery cache with replicated content.
- The surrogate serves the content.
A critical element for obvious reasons. Protection of intellectual property and getting compensated for its use can only happen when content requests have been properly processed and validated, i.e., authenticated. Gibbs explained that authentication methods used by CDNs include secure tokens, hash-based message authentication code (HMAC), and Shockwave Flash (SWF) verification. He did not note that all have their strengths and weakness since determined hackers have proven adept at circumventing even the most comprehensive authentication methodologies, but each can be highly effective and the choice of which of them, and possibly in combination, is something to be discussed with your solution provider with consideration for such things as ease-of-use and administration entering the mix.
Other crucial CDN delivery functions are summarized below:
Geo-configuration – mechanism for applying policy to content delivery; defines where content can be stored and where and to whom it can be delivered.
Cache selection – process that determines which cache will deliver the content, taking into account cost, performance, location, and protocol among other factors.
Request routing – combining of all available information about end user, requested resource and state of the network, so the most appropriate surrogate can be selected for content delivery.
Logging/auditing – measurement of delivery events, for reporting and billing purposes.
Management/control – responsible for the configuration and provisioning of CDN services.
Management and configuration – tools for dynamically configuring services and a balancing them across devices based on load and capacity demand.
Monitoring – components that provider relevant hardware and service alerts when problems occur.
Content owner management and reporting – real-time viewing statistics and delivery information crucial for managing content and delivery portals.
In the blog post, Gibbs recommends that providers use a range of delivery device specifications to achieve consistent delivery and high QoE, since specific content services many require different capacities or capabilities. For example, video on demand (VoD) services require large capacity edge disk caches, whereas live streaming services require higher throughputs and memory rather than larger disk caches.
“The surge in consumer demand for high quality multimedia entertainment on television, personal computers and mobile devices has had a profound impact on the network infrastructures and business models in place,” summarized Gibbs in the blog post.
That is actually a bit of an understatement. Reality is, based on sales of iPads and other tablets, and the explosive growth of the smartphone population and their users’ insatiable appetites for both streamed and interactive video (from real-time teleconferencing to watch movies to interactive gaming), a tsunami of video traffic is heading operators way and user expectations of quality experiences on every video-enable device they own and operate are high. The old ways of delivering video to specific places with a limited number of screen types is over.
New ways of meeting the requirements of the era of demand for digital video being everywhere are necessitating carriers to rethink, and do so quickly, how best to deliver content and do so securely, at high quality, with optimized network performance and at a profit. To learn more about solutions to the challenges of delivering quality video content everywhere check out the links above and also the Velocix white paper, Video Distribution in the Digital Lifestyle Era…”