Fundamentals, Design, and Evolution
This edition first published 2017
© 2017 John Wiley & Sons, Inc.
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Library of Congress Cataloguing‐in‐Publication Data
Names: Robinson, Dom, author.
Title: Content delivery networks : fundamentals, design, and evolution / Dom Robinson.
Description: Hoboken, NJ : John Wiley & Sons, 2017. | Includes bibliographical references and index. |
Identifiers: LCCN 2017009407 (print) | LCCN 2017014475 (ebook) | ISBN 9781119249887 (pdf) | ISBN 9781119249894 (epub) | ISBN 9781119249870 (cloth)
Subjects: LCSH: Computer networks. | Internetworking (Telecommunication)
Classification: LCC TK5105.5 (ebook) | LCC TK5105.5 .R6255 2017 (print) | DDC 004.6–dc23
LC record available at https://lccn.loc.gov/2017009407
Cover Design: Wiley
Cover Image: © MickeyCZ/Gettyimages
So family had my credit last time: this time it’s professional!
Thanks and credits:
To those who inspire and allow me the honor to work with them: Adrian Roe and Steve Strong.
To those who have travelled much of the journey with me: Steve Miller‐Jones, Tim Thompson, Tim Gebbett, Dane Streeter, Dom Pates, and Michael O'Rourke
To those who set me on key paths in life but themselves are no longer with us: Chris Daniels and Brian Smith (my Godfather) ‐ RIP both.
To those who gave me a place in the industry: Eric Schumacher‐Rasmussen, Dan Rayburn, Tim Siglin, Jan Ozer, Sjoerd Vogt, Jose Castillo and Joel Unickow and the Streamingmedia.com extended family.
To some of our clients for allowing us to address some very big complicated technical challenges for them: Andreas Heidoetting, Simon Ball, Osman Sen Chadun and Jon Holden‐Dye, Ken Takagi and Mark Myslinski
To these guys who have shepherded my meanderings in various ways over the years: Steve Hatch, Richard Trimble, Tony Ballardie, John Riordan, Eric Van Der Kleij, Harvi Bains, Nick Lansman, Donald Miller‐Jones, Daniel Montuschi, Steve Woolcock, Elle Todd, and John Enser.
To these industry figures who have made key contributions to the sector over the years: Ben Waggoner, Greg Shepherd, Jon Crowcroft, Steve Deering, Kon Wilms, Mark East, Richard Lindsay‐Davis, Lee Atkinson and Stef van der Ziel.
To Mukaddim Pathan ‐ whose nudge ultimately made this book happen (and of course to the entire Wiley team for just being absolutely great!)
To the cast of thousands who have been part of this story (which includes all my readers!)
..and finally to Vint Cerf for both, inventing the Internet, and for taking the time to help me with personal projects on a number of occasions over the years.
Provides the reader with comprehensive insight into the structural decisions that can to be made when architecting a content distribution system that uses IP‐based networks
The narrative of this book draws on a wealth of real‐world and practical experience that the author has accrued through two decades of coalface experience architecting and delivering large, mission critical live video, webcasts, and radio streaming online, over both the Internet and private IP networks.
From this loosely defined “tradeperson’s” standpoint, rather than the often explored tightly academic or business‐sales point of view, this book takes a broad, humored, and at times pencil‐sucking look at the art of building content delivery workflows.
This book aims to talk in backroom engineers’ English about the challenges faced in the real world, and to stimulate the reader to think extremely broadly about the options and problem spaces, and how to ensure that delivery is always, at the least, “good enough” for the operator’s and consumers’ commercial objectives.
As we enter what the author calls the “third generation of CDN,” architects who are new to the area can use this text to draw on the author’s own practical experience over the first two generations.
The book will also be an interesting read for those who have themselves built large infrastructure, providing a moment to reflect on other ways around problems. It will be a useful quick‐start tool for those who are trying to understand the complex challenges of large‐scale content delivery.
Not one for hiding opinion, the author also throws a number of challenging “what if” scenarios into the discussion to highlight some possible long‐term design architectures that today may be a little fantastical but tomorrow may evolve based on the clear demand that such architectures could reach, should the commercial model evolve in line.
This discussion zooms in on the recent evolution of software‐defined networking and the changes that this schism will bring as capabilities for many players in the network stack become unlimited, and infrastructure allocated to a particular task can be repurposed at the flick of a bit.
While content delivery network architecture texts typically focus on current and forthcoming best practice, few take a deep retrospective view and embrace the cycles in the sector. CDNs also typically comprise 20% of their engineering work on video despite its being 80% of their traffic overhead. The author has focused on live video and audio transmission because the problems span so many layers of the network stack. There are, of course, many application‐specific challenges, with particularly gaming and conferencing and to a lesser extent dynamic website acceleration and small object or large file delivery. Some of these do cause network layer issues, but generally the traffic is not impacting to a network operator – it is impacting to the Software as a Service provider or the application user. There are many complex issues that can be explored, and many are touched on in this book; however, for the main part, the core focus of this book is on live (and to a lesser extent on‐demand) video delivery – TV, radio, video, and live audio over IP networks.
Starting in 1973, streaming audio and subsequently video have been baked into the IP protocols. With the web making the quick discovery of content near ubiquitous, the demand for not only huge volumes of text but also for web apps, and significantly for high‐quality video, has exploded.
The likes of the BBC, YouTube, Netflix, and countless other online publishers, have lit up the information highway with literally inconceivable amounts of information conveyed in huge quantities of bytes. Those data have to be delivered to destinations by someone, and the dark art these people practice is called content delivery networking.
Over the past 20 years we have seen several trends emerge, and these exist at both the micro level, where we are encoding pixels of video into a streaming format, and the macro level, where millions of users are able to consume content from hundreds of thousands of servers, reliably and with a great deal of resilience.
Trends in GPUs are changing how encoding resources are deployed. Evolutions in distributed computing are bringing about a macro change in the architecture of these types of services.
This evolution promises greater service levels, more flexibility to meet the customers’ exact requirements, and new security challenges as infrastructure becomes increasingly shared in multi‐tenant public cloud models.
Telecoms network operators are now seeing IP services as a core part of their businesses, and their understanding of their own internal content delivery architecture requirements is a key driver for their rapid adoption of a software operating model. Soon operators will, at‐will, be able to deliver the CDN as an SaaS model on their own infrastructure, and additionally offer other SaaS models in the same infrastructure, providing risk mitigation as they try to underpin services for an ever more divergent target market.
The book describes the historical context of the streaming media and content delivery market from the unique perspective of the author who is a true native to the sector. It draws heavily on personal experience and hands‐on examples from 20 years of live webcast production through to public company infrastructure architecture. There are few in the industry who can boast such a rich and varied practical experience across the sector, and this unique insight is fundamental to the narrative.
Aside from the anecdotal and practical commentary, the book takes the implementer through a wide range of design considerations for different network topologies, starting with the author’s own requirement filtration processes through to initial sketches, through to roles and responsibilities, and to the complexity of managing change in established teams, agile as opposed to waterfall considerations, in the context of large blue chips, security and commercial models, and value chain alignment.
This widely embracing viewpoint, supported by examples ranging from IETF discussions, regulatory considerations, policy formation, coders, hardware vendors network operators, and more, is rarely available from one author. The author draws on conversations with peers in the industry, and in the course of writing, he gathers their comments and input too.
While many books on these topic slice and dice these seemingly unrelated schools of thinking into their constituent parts of commercial, technical, operational (etc.), this book can help service designers embrace the worldview of influences that need to be considered when architecting a robust and high‐quality content delivery service for today’s online consumers and business users.
Today’s market is just about to fully enter what the author call its third generation.
As the SDN/NFV models stimulate understanding across the Telco sector, there is about to be a tech refresh like no other: all the hardware that has traditionally been dedicated to task is going to become software driven in entirety. The Telco operators who were about to deploy Gen2 CDNs are holding back to see how the underlying infrastructure is going to evolve, to then deploy their CDN as a gen3 model using the network’s built in resources to deploy the CDN as an SaaS and when a client needs it.
That cycle is going to take a further three to five years.
As it happens, service architects are going to be planning more against customer requirement than against “productizability,” and this requires a breadth of thinking at the COO / CTO level from every engineer and commercial participant too.
Designing a CDN for tomorrow is a broad challenge – and this book strives to get the reader thinking like a content delivery network designer.
Target: Streaming media readership, IP / cable/ satellite / Telco / mobile and TV operators, content producers, ISPs, policy and regulatory (net neutrality and content rights), and all stakeholders in networks that may deliver large quantities of video or audio (and data / applications too).
The book is intended to start with a basic introduction, and while it will expect to push the limits of even advanced academics at times, the narrative will attempt to keep even nontechnical readers immersed in the commentary.