TECHNOLOGY TRENDS CONTENT DELIVERY NETWORKS CACHE INJECTION
Operators are turning to content delivery networks to ease the Internet traffi c burden, and that could result in new services and revenue streams. By Roy Rubenstein
of IP traffic across their infrastructure. Deploying a CDN that stores popular content close to users also promises new revenue opportunities, enabling opera- tors to sell use of their CDNs to content providers and to deliver new services such as multi-screen video. But CDNs pose their own challenges for
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operators: key among them, it remains unproven whether content providers will embrace operators’ CDNs, build their own or use those of specialist providers. In addition, not all traffic is suitable for CDNs for technical or commercial reasons—one market research firm esti- mates the proportion to be as high as 60% of all traffic (see box p.10). “The business case [for CDNs] is very
uncertain, but operators are clear that they have to do something,” says Rob Gallagher, principal analyst and head of broadband and TV research at Informa Telecoms and Media. A CDN can be viewed as a collection of
algorithms that reside in the network to keep track of all the content requested by users. “It tracks usage and demand of content, it knows the network topology and where the users are, and then moves content about the network, from central- ised storage to distributed caches far closer to the user,” says Jim Guillet, direc- tor of marketing at Alcatel-Lucent. As well as saving network capacity, such content placement provides end users with an improved service experience by reducing network latency. Organisations that already use CDNs
include media and entertainment content providers—such as Google, Facebook and traditional broadcasters—enterprises that are looking to improve their Web site performance, and ISPs. Akamai Technologies has been provid-
ing its CDN to ISPs and enterprises for over a decade, and more recent key CDN
May 2011
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ontent delivery networks are set to play a major role in how opera- tors tackle the relentless growth
players include Limelight Networks, EdgeCast Networks and Level 3 Communications. Now telcos are entering the market with their own CDNs, as a service offering and as a way to cope with their own traffic burden. “It is very hard to find a major operator, or even a tier-two operator, that isn’t committed to some kind of CDN strategy,” says Gallagher. Acquisitions could be one route to
creating CDN scale. Last month Level 3 agreed to acquire Global Crossing for US$1.9 billion, creating a combined company with connections to 70 coun- tries and extending Level 3’s CDN assets out from its US stronghold to Latin America and Asia. Rapid traffic growth requires signifi-
cant network investment, yet operators benefit only marginally from the reve- nues Internet traffic is generating, says James Segil, president of EdgeCast Networks (Technology Trends, April 2011). “Operators are the mule that has to carry everything,” says Segil. AT&T says 30% of core traffic on its
network is cacheable content destined for its customers, and says a CDN approach is currently the only way to manage traffic growth cost-effectively. Moreover, an AT&T/Exabyte study forecasts network traffic is likely to expand by 50% per year over the next 10 years. According to analysis from Juniper
Networks, CDNs can have a significant impact on Internet traffic: “For a wireline residential service provider offering 10-Mbit/s broadband links, implementing a CDN saves between 30%–50% of Internet traffic,” says David Noguer Bau, head of service provider marketing at Juniper. Storing content closer to users also
benefits their service experience. Video traffic is sensitive to bandwidth fluctua- tions and network latency, and the closer the content the fewer congestion points the traffic must cross. New protocols such as HTTP adaptive streaming work by the end device such as an iPad requesting
content in segments while assessing the bandwidth conditions available. If condi- tions are good the device can request higher resolution video segments. “If content is closer to the consumer
there is less latency and points of conten- tion such that the whole adaptive mechanism works that much better,” says Guillet at Alcatel-Lucent. “If there was no bandwidth problem,
you could argue that all these third-party CDNs could easily serve CDN traffic in centralised places in the network,” says Santosh Krishnan, vice president of busi- ness development at Verivue. “But now that bandwidth is exploding there is a compelling reason to bring CDN tech- nology even closer to the user.” Verivue provides CDN platforms to
service providers. In April, Polish opera- tor Telekomunikacja Polska, part of the France Telecom Group, announced it had deployed Verivue’s CDN technology after three years of trials, says Krishnan. At the core of a CDN are the origin
servers and storage: popular content is sent by the origin servers to the CDN edge where the media servers and edge caches reside. “It is not cost-effective to store all the content at all the edges,” says Derek Gough, director of product management at Level 3 Communications. “We can intelligently populate the caches with ‘short-tail’ content that is the most popular.” Content is cleared from the cache once it ceases to be popular, but a copy remains in the origin storage should it become so again. The degree of cacheing efficiency that
can be achieved using a CDN is striking. For example, Akamai caches 95% of Facebook’s traffic through its CDN, according to Michael Howard, principal analyst at Infonetics Research. Operators’ CDNs differ from the global
specialists in that their reach is confined to their networks, often spanning one or several countries at most. But operators have the advantage that they can place the
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