The Future Of CDN:

Hybrid & Federation Models to Augment Private Infrastructure

Private CDN vs CDN as a Service

High bandwidth delivery requires new hardware, capital which even a stable business will have to think carefully about spending. Future proofing the network against predicted growth complicates this even further; when constructing a private CDN, companies should provision enough capacity to easily handle the current peak traffic, yet most of this hardware will be under-utilised off-peak. CDNs which serve multiple services will have the advantage of different usage patterns, meaning peaks are unlikely to line up and cause issues with capacity.

The argument between a service model CDN, where one buys bandwidth or pays-by-usage and making a private CDN comes down to three major factors: Costs (capital vs Operational), Performance and Coverage. Although the capital expenses of building a private CDN are high, with good utilisation, the ongoing costs will be much lower than a service CDN, and, when coupled with better tuned behaviour, can give a superior experience all round.

Coverage and how it affects Performance can be a huge issue for localised media companies. In the case of a large audience within a single, under-served country, most CDN services perform poorly due to the lack of infrastructures and limited PoPs. The provision of scalable infrastructures to achieve amble coverage is often a substantial entry barrier for new CDN providers and also a huge consideration for existing providers in terms of commercial viability.

Generally, only local companies, with close knowledge of their customer base and strong relationships with the local ISPs can get good coverage, close to the edge. Areas where network infrastructure is relatively immature, or has poor bandwidth due to geographical realities, often seen in South East Asia (and much of the world outside Europe and North America), can benefit from more distributed PoP capacity.

The Need For CDN

With global internet traffic on the rise, much of it streamed and on-demand video content, pressure on backhaul infrastructure and on last-mile bandwidth has caused a huge increase in CDN usage in the last few years. This is only set to speed up as businesses compete to match consumers’ increasing demand for a faster, smoother user experience.

A CDN consists of a series of appliance which serve high bandwidth traffic, usually organised into physical locations called Points of Presence (PoPs), which comprise the “edge”. These servers in turn fetch their files from an Origin. Users are directed to their nearest PoP using DNS or HTTP routing, or by the Internet Service Provider (ISP) directly. The servers which make up the edge can be owned by the content provider (private CDN), a CDN provider (CDN service) or a mixture of the two (Hybrid and Federation).

CDNs allow content distributers to place their content near or at the edge, reducing the amount of traffic going back to their central servers while increasing Quality Of Experience (QoE) for their users with improved loading speed and stronger crash resistance. In short, a CDN minimizes the distance between a user and the servers.

As much as it benefits the end-users, service providers also enjoy a large reduction in bandwidth consumption and the capability to handle high traffic loads, thus lowering costs and contention in their infrastructure.

Fast Delivery

Federated CDN

Another interesting alternative is the federated CDN; a CDN, built by the content provider, which primarily serves their content, but also other’s traffic along side. The Federation model of CDN allows companies to make an investment in infrastructure which will last for years, even with growth, and will generate income from the day it is installed. This way companies get a fantastic return on investment while reducing the risk of a large capital investment, all while building future proof infrastructure and a better quality of experience for their users.

This benefits both the content provider as well as the CDN provider; the content provider gets the network infrastructure they need with a much quicker Return on Investment (ROI) and less exposure to their own growth variability while the CDN provider gets access to an expanded delivery network in areas where CDN service demand is not high enough to justify the capital outlay on its own.

Because the content provider has control of their infrastructure, they can fully utilise their local knowledge and relationships to get smaller, lower cost PoPs out closer to the edge in places where demand is high. Few CDN providers offer an option of such close proximity to the edge because such deployments have high installation and administration costs, and their offerings are often targeted at areas with high capacity, cheap backhaul, where small PoPs are not cost effective.

Hybrid CDN

There is an option which helps solve these issues; Hybrid CDN, where private infrastructure is augmented by a global CDN service network, enabling better service for non-local users as well as more redundancy and resilience in the case of a failure. This means the content provider can focus on coverage of their local users, knowing their global users will still get good service. The Hybrid CDN model offers extra capacity at peak, meaning private CDNs can be sized to easily serve every-day traffic, but without so much worry about future growth or special events. This allows the purchaser to tune their capital expenditure and ongoing operational costs to serve their needs in the most cost effective way.

Hybrid CDN rollout is a simple process: firstly, hardware is purchased and provisioned in multiple PoPs around a provider’s core users, to best provide both bandwidth savings and quality of service. These servers are then added to a private edge, separately from the global CDN service edge. Custom routing rules mean that traffic is routed to the best PoP, primarily to the private edge, with out-of-area users served from the global CDN and fail-overs so that traffic is served even in the event of outages and changes to the network. The customer will generally not pay for any traffic delivered from their PoPs but will pay a fixed rate for traffic delivered on their behalf from the global CDN service.

Traditionally, infrastructure would be sized to cope with even the highest peaks, along with redundancy which allows multiple components to fail and the traffic still be delivered. This can lead to hardware requirements well in excess of day to day needs, something which can be avoided by sharing disparities in traffic capacity and traffic actuality with a global network.

Private CDN built with SwiftCDN

SwiftServe CDN

Content

FederatedCDN

FederatedCDN

FederatedCDN

SwiftServe CDN

About ConversantConversant is a privately held technology company with a strong regional presence in Asia. We focus on developing and offering hybrid cloud based services for digital media enablement. As the digital media industry continues to grow rapidly around video content and mobile applications, our cloud based offerings enable content providers and network service providers to effectively monetise their digital content offerings. For more information on Conversant and our hybrid cloud offerings, please contact sales@conversant.com.sg or visit www.conversant.tv.

ConclusionIn conclusion, with increasing content consumption globally and many markets under-served for CDN capacity at the edge, Hybrid CDN allows growing media companies to build a CDN without the extra capacity needed to handle failures, out of country usage and extraordinary peaks. Alternatively, where more capital is available, Federation CDN offers a great way for businesses to build more complete infrastructure to increase quality of service, lower cost, generate extra revenue and also build future-proofed capacity. Without a doubt, Hybrid and Private CDNs are going to be key to establishing the edge capacity that consumers need in the coming years.

Notes on CDN adoptionThe drive for CDN usage is amplified by rapidly increasing HTTPS adoption, with many major video services and social media platforms moving over to secure connections, including YouTube and Netflix, who are completely encrypted. However, the difficulty in caching has forced many ISPs to look for other ways of moving the serving of content closer to their customers.

Getting content closer to the edge has major benefits, primarily the reduction in bandwidth over the core of the network: long, high-bandwidth connections tend to be expensive, and by moving the content to the edge, cost is massively reduced. If the link between user and content origin is under contention, with high round trip times and packet loss, effective, useful bandwidth will be reduced further, this in turn translate into huge benefit for both the infrastructure and the end user’s QoE.

In fact, over connections with high packet loss or high latency, and the poor Transmission Control Protocol (TCP) behaviour of clients and servers will lead to extremely low application layer bandwidth to the point where it is impractical to make large HTTP requests. By bringing the server to the edge, and tuning the upstream and downstream TCP behaviour, the connections can be better utilised and less time is spent resending over expensive links. Furthermore, with reduced upstream traffic, these links are naturally under less contention, resulting in much quicker connections.

Case Study: StarHubGo leverages the SwiftServe CDN Federation

Singapore telecommunications service provider StarHub has developed an OTT video streaming service called StarHubGo, which is bundled as part of its StarHub TV offering, and also sold as stand-alone service. To deliver the service, StarHub selected SwiftServe’s hybrid CDN. The CDN enables them to deliver streaming both on-net, while also being able to leverage the capacity and reach of Asia’s largest CDN Federation.

The scale of the SwiftServe CDN Federation is particularly crucial when StarHubGo provides coverage of extremely popular events, as was the case for the 2016 Rio Olympics or the Manny Pacquiao-Timothy Bradley fight in April 10, 2016. The Federation enables StarHub to “burst” beyond the capacity of their own CDN on-net capacity, to maintain a high quality service delivery to their customers.