Over 80 per cent of the top 10,000 websites are using a Content Delivery Network (CDNs) to distribute everything from webpages, video and games to downloadable objects, streamable media, and software updates. Brands and website owners rely on them to provide a dependable, geographically spread solution to deliver their content - often to a global audience - and as such, it’s a market predicted to grow in value from $10.9 billion in 2018 to $24.9 billion by 2025.
They play a vital role – without a CDN, content is served from the original location. This uses more processing power and bandwidth, taking longer to reach the user and resulting in increased load and an inferior user experience. However, with a CDN, content is ideally served from the closest CDN server. Delivery from the cache server reduces load on origin servers and provides content to the user faster, resulting in a superior user experience.
Reliability and performance are absolutely key because CDN failures can have a serious knock-on effect on the performance of the websites they serve. Recent examples of CDN downtime have often been made worse for brands who lost availability because they were using a single, pure-play CDN (a single provider using their own infrastructure). These are often designed as the most economical option and it doesn’t always follow that users will get the best performance.
The big challenge for single CDN strategies is that although they are sold on the basis of their speed, security and high availability, it’s not possible for a provider to guarantee 100 per cent uptime and the best performance all the time. In contrast, a multi-CDN strategy can increase global reach, while delivering high quality content and user experience, regardless of location. It also spreads the risk and minimises the impact of downtime.
How to build a multi CDN strategy
As a real-world example, imagine a situation where a local broadcasting company offers online video streams in their home country. Their national and local traffic patterns are predictable and the broadcaster has enough demand to justify building a tailored and dedicated private CDN within that country. However, the broadcaster also wants to give users abroad an optimal experience, which will require a more geographically dispersed approach.
In addition, the broadcaster also has various unpredictable live events (a sporting event, for example) for which viewer numbers are unknown and unpredictable. The broadcaster does not want to deploy and pay for the extra infrastructure and connectivity to handle the spikes for these events as they normally only last a few hours, while the rest of the time it sits mostly idle. This is where a multi-CDN approach comes in – the majority of the national traffic is handled by the company’s private CDN deployment, but it has the ability to offload overflow traffic to the multi-CDN to achieve global reach and near-infinite local scale. This way both its global users and live events are delivered optimally in any given scenario.
There are numerous other use cases, but for any organisation designing a multi-CDN strategy, it’s a good idea to build a foundation based on traffic type and typically application requirements. Ideally, the strategy leverages performance metrics in the decision-making process by selecting the ‘best’ performing CDN, i.e., the service receiving the highest score across the board. In that case, the evaluation is based on new QoE metrics for the specific region and specific pieces of content in question, alongside the ISP and end user devices accessing the content.
Aside from those top-level strategic points, there are also issues around reliability, performance and cost to consider:
- Reliability: Major providers will emphasise their reliability data and the ambitious uptime objectives they set. While that’s important, no organisation is immune to technology downtime, security problems or acts of god. A multi-CDN strategy can spread the reliability risk and give site owners confidence that the reliability of their entire network is not a risk from a single point of failure.
- Performance: Multi-CDNs are usually deployed as a combination of various PoPs from different CDN providers, typically offering more PoPs across a wider area than single-CDN vendors. Not only does this ensure optimal performance, but it can be scaled according to need right across the world.
- Cost: Configuring a multi-CDN solution presents both opportunities and risks. Typically, custom tooling is needed to integrate the various service providers. Challenges can arise when organisations do this manually across several providers, because errors can creep in, sometimes further complicated by how the respective CDN networks set up requirements of each service. As a result, the time and expense can add unnecessary cost, and even when deployed, there is often more tuning and changes that need to take place, which can also add to the budget.
However, using a single provider to manage services seamlessly over the connected CDNs means it implemented as one solution. This removes the burden of having to manage multiple CDN providers at the same time. Distributing traffic volume over multiple CDNs also means the flow is shared across each individual network, and because of this perceived decrease, a vendor may in fact charge more. This issue can be avoided when a multi-CDN strategy via a single managed provider, who can aggregate the traffic and ensure better purchase power across the individual CDNs.
Against the backdrop of rapid data growth and media consumption, organisations operating single-CDNs may find it beneficial to revisit their approach. Think of it this way: according to Statista, as of July this year over 4.33 billion people were active internet users, which effectively translates into 56 per cent of the world’s population. We now live in a hyper-connected world with expectations of 100 per cent uptime, at all times. For those organisations that rely on content delivery for part or all of their revenue, this can only be achieved with a strong multi-CDN strategy, for better user-experiences through more coverage, performance and redundancy.
Wilfried Dudink, Managing Director, Leaseweb CDN