The Benefits of a Multi-CDN Strategy

Increasing consumer demand for streaming video, online gaming, and downloads—along with growing expectations of quality of experience (QofE)—is causing content owners and distributors to rethink their content delivery strategies. The leaders in online delivery have discovered that blending multiple CDNs will provide their users with a higher quality viewing experience coupled with the opportunity to optimize delivery costs. Additionally, multi-vendor strategies offer more reliability and predictability when problems hit the global Internet. These competitive advantages have established multi-CDN architectures as a best practice in the industry.

Considerations for a Multi-CDN Deployment

Deploying IP video or other media on multiple CDNs goes beyond adding more of the same to the mix. And, it’s also not exclusively about reducing costs. The process involves evaluating each CDN based on coverage, speed, cost, scalability, competencies and flexibility.

CDNs vary dramatically in capability and performance. Not every CDN is functional for all purposes, and variations exist in geographic delivery footprints, feature sets and openness to participation in a multi-CDN fabric. Due to the differences between CDNs and their commercial objectives, careful evaluation of your needs and the vendor’s capabilities is crucial to identifying the optimal partners to add to your CDN mix. Here are some suggestions to get the most out of your multi-CDN environment.

1. Look for distinct network advantages
   Leveraging the advantages of multiple CDNs requires analysis of each CDN’s geographic coverage and architecture of their caching infrastructure, which can have a dramatic impact on overall performance and reliability. Take into consideration the location, quantity, and overall placement of caches.  Where are caches located? Are the caches connected through a network that is owned and operated by the CDN provider? How is redundancy managed across caches to handle failovers? An additional CDN that can optimize the positioning of content can improve consumer engagement. In addition, having multiple options in busy markets offers load balancing during peak traffic periods and reduces the risk of service downtime and outages.
2. Evaluate CDN strengths based on traffic type
   CDNs offer a wide range of solutions. Some are tailored to support video services, whereas others are focused on e-commerce site acceleration, security, or small object delivery. As online media consumption has exploded, some CDNs have not scaled to accommodate the file sizes required for certain content like large games or high bitrate video. They may also lack a robust set of features tailored to support a true broadcast-quality video experience.

When considering a multi-CDN strategy, make sure the individual CDNs can support, or perhaps even specialize, in the specific applications that are most important to you. For example, a CDN that is purpose-built to transport video and large objects is critical for any streaming video service and can be a valuable addition to your network architecture.  Additionally, understand the goals of the vendor; do they align with your goals and initiatives of delivering the best service to customers and subscribers?

1. Determine how to blend CDNs
   A good multi-CDN implementation makes the best routing decisions for each user based on a number of weighted variables.  Routing can be predetermined based on a specific geo/network, real-time performance statistics or cost. You will need to decide if you want to engineer this capability directly into your application or use an external vendor. Simple DNS or HTTP routing based on geo/ASN is fairly straightforward to develop but does require development cycles and ongoing maintenance. Additionally, vendors, such as Cedexis and Conviva, use real-time statistics (e.g. response time, cold-start times, etc.) on CDNs to automatically route traffic to the best performing CDN.   
2. Gauge each CDN’s flexibility and avoid proprietary “traps”
   When considering a potential vendor to add to your existing fabric of CDNs, it is important to determine if they truly embrace a multi-CDN approach, if they can seamlessly integrate into your multi-CDN strategy, and if they will provide long-term value. Are their features based on open standards, which will operate seamlessly across multiple CDNs, or are they using proprietary methods and technologies as a means to lock customers exclusively into their CDN solution?  How flexible are the terms and structure of the contract?  Do commit levels or other obligations hinder (as opposed to facilitate) utilizing other CDNs?  Also, if utilizing your CDN provider for origin services, will all CDNs have equal access to the originated content or only the CDN providing the origin? Look for multi-CDN partners with an open, standards-based architecture and simple agreements that facilitate, versus hinder, the use of a multi-CDN environment.

Strategic implementation of multiple CDNs is the best path to ensure you are competitive, now and in the future. Multiple CDNs enable you to establish a hierarchical distribution of content across multiple tiers of caches and different networks, helping to optimize performance, reduce delivery costs and increase reliability. Most importantly, multiple CDNs enable better user engagement, which leads to higher subscriber retention, faster growth, and additional advertising revenue.

Given the rise and projections in online media consumption, now is the time to consider deploying multiple CDNs. And, if you currently operate a multi-CDN environment, now is the time to evaluate your mix of providers to ensure the initiatives most important to you are fully supported.