By Nabil Kanan, Principal Product Manager

More and more media companies are transitioning to a multi-CDN strategy to stream content across multiple networks to achieve greater scalability and optimize the quality of experience (QoE) for their subscribers, as well as for disaster recovery and business contractual reasons. In addition, having greater control over content distribution is enabling these companies to benefit from better pricing deals, more capacity, and service reliability. However, much like choosing the right CDN, selecting the right multi-CDN solution requires a thorough understanding of a company's individual needs and how best to optimize its content delivery.

Why use a multi-CDN?

Spreading traffic over more than one CDN has several advantages. It protects broadcasters and content providers against slowdowns and downtime; if one provider's network experiences an outage, traffic can be routed through another network. Also, adding CDN capacity in more geographic locations, guarantees that content is loading as fast as possible and at the needed video bitrate, regardless of the end user's location. Lastly, by sending content via the best performing CDN, content providers can expect faster startup times, less rebuffering, and high-quality video playback resulting in happier, loyal subscribers.

What to look for in a multi-CDN solution

Regardless of how much control and customizability a customer wants for their multi-CDN approach, there are a few key elements that all good solutions share.

• They integrate with existing workflows. On a baseline level, any multi-CDN solution has to support existing tools and workflows. Some solutions sit on top of existing workflows, introducing new complications to the system instead of seamlessly integrating with it.
• They track quality metrics. The ability to switch between CDNs is only as useful as the data informing the decision. That's why it's important to have a comprehensive data pipeline providing critical information to a decisioning engine. This lets broadcasters and content owners know how a shift in CDNs is impacting traffic and the end user's experience.
• They offer a wide choice of CDNs. Any good multi-CDN product should give customers the flexibility to select any available CDN and any distribution configuration, rather than locking them into a narrow set of options.

Smartplay Stream Routing

With Stream Routing, Verizon Media's multi-CDN solution, customers exercise a great deal of control over how their content is delivered with the flexibility to control what content is routed to which CDNs at any given time, for every event, every channel, and over different geographic regions. This is very advantageous if a company needs to honor pre-existing commitments to particular CDN providers or needs a single additional CDN to operate in a specific region. 

Recently, we expanded our solution to give customers additional flexibility in how they optimize their video delivery worldwide. With dynamic decisioning, customers can augment their configured rulesets for content distribution and further optimize performance across multiple CDNs. This approach operates like a meta-CDN, automatically redirecting video streaming traffic and load-shifting to ensure consistent video quality at all times. Our solution is CDN-agnostic meaning that decisions about where to route traffic are made purely on performance metrics with data originating server-side as well as client-side. 

The following diagram outlines the key areas and benefits of our multi-CDN solution:

1. Data aggregation: One key advantage of the data we acquire to inform stream routing decisions is the ability to capture input from Verizon Media O&O properties (i.e., Yahoo) in addition to other third-party data and server-side integrations with real-time logging (where available) from third-party CDN providers. This gives a more comprehensive view of the state of the network and delivery options feeding our decisioning engine.
2. Decisioning: The decisioning engine incorporates the information from the customer's configured rulesets with the aggregated data and leverages prediction algorithms and Verizon Media's deep and proven expertise in optimizing delivery across multiple CDN's to get to the optimal decision for a given session. This decision instructs the manifest server to update the URLs being communicated to the player to fetch media content. 
3. Switch: The manifest server that maintains 1:1 sessions with individual players acts as the "switch" in steering traffic optimally across the available CDNs. Rather than using external network devices like load balancers, this solution means the high availability architecture available with Smartplay's manifest server is acting natively to instruct the player to fetch content from the optimal CDN. 
4. Media content serving: With the selected CDN signaled to the player through the manifest, the player then proceeds to request the media content from that CDN. In the case of a cache miss, the CDN will ultimately do an origin fill from the Verizon Media platform's media origin server, and the content will be cached appropriately for subsequent requests from that edge part of the selected CDN.

The movement toward multi-CDN began with media conglomerates who needed the bandwidth for video streaming on a grand scale. Today, a multi-CDN approach is accessible and affordable for companies of any size that want fast, reliable content delivery. 

To see a demo of Smartplay Stream Routing, visit Stand 5.B64 at IBC this month in Amsterdam. Schedule a meeting now.