Multi-CDN Strategy: Benefits and Best Practices

What is Multi-CDN?

A CDN (Content Delivery Network) is a network of geographically distributed servers that brings web content closer to where end users are located, to ensure high availability, optimized performance and low latency. Multi-CDN is the practice of employing a number of CDN providers simultaneously. This method augments the performance benefits of using a CDN while also ensuring redundancy and resilience and reducing costs.

To implement a M-CDN, organizations can use traffic management tools or Multi-CDN switching solutions that distribute and route content across the various CDN providers. Distribution is dynamic and will be determined and optimized in real-time, based on factors like performance, geographic reach, costs, use cases, and real-time conditions.

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Benefits of a M-CDN

There are multiple advantages for a Multi-CDN implementation. Some key advantages include:

1. Network Redundancy

The primary and most important advantage of a Multi-CDN strategy is redundancy, and, consequently, improved reliability. Outages are a common occurrence; a global outage could take the entire network down while local outages could force the CDN vendor to serve the traffic from a non-local PoP. The result would be a performance drop in the end users’ experience, often causing the application to become unusable. While these occurrences take place "only" a few times a year, local outages happen on a weekly, or even daily, basis.

A M-CDN enables enacting a failover strategy with additional CDN providers that have not been impacted. This ensures up to 5-nines of availability, minimizes the impact of disruptions, enables meeting SLAs and reduces the risk of a single point of failure.

2. Enhanced Performance

Another significant advantage of using multiple CDN providers is the improved content delivery performance for end users. Different CDN providers cover different regions to different extents. When using a single CDN, the organization is dependent on the CDN provider’s geographical coverage and server infrastructure. This coverage may not align with the organization's needs at all times.

Distributing content across multiple CDNs allows switching to the CDN with the best coverage and lowest latency for each user at any given time. This will result in faster load times that improve the user experience.

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3. Cost Optimization

M-CDN setups can help optimize content delivery costs. This is done by selectively choosing when to use different types of CDNs. While high premium CDNs provide a full set of features - including security services, edge computing and more - these come at a high cost. Standard CDNs, on the other hand, provide a more basic set of features, but at a lower cost. Organizations can use premium CDNs for critical tasks while cutting costs when performing simple or lower priority tasks by using standard CDNs.

In addition, different CDN providers offer competitive pricing models and packages. Organizations can select the most cost-effective option for each region or traffic type, reducing overall CDN expenses.

4. Flexibility

Multi-CDNs enable network professionals, IT, and DevOps teams to maximize the benefits offered by different CDN vendors. They provide flexibility in pricing by allowing the selection of the serving provider in specific areas or for specific portions of the traffic. The multi-vendor approach also allows leveraging the unique capabilities, such as unique Edge Computing functionality, offered by different providers. This flexibility provides customers with more control, increased bargaining power, and prevents them from being locked into a specific provider.

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Best Practices for Implementing a Multi-CDN

While the advantages of a M-CDN are clear, implementation is not as straightforward. A cautious approach is crucial when transitioning to a M-CDN architecture. The configuration of new CDNs is intricate and prone to errors. Even minor misconfigurations can lead to disruptive traffic interruptions.

To ensure a smooth transition, it is highly recommended to take the following best practices:

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1. Cherry Pick Your CDNs

Conduct a thorough evaluation of different CDN providers based on the requirements from best practice #1. Consider factors such as geographic coverage, server infrastructure, performance, CDN scalability, pricing models, features, and support services. Evaluate how well each provider can meet your specific requirements and objectives. Narrow the final choice down to two providers, run a POC and A/B test them over the course of a few weeks to determine which one can best answer your requirements.

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2. Configure Your New CDN

To effectively configure your new CDN, you need to replicate the settings of your primary CDN. Each role, policy and behavior needs to be manually and meticulously configured to align with the new CDN's engine, utilizing its API. Then, rigorous testing is necessary to ensure it functions properly. Otherwise, the result may be a deteriorated user experience, traffic loss and service unavailability.

3. Transit the Traffic Safely and Gradually

Once the CDN is configured, it’s time to proceed with a seamless and uninterrupted traffic transition that is based on Multi-CDN switching. It is recommended to employ an active/active strategy in a gradual manner. Begin by directing a small portion of the traffic to the new CDN. Progressively increase the volume of traffic being routed through it until the desired level is reached and you can rely on real-time switching.

4. Implement Traffic Management Tools

Utilize specialized traffic management tools or solutions to implement and manage your M-CDN effectively. Implementing such tools simplifies the management of a complex Multi-CDN environment. These tools can help automate traffic routing, monitor performance, collect data for analysis, and dynamically adjust traffic distribution based on real-time conditions. Make sure to never starve a CDN vendor - always keep all vendors with a portion of the traffic to keep the cache warm.

Many organizations use a DNS switching service, which routes traffic between the different CDNs. However, this method can become too rigid when conditions are dynamic, as it does not adjust levels of traffic according to changing needs. A DNS switching service also does not provide visibility into the traffic, making traffic management challenging and less accurate.

Alternatively, a Virtual Edge solution, a technology developed by IO River, provides visibility into traffic while enabling traffic routing management through a single interface. A Virtual Edge also simplifies the CDN configuration process by enabling IT, DevOps or network professionals to configure the CDN only once, and without having to manually configure each one. Traffic can then be safely and gradually rerouted. In case of an error, a Virtual Edge solution also enables reverting to the previous configuration easily and quickly.

5. Monitor and Optimize Performance and Availability

Continuously monitor the performance of each CDN provider and the overall M-CDN setup. Use real-time analytics and monitoring tools to detect any downtime and outages and to gather metrics like response times, latency and availability. Analyze this data to identify areas where you can improve and optimize traffic distribution for optimal performance.

6. Implement Failover and Redundancy Mechanisms

Failover and redundancy mechanisms can help ensure high availability and reliability. Define backup plans and strategies to automatically reroute traffic in case of CDN provider outages or performance issues. This helps minimize service disruptions and ensures consistent content delivery to end users. Avoid any manual failover plans - they fail to execute when you need them.

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Next Steps for IT Infrastructure, Network and DevOps Leaders

A M-CDN can be very beneficial for your organization, ensuring your traffic is always optimized and all global users get first-class citizen treatment. When determining how to transition from a single CDN vendor to a M-CDN, the first and most critical step is to define your KPIs. This will help you ensure you are en route to the desired outcome.

When you begin the transition, make sure to take it slowly and implement the new setup gradually. It is also recommended to have experienced professionals accompany you throughout the process. They will help you avoid any mistakes and ensure you and your users can benefit from the reliability and improved performance a Multi-CDN can provide.

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To learn more about IO River, the most advanced Virtual Edge solution for your Multi-CDN strategy, click here.

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