Every time someone asks me about Multi-CDN, I can already see where the conversation is going.
“Do I really need it?” → Probably.
“But isn’t it a nightmare to set up?” → Not if you know what you’re doing.
When it comes to live streaming, you never know where your end user will be watching from. If your audience extends beyond a single city or country, sooner or later you will need to consider using a CDN (Content Delivery Network).
But here’s where things get tricky—locking yourself into a single CDN provider can be painful.
Why?
No single CDN performs equally well everywhere. Some regions will have latency issues, lower bandwidth, or poor ISP compatibility.
Even a reliable CDN isn’t foolproof. Outages happen, ISPs have issues, and—let’s be honest—things break.
CDNs can disappear overnight. Remember Edgio? (R.I.P.)
Given all that, the logical solution is Multi-CDN—using multiple CDNs in tandem to ensure better performance, reliability, and resilience.
A Multi-CDN strategy helps mitigate these risks, preventing outages and regional slowdowns while delivering an uncompromised quality of experience for your audience.
But just having multiple CDN accounts isn’t enough—how you implement and manage them is what really makes the difference.
Here’s what actually matters…
The Right Way to Implement Multi-CDN Switching
Can’t I just sign up for a few CDNs and call it a day?
Not really. If you want to deliver a flawless user experience, you need to go a step further.
Multi-CDN isn’t just about having multiple CDN accounts—it’s about how you route traffic between them and how you switch if something goes wrong.
The Three Approaches to Multi-CDN Switching
There are three main techniques to direct the end user to a particular CDN:
DNS Balancing: The Easy but Limited Approach. By manipulating the DNS records, you can distribute the load evenly among several CDNs or remove one in case of failure. This approach is very simple to implement, but lacks flexibility. You’ll soon find that it’s not enough.
Server-Side Switching: Smarter, But Not Perfect. A more advanced method where the backend decides which CDN to use. When a user requests a stream, the backend analyzes their IP and metadata, then returns a link to the best CDN or redirects them. This works well—until you need seamless mid-stream switching.
Client-Side Switching: The Ultimate Solution. This is the most sophisticated approach, requiring implementation on both backend and client apps. A pre-ordered list of CDNs is sent to the client app along with the stream manifest. The player can switch CDNs dynamically if performance drops.
The Good News?
You may think that developing client-side switching for each platform is too time-consuming, and you would be totally right.
But here’s the kicker… your player already knows how to do this.
Back in 2021, Apple introduced Content Steering as part of the HLS standard—a game-changer for Multi-CDN switching. With Content Steering, you can not only send a list of alternative CDNs to the client but also manage their priorities on the fly without interrupting the stream itself. The technology proved so effective that DASH-IF adopted it for MPEG-DASH.
The best part is most major players already support it:
- Apple AVPlayer (iOS/macOS/tvOS)
- Video.js, Shaka Player (Web/SmartTV)
- Roku and more
The Bad News?
ExoPlayer (Android) still doesn’t support Content Steering. But don’t worry—we are going to help Google with that soon…
It turns out, in order to get a Multi-CDN setup right, all you need to do is form the right manifest according to the content steering specification.
Well… almost.
How Do I Decide Which CDN to Use?
Okay, I have multiple CDNs… but how do I decide which one to use for each user?
The answer? QoE (Quality of Experience) Metrics.
QoE metrics help determine which CDN performs better for a specific user. If you’re already collecting data from your client apps, great—you’re in good shape. If not, start now. But do not rush to hire a team of engineers—you can enable this with just one setting in your player.
Thanks to the Consumer Technology Association (CTA)™, we have a standardized specification:
Common Media Client Data (CMCD)—a protocol that allows media players to send key performance metrics with every request.
Why Does CMCD Matter?
Using CMCD, you can enrich your CDN logs with client-side performance data, including:
- Buffer length – How long playback can continue before rebuffering.
- Rebuffering ratio – The percentage of time spent buffering vs. playing.
- Throughput – The measured download speed during playback.
- Average and top bitrate – The typical and peak streaming quality experienced.
- Playback duration – How long the user actually watches before stopping.
You can group requests by playback session and evaluate session success from the user’s perspective. By averaging session scores over time, you get a real performance ranking for each CDN—helping you make smarter routing decisions.
How Content Steering Works
Step 1: Manifest Request:
The client app (on mobile, TV, or web) requests a stream manifest from the Content Steering service.
Step 2: Manifest Optimization:
The Content Steering service retrieves the original manifest from one of the CDNs and modifies it by embedding content steering tags. These tags list multiple CDN options based on business rules and real-time CDN performance metrics from the QoE service.
Step 3: Content Loading and Feedback Loop:
- This data is collected by the QoE service, which continuously analyzes CDN performance and informs future steering decisions.
- The client app starts streaming content from the highest-priority CDN.
- It periodically refreshes the steering manifest to update the CDN priority.
- With each request, the client app sends Common Media Client Data (CMCD) statistics to the CDN.
Figure 1. How Content Steering Works
How Does Multi-CDN Impact Playback Security?
For a single-CDN setup, authentication is straightforward—you use tokens, geo-restrictions, or both.
But with Multi-CDN, authentication gets tricky. Why?
- Every CDN has a different token implementation.
- Some CDNs (e.g., CDN77) use a token in the path.
- Others (Akamai) have a short access token in the query and a long session token in the path.
- Each CDN has its own parameters and hashing methods.
Bottom line: You’ll need to implement a token generator for each CDN to secure your stream links. There’s no way around this.
Won’t Multi-CDN Increase Traffic to My Origin?
Yes. Live streaming is NOT cache-friendly.
Media playlists update frequently, making a 100% cache hit ratio nearly impossible. As your audience becomes more distributed, origin traffic spikes increase, putting additional strain on your infrastructure. With Multi-CDN, the issue is further amplified since multiple CDNs pull content from the origin, leading to even higher traffic loads.
The Solution? Shielding.
To protect your origin, use shielding, where edge servers request files from intermediate PoP instead of the origin server.
You can even use one of your CDN as a shield—but be careful to avoid a single point of failure.
Technical challenges are just one part of the equation—scalability, costs, and operational complexity are equally important when deciding whether Multi-CDN is the right approach.
Business Considerations: Is Multi-CDN Worth It?
At this point, you might be wondering—is Multi-CDN worth the extra complexity?
From a business perspective, three key factors matter:
Reliability & SLAs: Relying on a single CDN means your uptime is only as good as your provider’s. Multi-CDN reduces risk, but ensuring a consistent QoE requires active monitoring and smart traffic steering. :
Cost vs. Performance: Multi-CDN can help lower costs by dynamically routing traffic to the most cost-effective provider. Some CDNs offer better pricing in specific regions, allowing for strategic cost savings. However, the trade-off is managing multiple contracts, pricing models, and operational complexity.
Complexity & Automation: Adding more CDNs increases complexity—manual traffic routing simply doesn’t scale. But with strong automation and real-time decision-making, you can turn that complexity into a strategic advantage, ensuring smarter traffic distribution and seamless failover.
The Takeaway? Multi-CDN boosts reliability and cost efficiency, but success depends on smart routing and automation.
Conclusion
Relying on a single CDN is a high-risk strategy. A Multi-CDN approach helps mitigate regional issues, prevent failures, and ensure seamless, high-quality streaming. By leveraging intelligent traffic routing, client-side switching, and QoE metrics, you can dynamically optimize delivery in real time.
Standardized technologies like Content Steering and CMCD make Multi-CDN adoption easier, but implementation challenges remain.
The good news? With the right setup, you can turn complexity into a competitive advantage. And that’s where we can help—Setplex’s Streampool provides automated Multi-CDN switching, smart traffic routing, and real-time performance optimization, so you can focus on delivering an uninterrupted streaming experience.
Curious about how to implement a Multi-CDN strategy for your platform?
Setplex helps streaming providers seamlessly integrate Multi-CDN. Whether you’re looking to reduce downtime, improve QoE, or automate CDN switching, we can help you get there—without the complexity.
Connect with Sergey on LinkedIn.
Book a demo of Streampool to see how Setplex simplifies Multi-CDN.
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