What Is a CDN and Why Is It Critical to Live Streaming?January 11, 2019
Video streaming is skyrocketing, causing an exponential growth in the content delivery network (CDN) market. By 2022, 72 percent of all internet traffic will cross CDNs — up from 56 percent in 2017.*
When delivering low-latency video streams across the world, you need more than just a single server. You need a CDN sprawling the globe. That’s why 10 of the top 10 streaming CDNs have Wowza Streaming Engine™ software built into their ecosystem.
Why are CDNs critical to live streaming and do you need one for your workflow? Read on to learn more.
What Is a CDN?
As the name suggests, a content delivery network (CDN) is a system of geographically distributed servers used to transport media files. This removes the bottleneck of traffic that could result from delivering streams with a single server, as they require only a single stream for each rendition of an outbound video.
Ever wondered how Amazon ships packages so quickly? A CDN works in the same way. Think of Amazon’s headquarters as an origin server, and Amazon’s distribution centers as edge servers.
When you submit an order to Amazon, the distribution center closest to you attempts to fill it. That warehouse will either have the product available to send directly, or they will request it from another distribution center.
Likewise, when you attempt to stream a video from a CDN, the edge server closest to you attempts to deliver it. The server will either have the media files cached, or it will send a request to another server that does.
Amazon streamlines delivery by distributing goods from these local warehouses, rather than shipping each item directly from their central hub. Content delivery networks streamline delivery by sending streams from local servers, rather than sending them directly from the origin server each time.
Hence, a CDN uses a large network of servers placed strategically around the globe to distribute content quickly. Once the content is posted, it populates all over the world. When a user wants to watch it, the CDN selects the server closest to them to deliver it. The media files remain ready for another user in the same area once cached on a local server.
What Are the Benefits of Using a CDN for Live Streaming?
By connecting servers across the globe, CDNs create superhighways that truncate the time it takes to deliver video streams from origin to end user. Sharing the workload across a network of servers also improves scalability should viewership increase.
Specific benefits of streaming with a CDN include:
- Scalability. This is the biggest selling point of using a CDN. It’s the fastest, most reliable way to get your content in front of numerous viewers anywhere in the world. CDNs can accommodate viral viewership spikes and larger-than-expected live audiences.
- Speed. CDNs deliver content at low latency. Other methods of streaming may use slower “side roads” to deliver content. But CDNs use speedy superhighways to send streams to vast audiences across the globe. While your ISP or local network may slow delivery down at the first and last leg, the CDN will bypass any traffic in between.
- Quality. Streaming through a CDN allows you to achieve the highest possible sound quality and video resolution. It also provides the best user experience by minimizing buffering and delays.
- Security. Finally, CDNs provide an extra layer of security. Streaming through a CDN can help prevent distributed denial of service (DDoS) attacks, which occur when a site or resource is flooded by multiple, simultaneous attempts to breach it. That’s because a redundant CDN with multiple access points enables failover. By comparison, you won’t have any back-up options when streaming with a single server.
When Is a CDN Not a Good Fit?
CDNs provide many benefits, but they don’t make sense for every use case. A CDN isn’t the best fit for the following scenarios:
- Small-scale streaming. If you have a small number of viewers and/or your geographic scale is limited, you probably don’t need a CDN. Generally, unless they are widely distributed, you can stream to all your users from a single server. The more elements you introduce into your streaming workflow, the more opportunities for failure — so why do so unless you have to?
- Limited budget. We recommend that you compare the egress cost to the cost of a CDN, as this can vary based on deployment. There are both paid and free CDN options available.
Paid vs. Free CDN Services
Using Wowza technology or another paid service comes with a near-guarantee of reliability and quality. On the other hand, free CDNs such as Facebook, YouTube, Twitch and other streaming services won’t break the bank — but you get what you pay for. Support is limited, and if something goes wrong during streaming, there may be no recourse.
These free services may offer access to huge numbers of viewers, but viewers will assume it’s your fault should any technical difficulties ensue. When the stakes are high, such as with hyped-up live events or important business meetings, your best bet is to use a paid CDN.
Types of CDNs
Most websites offering streaming use CDNs. For example, Google, Facebook, and Amazon have proprietary CDNs, and each one specializes in the particular type of service that they provide.
The Wowza CDN is built on top of Akamai’s, which deals specifically with audio and video transmission. Hence, our network is designed for getting this type of data to users with high reliability and availability.
And there’s more good news. The Wowza Streaming Cloud™ service automatically leverages the Wowza CDN to scale live streams on demand. Additionally, it’s available as an add-on stream target for Wowza Streaming Engine subscriptions. We also provide access to Facebook Live, YouTube Live, Limelight Networks, and TATA Communications.
Explore our product portfolio to find out which one is right for your streaming workflow.