How to Reduce Egress Traffic Costs with a CDN

For many customers, egress traffic (the amount of data transferred out of their origin infrastructure) is a primary cost driver. Egress is particularly a huge cost element for video and audio streaming customers as well as large download providers. To provide our customers with a better view of this, we introduced a new metric: Origin Offload.

Origin Offload measures the ratio of bytes served to end users that were cached inside the CDN (not fetched from the origin), over total bytes served to end users for the service. An Origin Offload of 100% means all bytes were served from the CDN.

Benefits of Origin Offload

One of the key benefits of a CDN is to serve as much as possible from cache and offload as much traffic as possible from your servers at origin. This can translate into cost savings through (sometimes massive) reductions in egress charges, but it can also reduce your costs in other ways. If your origin servers are protected from traffic spikes, bot attacks, and generally made to handle a small percentage of requests, then you can reduce the number of servers you’re running and cut your CapEx and maintenance expenditures as well.

Choosing one specific POP to serve as an origin shield gives you a guarantee that all other requests, even from other POPs on the CDN network, will go to that POP rather than your origin server in order to provide the maximum amount of offload from your servers, and ensure that the CDN is handling as much work for you as possible. Another feature you’ll want that helps with offload is request collapsing. This bundles multiple requests for the same piece of content across the entire network so that your origin only has to serve that content once rather than individually for each request. This is particularly useful if a piece of content expires out of cache and then at a later point there are many concurrent requests for it across the network.

You can also look for CDNs that can keep your content live and in cache longer. “Least recently used” (LRU) refers to content that a POP deletes from its memory because it’s in low demand, to make room for other content that’s in higher demand. More powerful POPs are built with higher-end and higher-capacity components that can store more and therefore expire it less often. With more powerful POPs, your content is subject to deletion as LRU less often. The CDN will store it longer and handle more requests without going back to your servers. By contrast, POPs with less storage capacity must delete LRU content much more often to make room for the other content they’re serving. Every time your content cycles out of their cache they need to go get it from your origin servers. If hundreds and hundreds of POPs on a global network regularly need to re-request content from your origin because it’s always cycling out of cache, it will add up to significant costs.

Many organizations need to use multiple CDNs in combination. Some CDNs can be difficult to manage efficiently alongside their counterparts or don’t have features to help you coordinate a multi-CDN strategy, but that’s not true for all CDNs, especially about origin shielding. Selecting a CDN that helps coordinate the shielding between your origin and ALL of the CDNs that are a part of your strategy is key to maximizing both your performance and cost efficiency.

Save on Egress with a better CDN

Regardless of who you are or what industry you work in, you still need to take advantage of a huge opportunity to save big by reducing egress charges, reducing the amount of traffic to your origin, and providing a better and faster user experience.

If you’re looking for further help assessing your CDN options, download the Definitive CDN Buyer’s Guide. It contains helpful insights on performance and much more. Get help evaluating across topics like infrastructure, origin shielding, real-time features, configurability, reliability, logging, and pricing.