Edge Locations:AWS Global Infrastructure

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What is a edge location?

The final major piece of the AWS infrastructure puzzle is its network of edge locations. An edge location is a site where AWS deploys physical server infrastructure to provide lowlatency user access to Amazon-based data

That definition is correct, but it does sound suspiciously like the way you’d define any other AWS data center, doesn’t it? The important difference is that your garden-variety data centers are designed to offer the full range of AWS services, including the complete set of EC2 instance types and the networking infrastructure customers would need to shape their compute environments. Edge locations, on the other hand, are much more focused on a smaller set of roles and will therefore stock a much narrower set of hardware.

So, what actually happens at those edge locations? You can think of them as a front-line resource for directing the kind of network traffic that can most benefit from speed.

Edge Locations and CloudFront

Perhaps the best-known tenant of edge locations is CloudFront, Amazon’s CDN service. How does that work? Let’s say you’re hosting large media fi les in S3 buckets. If users would have to retrieve their fi les directly from the bucket each time they were requested, delivery—especially to end users living continents away from the bucket location—would be relatively slow. But if you could store cached copies of the most popular fi les on servers located geographically close to your users, then they wouldn’t have to wait for the original file to be retrieved but could be enjoying the cached copy in a fraction of the time.

Regional Edge Cache Locations

In addition to the fleet of regular edge locations, Amazon has further enhanced CloudFront functionality by adding what it calls a regional edge cache. The idea is that CloudFront- served objects are maintained in edge location caches only as long as there’s a steady flow of requests. Once the rate of new requests drops off, an object will be deleted from the cache, and future requests will need to travel all the way back to the origin server (like an S3 bucket).

Objects rejected by edge locations can be moved to the regional edge caches. There aren’t as many such locations worldwide, so the response times for many user requests won’t be as fast, but that’ll still probably be better than having to go all the way back to the origin. By design, regional edge cache locations are more capable of handling less-popular content.