“Look, Ma, no probes!” — Characterizing CDNs’ latencies with passive measurement

Something that comes up a lot at Cloudflare is how well our network and systems are performing. Like many service providers, we need to be engaged in a constant process of introspection to evaluate aspects of Cloudflare’s service with respect to customers, within our own network and systems and, as was the case in a recent blog post, the clients (such as web browsers). Many of these questions are obvious, but answering them is decisive in opening paths to new and improved services. The important point here is that it’s relatively straightforward to monitor and assess aspects of our service we can see or measure directly.

However, for certain aspects of our performance we may not have access to the necessary data, for a number of reasons. For instance, the data sources may be outside our network perimeter, or we may avoid collecting certain measurements that would violate the privacy of end users. In particular, the questions below are important to gain a better understanding of our performance, but harder to answer due to limitations in data availability:

• How much better (or worse!) are we doing compared to other service providers (CDNs) by being in certain locations?
• Can Continue reading