We have learned that Internet traffic volume is a key determinant as to whether peering makes sense financially. Video represents a proportionately larger amount of traffic when compared against e-mail, web browsing, and other traditional request-response messages. Amplifying the importance of video traffic is the fact that not only is it a larger amount of traffic, but it is also an increasingly popular type of traffic across the Internet. As it turns out, Content Delivery Networks (CDNs) are really good at distributing video to the edge for offloading to the last mile consumers.
Definition: A Content Delivery Network (CDN) is an entity that distributes web objects and network services as close as possible to the access network customers.
The CDN player (Figure 10-6) is similar to the Tier 2 ISP but instead of handling a steady stream of content, they distribute any “web objects” to caches at the edge. Today the service is priced the same as Internet Transit, so for modeling purposes we will make the simplifying assumption that the CDN is essentially providing transit - just a much better performing one due to the caching at their edge.
Figure10-6. The Content Delivery Network model.
Notes from the field.
CDNs Pushing Massive Traffic volumes
Around 2006, YouTube was starting to gain popularity and started using CDN services for the most popular most viral content. The community started noticing the CDN guys were deploying massive peering gear. At the time, most were peering at 1Gbps, and perhaps an occasional 10Gbps connection. I was traveling the peering speaking circuit with the CDN guys who were deploying 10G and occasionally multiple 10G connections to the peering infrastructure. To some CDNs, videos are just another web object to be distributed at the edge of their network. These objects however are very large, so the wakes set off by movement by the CDNs were starting to be felt in a big way. The CDNs, as very large volume open peers, quickly became significant players in the Internet Peering Ecosystem.