How does NDN differ from CDNs?

A content distribution network (CDN) is a good example of service that is implemented as an overlay on today’s TCP/IP architecture to meet the demand for scalable content distribution, when the same content is requested by many users. CDN customers tend to be relatively large content owners who are willing to pay for higher performance delivery of their content. Content producers without CDN services would face load and performance challenges if/once their content becomes popular.

CDNs operate at the application layer, which gives rise to two issues: how to get customer content requests into the CDN system (a common solution is for the CDN provider to host DNS service for the domain name of the content it serves); and mapping each request to the nearest CDN node serving the content. NDN works directly at network layer and naturally forwards Interest packets along the best paths to the desired data.

Are there any commonalities between IP and NDN architectures?

Both architectures share the same hourglass shape, with the IP/NDN layer as the narrow waist.
Both send datagrams.
Both follow end-to-end principle.
Both use their own namespace for data delivery (i.e. IP uses IP addresses to deliver datagrams between IP nodes; NDN uses the application name space to deliver datagrams between NDN nodes).

What will the role of ICN be on the Internet in 20 years? Will it be the dominant paradigm of communications?

It’s the dominant paradigm now. YouTube, Netflix, Amazon, iTunes, …, are pure ICN and account for more than half of the world’s internet traffic. But today’s ICN-over-IP is inefficient and unsecure because the information-centric overlay is a poor match to the Internet’s conversationally-oriented underlay. The Internet is also already mostly mobile devices (whose users are also content-focused), which the IP architecture does not support well.  Finally, the IP architecture was not designed to naturally support secure communication or secure data distribution. Rather than ignore the growing incongruity between the architecture and global use of the Internet, we are inspired to design, develop, and incrementally deploy an architecture that `catches up’ with the dominant paradigm of communications today.

This architectural incongruity is analogous to the one between packet-oriented IP overlay and circuit-oriented telephony underlay during the Internet’s first 20 years. Imagine the 1990 question “What will be the role of the internet in the global telephony system 20 years from now?”  We now know the answer was “the global telephony system became just one of many applications running over IP internet,” i.e., the overlay became the underlay because it did more, better. We predict we could substitute `Internet’ for `telephony system’ and `NDN/ICN’ for `IP internet’ to move the clock forward 20 years.


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