I have been taking a free networking class from Stanford University’s online “open source” education platform. I have really been enjoying the first unit of the course as it has started filling in some gaps in the foundation of my understanding regarding networking, the internet, and TCP/IP. I highly recommend this to anyone that has been in IT for a while but has never taken a more “academic” approach to their work. Okay, so that is my plug for free education. You can check out more here if interested: https://lagunita.stanford.edu/

OSI 7-Layer Model, TCP/IP 4-Layer Model
One of the gaps in my understanding of networking has to do with the OSI 7-layer networking model and the more simplified TCP/IP 4-Layer model (which was developed by DARPA? and predates the OSI Model). I didn’t even realize there was anything other than the 7-Layer model until taking this class and furthermore didn’t realize that while the OSI model gets talked about and referenced more frequently, academia (I think… and perhaps the industry) is shifting to using the simpler 4-layer model for discussion, understanding, and development regarding networking. Please don’t take any of this as gospel truth, this is just my understanding based on coursework and reading. I also find it much easier to think about and reference the 4-layer model. If you are curious how the two compare, this technet article is an interesting read, Technet: TCP/IP Protocol Architecture. Okay, so for this article, I will be sticking with what I am most comfortable with at this point and will be talking about and referencing the 4-layer TCP/IP model and discussing how VPN works. (more…)