Since you will be filling in the details through your readings, I wanted to focus on two conceptual areas which I think will really help tie together the details into a larger framework for understanding the historical trajectory of development on the Internet.
First, networks… they come in all sizes, but the ones you’ve probably heard about are a LAN (Local Area Network) and a WAN (Wide Area Network). Obviously, they are both networks, and the important thing to realize is that there is not a clear line delineating the two (unless you are a techie). It depends on your perspective when defining the network you are referring to. For instance, inside the Bloustein building, there are likely several separate LANs (at least two) that connect to a WAN (College Ave). But then the College Ave WAN connects to an even larger WAN (New Brunswick). And perhaps the New Brunswick campus connects to an even larger WAN (Rutgers University). I’m not saying that’s exactly how it is, but I think you get the point of the example… there are LANs within LANs, within WANs, within WANs. Confused yet? I think that the graphic contained in this blog post does a great job of explaining it visually, in terms of the history of the Internet.
Blog link: Dion Hitchcliffe’s Web 2.0 blog
Second, layers… a very important concept to understanding what makes your web experience “seamless”. The Internet is more or less built on the OSI model, which is a layered model. You can see some images here:
Google image search: http://tinyurl.com/yv9he8
Without getting into detail, I’ll do a quick summary.
| Layer 1 (physical) | cables and electricity |
| Layer 2 (data link) | your network card (wireless or wired, Bluetooth or cellular) |
| Layer 3 (network) | cable modems and routers |
| Layer 4 (transport) | “Hey, did you get my message? If not, I’ll send again” |
| Layer 5 (session) | handling multiple conversations (think instant messaging) |
| Layer 6 (presentation) | interpreting between different computer languages |
| Layer 7 (application) | AOL Instant Messenger, Firefox |
Basically, if you start at layer 7, communication heads down the “stack” of layers, and then gets passed up the “stack” on the receiving end. More detail below.
Permanent site: Answers.com – OSI Model
To wrap up, networks and layers are crucial concepts to understanding the Internet. To give you a preview of what’s coming next, the new wave of “mashups” such as Google Maps, video sharing, wikis and blogs fit into the OSI model as new Layer 8, what I will call “platform”. It’s something you use, but you still need a host application to run it. More on that next time…
