Tag: OSI Model

Previous article:

• OSI Layers 1 & 2

Layers 3 and 4 are then “network” and “transport” layer, respectively.

While layer 1 and 2 had to do with local traffic, the next two layers create the standards and protocols by which all these local networks can talk to each other (“internetworking”).  They scale to a global scale.

OSI Layer 3 – Network Layer

The network layer that currently dominates the world is the IP protocol.  Nearly everyone has heard of an IP address by now, probably in frustration as they tried to configure a home device or internet connection.

The power of the IP protocol is in its superior route-ability.  There have been other protocols that work well in certain circumstances, but IP proved to be the brilliant solution that literally created the internet.

IPs superior routability stems from it’s super simple addressing scheme, in which you take a bunch of numbers (an address), apply another set of numbers (called a mask) and end up with a neatly sliced network-host dileneation.

You can think of the network as the street you live on, and the host as the house in which you live.  In the following examples, the blue is the network/street, and the red is the host/house.

3472 Oak Street

10.29.44.6

But IP addressing is far more powerful than a street address, in that the networks can then further be sliced up using masks.  A mask is another set of numbers that defines which part of the address is being addressed.  So you could further say:

Cleveland, Ohio

10.28.44.6

Where orange is the locality and green is the larger area.  This slicing can get even more granular and complex as needed.

I won’t risk complicating a simple and elegant system in trying to address it in one blog post.  But the upshot is that millions of devices called routers can reliably and effectively transport huge amounts of data through multiple other routers and back.  It’s not uncommon for traffic to go through 10-20 routers on its way to a destination.

OSI Layer 4 – Transport Layer

Layer 4 is the layer that defines a conversation.  Take this human example of TCP (Transmission Control Protocol):

Sally: Hello is this joe?

Joe: Yes!  This is joe.

Sally: Great!  Here’s some info…..*garbled*

Joe: I’m sorry, can you repeat that?  Also can you speak a little slower?

Sally: Sure…here…is….some…information…for you.  Did you get that?

Joe:  Yes I got it. I will deliver it to the appropriate party.

This conversation is a representation of a TCP conversation that happens trillions of times a day.   In contrast, here’s an example of UDP (User Datagram Protocol:

Sally:  Hey, I’m shouting this to Joe!  Joe, if you can hear me here some information for you!

Both of these conversations do essentially the same thing, but with a different set of requirements.  These requirements are defined by a layer 4 protocol.

Across layer 3 and 4, there are several protocols and combinations of protocols that assist communication.  They help control speed of transmission, choosing the best route between hosts, and several other critical functions that help ensure data gets from point A to point B.

Implications for Freedom and Democracy

The creation of a redundant, reliable packet-switched (vs. circuit-switched) network of communications was created for two reasons.  First, the number of computers in the world was very small, and people needed access to them without being physically present.  Second, the military needed a way to maintain control of nuclear resources and communications in the even of a nuclear war.

These two goals are somewhat in dispute.  And that makes complete sense given the supply of movie plots where scientific discovery was unwittingly being used for the military.   It’s pretty obvious that everyone involved had their own goals in mind.

But, the implications for today are clear.  Using these technologies, you can send data reliably from a very localized device to another very localized device anywhere around the world.  We are seeing this play out now in Ukraine.  This is a unique enough situation that I will post about it separately.

Because these systems were designed to create access via large scale, they ensure that anyone in the world can communicate with another.  They can do this directly and without reliance on a mediator or central 3rd party.

Because these systems were designed, at some level, to survive nuclear hostilities, they are inherently robust and redundant.  Getting in the way of these connections is very hard.

Freedom loves communication and the free flow of information.  Indeed, it depends on it.  Layers 1-4 are great enablers of freedom.

Next articles:

• OSI Layers 5 & 6
• OSI Layer 7

 

 

So let’s look at the first 2 layers of the OSI model.  These are the “Physical” layer and the “Data Link” layer.  These layers are separate and distinct, but in practical application they are usually part of the same implementation.

The physical layer (layer 1) is, as it implies, concerned with the physical elements of a connection.  Voltages, pin-outs, mechanical considerations, connectors, etc.  In the case of fiber optics, it deals with wavelengths and supported configurations such as single or multi mode.  Because it is physical, this layer tends to be focused on local networks or networks with fewer participants.

Because of the radically different technologies out there at the physical layer, there is not really a standard unit of data.  It can be very different depending on topology.

The Data Link layer (layer 2) defines the formats of data that will be communicated on top of layer 1.  How data is divided up into chunks, how things on a local network will be  addressed (such as MAC addresses), and how a system will know what chunk of data belongs to which device.  These are usually called “frames”.

For layer 1 and 2, most people will have used twisted pair ethernet or various forms of WiFi.  If you used a computer at work in the 80’s or 90’s, you may have used other forms of Ethernet or even Token Ring.  If you’re really fancy, you may have fiber ethernet coming to your house.

Whatever the case, the implication for freedom and democracy is interoperability.  Layer 1 and 2 ensure that your devices can talk to each other at the most basic level.

Information is very important to freedom and democracy.  Indeed, it’s why the 1st amendment exists and has been upheld and bolstered as technology advances.  Being able to consume and produce information freely is vital to the concept of liberty.

We forget than not too long ago our television, our record player (or 8-track!), our camera, our phones, and anything else all lived in separate worlds.  You couldn’t listen to a podcast or stream a news channel across the platform of your choice.  Or, more importantly, you couldn’t make a podcast or vlog from the platform at all.

Layer 1 and layer 2 interoperability allows your phone to stream a video connection to loved ones.  It allows you to listen to a podcast.  If you don’t like the selection of news channels, you can download and view another in the local medium of your choice.

It makes it extremely easy for manufacturers to create cheap and reliable tech that allows all of this.  If one tries to make things too proprietary, other things wont’ work with it.

(Having said that, you can also see the creators  intent and values of layer 1 and 2 technology.  If you’ve ever setup an ethernet network or even a more modern WiFi network, it’s still a pretty localized technical process.)

Layers 1 and 2 are important because they are closest to us.  And the bring the concepts of electronic freedom into our living room.

Next articles:

• OSI Layers 3 & 4
• OSI Layers 5 & 6
• OSI Layer 7

If you got this far past the title, you’re either a techie, or really bored, or both.  But I think it’s a really important juxtaposition in understanding the current state of things.

Marshall McLuhan coined the term “The medium is the message” in the 1960’s book Understanding Media: The Extensions of Man.  I haven’t read this book yet, although I’ve ordered it.  I have watched a few of his interviews.

McLuhan’s point was that the overall effect of a communication medium is far more important that the specific message conveyed.  The effect of television on humanity is for more important than a television show.  An example I can think of from my generation is that MTV’s effect on youth was not so much based on the content, but on the overall effect of television’s ability to capture the attention of people our age and change our thoughts and values.

This thought emerged from the primordial ooze of electronic communication in the 1960’s.  How profound is the message today?  Just look around at people staring at their phones, or the number of phones hoisted in the air during a concert.  Is what the people recording or reading nearly as important as the effect the smart phone has had on everyone?  I look forward to reading more of McLuhan’s work.

I have personally found this assertion directly observable in the creation of this blog.  Even after 2-3 blog entries I’m experiencing an increase in wonder and learning that I had back 20 years ago when the blog concept first manifested.  This form of electronic medium seems to have a positive effect on me, at least.

So to connect dots with McLuhan,  I am delving into my own related theory of tech with this blog: The intent of the creator, and values of the creator, have significant effect on the capabilities of a created technology.  And further, if we understand the intent and values of the people who created the technology we can apply this info in ways that help us fulfil our own goals.  This seems obvious but hopefully I’ll demonstrate that it isn’t always obvious.  (It’s probable that none of this is original thought.  I just haven’t found it illustrated anywhere else yet.)

The 3rd critical idea that enters this arena is the Open Systems Interconnection (OSI) model.    The OSI model is a conceptual model that helps design and explain interoperability between systems.  It is a good way of separating and identifying the technologies that are a part of nearly every aspect of our lives ‘these days’.

Because the OSI model describes 7 layers of communication medium, we can use it in concert with the prior concepts to start to figure out what happened, what’s currently going on, and where it can all lead.  We can do this at all 7 levels.  (And I’ll argue that there’s an 8th.)

Let’s squish all this together.  We can parse the building blocks of our electronic experience using the OSI model.  We can then use some of McLuhans ideas to analyze the effect of each of these aspects.  We can also look at the intent and values of the creation/creators to gain further insight into how the mediums can be implemented or re-implemented.

Maybe we can identify some of the negative things happening, and come up with ways to fix them.

From a conceptual standpoint, the Internet developed from the ground up starting in the early 1900s.  It started with theories of information and hard science (voltages, frequencies, and the like), that went really deep into math and science in ways that will give you tremendous respect for that $99 router at best buy.

The efforts then moved into methods of connectivity as the Cold War started in the 50’s and 60’s.  It was during this time that a middle layer of building blocks was created, which ensured robust connectivity and flexibility in the network.  After many different efforts and competing theories, the TCP/IP standard was implemented on January 1, 1983.

When the Internet was opened to the public, the upper layers developed in earnest.  Some early protocols like SMTP (email) and FTP (file transfer) were updated and still exist.  Others, like Gopher, were replaced by HTTP and the now-ubiquitous World Wide Web in 1991.  Protocols that were easy and effective survived.  Others were updated or dropped.

(Techies out there will see that this process was really about climbing the ladder of what is now called the OSI model.)

The takeaway here is that the Internet developed like this:

• How can we make something that works using physics, electricity, and connectivity?
• How can we arrange this thing so that it works well even when powerful entities don’t want it to work at all?
• Now that everything is connected, how can we share information in a way that accessible and easy on a huge scale?

It was in this 3rd bullet point where things started to go really well.  As we shall see in subsequent posts, it was also where the seeds of censorship were sewn.

As the use of the Internet via the World Wide Web quickly (but also slowly) exploded, finding information was about to become an issue.   The Web was a library of documents with no organization and no index.  Think of a stack of 100 unlabeled books in a dark closet and all you have is a flashlight to find what you’re looking for.

The problem was so obvious that multiple entities began solving it in multiple ways when the web was but a flicker in a PhD’s desktop.

Jumpstation went live in 1993 when the total number of websites was less than 200.

Webcrawler, Lycos, and Excite followed in 1994.  When the total number  of sites grew to around 20,000.

Altavista and Yahoo started in ’95-’96 when the total number of sites was still well below 500,000.

Dogpile and AskJeeves started around ’96.  And, of course, the 1-Trillion-plus gorilla of Google started in 1998 at the dawn of the d0t-com era.  By then the number of web pages was well into the millions and tens of millions.

An undefinably large amount of work by brilliant individuals had created the ultimate information sharing tool.  In around 80 years, humanity had gone from theory on a page to an invention that had the potential to fundamentally change the direction of our history.

But it would also do so by subtly changing fundamentals and definitions that had been taken for granted for quite a while.  In making so many connections, we had created a very dynamic vessel for defining and changing what things mean.

This change could include the very intent of the invention and purpose for inventing it.