Communication Protocolss & Models

[M44y4]

Why are communication protocols and models important?

[CimmerianX]

This sounds like homework....

[L7Sqr]

You are experiencing a failure of one right now.

Had you opened with something like: "I'm interested in learning about the types of communication protocols that exist and their strengths and weaknesses. So far, I've looked into X, Y, and Z and I see this. Unfortunately, I feel like there is more that I am not looking at, can you help point me in the correct direction?"

You may have gotten some help. Unfortunately, you did not.

This is at least one data point for why communication protocol is important and the consequence of not following community models.

[M44y4]

Okay so ill be honest it sort of is a part of an assignment.
I did do some research on the topic...and I came up with:

"Network protocols are needed so that information can be exchanged between two or more systems for example; a Mac and a PC can both use TCP/IP as their network protocol in order to exchange information. In other words if we don’t have protocols we won’t be able to communicate between different devices."

But.... im sure its pretty obvious I have no idea what im talking about :/ so alittle help please?

[L7Sqr]

Good. Now abstract that a little bit. Consider what it means to talk to someone over the telephone - lets be simple and say a land line and avoid cell phones.
There is a protocol for talking to someone over the phone; you cant simply start talking outloud into your bedroom and expect that your Aunt in Tulsa is gonna get the 'message.' For a telephone conversation you should follow some order:

• Pick up the phone
• Dial the number that is unique to your Aunt
• Wait for the mechanics of the telephone lines to ring your Aunts phone remotely
• Your Aunt hears the ring and picks up the phone
• Your Aunt says hello
• You greet your Aunt and begin to have a conversation
• Eventually, you both bid farewell
• Both ends of the connection are hung-up.

That order is crucial. Talking into the phone before dialing seems ridiculous when you say it aloud but anyone who knows how to use a phone follows the general protocol of telephones.

It is the same thing with any two (or more) systems that need to communicate with each other. There need to be rules. Participants need to follow the rules. Without that, communication is about as effective as talking to yourself in your bedroom.

[M44y4]

Oh I get it...so protocols are like the steps that need to be taken in order for the communication between the two networks to be successful!
But then...where do the models fit into all of this?

(Thank you soso much for your answer @L7Sqr)

[JorgeM]

so protocols are like the steps that need to be taken in order for the communication between the two networks to be successful!

A protocol is the set of rules that define how the communication can occur.

In the other thread I gave you the example about two people speaking. Think of speaking English as the protocol. First you have to make sure that the person you are going to speak with can also speak English.

Then communication can start....

You follow certain rules..in English you apply grammar rules. You just dont start saying random words correct? You have to follow grammar rules so the person you are speaking to can understand what you are saying. At some point at the end of a statement, you pause and give the other person a chance to respond. That person has to follow the same rules you followed for you to understand.

What happens if you are speaking and the other person interrupts you.. you talk for a bit more and stop. You may get upset and tell the other person to be quite, or you may allow them to keep speaking.

If both of you do not abide by the same rules, you wont be able to communicate.

These are simply rules in a language...rules of a protocol.

Where does this fit in the models...There are various protocols at different layers. Each layer depends on the layer below and above.

As the packets are created to send to the target system. protocols are high level protocols are in the center of the packet, and the lower protocols "wrap" their protocol information around them. When the packet gets to the target system, the protocols are unwrapped and sent up the stack until the conversation can be put back together for the awaiting application.

This is really a high level explanation.

[L7Sqr]

Models mostly subsume the protocol and add additional structure rules and format guidelines for implementors.

For example, TCP is a protocol that is driven by a finite state machine (this is similar to my example above). That alone is not sufficient for a Windows machine and a Linux machine to immediately connect. Sure there is the SYN portion of the protocol, but what does the packet look like? If Windows sends a packet that is 1237 bytes and Linux deals with TCP packets of size 1200 bytes or less then there is going to be problems.

Fortunately, there are a set of fixed constructs to be used when speaking TCP (or other agreed upon protocol) - these are universal. Usually, they can be found spelled out in RFCs. They (try) to provide the minimum necessary to ensure a sustainable system given all parties adhere to the rules.

The layering of packets types in a network ([Ethernet[IP[TCP[...]]]]), what these packets look like, the state machines that provide connectivity; these are all part of the system.

[M44y4]

Thank you so so much guys! @L7Sqr & @JorgeM.:)