teh allmighteh gogeta70 O_O wrote: Introduction
First off, i'd like to say that this tutorial only covers the basics of networking, but will lead you into a more in-depth understanding of what happens when you request a web page, or send data to a server. This tutorial will cover the seven layers of the OSI (open systems interconnection) model, different types of network cables, and IP address classification. Routers, switches, bridges, and other networking hardware are, for the most part, out of the scope of this tutorial. With that said, let's get started...
1. Open Systems Interconnection (OSI) Model
The OSI model has seven layers, each layer does it's own job in getting data from point a, to point b. The seven layers are as follows:
Application
Presentation
Session
Transport
Network
Data-link
Physical
1.a Application
The application layer, the 7th layer of the OSI model, is the layer we interact with the most. While it may sound like it means 'users interacting with a network application,' that is not the case. This layer is responsible for allocating network resources, opening the port and binding the port to your address, identifying the communication partners, and synchronizing communication. This means that the application layer assures that there is enough network resources to do the required task, opens the port and prepares it to send and/or receive data, checking to make sure the client (person you're sending data to) is available, and keeping in sync with the client's computer.
1.b Presentation
The presentation layer is the 6th layer of the OSI model. The sole purpose of this layer is to convert the information received from the application layer into universally readable data. This is called Protocol Data Units (PDU's). It then passes the PDU's down to the session layer.
1.c Session
The session layer is the 5th layer of the OSI model, and is responsible for initiating, maintaining, and terminating communication between client and host. It is capable of providing for full-duplex, half-duplex, and simplex (we'll go over these momentarily) operation.
1.d Transport
The transport layer, the 4th layer of the OSI model, is responsible for insuring that the data maintains integrity and reaches it's specified destination. In this layer, the data is segmented, and a checksum is generated for each segment (aka packet). (If i remember correctly...) This layer is also where ACK-SYN happens. These stand for acknowledgement and synchronization. To initiate a connection, an ACK-SYN request is sent, the server replies with an 'ACK'. As well, after every segment, or packet is sent, an 'ACK' is also received from the server. Any time an 'ACK' is not received, the segment(or packet) is resent, until it is acknowledged.
1.e Network
The network layer, which is the 3rd layer of the OSI model, is responsible for splitting the data into the proper length (1,400 kb is roughly the max. size segment allowed), as well as choosing the best path to send the data (called routing). On the receiving end, this layer also reassembles the data into it's original sizes (if the segments were larger than 1,400 kb, it reassembles the split segments).
1.f Data-link
The data-link layer, which is the 2nd layer of the OSI model, is mainly responsible for working with the transport layer in error correction. Originally, this layer was used for PPP (point-to-point protocol). This layer simply does a CRC32 check on the checksum generated in the transport layer.
1.g Physical.
As you may guess, the physical layer, the 1st layer of the OSI model, is all about the physical medium through which your data travels to reach it's destination. This includes everything from your Network Interface Card, and your Router, to the Hubs and Repeaters used by your ISP.
1.1 IP Address Classification
IP Addresses are classified into 5 classes: A, B, C, D, & E. However, D and E are reserved, and not currently in use. Here are what defines the first 3 classes:
class 1st ip octet
A - 0-126
B - 128-191
C - 192-223
You may have noticed that 127 is not included in those classes. This is because it is a loopback address, meant only for local adressing.
2.0 Networking cables
There are actually several types of networking cables, and most of them are beyond the scope of this tutorial, but for now, we will cover the most commonly used cables today.
One of the most common types of cables are Unshielded Twisted Pair cables (UTP cables). These are referring to cables like your Ethernet CAT 5 cables. These utp's are favored due to the fact that they are small, and you can fit a lot of them in a small area, as well as they are flexible and inexpensive. However, one big disadvantage is it's susceptibility to electromagnetic interference.
Another very common cable is the STP cables, or Shielded Twisted Pair cables. These are referring to cables like coaxial cables. Inside these cables is a layer of foil, which surrounds the copper wiring, which is then covered with a thick layer of rubber to prevent damage to the cord. The major advantage of this cord is that it is unaffected by electromagnetic interference, though it cannot bend very well and is bulky.
Fiber optic cables are the newest, and fastest means of data transfer we have. It uses a digital signal, instead of an analog signal, and can transfer data at rates of several gigabytes per second.
-Subsection: analog vs. digital
The difference between analog and digital waves is frequency and voltage. Analog waves have slightly varying voltages and frequencies, while digital waves are precisely timed pulses of unchanging voltage or frequency.
3.0 IP Addresses
Side note: this section was originally on subnetting, but i may do an individual tutorial on it instead because of the size this tutorial was getting to be.
To better understand IP addressing, you must first know how to convert an IP into it's 32bit binary form. This is rather simple. To begin, let's take a random IP, say 139.44.241.173. To convert, you simply take each octet, and do as follows:
sorry, quick side tutorial:
Each binary bit (8 bits = 1 byte) is equal to a specific value, which is as follows: take the following binary byte: 11010001. Now, from the left, write it vertically:
1 * 128 = 128
1 * 64 = 64
0 * 32 = 0
1 * 16 = 16
0 * 8 = 0
0 * 4 = 0
0 * 2 = 0
1 * 1 = 1
Add up all the totals... 128+64 = 192+16 = 208+1 = 209. so 11010001 = 209.
End quick tutorial here.
Anyway, to convert an IP to binary, take each octet and do the following:
139 - 128 = 11 (binary 1)
11 - 64 = -53 (binary 0)
11 - 32 = -21 (binary 0)
11 - 16 = -5 (binary 0)
11 - 8 = 3 (binary 1)
3 - 4 = -1 (binary 0)
3 - 2 = 1 (binary 1)
1 - 1 = 0 (binary 1)
So that octet = 10001011.
So now we know that 139.44.241.173 = 10001011.00101100.11110001.10101101. This is one of the easiest ways to convert an IP into a binary address.
Basic Networking Tutorial
Basic Networking Tutorial
Hello everyone. For all that don't know, i'm in the middle of military training for computers and networking. This is simply a tutorial on what i have been learning recently. Enjoy!
¯\_(ツ)_/¯ It works on my machine...
expecting the tutorial.and here is a nice introductionThe IP part of the tutorial is incomplete. I'll be posting a tutorial about IP's and Subnetting here soon.
http://www.learntosubnet.com/
DNR ok's this link. Read the rules on posting links