IP - Internet Protocol

10:38:00 PM | 0 Comments

I) TCI/IP Model :

First of all, let's talk a little bit about TCP/IP model .
When we talk to each other, we use the same language so everyone can understand .
If computer A wants to send file to computer B, both of them need to use the same language called "Protocol" .

TCP /IP is the most popular stack of Protocols our computers use nowaday to communicate .
TCP/ IP actually is a set of many protocols (for example when computer wants to send e-mail, it uses a protocol named SMTP, when it sends file - it uses FTP ....),  its name is represented by 2 protocols : TCP & IP . So hence the name TCP/IP .

II) IP Address :
 1) Introduction to IP Address :

- Every computer has to have at least 1 IP address to communicate with others . Just like my house has a address so some girls can send me some gifts .
- When we talk about IP address, we often talk about IP v4 (v = Version) : It comprises 32 bits (1 & 0) , and divides to 4 portions (called Octet ) separated by 3 dots (.) :
For example : 10000000.11000000.10000001.00000001 
- It's kind of hard to remember so people write it in decimal number : 128.192.129.1
(* You need to know how to convert from Binary to Decimal Number - just search on Google)

- IP addresses also have 2 parts : Host ID and Net ID , just like your house's address has Street number and House number .


2) IP address class :

- Classes help us to determine how many bits  net id (or host id) owned , notice : bits net id + bits host id = 32 (please take a look at the figure above) .

- Five classes : 
  • Class A : Net ID owns 8 bits, Host ID owns 24 bits .
  • Class B : ------------- 16 -------------------16 .
  • Class C : ------------- 24 -------------------8 .
  • Class D & E : are used for research & multicast .
- So how to know which class this IP address  1.2.3.4 belongs to ? 
- Focus on first octet, for example IP address is X.Y.Z.T 
if
  • X from 1     -> 126 : This IP belongs to class A
  • X from 128 -> 191 : This IP belongs to class B
  • X from 192 -> 223 : This IP belongs to class C
  • X from 224 -> 239 : This IP belongs to class D
  • X from 240 -> 255 : This IP belongs to class E
 X = 127 is used for other purposes . For example : 127.0.0.1 is called loopback address .

3) Public & Private IP address :

a) Public IP address : 
- In WAN (Internet)
- Is provided by Service Provider
- Unique in Internet

b) Private IP address : 
- In LAN (Local Area Network)
- Is provided by Administrator .



Network Topologies & Network Devices

9:59:00 AM | 0 Comments

Alright, before starting to learn specific skills about Windows Server . You need some basic understandings in  Networking fundamental.

If you've been through this before, you can skip it, but make sure that you have a glance to know what it is .

I) Network Topology : 

Network Topology is kind of shape of Network in your house, your office or your school .

1/ Token Ring : 



As its name says : all computers connect to a "Ring". If the ring is broken somewhere,  computer cannot communicate with each other .
Just one computer can send data at a time .
Data are sent one-way (clockwise or counter clockwise)
Use method called "Token Passing" - it means if a computer want to send data, it needs a token (like a priority) , taken from other computers .
So, data transfer speed is slow ~ 10 Mbps
=> This Topology is oblivion .

2/ Bus :


 

The two end-points are called Terminators .
Computers connect to the Bus by T-connector .
If computer 1 want to send data to computer 4, data must be send to computer 2, computer 3 ... => Not assure for security .
If 2 computers are sending data simultaneously - bandwidth is divided by 2 and  so forth .
This topology is easy to expand (just connect a computer to the Bus)
Because of slow speed, it is no longer used in modern Network.


3/ Star :
There is always a central device (called HUB - in this figure) .
Every computer becomes a member by connecting to central device .
Speed : 100 Mbps
Easy to deploy and expand .

=> The most popular Network topology is used nowaday .

There're also many topologies, but we just focus on the main ones ; you can find out more about them by doing some Google searches.

II) Network Devices :

1)  Network Interface Card (NIC) - or Network Adapter :

- It's a part of your computer (behind a CPU-Case)
- Help computers to communicate to each other, and connect to central device - also .
- To recognise each other, NIC has something called : Address . Imagine that NIC is a house - if I need to send email to you - I need your House's address, right ?
- NIC has 2 types of address :
+  Physical address (MAC address) : Producer provides and cannot be changed - It's unique .
+ Logical address (Netowork address - IP address) : can be changed by administrator .


2/ Central devices :

Today,  Hub is no longer used; instead , we use Switch which provides more efficient functions and enhance speed of transfer, also .

Central devices are used in Star Topology as I wrote in previous section.



3/ Cable :

2 types of cable :
- UTP : Unshielded Twisted Pair . Cheap.


- STP : Shielded Twisted  Pair . Cover by copper to avoid interferences . Expensive 3 times when compare to UTP cable .