Basic of Internet and Computer - Network lessons for beginners

Basic of Internet and Computer - Network

This lesson target for,
Beginners who are interested in mechanisms of the internet. 
People who have set up a network using a computer but don’t quite understand the mechanisms.
People who begin to manage the network.

In this lesson cover these topics,

The Mechanisms of the Internet

TCP / IP
- its role and functions
- real-life examples and review

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What is the Internet

Multiple networks (clouds) connected to each other.

The Internet was initially created for military purposes.

• Research labs and universities in the U.S. were connected.
• Later, Corporations and general public groups were also connected, expanding to the current internet.

Various kind of data can be exchanged.

• Anything that can be done on a computer

The mechanisms of the Internet

Let’s get rid of the abstract cloud image

Mechanism inside the cloud

Internet is an aggregation of the network
To communicate with each other, we need certain agreements.
* mechanism to communicate among systems of various makers, OS and CPU

Protocol

What is Protocol

Like a rule of daily life

• when one person speaks Japanese and another speaks English, they cannot understand each other.

We need to make a rule.

Computer Protocol

A set of agreements for communication procedures.

• How the data is interpreted/ How the data is sent as electronic signals.

Protocol is necessary for the Internet  - TCP / IP

What is TCP /IP?

• The innermost core of Internet Protocol
• TCP: Transmission Control Protocol
• IP: Internet Protocol 

The Internet has a structure of several different layers.

• The functions necessary for communication are divided up and split into different layers.

The functions necessary for communication are divided. These split-up unite are called “layers”
Introduce a hypothetical situation to understand the hierarchical structure.

Ex -

• Call the newspaper office, and subscribe
• Order a regular newspaper and a sports newspaper.
• Receive a newspaper tomorrow.

There are a number of mechanisms and an assignment of roles

Role assignment in newspaper model

• Roles are assigned to each function and work. - each role is called “layer”
• Each layer concentrates on its own job and together achieves a large service.
• This concept is actually important in considering the mechanism of the internet. 

Role and function of each layer of TCP/IP 

The function of each layer is very simple.
There is a concept of top and bottom layers.
     - The closer to the bottom layer, the more physical
     - Towards the top is more logical aspects.

Hardware layer

       - The cable in which the electronic signal flows.
       - The cable such as phone lines.
       - Size and shape of connector and the arrangement of the pins are also defined.

Network Layer

       - Procedure for communication and standards for communication are defined.

       - This layer converts data to electronic signals.    

Internet Layer

      - Identify the recipient of a communication

       - Decide the way to send the Data.

Transport Layer

      - Determine which program to pass the received data to. 

Application Layer

     - The portion that the user can touch directly.

Services provided to users Home page, Email, Chat, etc.

Role assignments in a hierarchical structure

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TCP / IP

Procedure to explain the roles and functions of each layer.

• I’ll start from the bottom layer and describe the functions and roles of each.
• An example such as “One day I was told this.”
• Explain the functions and roles of each layer.
• Introduce examples of set-up procedures.

Roles and functions of each layer

“One day I was told this.”

• I bought a new hub, so will your plugin that 10BaseT cable over there? I am counting on you.
• Wait a minute. What is the hub? I don’t understand.
• These words have to do with the Network layer and Hardware layer.  

Network layer / Hardware layer

Roles

      - converting data to electronic signals.
      - equipment and cables connecting machines physically.

Keywords

      -  network equipment
      -  cable

What is Network equipment

Physical hardware for communication.
       - this is where the electronic signals flow.

Examples of network equipment
         - Network interface card
         - Hub
         - Router
         - Switch

Network Interface Card (NIC)

       - This card connects PC to the Network.
       - The data is converted into electronic signals.
       - You need the card which would match communication standard you use.

Hub

Correcting device to connect multiple numbers of equipment.
It receives and sends electronic signals.

Router 

Equipment to connect different IP networks.
       - “IP network ” is explained in detail in the next Internet layer.
       - The router decides where the data should be delivered.

Cable

A physical line that connects network equipment.
        - The electronic signals flow through here.
Typical cable use for LAN
        - Ethernet ( 10BASE-T, 100BASE-T )
                 - UTP cable
        - Giga-bit Ethernet ( 1000BASE-sx )
                 * Optical Fiber cable
        - FDDI, ATM
              - Optical Fiber cable

What was that request?

I bought a new Hub, so will your plugin that 10BaseT cable over there?

Real-life example

Connect PC and Hub
        - You would only need to connect a particular cable.
        - The type of a cable: LAN cable ( UTP-5 )   

One day I was told this

The new machine arrived, so could you set up the network? The IP address is 192.168.0.10, and the netmask is 255.255.255.0

What is an IP address? These words have to do with IP of Internet layer.

Internet layer IP

Roles

       - Identify the recipient of the communication.
       - Create packets.

Keywords

       - IP Address
       - Netmask

Functions and Roles of IP

• The data to be sent is broken down into small packages called “packets.”
• Packets are transported by routers.
• In case of congestion, the packet is sometimes thrown away.
• IP is “Best-Effort protocol.”
• An IP address, a unique number to identify the party you’re communicating with, is defined.   

What is an IP address?

• An IP address is a unique number to identify the party you’re communicating with.
• In order to communicate using the IP protocol, the equipment needs at least one IP address.
• It is impossible to have a duplicate IP address on the Internet.

Example of assigning an IP address to host

The IP address and binary numbers

• IP addresses are represented by binary numbers. 
• What are binary numbers?
• Numbers represented only by 0 and 1
• The digit of a binary number is called a “bit”

The scale of using binary numbers to represent decimal numbers.

• 4 digit decimal number : 0 to 9999 (10,000 different options)
• 4 digit binary number   : 0 to 1111 (16 different options)
• 8 digit binary number   : 0 to 11111111 (256 different options)

How the IP address is written out?

The IP address is created with a 32 bit (32 digits) binary number.

11000000101010000000000000001010

It’s almost impossible to memorize. So, after every 8 bit, it’s cut by a period, and each block is written as a decimal number.

11000000 . 10101000 . 00000000 . 00001010192 . 168 . 0 . 10

Identification of the party you are communicating with

Internet is an aggregation of networks.
It would be easier if you could specify which network he/she belongs and which host he/she uses.
IP address enables that.This network is called IP network. 

Structure of IP address

An IP address is split up into the “network part” and “host part”

It would basically be the same as the name of an apartment and the apartment number.

Example: New Hostel – 023 or NG16

Length of the network part

Ones the length of the network part is decided, then the length of the host part is determined

In here 8 bit were allocated as the host part, the host part would have 256 options.

Where the network number part ends.

Just by looking at IP address, you can’t tell where the network number part ends.
A marker called netmask is used.

Netmask

• It’s in a 32-bit format, same as the IP address.
• The network part is indicated with all 1s. Then the remaining host part is indicated with 0s.
• Note that netmask is just a mark, not an address.

IP address with special meaning

► All numbers in host part are 0.
    - Example: 192.168.0.0
    - This address represents the apartment name.
    - This kind of IP address is not assigned to equipment.

► All numbers in host part are 1
   - Example: 192.168.0.255
   - This is called a “Broadcast Address”.
   - It is used to communicate with all machines within the same network.
   - It is not assigned to equipment.

Organization managing IP addresses

• As IP address is a shared resource of the world, Fairness is necessary.
• To avoid duplicates of IP addresses.
• In Japan, JPNIC is managing IP address.
• JPNIC assigns IP addresses to ISP and ISP assigns some of them to users,

IP address is limited resources

► Total number of IP address
   - 32 bit = about 4.3 billion.
   - The total population of earth is now approximately 6 billion, so it’s not enough for everyone to get one IP address.

► We need to make good use of this limited supply.
   - Use both global address and private address.

Global address

• It’s accessible from anywhere in the world - Example: Web server, Mail server
• It must be unique on the Internet

Private address

► Prevent the depletion of addresses.

• It can be used freely by individuals or companies.
• There’s no need to worry about an overlap of IP addresses.
• It can’t be accessed directly from the Internet.

► Rang of private address

• 10.0.0.0 ~ 10.255.255.255
• 172.16.0.0 ~ 172.31.255.255
• 192.168.0.0 ~ 192.168.255.255  

How to use IP address

• Web server, Mail server  - Global address
• PCs in company LAN - Private address
• By using both, we can save the IP address.

Restrictions of IP address

The Internet cannot be directly accessed with a private address.

• “Proxy” solves this problem.
• It’s possible to use some of the services such as e-mail and website browsing.  

What was the request 

The new machine arrived , so could you set up the network?

• The IP address is 192.168.0.10, and the netmask is 255.255.255.0

Set up on Windows

- Open the “property” of “Network computer”
- Open the “property” of NIC (it is said “TCP/IP” here)
- Items to be set

• IP address - 192.168.0.10
• Netmask - 255.255.255.0

Set up the default gateway

► That machine from earlier – 1 forgot about setting up the route.
Would you set the default gateway as 192.168.0.254?
► How to do the routing.
These words have to do with routing, the way to deliver the packets.

Internet layer - Routing

► Role - Deliver the data to the destination
► Keyword

• Router
• Routing protocol
• Default gateway

How to carry?

• Routers carry the packets to the destination.
• A router is necessary to carry the data.
• It’s called “routing information”.
• Routers need right routing information. 

What is routing information

How to create routing information?

► Settings can be done manually.

• If the scale of the network is large, it becomes difficult to do the settings manually.
• There is constant change within the network.

► Mechanism to automatically create routing information

• Routing Protocol

► Let’s learn about routing protocol.

Principle of routing protocol

• Routers have directly connected networks in routing information.
• Routers can communicate with other routers within the same network.
• Routers exchange routing information each other and add routes. - Exchange is done periodically.