IP Adress

Senin, 28 Juni 2010

1. What is IP address?

How computers are connected to the Internet network are interconnected and send messages? This problem is analogous to the problem of sending a letter in the real world. I suppose that is domiciled in Aquarius 16 Bandung Hifni want to send a letter to the address at No. 100 street xxx Condongcatur Sleman. First I will write the contents of my letter in a paper. Then I enter the letter into an envelope. Why do I put in the envelope? So that my mail is protected. By using the envelope, the risk of damage to my letter will be smaller than not using envelopes. After that I will write Hifni address on the envelope the letter, and never forgot a name Hifni, because if not written down his name, the letter could be lost to the brother or sister. I also wrote down my name and address on the back of the envelope, so that if Hifni want to reply to my letter, he knows my address. If the correct mailing address, stamp enough, and a route to the house can be impassable Hifni, the letter would arrive.

In this first lecture we will discuss one important component in a computer network. Components that are IP (Internet Protocol) address, which is analogous to a home address on sending a letter above. IP address (version 4) is made up of binary numbers (0 and 1) as long as 32 bits (binary digits) which is divided into four segments. Each segment consists of eight bits. It means to have a decimal value of 0 (00000000) to 255 (11,111,111). So roughly it can be concluded that the number of addresses that can be used by computers worldwide are connected to the internet as much as 232 units (although there is a specific IP that is not used by special reasons). To simplify the reading, IP addresses are usually written in decimal for example 167.205.35.31. IP address structure is divided into two parts, namely Network ID and Host ID. As the name implies, Network ID serves to identify at which a computer network is located, while the Host ID serves to identify a computer (host) on a network. In one network, the host ID must be unique, as an analogy in one way, there can be no home with the same numbers. Different networks separated by routers network id.

2. IP address classes

IP addresses are divided into five classes A to E. The IP address that is used generally divided into three classes, while two other classes used for specific purposes. This is to facilitate the distribution of IP addresses worldwide.

Class A:

- Format: 0nnnnnnn.hhhhhhhh.hhhhhhhh.hhhhhhhh
- First Bit: 0
- Long-Network ID: 8 bits
- Long Host ID: 24 bits
- The first byte: 0-127
- Total: 126 class A (0 and 127 are reserved)
- IP Range: 1.xxx.xxx.xxx until 126.xxx.xxx.xxx
- Number of IP: 16,777,214 IP addresses in each class A

This class of IP addresses given to a very large network, which in every network there are about 16 million hosts.

Class B:

- Format: 10nnnnnn.nnnnnnnn.hhhhhhhh.hhhhhhhh
- The first two bits: 10
- Long-Network ID: 16 bits
- Long Host ID: 16 bits
- The first byte: 128-191
- Amount: 16 384 class B
- Range IP: 128.0.xxx.xxx to 191.155.xxx.xxx
- Total IP: 65 535 IP addresses for each class B

This class of IP addresses given to network with medium-large size. Examples are the ITB campus network that gets the class B IP address allocations (thanks to Onno W. Purbo), with a network id 167 205.

Class C:

- Format: 110nnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh
- The first three bits: 110
- Long-Network ID: 24 bits
- Long Host ID: 8 bits
- The first byte: 192-223
- Number: 2,097,152 Class C
- IP Range: 192.0.0.xxx until 223.255.255.xxx
- Number of IP: 254 IP addresses for each class C

This class IP networks are allocated for small size.

Class D IP multicast address that is used as a number of computer use with an application. An example is the application of real-time video conference involving more than two hosts, such as that held at the ITB in the course of SOI (School on Internet) along with several universities in Asia. IP feature of class D is its first four bits 1110. IP E-class (the first four bits 1111) are allocated for experimental purposes.

3. Which need to be considered in the selection of IP addresses

A basic rule elections Network ID and Host ID:

- Network ID should not be valued at 127. Because Network ID 127 is used as a loopback address is the address used by computers to refer to himself.
- Network ID and Host ID can not be totaled 255 (all bits set to 1). Nework ID or Host ID which totaled 255 is the network broadcast address. When sent a message to the entire host alamt broadcast on the network will receive that message.
- Network ID and Host ID can not be entirely value 0 (all bits set to 0). IP address with all host id value 0 is defined as a network address that points to the network, not to the host.
- Host ID must be unique within a network.

4. Cover

So, with the development of internet users, IP addresses available no less. The designer first IP address did not think that would be such a rapid development of internet. Then what's the solution? There are several alternatives that are now underway. First to reduce usage by IP address subnetting, Supernetting, NAT, etc.. Second, do the migration from IP version 4 to IP version 6 which has allocated up to 3.4 x 1038.
To view your IP configuration, open a command prompt (Windows) and then type ipconfig / all and press Enter. For UNIX, open a shell / terminal and then type ifconfig and press enter. IP address on a computer can be determined by static or dynamic. The determination is done by setting the static IP address on the computer directly. While the dynamic determination is done by using a dial up ISP (internet service provider) or by connecting themselves with the DHCP server (Dynamic Host Configuration Protocol). For example, computers in the lab Informatics Association Informatics Engineering, ITB I get a dynamic IPnya through ns.if.itb.ac.id server so IPnya address at a time can change automatically. The advantage of using DHCP is able to prevent IP conflict or the presence of the same IP address on one network.