NETWORK computer is a collection of computers, printers and other equipment that is connected in one unit. Information and data moving through the cable-cable or without cable so that the computer network allows users to exchange documents and data, the print on the printer and the same with the hardware / software that is connected in a network.
1) Type of network
In general, a computer network consisting of five types:
a) Local Area Network (LAN), a network of private property in a building or campus-sized to several kilometers. LAN is often used to connect personal computers and workstations in a company office or factory for shared resources (resouce, for example, printers) and exchange information.
b) Metropolitan Area Network (MAN)
Metropolitan Area Network (MAN), basically a wireless version of the larger size and usually use the same technology to the LAN. MAN may include the company's offices are also located close to or a city and can be used for personal (private) or public. MAN is able to support data and voice, can even relate to the cable television network.
c) Wide Area Network (WAN), its scope covers a wide geographical area, often covering a country and even continent. WAN consists of a collection of machines that aim to run the programs (applications) user.
d) Internet
In fact there are many networks in the world, often using the hardware and software that is different. People are often connected to the network hopes to be able to communicate with other people connected to the other network. Desire such as this requires a relationship between a network that is often not compatibel and different. Usually to do this required a machine called a gateway in order to make contact and conduct the necessary translation, both hardware and software. Terinterkoneksi collection of networks that is what is called the Internet.
e) Wireless (Networking without cable), cable network without a solution to komukasi that can not be done with the network cables. For example, people who want to get information or make communication even when the car is above or aircraft, the network is absolutely necessary because without a cable connection cable may not be made in the car or plane. At this time without a network cable is used with a flare using the satellite service and is able to provide access speed faster than the network cables.
2) Network topology
Topology is a way of connecting a computer with other computers so that the network formed. That at this time how many are used Bus, Token-Ring, and Star Network. Each topology has unique characteristics, with its own advantages and kekurangannya.
a) Bus topology
Bus topology is used on a single cable or cable center in which all workstations and servers are linked.
Gambar3. Network topology bus
Benefits
Save the cable
Cable layout simple
Development of the network or adding new workstation can be done easily without disrupting other workstation
Losses
Fault detection and isolation is very small
Density of the traffic on main routes
Weakness of this topology is when there is interference in the center of the cable along the entire network to crash akan
Repeater is required for long-distance
b) Token Ring topology
In the Ring topology all workstations and servers linked to form a pattern so that the circle or ring. Each workstation or server will receive and pass information from one computer to another, if the addresses are the appropriate information is received and when the information will not be missed.
Figure 4. Topology network Token-Ring
Weakness of this topology is each node in the network will always be involved to manage the information missed in the network, so that when there is interference of a node in the entire network will be disrupted.
Ring topology is the benefits of a collision or no collision of data such as the Bus topology, because only one node can transmit data at a time.
c) Star topology
In the Star topology, each workstation is connected directly to a server or hub. The advantages of this topology type Star is that with the cable for each workstation to the server, or the wide bandwidth communication channels in the cable so that the width of the akan akan improve network performance overall. And also when there is a disruption in the cable path interference will only occur in the communication between the workstation with the server, the network as a whole does not experience interference. Weakness of the Star topology is the cable that needs greater than the other topology.
Figure 5. Star Network topology
Benefits
Most flexible
Installation / changes to the station is very easy and does not disrupt the network
Centralized control
Ease of detection and fault isolation / damage management network
Losses
Spendthrift cable
Need special handling
Control center (HUB) be a critical element
4) Type Network
Network type closely related to the network operating system. There are two type network, the client-server type network and peer to peer.
a) Client-Server Network
Servers are computers that provide facilities for the other computers in the network and client-computer is the computer that receives or uses facilities provided by the server. Server in the network client-server type is called the Dedicated Server as pure as the server that provides the facility to the server and the workstation can not act as a workstation.
Excellence
More high-speed access for the provision of facilities and network management is done exclusively by a single computer (server) that is not burdened with other tasks, such as a workstation.
System administration and network security is better, because there is a duty as a computer network administrator, who manages the system administration and network security.
Data backup system is better, because in the network client-server backup is done centrally on the server, which will membackup all the data used in the network.
Weakness
Operational costs are relatively more expensive.
Required the existence of a special computer for more berkemampuan assigned as the server.
Of the network depends on the server. When the server to crash the entire network will be disrupted.
b) Peer To Peer Network
When the review of the role of the two types of server network, the network server in the peer to peer type termed non-dedicated server, because the server does not act as a server at once pure but can act as a workstation.
Excellence
Between computers in a network can share each other that it has facilities such as: hard, drive, fax / modem, printer.
Operational costs are relatively cheap compared with the type of client-server network, one of them because they do not require any server that has a special ability to organize and provide facilities network.
Work of the network does not depend on a single server. So when one of the computer / peer dead or damaged, the network as a whole will not experience interference.
Weakness
Troubleshooting a network is relatively more difficult, because in the network peer to peer type of each computer will be able to engage in communication that exists. In client-server network, the communication between the server with the workstation.
Lower performance compared with client-server network, because every computer / peer must manage in addition to the facility network must also manage the job or the application itself.
Network security system is determined by each user to manage the security of each facility owned.
Because the network data in each computer in the network, the backups should be done by each machine.
5) Network Protocol
To carry out various communications vendor computer needed a basic rule that the standard and approved by various parties. As well as two different nations, the need to communicate with translators / interpreters, or a language that is understood both sides.
In the world of computer and telecommunications interpreter with the identical protocol. For that the world body that handled the standardization of ISO (International Standardization Organization) standard to make the rules known by the name of OSI reference model (Open Systems interconnection). Thus, all vendors are expected to telecommunication device model must be guided by this reference in developing protocolnya.
OSI reference model consists of 7 layers, from physical layer up to the application. Reference model is not only useful for LAN products, but in building the Internet even though the network is required. Relationships between the OSI reference model with the Internet protocol can be seen in table 1 below:
Table 1. Relationships between the OSI model with the Internet protocol
OSI Model
TCP / IP
Protocol TCP / IP
No
Layer
Protocol Name
Usefulness
7
Applications
Applications
DHCP (Dynamic Host Configuration Protocol)
Distribution protocol for IP on the network with a limited number of IP
DNS (Domain Name Server)
Data base machine and the domain name IP number
FTP (File Transfer Protocol)
Protocol for file transfer
HTTP (Hyper Text Transfer Protocol)
Protocol to transfer HTML files and Web
MIME (Multipurpose Internet Mail Extention)
Protocol to send a binary file in text form
NNTP (Network News Transfer Protocol)
Protocol to receive and send newsgroups
POP (Post Office Protocol)
Protocol to retrieve mail from the server
SMB (Server Message Block)
Protocol to transfer various file server DOS and Windows
6
Presentations
SMTP (Simple Mail Transfer Protocol)
Protocol for the exchange of mail
SNMP (Simple Network Management Protocol)
Protocol for network menejemen
Telnet
Protocol for remote access from
TFTP (Trivial FTP)
Protocol for file transfer
5
Sessi
NetBIOS (Network Basic Input Output System)
BIOS standard network
RPC (Remote Procedure Call)
Remote procedure calling
Socket
Input Output for the network type of BSD-UNIX
4
Transport
Transport
TCP (Transmission Control Protocol)
Exchange of data-oriented protocol (connection oriented)
UDP (User Datagram Protocol)
Data exchange protocol, non-oriented (connectionless)
3
Network
Internet
IP (Internet Protocol)
Routing protocol to set
RIP (Routing Information Protocol)
Routing protocol to select
ARP (Address Resolution Protocol)
Protocol to get hardware information from the IP number
RARP (Reverse ARP)
Protocol to obtain information from the hardware IP number
(Continued Table 1)
2
Data link LLC
Network interface
PPP (Point to Point Protocol)
Protocol for point to point
Data Link
MAC
Slip (Serial Line Internet Protocol)
Protocol by using the serial connection
1
Physical
Ethernet, FDDI, ISDN, ATM
Standards to network problems not only done by the ISO, but also held by other world bodies such as ITU (International Telecommunication Union), ANSI (American National Standard Institute), NCITS (National Committee for Information Technology Standardization), even by the professional associations IEEE (Institute of Electrical and Electronics Engineers) and the ATM-Forum in the United States. In practice even vendor-vendor LAN products that have generated the IEEE standard.
6) IP Address
IP address is the address given on the network equipment and computer network that uses TCP / IP. IP address consists of 32 bit binary number that can be written as four decimal digit groups separated
by a period such as 193.160.5.1.
Table 2. Example of IP Address
Network ID
Host ID
193
160
5
1
IP address consists of two parts, namely the network ID and host ID, which determine the network ID address of the computer network, while the host ID determines the host address (computer, router, switch). Therefore IP address to give complete address along with a host network address where the host is located.
Class-class IP Address
For ease of use, depending on the needs of the user, IP address is divided into three classes as shown in the table below
Table 3. The division of class IP Address
Class
Network ID
Host ID
Default Sub-net Mask
A
xxx.0.0.1
xxx.255.255.254
255.0.0.0
B
xxx.xxx.0.1
xxx.xxx.255.254
255.255.0.0
C
xxx.xxx.xxx.1
xxx.xxx.xxx.254
255.255.255.0
IP address assigned to the class A network with the number of hosts that are very large. IP Range 1.xxx.xxx.xxx. - 126.xxx.xxx.xxx, there are 16,777,214 (16 million) on the IP address of each class A. In the class A IP address, network ID is the first 8 bits, while the host ID is 24 bits next. Thus, how to read IP address class A, for example, 113.46.5.6 is:
Network ID = 113
Host ID = 46.5.6
IP address on the mean number 46.5.6 host on the network number 113.
Class B IP address is usually allocated to the network medium and large sized. In the class B IP address, network ID is the 16 bit first, while the host ID is 16 bits next. Thus, how to read the class B IP address, for example, 132.92.121.1:
Network ID = 132.92
Host ID = 121.1
IP address on the host means that the number on the 121.1 network number 132.92. With the long 16 bit host ID, the network with the IP address class B can accommodate around 65,000 hosts. IP Range 128.0.xxx.xxx - 191.155.xxx.xxx.
Class C IP address originally used for small-sized network (LAN). Host ID is the last 8 bits. With this configuration, can be formed about 2 million network with each network has 256 IP address. IP Range 192.0.0.xxx - 223.255.255.x.
Allocation of IP address is basically the process of selecting the network ID and host ID is right to a network. Right or not depending on the configuration of this purpose be achieved, which is allocated IP address as efficiently as possible.
7) Domain Name System (DNS)
Domain Name System (DNS) is a system that allows the name of a host computer on the network or the Internet IP address to be ditranslasikan. In giving the name, the DNS hierarchy architecture:
a) Root-level domain: the top level is shown as a dot (.).
b) Top-level domain: category code, or state organizations such as:. com to be used by the company;. edu to be used by universities;. gov for use by government agencies. In addition to distinguish by the name of a country with other countries to use a sign for example. Ps to Indonesia or. Au for australia.
c) Second-level domain: the name for the organization or company, such as microsoft.com, yahoo.com, and others.
8) DHCP (Dynamic Host Configuration Protocol)
IP address and subnet mask can be provided automatically using Dynamic Host Configuration Protocol or filled manually. DHCP function to provide IP address automatically on computers that use TCP / IP. DHCP working relationship with the client-server, where the DHCP server provides the IP address of a group that can be provided in the DHCP client. In providing this IP address, DHCP IP address only lend it. So the IP address this ongoing dynamic.
