Dalam membahas jaringan komputer, memang terlihat bahwa yang sering dianggap sebagai dasarnya adalah topologi jaringan itu sendiri. Memang benar, topologi jaringan menggambarkan bagaimana sebuah jaringan tersusun dan memperlihatkan aliran lalulintas data yang terjadi dari sebuah jaringan komputer.
Namun tanpa mengesampingkan peran topologi, ternyata masih ada unsur yang terbilang lebih mendasar dari sebuah jaringan. Kelima dasar ini bisa dibilang jauh lebih mendasar ketimbang sebuah topologi. Mengapa demikian? karena tanpa adanya 5 hal ini, tidak mungkin sebuah komputer bisa saling terhubung satu sama lain.
Berikut adalah 5 hal dasar dan sangat penting dalam membangun sebuah jaringan komputer
1. Interfaces Jaringan
Setiap device yang akan terhubung ke dalam sebuah jaringan haruslah memiliki interfaces. Dalam komputer terdapat NIC (network interface card) sebagai interface yang digunakan untuk saling terhubung dengan jaringan. Selain komputer perangkat lain juga memakai NIc agar bisa terhubung ke sebuah jaringan, seperti halnya HUB, Switch, Router, dan Lain-lain. Beberapa hal yang wajib diperhatikan dalam memilih NIC yaitu:
Kecepatan tertinggi sebuah NIC adalah 1000 Megabit per detik
2. Media Transmisi
Media transmisi adalah sebuah alat yang menjadi penghubung antara komputer satu dengan komputer lain atau komputer dengan perangkat jaringan lain (hub, switch, router, dll) dalam sebuah jaringan komputer.Saat ini ada dua media transmisi yang biasa digunakan, yaitu kabel dan nirkabel (wireless). Beberapa jenis kabel yang sering digunakan untuk membentuk sebuah jaringan diantaranya adalah UTP, STP, Coaxial, dan Fiber Optik. Beberapa hal yang perlu diperhatikan terkait penggunaan media kabel adalah:
Panjang maksimum agar sanggup menghantarkan data
Jenis konektor yang digunakan (beda kabel, beda konektor)
3. Network Operating System, disingkat NOS
Network Operating System juga memiliki peranan yang sangat penting. NOS ini dikembangakandan dipakai untuk menunjang kinerja dari jaringan komputer. termasuk juga sebagai pendukung system keamanan, sharing, dan juga client server. Beberapa sistem operasi yang biasa digunakan untuk jaringan adalah Linux (biasa digunakan untuk server), MikroTik RouterOS (sistem operasi ini dikhususkan untuk router) windows server (2003, 2008, 2012), dan Windows Client (XP, Vista, 7, 8, 8.1)
4. Network Device (Perangkat pendukung jaringan)
Network device adalah peralatan yang digunankan dalam networking sebagai penunjang system jaringan. Contoh network divice adalah switch, Hub, repeater, router dan modem.
5. Network Protocol
Network protocol adalah aturan-aturan yang diberlakukan terntang bagaimana setiap komponen dalam sebuah jaringan komputer harus berkomunikasi. Secara dasar protocol dibedakan atas communication protocol, transport protocol dan application protocol.
Contoh communication protocol adalah Internet Protocol atau IP, IPX, Netbeui.
Contoh transport protocol adalah TCP dan UDP.
Contoh Applications protocol adalah FTP, HTTP, HTTPS dan sebagainya.
Kelima dasar ini adalah dasar terbentuknya sebuah jaringan komputer yang memungkinkan dua komputer atau lebih saling berkomunkasi, berbagi informasi satu sama lain. Tanpa adanya kelima hal ini, maka tidak akan ada juga yang namanya internet, facebook, twitter, chatting, dan lain sebagainya. Semoga bermanfaat.
Webopedia Study Guide SectionGetting Started: Key Terms to Know
Webopedia Study Guide SectionDefining a Network
Webopedia Study Guide SectionDifferent Types of Networks
Webopedia Study Guide SectionThe Importance of Network Standards
Webopedia Study Guide SectionNetwork Components, Devices and Functions
Webopedia Study Guide SectionNetwork Models
Webopedia Study Guide SectionThe 7 Layers of the OSI Model
Webopedia Study Guide SectionThe TCP/IP model
Webopedia Study Guide SectionNetwork Topologies
1 | Getting Started: Key Terms to Know
The following definitions will help you to better understand computer networks:
2 | Defining a Network
A network is a group of two or more computer systems or other devices that are linked together to exchange data. Networks share resources, exchange files and electronic communications. For example, networked computers can share files or multiple computers on the network can share the same printer.
3 | Different Types of Networks
There are many types of computer networks. Common types of networks include the following:
Local-area network (LAN): The computers are geographically close together (that is, in the same building).
Wide-area network (WAN): The computers are farther apart and are connected by telephone lines or radio waves.
Metropolitan-area network (MAN): A data network designed for a town or city.
Home-area network (HAN): A network contained within a user’s home that connects a person’s digital devices.
Virtual private network (VPN): A network that is constructed by using public wires — usually the Internet — to connect to a private network, such as a company’s internal network.
Storage area network (SAN): A high-speed network of storage devices that also connects those storage devices with servers.
4 | The Importance of Network Standards
Network standards are important to ensure that hardware and software can work together. Without standards you could not easily develop a network to share information.
Networking standards can be categorized in one of two ways: formal and de facto (informal). Formal standards are developed by industry organizations or governments.
Formal standards exist for network layer software, data link layer, hardware and so on. Formal standardization is a lengthy process of developing the specification, identifying choices and industry acceptance.
There are a several leading organizations for standardization including The International Organization for Standardization (ISO) and The American National Standards Institute (ANSI). The most known standards organization in the world is the Internet Engineering Task Force (IETF). IETF sets the standards that govern how much of the Internet operates.
The second category of networking standards is de facto standards. These standards typically emerge in the marketplace and are supported by technology vendors but have no official backing. For example, Microsoft Windows is a de facto standard, but is not formally recognized by any standards organization. It is simply widely recognized and accepted.
5 | Network Components, Devices and Functions
Networks share common devices and functions, such as servers, transmission media (the cabling used to connect the network) clients, shared data (e.g. files and email), network cards, printers and other peripheral devices.
The following is a brief introduction to common network components and devices. You can click any link below to read the full Webopedia definition:
Server: A computer or device on a network that manages network resources. Servers are often dedicated, meaning that they perform no other tasks besides their server tasks.
Client: A client is an application that runs on a personal computer or workstation and relies on a server to perform some operations.
Devices: Computer devices, such as a CD-ROM drive or printer, that is not part of the essential computer. Examples of devices include disk drives, printers, and modems.
Transmission Media: the type of physical system used to carry a communication signal from one system to another. Examples of transmission media include twisted-pair cable, coaxial cable, and fiber optic cable.
Network Operating System (NOS): A network operating system includes special functions for connecting computers and devices into a local-area network (LAN). The term network operating system is generally reserved for software that enhances a basic operating system by adding networking features.
Operating System: Operating systems provide a software platform on top of which other programs, called application programs, can run. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
Network Interface Card (NIC): An expansion board you insert into a computer so the computer can be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks.
Hub: A common connection point for devices in a network. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.
Switch: A device that filters and forwards packets between LAN segments. Switches operate at the data link layer (layer 2) and sometimes the network layer (layer 3) of the OSI Reference Model.
Router: A router is a device that forwards data packets along networks. A router is connected to at least two networks and is located at gateways, the places where two or more networks connect.
Gateway: A node on a network that serves as an entrance to another network.
Bridge: A device that connects two local-area networks (LANs), or two segments of the same LAN that use the same protocol
Channel Service Unit/Digital Service Unit (CSU/DSU): The CSU is a device that connects a terminal to a digital line. Typically, the two devices are packaged as a single unit.
Terminal Adapter (ISDN Adapter): A device that connects a computer to an external digital communications line, such as an ISDN line. A terminal adapter is a bit like a modem but only needs to pass along digital signals.
Access Point: A hardware device or a computer’s software that acts as a communication hub for users of a wireless device to connect to a wired LAN.
Modem (modulator-demodulator): A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines.
Firewall: A system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both.
MAC Address: A MAC (Media Access Control) address, sometimes referred to as a hardware address or physical address, is an ID code that’s assigned to a network adapter or any device with built-in networking capability.
6 | Network Models
To simplify networks, everything is separated in layers and each layer handles specific tasks and is independent of all other layers. Control is passed from one layer to the next, starting at the top layer in one station, and proceeding to the bottom layer, over the channel to the next station and back up the hierarchy. Network models are used to define a set of network layers and how they interact. The two most widely recognized network models include the TCP/IP Model and the OSI Network Model.
7 | The 7 Layers of the OSI Model
The Open System Interconnect (OSI) is an open standard for all communication systems.The OSI model defines a networking framework to implement protocols in seven layers.
This layer conveys the bit stream – electrical impulse, light or radio signal — through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Examples include Ethernet, FDDI, B8ZS, V.35, V.24, RJ45.
Data Link Layer
At this layer, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronization. The data link layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. Examples include PPP, FDDI, ATM, IEEE 802.5/ 802.2, IEEE 802.3/802.2, HDLC, Frame Relay.
This layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. Routing and forwarding are functions of this layer, as well as addressing, internetworking, error handling, congestion control and packet sequencing. Examples include AppleTalk DDP, IP, IPX.
This layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. It ensures complete data transfer.Examples include SPX, TCP, UDP.
This layer establishes, manages and terminates connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end. Examples include NFS, NetBios names, RPC, SQL.
This layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. Examples include encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI.
This layer supports application and end-user processes. Communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services. Examples include WWW browsers, NFS, SNMP, Telnet, HTTP, FTP
8 | The TCP/IP Model
The TCP/IP network model is a four-layer reference model. All protocols that belong to the TCP/IP protocol suite are located in the top three layers of this model.
Defines TCP/IP application protocols and how host programs interface with transport layer services to use the network. Protocol examples include HTTP, Telnet, FTP, TFTP, SNMP, DNS, SMTP.
Provides communication session management between host computers. Defines the level of service and status of the connection used when transporting data. Protocol examples include TCP, UDP, RTP.
Packages data into IP datagrams, which contain source and destination address information that is used to forward the datagrams between hosts and across networks. Performs routing of IP datagrams. Protocol examples include IP, ICMP, ARP, RARP.
Specifies details of how data is physically sent through the network, including how bits are electrically signaled by hardware devices that interface directly with a network medium, such as coaxial cable, optical fiber, or twisted-pair copper wire. Protocol examples include Ethernet, Token Ring, FDDI, X.25, Frame Relay, RS-232, v.35.
Each layer of the TCP/IP model corresponds to one or more layers of the seven-layer Open Systems Interconnection (OSI) reference model.
9 | Network Topologies
Network topology refers to the shape or the arrangement of the different elements in a computer network (i.e. links and nodes). Network Topology defines how different nodes in a network are connected to each other and how they communicate is determined by the network’s topology.
Topologies are either physical or logical. There are four principal topologies used in LANs.
All devices are connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks.
How is it used?
When a devise wants to communicate with another device on the network it sends a broadcast message onto the wire that all of the other devices can see, but only the intended recipient actually accepts and processes the message.
Failure of one station does not affect the others.
Well suited for temporary networks that must be set up quickly.
Simple and easy to setup.
Uses the least amount of cable to setup; cost effective.
Has a collision handling system which ensures that data will travel without errors and is delivered correctly.
The whole network shuts down if there is a break in the main cable.
Difficult to identify the problem when the entire network shuts down.
Limits the number of nodes you can set up for one single cable.
As the number of computers in the network increases the data transfer rate goes down.
If the data transfer rate is high then the bus network performs poorly because the data travels in a stream and cannot be overloaded.
Social and Ethical Issues
A bus topology is a little more reliable that the others because if one station shuts down it does not effect the others. If there is a break in the main chamber then it shuts down the whole network. As far as integrity I think it is good because even though other devices can see the message you send the only one that can accept it is the intended recipient.
All devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it.
What is Ring Topology?
A ring topology is a network topology or circuit arrangement in which each network device is attached along the same signal path to two other devices, forming a path in the shape of a ring. Each device in the network that is also referred to as node handles every message that flows through the ring. Each node in the ring has a unique address. Since in a ring topology there is only one pathway between any two nodes, ring networks are generally disrupted by the failure of a single link.
How does it used?
The redundant topologies are used to eliminate network downtime caused by a single point of failure. All networks need redundancy for enhanced reliability. Network reliability is achieved through reliable equipment and network designs that are tolerant to failures and faults. The FDDI(Fiber distributed data interface) networks overcome the disruption in the network by sending data on a clockwise and a counterclockwise ring. In case there is a break in data flow,the data is wrapped back onto the complementary ring before it reaches the end of the cable thereby maintaining a path to every node within the complementary ring.
Advantage of using Ring Topology
An orderly network where every device has access to the token and the opportunity to transmit
Under heavy network load performs better than a start topology.
To manage the connectivity between the computers it does not need network server
Disadvantage of using Ring Topology Ring Topology – The ITGS Wiki at BHS
One malfunctioning workstation can throw away the entire network.
Moves, adds and changes of devices can affect the entire network .
It is slower than an Ethernet network.
Social and Ethical Issue
As it stated above, adding and changing of the computer can effect the other computers that are connected from it. If a person have a basic knowledge of computer, it is easy to get, or edit the information from the other computer, and this can effect equality of access. Also the flow of the data is only from one direction or the other, some people can take this as advantage and restrict or control the data from coming in to their computer.For example, the main computer can be set to restrict curtain information that can be valuable to others.
All devices are connected to a central hub. Star networks are relatively easy to install and manage, but bottlenecks can occur because all data must pass through the hub.
What is Star Topology?
In a star network, each node is connected to a central device called a hub,which takes a signal that comes from any node and passes it along to all the other nodes in the network. Home networks usually use the star topology.A node can be anything from a computer to a printer.
How does it work?
Any data that is passed from one “node” to another is passed via the central hub before reaching A more realistic view of the nodes of a star topologyits destination. the hub controls all functions of the network. This type of topology can be used with coaxial or fiber optic cable.
Compared to the bus topology, a star network usually requires more cable.
If the Hub fails, the whole network fails.
It can be used for large networks, not just the home, because it is easier to expand.
With this particular topology, the problems are easier to fix because they isolate themselves.
If a failure were to occur in any of the cables, it will only take down one computer’s network access and not the entire network, where as in a bus topology, where multiple terminals crash.
Social and Ethical Implications
There are three types of hubs:
A Passive Hub serves simply as a conduit for the data, enabling it to go from one node to another.Passive hubs seem to be the best type of hub to use when trying to create a network for small businesses or homes, because they are just conduits; they do not use much intelligence to move around data from one to another. But that can also serve as a problem. It can make copies of the information and send it to all connected nodes. For instance, if one node decides to post an objectionable picture, they all the other nodes have the possibility of getting it. Also, if one node decides to do their taxes on that particular computer, then all the other computers can obtain that same tax information.
Intelligent Hubs (manageable hubs) include additional features that enables an administrator to monitor the traffic passing through the hub and to configure each port in the hub. Intelligent hubs allows administrators to monitor all the data passing through between nodes. Although it can be used as a preventive measure to avoid possible lawsuits or problems within the work environment, it can also be considered a leakage of privacy. Users of the nodes will essentially have “Big Brother” watching them.
A Switching Hub actually reads the destination address of each packet and then forwards the packet to the correct port. Switching hubs can have problems of reliability. It reads each packet of data and forwards it to the corresponding node. If it is private information, and the hub misreads the packet of data and sends it to the wrong node, huge issues can result. For example, if an administrator of a company tries to send an email to an employee stating that the employee is fired, but the switching hub gives it to the wrong node, and a different employee receives the email, then huge miscommunication issues can result from the unreliability of a switching hub.
A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable.
What is Tree Topology?
Tree Topology the combination of the Bus Topology and the Star Topology. The tree like structure allows you to have many server on the network, and you can branch out the network’s in many ways.
How is Tree Topology Used?
Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.
Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the “root” of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.
A Tree Topology is supported by many network vendors ad even hardware vendors.
A point to point connection is possible with Tree Networks.
All the computers have access to the larger and their immediate networks.
Best topology for branched out networks.
In a Network Topology the length of the network depends on the type of cable that is being used.
The Tree Topology network entirely depend on the trunk which is the main backbone of the network. If that has to fail then the entire network would fail. Since the Tree Topology network is big it is difficult to configure and can get complicated after a certain point.
Social and Ethical Implications
Reliability: The tree topology networks is entirely dependant on the trunk union is the main backbone on the network.If that would ever fail then the entire network would fail.
These topologies can also be mixed. For example, a bus-star network consists of a high-bandwidth bus, called the backbone, which connects a collections of slower-bandwidth star segments.
Charles Babbage, (born December 26, 1791, London, England—died October 18, 1871, London), English mathematician and inventor who is credited with having conceived the first automatic digital computer.
In 1812 Babbage helped found the Analytical Society, whose object was to introduce developments from the European continent into English mathematics. In 1816 he was elected a fellow of the Royal Society of London. He was instrumental in founding the Royal Astronomical (1820) and Statistical (1834) societies.
Charles Babbage. Wellcome Library, London (CC BY 4.0)
The idea of mechanically calculating mathematical tables first came to Babbage in 1812 or 1813. Later he made a small calculator that could perform certain mathematical computations to eight decimals. Then in 1823 he obtained government support for the design of a projected machine, the Difference Engine, with a 20-decimal capacity. Its construction required the development of mechanical engineering techniques, to which Babbage of necessity devoted himself. In the meantime (1828–39), he served as Lucasian Professor of Mathematics at the University of Cambridge.
The Difference EngineThe completed portion of Charles Babbage’s Difference Engine, 1832. This advanced calculator was intended to produce logarithm tables used in navigation. The value of numbers was represented by the positions of the toothed wheels marked with decimal numbers.
The Difference Engine Science Museum London
During the mid-1830s Babbage developed plans for the Analytical Engine, the forerunner of the modern digital computer. In that device he envisioned the capability of performing any arithmetical operation on the basis of instructions from punched cards, a memory unit in which to store numbers, sequential control, and most of the other basic elements of the present-day computer. In 1843 Babbage’s friend mathematician Ada Lovelace translated a French paper about the Analytical Engine and, in her own annotations, published how it could perform a sequence of calculations, the first computer program. The Analytical Engine, however, was never completed. Babbage’s design was forgotten until his unpublished notebooks were discovered in 1937. In 1991 British scientists built Difference Engine No. 2—accurate to 31 digits—to Babbage’s specifications, and in 2000 the printer for the Difference Engine was also built.
Babbage made notable contributions in other areas as well. He assisted in establishing the modern postal system in England and compiled the first reliable actuarial tables. He also invented a type of speedometer and the locomotive cowcatcher.
Charles Babbage, engraving from 1871. Library of Congress, Washington, D.C. (file no. LC-USZ62-66023)