Bill Hewlett


Dari Wikipedia bahasa Indonesia, ensiklopedia bebas


Hewlett (kiri) dan Alan Tripp di Pusat Pendidikan SCORE! tahun 1993

Bill Hewlett Data

Bill Hewlett bioData

William Redington Hewlett atau Bill Hewlett (20 Mei 1913-12 Januari 2001) adalah pengusaha yang bersama David Packard mendirikan Hewlett-Packard Company (HP). Ia tidak lagi menjabat presiden direktur sejak tahun 1977, dan pensiun dari jabatan CEO tahun berikutnya. Hewlett masih menjabat ketua dewan eksekutif HP hingga diangkat menjadi wakil ketua dewan pada tahun 1983. Jabatan direktur emeritus terus dijabatnya dari 1987 hingga tutup usia, 12 Januari 2001.

Ia dilahirkan di Ann Arbor, Michigan, 20 Mei 1913 dari ayah seorang dokter. Ketika ia berusia 3 tahun, keluarganya pindah ke California ketika ayahnya, Albion Walter Hewlett, diterima bekerja di Sekolah Kedokteran Universitas Stanford. Ayahnya meninggal ketika Bill berusia 12 tahun. Setelah menamatkan Sekolah Menengah Atas Lowell di San Francisco, ia kuliah di Universitas Stanford pada tahun 1930 hingga tamat dengan gelar Bachelor of Arts (1934). Ia melanjutkan ke Institut Teknologi Massachusetts hingga tamat dengan gelar magister EECS (teknik listrik dan ilmu komputer) pada tahun 1936, dan kembali ke Universitas Stanford pada 1936 hingga mendapat gelar magister teknik listrik pada tahun 1939. Ketika mahasiswa, ia adalah anggota fraternitas Kappa Sigma.

Hewlett bertemu Packard sewaktu masih kuliah tingkat sarjana di Stanford. Pada bulan Agustus 1937, mereka berdua berniat mendirikan usaha bersama. Perusahaan tersebut diberi nama Hewlett-Packard Company dan didirikan pada 1 Januari 1939. Produk pertama mereka adalah osilator audio resistansi-kapasitansi yang didesain Hewlett di program pascasarjana. Pabrik pertama mereka adalah sebuah garasi kecil di Palo Alto yang didirikan dengan modal awal AS$538.

Hewlett aktif di HP hingga tahun 1987, dan sempat bertugas sebagai tentara Angkatan Darat AS selama Perang Dunia II, termasuk sebagai kepala bagian elektronik untuk Divisi Pengembangan, Staf Khusus Departemen Perang. Seusai perang, ia menjadi anggota peninjau industri di Jepang. Setelah berada kembali di Palo Alto, Hewlett diangkat sebagai wakil presiden direktur HP pada tahun 1947, dipilih sebagai wakil presiden direktur eksekutif (1957), presiden direktur (1964), hingga menduduki jabatan CEO (1969).

Pada tahun 1939, Hewlett menikah dengan Flora Lamson. Keduanya mendapat lima orang anak, Eleanor, Walter, James, William, dan Mary. Pada tahun 1966, Hewlett dan Flora mendirikan yayasan bernama William and Flora Hewlett Foundation. Setelah Flora Hewlett meninggal tahun 1977, Hewlett menikahi istri kedua, Rosemary Bradford pada tahun 1978. Bill Hewllet, 87 tahun, meninggal dunia pada 12 Januari 2001.

William Redington Hewlett

Bill Hewlett was one of the twentieth century’s most remarkable men, and one of America’s most uncommon.

This quiet, self-effacing man, together with his longtime friend and partner, David Packard, changed the world and helped usher in the modern technological age.

Their co-founding of the Hewlett-Packard Company in 1939 (Hewlett won the coin-toss to decide which name would come first and which second in naming the company) was Silicon Valley’s defining partnership. It was also the valley’s first major start-up company, and one of its most successful, ranking at Hewlett’s death as the nation’s thirteenth largest business, with annual sales of nearly $50 billion and some ninety thousand employees in 120 countries.


William Redington Hewlett was born 20 May 1913 in Ann Arbor, Michigan, where his father, a respected physician, served on the faculty of the university’s medical school.

The family’s subsequent move to California when Bill was three years old, occasioned by his father’s acceptance of a faculty position at Stanford University, introduced young Bill to the cultural, scientific, and literary world of a dynamic and growing San Francisco Bay Area, anchored on the East Bay by the University of California at Berkeley and on the West Bay by Stanford University, and centered in the vibrant, brash, and whimsical city of San Francisco, where the family lived.

Although the father died suddenly when Bill was twelve, the family rallied. Bill was enrolled in San Francisco’s Lowell High School, and life moved on. His high school years were not academically noteworthy, doubtless influenced by the then little noticed and rarely accommodated dyslexia with which he dealt all of his life; but his intellectual curiosity, his incessant “tinkering” as he called it when he sought to understand how things worked, and his sterling character, won the admiration and respect of his high school principal, who encouraged Stanford to take a chance on Bill. Bill was admitted as a freshman in 1930.

Hewlett was fortunate to have studied under and to have been mentored by Frederick Terman, one of Stanford’s most famous professors, who was to a great degree responsible for the subsequent development of Silicon Valley.

Upon completing his engineering studies at Stanford in 1934, Hewlett studied at, and earned a master’s degree in engineering from, MIT, returning to Stanford in 1936 to continue his graduate studies in engineering. Hewlett and his fellow student and close friend David Packard, with Terman’s encouragement, formed the Hewlett-Packard Company in 1939 (its corporate offices and laboratories being located in Packard’s garage at home in Palo Alto). With the exception of four years during World War II when he served as an officer in the U.S. Army, Hewlett’s professional life was committed to the building of the company.

“He was indifferent to the trappings of wealth, but used his to help others and to make good things happen.”

The year 1939 was also of signal importance in Hewlett’s life as he and Flora Lamson, whom he had been courting, married. They had five children and together raised them to adulthood until her untimely death in 1977.

Hewlett-Packard’s first commercially viable product, developed in Hewlett’s Stanford lab, was the audio oscillator. The Walt Disney Company purchased eight of the first ones for $71.50 each, for use in the 1940 film Fantasia. The product was also of use to medical doctors, hospitals and clinics, geologists, engineers, oil and mining companies, and the military, among others. This device launched Hewlett-Packard, whose products over the next sixty years captured the world’s admiration, and transformed the nature and character of technology, including its miniaturization in manufacturing, testing, measurements, copying, scanning, and calculating, and for the most sophisticated technological requirements of medicine, science, research, business, universities, and the military worldwide.

Hewlett and Packard oversaw the company with enviable management, technological, and scientific skills. They also managed the company with a new set of operating principles and with an intensely personal style that came to redefine much of American corporate life and culture, e.g., profit-sharing, employee stock ownership, flexible work hours, and health insurance. What came to be known as the “HP way” marked the company as a special place and made it nearly as famous for this unique business culture as its products later became for the inventive, cutting-edge technology that they consistently represented in the marketplace.

Hewlett regarded his employees as the foundation of Hewlett-Packard’s success and worked as comfortably with the most junior members of his engineering staff as he did with the most senior members of his management team. Hewlett never saw his employees as being mere interchangeable parts, nor as expendable; no, they were his partners, colleagues, and friends, and they counted. His fertile imagination and curiosity about how things worked, from childhood on, earned him the title of “true visionary” as he foresaw new answers to old and intractable problems and solutions to what had been unworkable answers. This he did in his notably quiet and unassuming way, and for all these reasons he is both remembered and respected by the tens of thousands of people whose lives he touched in the Hewlett-Packard Company for sixty-two years.

Hewlett was honored for his work both here and abroad by governments, universities, scholarly and scientific societies, trade associations, and all the others whose admiration and respect were expressed almost continuously in recent decades. In 1985, President Ronald Reagan conferred on Hewlett the Presidential Medal of Science, the nation’s highest recognition for scientific accomplishment.

Hewlett also served on several presidential commissions during his active years, participated in the affairs of the scholarly and scientific organizations to which he had been elected, and served on numerous boards and committees nationally and in his hometown of Palo Alto, California.

In his personal life, he lived modestly for one of his position, preferring to raise his five children in Palo Alto, to center Hewlett-Packard’s corporate interests within the city, and to participate in its civic affairs and in the work of his beloved Stanford.

He drove himself to work and occupied the same office (seemingly with the same furniture) for more than forty years, but, rather than work there, preferred to “walk around” the offices and labs to see what was happening and to engage, question, challenge, and encourage those who were doing the company’s work.

He was indifferent to the trappings of wealth, but used his to help others and to make good things happen.

His wants were remarkably simple and did not seem to be in any way the object of his professional life. He told me once that he did what interested him as an engineer and “the money just happened along.

“It was he who asked the right questions and left the answering to others. He helped us grow by learning from our mistakes and from the encouragement and confidence we all experienced when things went right.”

I recall one conversation involving Bill, his son Walter, and me at his home following a review of our upcoming meeting of his foundation’s board. Bill could not shop for a Christmas present for his second wife, Rosemary, owing to an operation from which he was then recovering. He asked Walter to shop for the gift he wanted, a pair of binoculars for Rosie’s bird-watching.

He gave Walter a hundred dollars for the purchase. Walter, who knew a great deal about binoculars and optics, suggested that his father might prefer one of the better German or Japanese binoculars that would cost not a hundred dollars but six to eight hundred dollars.

Bill was having none of this, and the matter was “discussed” for some twenty minutes. Finally, in exasperation, Bill said, “Walter, here is two hundred dollars. It is more than enough for a decent pair of binoculars. Please go buy it.”

All this after just settling on proposals to spend some $15 million of Bill’s money at our next board meeting.

He also loved and valued his friends, one of whom, Professor Herant Katchadourian of Stanford University, recalled the following story at Bill’s memorial: “I used to take Bill on long rides, usually to his beloved ranch, and we sometimes stopped at some hole in the wall for a bite to eat. When it came time to pay, I would say, ‘Please let me take care of it; I don’t think you can afford this place.’ He usually let me get away with it with his distinctive twinkle in the eye. But on one occasion, he insisted that he was going to pay the bill himself, and then it turned out that he had no money! I told him, ‘What is going to happen to you without friends like me?’ ‘I don’t know,’ he said, ‘I guess I would be homeless.’”

Many lives were touched by Hewlett through the remarkable scope and scale of his philanthropies. Stanford (his alma mater) and UC Berkeley (his late wife Flora’s alma mater) enjoyed his special attention.

These interests extended around the world: to population issues and the status of women, their education, and economic opportunities in Africa, Southeast Asia, and Latin America; to conflict resolution, particularly in eastern and southern Europe, the former republics of the Soviet Union, and the Middle East; to U.S.-Latin American relationships; to the needs of the nation’s liberal arts colleges and research universities; to the environment in the western United States; and to the improvement of K-12 education, the performing arts, and the many communities and neighborhoods of the San Francisco Bay Area. He also had a vital interest in his adopted California, and in 1994 founded the Public Policy Institute of California, to be guided by the longtime president of his foundation, Roger Heyns, chancellor emeritus of the Berkeley campus of the University of California.

The range of his philanthropy reflected his lifelong interests in other cultures and societies, in strengthening and improving the quality of life for disadvantaged people living in the Bay Area, in the health of the environment (he was an accomplished botanist and a lifelong climber, hiker, fisherman, hunter, and photographer of California’s high and coastal mountains, its wildlands, meadows, forests, rivers, and coastline and of much of the intermountain West as well), in the well-being and vibrancy of the communities and region in which he lived and in which Hewlett-Packard was located, and in music, which he deeply loved.

These philanthropies were accomplished by his personal generosity from funds he set aside, and through the work of the William and Flora Hewlett Foundation, created in 1966 by Hewlett and his first wife. The foundation now ranks as one of the nation’s largest. “Never stifle a generous impulse” was one of his favorite and best-known phrases; as was his custom, he practiced what he taught.

It was my honor to serve as president of his foundation from 1993 to 1999. Never once in those years did he ask me to make a grant or deny one, relying instead on the collective judgment of his independent trustees and the work of his professional staff within the foundation. And while he chaired the board for most of those years, I never once observed him seeking to impose his will or to otherwise stifle or limit discussion. To the contrary, it was he who asked the right questions and left the answering to others. He helped us grow by learning from our mistakes and from the encouragement and confidence we all experienced when things went right.

Bill was not fond of looking backward. Instead, he looked steadily forward, beyond most people’s more limited perspectives or the natural limits of their imaginations, searching for the nuances and subtleties of the problems encountered, discovering how, by redefining a problem, the solution was made clearer or even self-evident, challenging when complacency became confused with contentedness, and asking, always asking, if there was not a better way or a more fundamental question to ask. He was a great teacher in this sense, as well as a colleague; and he seemed to derive as much pleasure from the one as from the other.

Bill’s character, honesty, generosity, and quiet, self-effacing ways, to his great credit, have come to be as much respected as his company. These personal traits were the markers of one whose life should be a source of inspiration to the young and a cause of admiration and respect for the rest of us. At the Stanford Memorial Church, where the service memorializing his life was held on 20 January 2001, one of his grandchildren’s recollections on the printed program read in part:

In the end, his greatest gift to future generations was not the compass he could build with his hands, but his moral compass. Its cardinal points were knowledge, modesty, justice and hard work. His life was guided by what seem to me innate principles of rectitude. He never wavered at home or at work. He was true to himself and an example to us all. It is for this I am most grateful to him.

What an example he was to us all; and so he shall remain.

Note: This essay by David Pierpont Gardner was delivered on the occasion of Bill Hewlett’s memorial service. At the time, David was president of the William and Flora Hewlett Foundation and president emeritus, University of California and University of Utah. This is reprinted with permission from the Proceedings of the American Philosophical Society, vol. 147 , June 2003.



David Packard


Dari Wikipedia bahasa Indonesia, ensiklopedia bebas


David_Packard Data

David Packard (lahir 7 September 1912 – meninggal 26 Maret 1996 pada umur 83 tahun) adalah salah satu pendiri Hewlett-Packard. Ia lahir di Pueblo, Coloradi, menerima gelar sarjana muda dari Unversitas Stanford pada tahun 1934. Setelah itu ia bekerja di General Electric di Schenectady, New York.

Pada tahun 1934, ia kembali dari New York ke Stanford, tempat ia memperoleh gelar master dalam bidang teknik elektro pada tahun berikutnya. Pada tahun yang sama ia menikahi Lucile Salter, yang kemudian memberinya 4 otang anak, David, Nancy, Susan, dan Julie. Lucile Salter meninggal dunia pada 1987.

David_Packard bioData


Pada tahun 1939, ia dan William Hewlett mendirikan Hewlett Packard di garasinya dengan modal awal sebesar 538 dollar AS. Perusahaan itu, di mana kemudian terbukti bahwa Packard adalah pengelola yang piawai dan Hewlett yang memunculkan berbagai inovasi teknologi, berkembang menjadi produsen alat uji elektro dan alat pengukur terbesar di dunia. Perusahaan itu kemudian juga menjadi produsen utama kalkulator, komputer, dan mesin cetak laser dan tinta. Packard menceritakan dalam bukunya the HP way bahwa nama Hewlett Packard ditentukan lewat lemparan koin menjadi HP bukan PH.

Packard menjabat sebagai Presiden Hewlett-Packard dari tahun 1947 hingga 1964, CEO dan Ketua Dewan Direksi dari 1964 sampai 1968, dan Ketua Dewan Direksi dari 1972 hingga 1993. Pada saat ia meninggal pada tahun 1996, kepemilikan Packard di perusahaan tersebut mencapai lebih dari 1 miliar dolar AS.

Karier Politik

Sewaktu mulai menjabat pada tahun 1969, Presiden Richard Nixon menunjuk Packard sebagai Deputi Menteri Pertahanan AS di bawah Menteri Pertahanan Melvin Laird. Packard menjabat hingga tahun 1971, ketika kemudian ia mengundurkan diri dan pada tahun berikutnya kembali menjabat sebagai ketua dewan direksi HP. Pada tahun ’70-an dan ’80-an, Packard adalah penasihat utama Gedung Putih dalam pengadaan dan pengelolaan pertahanan.


Dari awal ’80-an hingga meninggalnya pada tahun 1996, Packard mendedikasikan sebagian besar waktu dan uangnya pada proyek-proyek filantropi. Dimulai dari anak mereka Nancy dan Julie, pada tahun 1978 David dan Lucile Packard menciptakan Yayasan Monterey Bay Aquarium. Pasangan itu menyumbangkan 55 juta Dollar AS untuk membangun akuarium yang baru, yang dibuka pada 1984 dengan eksekutif direkturnya Julie Packard. Pada tahun 1987, Packard menyumbangkan 13 juta dollar untuk mendirikan institut penelitian Monterrey Bay Aquarium, dan Sejas saat itu Yayasan Packard menyediakan 90% anggaran operacional institut tersebut. Atas kedermawanannya, ia dianugerahi penghargaan United States Military Academy’s Sylvanus Thayer Award pada tahun 1982 Pada tahun 1964, pasangan tersebut mendirikan Yayasan David dan Lucile Packard. Pada tahun 1986 mereka menyumbangkan 40 juta Dollar AS untuk membangun rumah sakit anak yang kemudian dikenal sebagai Lucile Salter Packard Children’s Hospital di Universitas Stanford. RS itu dibuka pada 1991.

Pada saat meninggal, ia memberikan kira-kira 4 miliar dollar AS pada Yayasan Packard termasuk di dalamnya properti berharga di Los Altos Hill. Ketiga putri Packard duduk dalam dewan wali amanah yayasan tersebut.


Pada 6 Desember 2006, Gubernur California Arnold Schwarzenegger memasukkan nama keluarga Packard dalam museum The California Museum for History, Women, and the Arts. Sebagai tokoh ternama California. Museum ini didirikan istri Gubernur Maria Shriver untuk menghormati warga California yang berani memimpikan, dan menjadi panutan dalam menginspirasi generasi baru untuk memikirkan, menciptakan, memengaruhi, dan menciptakan.” Nama David Packard juga memiliki tanker minyak atas namanya, yang dibangun pada tahun 1977, yang dioperasikan untuk Chevron, memiliki kapasitas berat mati 406.592 ton, dan didaftarkan di bawah bendera Bahama.


Thick Coaxial dan Thin Coaxial Cable


Thick Coaxial Cable


Kabel coaxial jenis ini dispesifikasikan berdasarkan standar IEEE 802.3 10BASE5, dimana kabel ini mempunyai diameter rata-rata 12mm, dan biasanya diberi warna kuning; kabel jenis ini biasa disebut sebagai standard ethernet atau thick Ethernet, atau hanya disingkat ThickNet, atau bahkan cuman disebut sebagai yellow cable.

Kabel Coaxial ini (RG-6) jika digunakan dalam jaringan mempunyai spesifikasi dan aturan sebagai berikut:

  • Setiap ujung harus diterminasi dengan terminator 50-ohm (dianjurkan menggunakan terminator yang sudah dirakit, bukan menggunakan satu buah resistor 50-ohm 1 watt, sebab resistor mempunyai disipasi tegangan yang lumayan lebar).
  • Maksimum 3 segment dengan peralatan terhubung (attached devices) atau berupa populated segments.
  • Setiap kartu jaringan mempunyai pemancar tambahan (external transceiver). * Setiap segment maksimum berisi 100 perangkat jaringan, termasuk dalam hal ini repeaters.
  • Maksimum panjang kabel per segment adalah 1.640 feet (atau sekitar 500 meter).
  • Maksimum jarak antar segment adalah 4.920 feet (atau sekitar 1500 meter).
  • Setiap segment harus diberi ground.
  • Jarang maksimum antara tap atau pencabang dari kabel utama ke perangkat (device) adalah 16 feet (sekitar 5 meter).
  • Jarang minimum antar tap adalah 8 feet (sekitar 2,5 meter).

Thin Coaxial Cable


Kabel coaxial jenis ini banyak dipergunakan di kalangan radio amatir, terutama untuk transceiver yang tidak memerlukan output daya yang besar. Untuk digunakan sebagai perangkat jaringan, kabel coaxial jenis ini harus memenuhi standar IEEE 802.3 10BASE2, dimana diameter rata-rata berkisar 5mm dan biasanya berwarna hitam atau warna gelap lainnya. Setiap perangkat (device) dihubungkan dengan BNC T-connector. Kabel jenis ini juga dikenal sebagai thin Ethernet atau ThinNet.

Kabel coaxial jenis ini, misalnya jenis RG-58 A/U atau C/U, jika diimplementasikan dengan Tconnector dan terminator dalam sebuah jaringan, harus mengikuti aturan sebagai berikut:

  • Setiap ujung kabel diberi terminator 50-ohm.
  • Panjang maksimal kabel adalah 1,000 feet (185 meter) per segment.
  • Setiap segment maksimum terkoneksi sebanyak 30 perangkat jaringan (devices)
  • Kartu jaringan cukup menggunakan transceiver yang onboard, tidak perlu tambahan transceiver, kecuali untuk repeater.
  • Maksimum ada 3 segment terhubung satu sama lain (populated segment).
  • Setiap segment sebaiknya dilengkapi dengan satu ground.
  • Panjang minimum antar T-Connector adalah 1,5 feet (0.5 meter).
  • Maksimum panjang kabel dalam satu segment adalah 1,818 feet (555 meter).
  • Setiap segment maksimum mempunyai 30 perangkat terkoneksi.

Peralatan pelanggan yang melewatkan data dari network customer atau komputer host untuk mentransmisikan data melalui WAN. DTE terhubung dengan Local Loop melalui DCE

# Demarcation Point

Sebuah titik yang didirikan pada sebuah gedung untuk memisahkanperalatan customer dari peralatan service provider

# Local Loop

Kabel telepon tembaga atau fiber yang menghubung-kan CPE pada penggunamenuju CO (Central Office – Carrier – Service Provider), nama lain Last Mile

# Central Office

Fasilitas pelayanan provider atau gedung/bangunnan dimana kabel telepon lokal dihubungkan ke long haul, semua peralatan digital, line komunikasi fiber optik melalui line pada sistem dari switch atau peralatan lain




Data Communincation Standards and Protocols | IEEE 802.3


Brief background of IEEE802 standards for LAN and MAN

While connecting computers through networks we need to have set of rules/standards for the data to travel from one computer to other computer. The right example for this can be road traffic rules. It’s self understood, why we need traffic rules while driving, in same sense for the data packets to travel from one computer terminal to other terminal they should also follow set of rules and regulations.

One such set of rules for the networking traffic to follow is IEEE802 standards. Its developed by IEEE (Institute of Electrical and Electronics Engineers, Inc.) The IEEE is the world’s leading professional association for the advancement of technology. It’s a non- profit organization offering its members immense benefits.

The standards such as IEEE 802 helps industry provide advantages such as, interoperability, low product cost, and easy to manage standards.

IEEE standards deal with only Local Area Networks (LAN) and Metropolitan Area Networks (MAN). See in the figure below, to know where exactly the IEEE802 standards are used in a OSI layer.



The IEEE 802 standards are further divided into many parts. They are,

  • IEEE 802.1 Bridging (networking) and Network Management
  • IEEE 802.2 Logical link control (upper part of data link layer)
  • IEEE 802.3 Ethernet (CSMA/CD)
  • IEEE 802.4 Token bus (disbanded)
  • IEEE 802.5 Defines the MAC layer for a Token Ring (inactive)
  • IEEE 802.6 Metropolitan Area Networks (disbanded)
  • IEEE 802.7 Broadband LAN using Coaxial Cable (disbanded)
  • IEEE 802.8 Fiber Optic TAG (disbanded)
  • IEEE 802.9 Integrated Services LAN (disbanded)
  • IEEE 802.10 Interoperable LAN Security (disbanded)
  • IEEE 802.11 Wireless LAN & Mesh (Wi-Fi certification)
  • IEEE 802.12 demand priority (disbanded)
  • IEEE 802.13 Not Used
  • IEEE 802.14 Cable modems (disbanded)
  • IEEE 802.15 Wireless PAN
  • IEEE 802.15.1 (Bluetooth certification)
  • IEEE 802.15.4 (ZigBee certification)
  • IEEE 802.16 Broadband Wireless Access (WiMAX certification)
  • IEEE 802.16e (Mobile) Broadband Wireless Access
  • IEEE 802.17 Resilient packet ring
  • IEEE 802.18 Radio Regulatory TAG
  • IEEE 802.19 Coexistence TAG
  • IEEE 802.20 Mobile Broadband Wireless Access
  • IEEE 802.21 Media Independent Handoff
  • IEEE 802.22 Wireless Regional Area Network

Here we discuss most popular and key parts of above list

IEEE 802.3 Ethernet (CSMA/CD)

A method called Carrier Sense Multiple Access with Collision Detection (CSMA/CD) was used to send data over shared single co-axial cable connected to all computers on a network. In this method, the computer terminals (also called as stations) transmits the data over cable whenever the cable is idle, If more than one station transmit at same time and if they collide, the transmission will be stopped by such stations. They will wait for some random time and restart transmission.

The concept of sharing single cable or wire between multiple stations was used for first time in Hawaiian Islands. It was called ALOHA systems; built to allow radio communication between machines located at different places in Hawaiian Islands. Later Xerox PARC built a 2.94 mbps CSMA/CD system to connect multiple personal computers on a single cable. It was named as Ethernet.
Ethernet or IEEE802.3 standards only define MAC (Data link) and Physical layer of standard OSI model.

Don’t confuse TCP/IP with Ethernet. TCP/IP defines Transport and network layers.

Wiring and cabling standards of 802.3

There are four cabling standards as per 802.3, each one has evolved over the time for their special advantages.

The four types of cables are,

1. 10Base5
2. 10Base2
3. 10Base-T
4. 10Base-F

The table below compares all four types of cables

four types of cables

The 10 in the technical name refer to data speed of 10Mbits/sec.

“Link Integrity” and “Auto-partition” are part of the 10BaseT specification. This means that all network equipment claiming compliance with 10BaseT must support Link Integrity and Auto-partitioning.

1 | 10Base5

10 Base5 is also called as ThickNet or thick Ethernet. It uses RG-8 thick coaxial trunk cable, which looks like orange colored garden hose. The cable is tapered with taps called vampire taps in which a pin is carefully forced halfway into the cable’s core. The connection can be made to the desired computer network interface card (NIC) from these vampire taps. ThickNet can travel 500 meters per segment, and it can have a maximum of 100 taps per segment. Each tap requires a minimum distance of 2.5 meters before the next tap and has a maximum drop distance of 50 meters. The cable must be terminated with a 50-ohm terminator resistor.

Due to its complex and slow nature 10Base5 is no more preferred. The severe drawback is entire line will fail for any single failure on the trunk. This cable can be termed as obsolete/outdated technology.

The one plus point of ThickNet is that, once it’s up and running, it will continue to do so until you tell it otherwise. Although it is slow and unwieldy, 10Base5 technology is very reliable.

Here is the figure showing how the cables are connected to Network Interface Cards inside the computer using 10base5.


2 | 10Base2

10Base2 is not very different from 10 Base5. The most notable physical difference between 10Base2 and 10Base5 is the size of the co-axial cable. 10Base2 is thinner than the 10Base5 and so is called as ThinNet or thin Ethernet. Another difference is that 10Base2 is set up in a daisy chain. Daisy chain is a wiring scheme in which, for example, device A is wired to device B, device B is wired to device C, device C is wired to device D, et cetera.

10Base2 uses BNC connectors attached to a thin coaxial cable. The maximum segment length of 10Base2 is 185 meters, and the maximum number of devices per segment is 30.

10Base is also outdated/obsolete technology. In rare cases it could be deployed as a backbone for a network.

Here is the figure showing how the cables are connected to Network Interface Cards inside the computer using 10base5.


3 | 10Base-T

10Base-T is the most popular cabling method. Its also called Standard Ethernet, or twisted pair, 10Base-T works on a star topology connecting all computers to a hub. It is best used with Category 5 cable (so it can be upgraded to Fast Ethernet) and can have a maximum of three hubs daisy-chained together.

Since it is simple and cheap to implement it is most opted one. The specifications of Standard Ethernet include the following:

  • It uses RJ45 connectors on unshielded twisted-pair (UTP) cable.
  • The maximum cable length is 100 meters (before a repeater is needed).
  • The maximum number of devices per segment is 1,024 (although performance will become quite poor before that number is ever reached).

The 10Base-T standard is best employed within a LAN where cost is a factor-and speed and distance are not.

Link Integrity is concerned with the condition of the cable between the network adapter and the hub. If the cable is broken, the hub will automatically disconnect that port.

Auto partitioning occurs when an Ethernet hub port experiences more than 31 collisions in a row. When this happens, the hub will turn off that port, essentially isolating the problem.

4 | 10Base-F

In 10BaseF the twisted copper wires are replaced by a optical fiber. 10Base-F uses a higher quality cabling technology, multimode (or single-mode) fiber-optic cable, to transport data. The particular technology has two subdivisions that must be addressed: the newer 10Base-FL and 10BaseFOIRL.

Because it is older, the 10BaseFOIRL (Fiber-optic Inter-repeater Link) technology doesn’t have quite the capabilities of the newer 10Base-FL. With 10BaseFOIRL, you have the following specs:

  • It’s based on IEEE 802.3.
  • The segment length is 1,000 meters.
  • There are three sizes of duplex multimode fiber: 50-, 62.5-, or 100-micron. Of these three, 62.5-micron is the most common.
  • ST or SMA 905 connectors are used by 10BaseFOIRL.
  • It must be used in a star configuration.
  • AUI connectors have to be connected to fiber transceivers.

The much-improved 10Base-FL technology offers a different set of specs:

  • It’s based on the 10Base-F IEEE 802.3 spec.
  • It’s able to interoperate with FOIRL and is designed to replace the FOIRL specification.
  • The segment length is 2,000 meters (if exclusively using 10Base-FL).
  • The maximum number of devices per segment is two; one is the station and the other is the hub.
  • The maximum number of repeaters that may be used between devices is two.
  • NICs with standard AUI ports must use a fiber-optic transceiver.

The benefits of optical fiber are, 

  • No radio or magnetic interference.
  • Transmissions are safe from electronic bugging,
  • Cable is extremely lightweight,

10Base-FL fiber-optic technologies are best implemented in long runs where reliability and security are critical.

Different types of cable topologies:

The four types of cable topologies are, linear, spine, tree, segmented.

Linear: The linear topology is like a single cable running in all portions of building. The stations are connected to the cable through tapping.


Spine: It looks like our back one spinal cord, where multiple numbers of horizontal cables are connected to a vertical line through special amplifiers or repeaters.



Tree: This is most general topology because a network with two paths between some pairs of stations would suffer from interference between the signals.



Segmented: Since each version of 802.3 has maximum cable length per segment, to allow larger networks, repeaters can connect multiple cables.


Repeater Network

Manchester Encoding: The normal binary logics of one and zero are no more used to send data from one station to other station. The reason of not using plain binary signal is they cause ambiguities resulting in false interpretation of sent data. The major culprit is zero, where even no data is sent the receiver can assume it as zero.

So to clear out the ambiguity or to ensure proper interpretation of data, a coding technique called Manchester coding is employed in IEEE802.3 standards.

There are two of Manchester coding, they are simple Manchester coding and differential Manchester coding.



  • Each bit is transmitted in a fixed time (the “period”).
  • A 0 is expressed by a low-to-high transition, a 1 by high-to-low transition (according to G.E. Thomas’ convention — in the IEEE 802.3 convention, the reverse is true).
  • The transitions which signify 0 or 1 occur at the midpoint of a period.
  • Transitions at the start of a period are overhead and don’t signify data.

Manchester Code always has a transition at the middle of each bit period and may (depending on the information to be transmitted) have a transition at the start of the period also. The direction of the mid-bit transition indicates the data. Transitions at the period boundaries do not carry information. They exist only to place the signal in the correct state to allow the mid-bit transition. Although this allows the signal to be self-clocking, it doubles the bandwidth requirement compared to NRZ coding schemes (or see also NRZI).

In the Thomas convention, the result is that the first half of a bit period matches the information bit and the second half is its complement.

If a Manchester encoded signal is inverted in communication, it is transformed from one convention to the other. This ambiguity can be overcome by using differential Manchester encoding.


Differential Manchester Encoding Shown in above figure is a variation of basic Manchester encoding.

A ‘1’ bit is indicated by making the first half of the signal equal to the last half of the previous bit’s signal i.e. no transition at the start of the bit-time. A ‘0’ bit is indicated by making the first half of the signal opposite to the last half of the previous bit’s signal i.e. a zero bit is indicated by a transition at the beginning of the bit-time. In the middle of the bit-time there is always a transition, whether from high to low, or low to high. A reversed scheme is possible, and no advantage is given by using either scheme.
All 802.3 baseband systems use Manchester encoding due to its simplicity. The high signal is +0.85 Volts and low signal is -0.85 V giving a DC value of 0 volts.

The 802.3 MAC sub layer protocol

The IEEE802.3 based Ethernet frame consists of preamble of 56 bit-size, start of the frame delimiter of 8bit size, destination address of 48 bit-size, sources address of 48 bit-size, type field to identify higher layer protocol of 16 bit-size, data field of variable bit-size, and frame check sequence field of 32 bit size.

The figure below explains better.


The 802.3 MAC sub layer protocol

802.3 Ethernet MAC sub layer Protocol Minimum Frame Size

  • Longest segment = 500 meters
  • At most 4 repeaters
  • Maximum LAN length is 2500 m
  • Maximum round-trip time is 50µsec
  • 10 Mbps implies 100 nsec / bit, 500 bits takes 50 µsec
  • 802.3 uses 512 bits (64 bytes) as minimum frame size

The binary Exponential Backoff Algorithm

Exponential backoff is an algorithm that uses feedback to multiplicatively decrease the rate of some process, in order to gradually find an acceptable rate. It is often used in network congestion avoidance to help determine the correct sending rate. For example, a sender might send a message, set a timer to wait 0.25 seconds for an acknowledgment, and if none arrives, retransmit the message and wait 0.5 seconds for an acknowledgment. It will continue to retry until it receives an acknowledgement and will wait, 1s, 2s, 4s, 8s, etc. each time before retrying.

Time slots are defined to be 51.2µsec during contention period. After i collisions, backoff random number of intervals between 0 and 2i -1. i is bounded at 10. After 16 attempts, the sender quits

Basic Intuition used in the algorithm is,

—– Assume that number of contending stations is small until proven otherwise
—– If i were fixed at 1023, lots of unnecessary waiting
—–If i were fixed at 1, potential for unbounded waiting

The performance of Ethernet (802.3)

Here we evaluate the perfromance of 802.3 under the conditions of full load and constant load.

Metcalfe and Boggs – ignore binary exponential backoff and assume constant probability, p, of retransmission in each slot probability that one station acquires a slot, A, is


k = number of stations ready to transmit
p = probability that a station will retransmit
A is maximized when p is 1/k
When p is 1/k, A –> 1/e as k –> infinity


is the probability that the contention window is j slots

Mean number of slots per contention is:


Each slot is bounded by 2t, so the mean window size is bounded by
Assuming optimal p (p = 1/k), A= 1/e and


Let P be the mean transmission time / frame


F = frame length
B = bandwidth
L = cable length
c = speed of light

P = F/B



As BL increases, efficiency decreases

Here is the chart showing channel effeciency V/S Number of stations trying to send



IEEE-802.3 Protocol


The IEEE-802.3 Protocol is based on the Xerox Network Standard (XNS) called Ethernet. The IEEE-802.3 Protocol is commonly called Ethernet but it is just one version. These are the four versions of the Ethernet frame:

  • Ethernet_802.2 Frame type used on Netware 3.12 & 4.01
  • Ethernet_802.3 Frame type used on Netware 3.x & 2.x (raw)
  • Ethernet_II Frame type used on DEC, TCP/IP
  • Ethernet_SNAP Frame type used on Appletalk (SubNet Access Protocol)

NOTE: The Source and Destination must have the same Ethernet Frame type in order to communicate.

CSMA / CD (Carrier Sense Multiple Access / Collision Detect)

Bus arbitration is performed on all versions of Ethernet using the CSMA / CD (Carrier Sense Multiple Access / Collision Detect) protocol. Bus arbitration is another way of discussing how to control who is allowed to talk on the medium (and when). Put simply, it is used to determine who’s turn it is to talk.

In CSMA / CD, all stations, on the same segment of cable, listen for the carrier signal. If they hear the carrier, then they know that someone else it talking on the wire. If they don’t hear carrier then they know that they can talk. This is called the Carrier Sense portion of CSMA / CD.

All stations share the same segment of cable, and can talk on it similar to a party line. This is the Multiple Access portion of CSMA / CD.

If 2 stations should attempt to talk at the same time, a collision is detected, and both stations back off–for a random amount of time–before they try again. This is the Collision Detect portion of CSMA/CD.

IEEE 802.3 Ethernet Media Types

The most common Ethernet variants

IEEE 802.3 defines five media types of IEEE 802.3 Ethernet Types shown below:

  • IEEE 802.3 10Base5 Thick Coax 10Mbps Baseband 500m
  • IEEE 802.3a 10Base2 Thin Coax 10Mbps Baseband 185m
  • IEEE803b 10Broad36 Broadband 10 Mbps Broadband 3600m
  • IEEE802.3e 1Base5 StarLAN 1 Mbps Baseband 500m
  • IEEE 802.3i 10BaseT Twisted Pair 10Mps Baseband 100m

IEEE 802.3 – 10Base5 (Thick Coax) is used only as backbones to networks. Backbones are lines that connect buildings & network equipment together (such as Bridges, Routers, Brouter, Hubs, Concentrators, Gateways, etc.). 10Base5 is now being replaced by either Thin Coax or fiber optics.

IEEE 802.3a – 10Base2 is commonly used in new installations as a backbone to connect buildings and network equipment together. 10Base2 (Thin Coax) is also used to connect work stations together, but the preferred choice is to use 10BaseT.

IEEE 802.3b – 10Broad36 is rarely used; it combines analog and digital signals together. Broadband means that a mixture of signals can be sent on the same medium.

IEEE 802.3e – StarLAN is a slow 1 Mbps standard that has been replaced by Thin Coax or Twisted Pair.

IEEE 802.3i – 10BaseT is commonly used to connect workstations to network hubs. The network hubs can use 10BaseT (Twisted Pair) to connect to other Hubs.

IEEE 802.3 10Base5 Thick Coax 10Mbps Baseband 500m

10Base5 Specifications : 

Coaxial Cable

Coaxial cable uses double-shielded 0.4 inch diameter RG8 coaxial cable (about the size of a garden hose). The cable is not flexible, and difficult to work with. The cable has a characteristic impedance of 50 ohms.

Connection to the workstation is made with a MAU Medium Attachment Unit (or Transceiver). The MAU physically and electrically attaches to the coaxial cable by a cable tap. The cable is pierced, and a connection is made (by a screw) to the center conductor.

The MAU is connected to the NIC (Network Interface Card) by the AUI (Attachment Unit Interface) cable. The AUI port on a NIC (and a MAU) is a DB15 connector. Maximum AUI cable length is 50 m.

Cable Termination and Connector

The standard termination is 50 +/-2 ohms. The end connector on the RG-8 cable is an “N” type connector. The cable is externally terminated with a resistor inside an N connector.


To minimize noise on the segment, the cable is grounded at the termination–at only one end. 

Maximum Nodes on a cable segment

On any single cable segment, the maximum allowed number of nodes or MAUs is 100.

Minimum Distance between nodes

Minimum distance between nodes, or MAUs, is 2.5 m (or 8 feet).

Velocity of propagation

The speed of the signal through the cable is 0.77c. (“c” is equal to the speed of light – 300,000,000 m/sec). The velocity of propagation for 10Base5 specification cable is equal to 0.77 x 300,000,000 m/sec. This is determined by cable capacitance. Maximum coaxial cable segment length is 500 m.

The maximum segment length is 500 m–or, a maximum 2.165 uSec propagation delay. Propagation delay is what actually determines the maximum length of the segment.

Propagation delay for a specific cable length in meters is calculated by:

What is the propagation delay for a 500 m length of 10Base5 cable?

Maximum Number of Segments

Maximum of 5 segments (with 4 repeaters) can be along the path between any 2 network nodes: 3 may be coax segments having a maximum delay of 2.165 uSec and 2 may be link segments having a maximum delay of 2.570 uSec.

With no link segments used, three populated coax segments can exist on a path.

The 5-4-3 Rule

The 5-4-3 Rule states that you are allowed five (5) segments, with four (4) repeaters, and three (3) populated segments.

Maximum Transfer Rate

The Maximum Data Transfer Rate for IEEE 802.3 is 10 Mbps (10,000,000 bits per second of data). In fact, data transfer is dependent on how many users are fighting for the bus–and how fast the user’s data can get on the bus.

Physical Bus / Logical Bus

IEEE 802.3 is a Physical Bus – the cable is physically laid out as 1 long cable with the network nodes attached to it. It is also treated as a Logical Bus – electronically and logically, it appears as one long cable, with the network nodes attached to it.

IEEE 802.3a 10Base2 Thin Coax 10Mbps Baseband 185m

Coaxial Cable

Uses RG-58A/U coaxial cable, 0.2 inch in diameter. The cable is flexible and easy to work with. The cable has a characteristic impedance of 50 ohms.

Connection to the workstation is made with either a MAU – Medium Attachment Unit / Transceiver, or directly to the NIC using a BNC TEE.

Most NICs have the MAU built-in for 10Base2. The 3C509 card in the lab have built-in MAUs for Coax (10Base2) and Twisted Pair (10BaseT). They also have a AUI connection for an external MAU, such as used in 10Base5. You can buy MAUs for 10Base2 and 10BaseT (if your NIC does not have them already built-in).

Cable Termination and Connector

The standard termination is 50 +/-2 ohms. The end connector is an “BNC” twist and lock-type connector. The cable is externally terminated with a special terminating BNC connector. BNC stands for Bayonet Navy Connector.


To minimize noise on the segment, the cable is floating. The IEEE 802.3a specifications calls for all BNC connectors and TEEs to be insulated. A common problem with 10Base2 is having the barrel of the BNC connector touching a heating duct or computer chassis.

The shield should be floating: it is not connected to electrical ground.

Maximum Nodes on a cable segment.

On any 1 cable segment, the maximum allowed number of nodes is 30.

Minimum Distance between Nodes

Minimum distance between nodes is 0.6 m (2 feet).

Velocity of propagation

The speed of the signal through the 10Base2 cable is 0.65c. (“c” is equal to the speed of light – 300,000,000 m/sec). The minimum velocity of propagation for 10Base2 specification cable is equal to 0.65 x 300,000,000 m/sec. This is determined by cable capacitance.

Maximum coaxial cable segment length 185 m.

The maximum segment length is 185 m (600 ft.), or a maximum 0.949 uSec propagation delay. Propagation delay, not distance, is what actually determines the maximum length of the segment. Propagation delay (units are seconds) is calculated by:

What is the propagation delay for a 185 m length of 10Base2 cable?

Maximum Number of Segments

Maximum of 5 segments (with 4 repeaters) can be along the path between any two network nodes: 3 may be coax segments having a maximum delay of 0.949 uSec, and 2 may be link segments having a maximum delay of 0.949 uSec.

With no link segments used, three populated coax segments can exist on a path.

Maximum Transfer Rate

The Maximum Data Transfer Rate for IEEE 802.3a is 10 Mbps (10,000,000 bits per second of data). In actual fact, data transfer is dependent on how many users are fighting for the bus–and how fast the user’s data can get on the bus.

Physical Bus/Logical Bus

IEEE 802.3a is a Physical Bus – the cable is physically laid out as one long cable, with the network nodes attached to it.

It is also treated as a Logical Bus – electronically and logically, it appears as one long cable, with the network nodes attached to it.

IEEE 802.3i 10BaseT Twisted Pair 10Mps Baseband 100m

Twisted Pair Cable

10BaseT uses unshielded twisted pair (UTP) cable. The cable is flexible and easy to work with. The cable has a characteristic impedance of 100 ohms. There are 2 pairs of twisted wires used with 10BaseT: separate Rx (receive) and Tx (transmit) pairs. The lines are balanced lines to minimize noise and there are a Rx+ & Rx- pair and a Tx+ & Tx- pair.

The nodes are connected to a MPR (multi port repeater), also called a Concentrator, or Hub. The cables are wired as straight-through cables: this means that the Node’s Rx & Tx lines connect directly to the Hub’s Rx & Tx lines respectively.

Two nodes can be directly connected together (bypassing the Hub) by using a Cross-over (X-over) cable. In a X-over cable, the Tx and Rx lines are crossed so that one node’s Tx lines go to the other node’s Rx lines–and vice versa.

Cable Termination and Connector

The standard termination is 100 ohms. The end connector is an “RJ45” quick disconnect connector. The cable is internally terminated at the NIC (Network Interface Card) and Hub.


To minimize noise on the segment, the cable is a balanced line with Rx- & Rx+ and Tx- & Tx+. There is no shielding: any noise that appears on the Rx+ wire will appear on the Rx- wire. When the 2 signals are combined, the noise cancels because Rx- & Rx+ is 180 degrees out of phase.

Maximum Nodes

For 10BaseT, the maximum allowed number of nodes is 128 (on one segment).

Maximum Distance between Nodes & Hub

The maximum distance between nodes & Hub is 100 m.

Velocity of propagation

The speed of the signal through the cable is 0.59c. (“c” is equal to the speed of light: 300,000,000 m/sec). The minimum velocity of propagation for 10Base5 specification cable is equal to 0.59 x 300,000,000 m/sec., and is determined by cable capacitance.

Maximum cable segment length 100 m

The maximum segment length is 100 m, or a maximum 0.565 uSec propagation delay. Propagation delay, not distance, is what actually determines the maximum length of the segment. Propagation delay (units are seconds) is calculated by the following:

What is the propagation delay for a 100 m length of 10BaseT cable?

Maximum Number of Segments

A maximum of 5 segments (with 4 repeaters) can be along the path that’s between any 2 network nodes: 3 may be coax segments, having a maximum delay of 0.565 uSec, and 2 may be link segments, having a maximum delay of 0.565 uSec. The 5-4-3 rule, and its special implications for IEEE 802.3i., will be discussed under Repeaters

Maximum Transfer Rate

The Maximum Data Transfer Rate for IEEE 802.3i is 10 Mbps (i.e. 10,000,000 bits per second of data). In actual fact, though, data transfer is dependent on how many users are fighting for the bus–and how fast the user’s data can get on the bus.

Physical Star / Logical Bus

IEEE 802.3a is a Physical Star. The cable is physically laid out as star pattern, with all twisted pair cables (AUIs) coming from the nodes to a central wiring closet (containing the Hub, or Multi-Port Repeater / Concentrator).

It is treated as a Logical Bus: electronically and logically, it appears as 1 long cable, with the network nodes attached to it. A node can be a client, a server, a workstation, or other hub.

MAC – Medium Access Control

The IEEE 802.3 Medium Access Control layer is physically located in the firmware (ROM) of the Network Interface Card. It is the link between the Data Link Layer and the Physical Layer of the OSI model, and logically resides in the lower portion of the Data Link Layer. There is only 1 MAC layer for all of the IEEE 802.3 versions (802.3, 802.3a, 802.3b, 802.3i, etc.).

The IEEE 802.3 Medium Access Control uses CSMA/CD (Carrier Sense Multiple Access/Collision Detect) to determine Bus Arbitration. The MAC layer is concerned with the order of the bits, and converting the Datagram from the Network Layer into Packets/Frames.


The Preamble is used to synchronize the receiving station’s clock. It consists of 7 bytes (consisting of 10101010 each).

Start Frame Delimiter (SFD)

The Start Frame Delimiter indicates the start of the frame. It consists of 1 byte of 10101011. It is an identical bit pattern to the preamble mentioned above, except for the last bit.

Start Frame Delimiter (SFD)

The Start Frame Delimiter indicates the start of the frame. It consists of 1 byte of 10101011. It is an identical bit pattern to the preamble, except for the last bit.

The Destination Address (DA)

The DA indicates the destination (receiving station) of the frame. It can be 2 or 6 octets long (16 or 48 bits); usually, it is 6 octets (the 2 octet version is used for compatibility with the original Ethernet frame from XNS, and is considered obsolete).

The DA field consists of the following:

I / G stands for Individual/Group. It indicates whether the destination is for an individual or for a multicast broadcast. It is one bit long, as shown below:

0 = Individual1 = Group

A multicast broadcast can be for everyone or for a group. For a multicast broadcast to all stations, the Destination Address = FFFFFFFFFFFFh (h – hexadecimal notation). To multicast to a specific group, unique addresses must be assigned to each station–by the Network Administrator.

U / L stands for Universal/Local. It allows for unique addresses. It is used to indicate whether or not a local naming convention is used, and is administered by the Network Administrator (not recommended – an incredible amount of work). The burnt-in ROM address is also used (and is recommended).

The 46-Bit Address Field consists of 46 bits. This address field indicates the destination NIC card’s address, which is burnt into the firmware (ROM) of the card. It can also be the unique name assigned to the card during the card’s initialization–by the Network Administrator.

Source Address (SA)

The Source Address indicates the source–or transmitting station–of the frame. It is identical in format to the Destination Address, but always has the I/G bit = 0 (Individual/Group Bit = Individual).

Length (L)

The Length field indicates the Length of the Information Field: it allows for variable-length frames. The minimum Information Field size is 46 octets and the maximum size is 1500 octets. When the Information Field size is less than 46 octets, the Pad field is used. Because the 802.3 MAC Frame has a Length field, there is no End Delimiter. The Length of the field is known and the receiving station counts the number of octets.

Information Field (Data)

The Information Field contains the Data from the next upper layer, the Logical Link Control Layer. It is commonly referred to as the LLC Data. The minimum Information Field size is 46 octets and the maximum size is 1500 octets.


The Pad is used to add octets–to the Information Field–to bring it up to the minimum size of 46 octets (if the Info Field is less than the minimum).

Frame Check Sequence (FCS)

The Frame Check Sequence is used for error-checking at the bit level. It is based on 32 bit CRC (Cyclic Redundancy Checking), and consists of 4 octets (4 x 8 = 32 bits). The FCS is calculated according to the contents of the DA, SA, L, Data and Pad fields.

Total Length of a MAC Frame

Min Size (octets) Max Size (octets)
Preamble 7 7
Start Frame Delimiter 1 1
Destination Address 6 6
Source Address 6 6
Length 2 2
Information Field 46 1500
Frame Check Sequence 4 4
TOTAL: 72 1526 Octets

Packet Sniffing

A packet sniffer captures packets from the Ethernet bus. The network interface card (NIC) acts in a mode called “promiscuous mode.” Promiscuous mode means that the NIC can look at all traffic on the wire, and not just traffic addressed to itself. Normally, the NIC ignores all traffic (except for packets addressed to itself, multicasts and broadcast packets).

The following captured packet is displayed in raw format. Raw format is hexadecimal numbers that are in rows of 16 digits (see below).

FF FF FF FF FF FF 00 20 AF 10 9A C0 00 25 E0 E003 FF FF
00 22 00 11 00 00 00 00 FF FF FF FF FFFF 04 52 00 00 00 00 00 20 AF 10
9A C0 40 0B 0001 00 04 00 00 00 00 00 00 00 00 00

Raw Captured Packet

Raw captured packets do not display the Preamble, Start Frame Delimiter or the Frame Check Sequence fields. These fields are used to inform the receiving station of a new frame, and also for error checking.

The breakdown of the packet (according to the Ethernet MAC frame) is shown below:

1st 6 bytes: FF-FF-FF-FF-FF-FF Destination MAC address
2nd 6 bytes: 00-20-AF-10-9A-C0 Source MAC address
Next 2 bytes: 0025 Length/Type field – IEEE 802.3 frame
Next 37 bytes Data
Last 9 bytes all 00s Pad

The length of the data in the Info field is 0025h, or 37 bytes long. The minimum Info field size is 46 bytes so the data is padded with 9 bytes of 00h.

The Length / Type field value is less than 05DCh (1500 in decimal). This statistic indicates that it is an Ethernet_802.2 frame (IEEE 802.3) that has a Logical Link Control layer (covered later) between the MAC layer and the Network layer.

If the value is 0800h, this indicates an Ethernet_II frame used for TCP/IP.

If the value is 8137, this indicates an Ethernet_802.3 (raw) frame used by pre 3.12 Netware.

The complete listing of the Length/Type field assignments is covered in Appendix C Ethernet Type Field.

Looking at the MAC block diagram, the data from the Info field is shown broken down (up, to be more exact) into the higher levels: Logical Link Control layer, Network layer and Transport layer. Note: A thorough knowledge of each of the layers, and quite a few handy reference books, are required in order to determine exactly what is happening. The remaining layers will be examined as an example only.

Note: Modern packet sniffer will break down the raw packet’s fields for you.

LLC Layer

The first 3 bytes of the data–in the Ethernet frame Info field– is the header of the Logical Link Control layer (LLC IEEE 802.2).

1st byte:E0Destination Service Access Port (DSAP)
2nd byte:E0Source Service Access Port (SSAP)3rd byte:03Control code

E0h indicates that it is a Novell Netware stack talking (source) to a Novell Netware stack (destination). The 03h is the LLC layer’s handshaking. The size of the LLC’s Data field is 34 bytes. The LLC layer is covered extensively in the next chapter (Chapter 34).

Network Layer

The data of the LLC layer becomes both the header and data of the layer above it (the Network layer). In this case, it is an IPX PDU (Protocol Data Unit). This is indicated by the first 2 bytes being FFFFh (the IPX checksum).

(Hex)1st 2 bytes:FFFFIPX Checksum
(always FFFFh, FCS does error checking)Next 2 bytes:0022IPX PDU length
allowable range 001Eh (30) to 0240h (576)Next byte:00Transport control field – hop count,
allowed 00 to 0Fh (15)Next byte:11Packet Type 11h (17) is Netware Core Protocol (NCP)
Next 4 bytes:00000000Destination network address, all 0s indicate local networkSegment number
in server autoexec.ncf fileNext 6 bytes:FFFFFFFFFFFFDestination host address
(same as dest MAC address)Next 2 bytes:0452Destination socket ,
Service Advertising ProtocolNext 4 bytes:00000000Source network address
(all 0s indicate local network)Next 6 bytes:0020AF109AC0Source host address
(same as soruce MAC address)Next 2 bytes:400BSource socket
(arbitrarily assigned starting at 4000h)Last 4 bytes:Data

The following tables describe the field values for the IPX PDU’s packet type and Socket numbers:
Packet TypeField Value PurposeNLSP00hNetware Link Services ProtocolRIP01hRouting Information
Protocol SAP04hService Advertising ProtocolSPX05hSequenced Packet ExchangeNCP11hNetware Core
ProtocolNetBIOS14hNetBIOS and other propagated packets

IPX Packet Type Field

Netware Socket Numbers and Processes

Socket NumberProcess451hNetware Core Protocol (NCP)452hService Advertising Protocol
(SAP)453hRouting Information Protocol (RIP)455hNovell NetBIOS456hDiagnostics9001Netware
Link Services Protocol (NLSP)9004IPXWAN Protocol

Transport Layer

The Network layer’s Data field becomes the Transport layer’s PDU. In this case, it is only 4 bytes long.

1st 2 bytes:0001Packet type (Standard Server Request)
Next 2 bytes:0004Service type (file server)

The following tables describe the values of the Service Advertising Protocol’s Packet Type and Service Type fields:

Field Value (hex)Packet Type01Standard Server Request02Standard
Server Reply03Nearest Server Request04Nearest Server Reply

SAP Packet Types

Field Value (hex)Service Type0000Unknown0003Print Queue0004File
Server0005Job Server0007Print Server0009Archive Server0024Remote Bridge Server0047
Advertising Print Server8000All values are reserved up to 8000FFFFWildcard

Example Packet Sniffing Summary

This packet is commonly called a Standard Server Request. It is broadcast (Destination FF-FF-FF-FF-FF-FF) on the local network (00-00-00-00) f rom a Novell Netware client. The client is looking for a file server to login in to. The server would respond with a Server Advertising Protocol PDU listing its services.

Cisco Certified Network Associate | CCNA



Apa itu CCNA?

Jawab :

CCNA adalah sertifikasi networking pada level dasar (associate) yang diperuntukkan bagi mahasiswa/engineer/umum yang ingin mendalami teknologinya Cisco.

Tidak hanya teknologinya saja yang dipelajari, tapi juga perangkatnya Cisco yaitu Router dan Switch.

CCNA saat ini menjadi requirement bagi engineer yang ingin terjun ke dunia teknologi informasi khususnya networking. Dengan memiliki CCNA, engineer memiliki prospek pekerjaan yang kompetitif untuk kedepannya.









1 |Bagaimana cara mendapatkan CCNA?

Jawab :

Anda mengikuti ujian sertifikasi (exam) di perwakilan Cisco yaitu Pearson Vue. Di Bandung misalnya Telkom PDC.

Sebelum mengikuti ujian, Anda harus mendaftar dulu. Untuk mengetahui lokasi ujian yang dekat dengan Anda, silahkan klik Locate Test Center.

Pada saat pendaftaran ujian, Anda akan ditanya kode ujiannya (exam code) untuk sertifikasi Cisco CCNA.


2 |Berapa kode ujian untuk CCNA?

Jawab :

Untuk CCNA kode ujiannya 200-120

3 |Berapa biaya ujian untuk CCNA?

Jawab :

Screenshot from 2016-08-23 14-18-26

Untuk CCNA harga ujiannya 295 USD

Biasanya Anda akan dikenai pajak dan biaya administrasi jika mengikuti ujian di perwakilan Pearson Vue. Biaya tersebut berbeda-beda tiap lembaga. Dan harga akhir yang harus dibayarkan tergantung kurs dollar pada saat Anda mendaftarkan diri untuk ujian.

Berdasarkan informasi dari marketing TelkomPDC pada 2 Nov 2015, biaya ujian CCNA 295 USD include administrasi totalnya Rp 4.700.000

4 |Bagaimana cara mendaftar ujian CCNA di lembaga testing center?

Jawab :

Berikut ini beberapa langkah praktis untuk mendaftar ujian CCNA :

  1. Kontak lembaga testing center pilihan Anda. Biasanya 1 atau 2 minggu sebelum waktu pelaksanaan ujian. Carilah yang dekat dengan lokasi Anda tinggal.
  2. Isi formulir pendaftaran ujian, biasanya terdapat kode ujian dan waktu pelaksanaan ujian. Setelah itu kirimkan kembali ke pihak testing center.
  3. Transfer biaya ujian ke lembaga testing center atau datang langsung dengan membayar cash
  4. Datang ke lokasi ujian 30 menit sebelum waktu pelaksanaan ujian
  5. Tips dari nixtrain : pada saat memilih jam ujian, hendaknya pilih yang pagi hari, misal jam 09.00 – 11.00. Karena pada jam ini biasanya belum melakukan aktivitas pekerjaan yang nantinya dapat mengganggu konsentrasi pada saat ujian.

5 |Bagaimana cara belajar untuk mendapatkan CCNA?

Jawab :

Untuk mendapatkan CCNA Anda bisa mengikuti salah satu dari tiga cara ini :
Pertama, belajar mandiri. Anda mencari sumber belajar dan mempraktikannya sendiri.

Kedua, mengikuti training di Cisco Academy/Cisco Learning Partner. Cisco Academy biasanya ada dikampus-kampus/SMK dan membutuhkan waktu yang lama untuk menempuh 4 modul CCNA. Cisco Learning Partner biasanya ada di kota2 besar seperti Jakarta.

Ketiga, mengikuti training FastTrack. Dengan program FastTrack Anda mendapatkan delivery materi dengan waktu yang relatif singkat, bisa 4-6 hari.


6 | Mengapa harus ikut training CCNA?

Jawab :

Tidak ada keharusan untuk mengikuti training CCNA ketika Anda ingin mengambil ujian CCNA. Cisco sendiri tidak menjadikan syarat training sebagai syarat untuk mengikuti ujian CCNA. Jika Anda sudah pede untuk ujian, bisa langsung daftar ke perwakilan Pearson Vue, tapi jika belum pede, disarankan untuk mengikuti training, karena jika Anda gagal dalam mengerjakan soal ujian CCNA maka Anda akan kehilangan 295 USD + biaya administrasi dan tidak bisa di retake lagi.

7 | Apa saja yang harus dipelajari biar bisa lulus ujian CCNA?

Jawab :

Materi ujian dapat dilihat di Exam Topics di sini. Agar Anda bisa lulus, Anda harus menguasai topik yang akan diujikan.

8 | Bagaimana kita tahu lulus ujian CCNA atau tidak?

Jawab :

Setelah Anda mendaftar ujian ke perwakilan Pearson Vue, selanjutnya Anda tinggal ujian pada hari dan jam yang telah ditentukan sendiri atau mengikuti jadwal dari perwakilan Pearson Vue.

Kemudian setelah Anda selesai ujian, begitu di submit jawaban yang telah diisi maka akan keluar hasilnya dan exam report akan dikirimkan oleh Admin ke email Anda, contoh seperti berikut ini : (Lihat pada status Grade : jika lulus isinya Pass, jika gagal isinya Failed)


Kalau sudah lulus CCNA, Anda akan mendapatkan nomor Cisco ID (atau biasanya disebut nomor cantik Cisco) dan nomor sertifikat dapat di verifikasi di web cisco (contohnya seperti dibawah ini)



9 | Berapa passing grade untuk ujian CCNA?

Jawab :

Passing grade adalah nilai minimal untuk lulus ujian CCNA. Anda harus mendapatkan score diatas 825 dari nilai total 1000. Jika dibawah 825 Anda tidak lulus ujian CCNA.




ccna-verified (1)

ccna-issued (1)

10 | Berapa soal yang harus saya kerjakan dan berapa lama waktunya ?

Jawab :

Berdasarkan informasi dari website Cisco, lama ujian 90 menit dan jumlah soal 50-60.
Untuk orang Indonesia lama waktu ujian 120 menit karena bukan native English.

11 |Bagaimana bentuk soal ujian CCNA?

Jawab :

Bentuk soal ujian bisa berupa :

  • Multiple-choice single answer
  • Multiple-choice multiple answer
  • Drag-and-drop
  • Fill-in-the-blank
  • Testlet
  • Simlet
  • Simulations (Lab)

12 | Jika sudah lulus CCNA, berapa lama masa aktif CCNA-nya?

Jawab :

Masa aktifnya 3 tahun, setelah itu bisa re-exam CCNA lagi atau bisa ngambil ujian diatasnya sebelum masa aktifnya habis.

13 |Apakah saya boleh menambahkan CCNA dibelakang nama saya di CV?


Selama sudah lulus menempuh ujian CCNA+masih aktif CCNA-nya, maka Anda boleh menambahkan CCNA dibelakang nama Anda, misalnya ‘Nama Anda, CCNA’.


Tabel Pilihan Macam-macam Sertifikasi Cisco

Tabel Pilihan Macam-macam sertifikasi cisco _ alvin-blctelkom

Screenshot at 2016-08-22 22-08-05

cisco 2

Kiat Sukses Menjadi Seorang Network Engineer


Kiat Sukses Menjadi Seorang Network Engineer

Antara lain adalah dengan mengikuti sertifikasi seperti sertifikasi CCNA (Cisco Certified Network Associate), meningkatkan pengalaman dan kemampuan problem solving dengan mengikuti training komputer, mengikuti kursus komputer. Silakan simak ulasan, tips dan kiat sukses menjadi seorang network engineer di artikel ini agar anda dapat memaksimalkan potensi yang ada didalam diri anda.




Intinya adalah ada keinginan untuk terus belajar dan belajar, serta mencoba untuk menerapkan apa yang didapat selama kursus, training, atau sertifikasi tersebut. Berikut ini akan sedikit dijabarkan bagaimana kiat sukses untuk para network engineer.

cisco 2

Selayang pandang tentang tugas dan kiat sukses menjadi seorang network engineer

Tabel Pilihan Macam-macam sertifikasi cisco _ alvin-blctelkom

Berdasarkan Merriam-Webster English Dictionary “Network” memiliki pengertian sebagai “sebuah lingkungan yang memiliki interkoneksi atau inter-relasi berupa keterkaitan atau pengelompokkan sebuah sistem” . Secara spesifik, network yang kita bahas disini adalah sebuah sistem interkoneksi perangkat komputer beserta beserta seluruh periferalnya (modem, router, switch, terminal dan sebagainya).

Sedangkan “Engineer” memiliki makna sebagai seseorang yang terdidik atau terlatih secara spesifik untuk bidang teknis tertentu.

Jika dilihat dari perspektif tugas yang lebih spesifik, profesi network engineer dapat dibagi lagi menjadi beberapa golongan profesi, antara lain networking engineer, system engineer, network analyst, network consultant, system manager, network manager, dan network associate. Pembagian ini didasarkan pada konsep tanggung jawab dan tugas yang lebih spesifik namun secara umum tetap berhubungan dengan sistem komputerisasi yang terintegrasi melalui jaringan.

Cakupan tugas (job description) seorang network engineer

Secara umum, seorang network engineer memiliki tugas untuk mengawasi atau melakukan instalasi, melakukan konfigurasi, dan melakukan pemeliharaan (maintenance) sistem informasi dan jaringan. Tanggung jawab umum yang biasanya menjadi tugas seorang network engineer adalah sebagai berikut :

  1. Melakukan instalasi hardware, sistem atau software baru yang digunakan dalam jaringan.
  2. Melakukan instalasi, konfigurasi, dan perawatan layanan jaringan (network services) dan perangkat jaringan.
  3. Mendukung fungsi administratif pada penggunaan perangkat jaringan.
  4. Mengatur protokol untuk pencadangan (backup) atau restorasi (restore) didalam sistem.
  5. Merencanakan dan memberikan dukungan untuk implementasi infrastruktur jaringan komputer.
  6. Melakukan perbaikan (troubleshooting) atau analisis terhadap server, komputer kerja (workstations) dan semua yang berkaitan dengan hal tersebut.
    Mendokumentasikan permasalahan-permasalahan yang terjadi didalam jaringan untuk referensi dimasa yang akan datang
  7. Memonitor kinerja sistem dan dapat mengimplementasikan performance tuning.
  8. Mengatur akun pengguna (users account), izin pengguna (users permission), serta implementasi firewall, dan sistem keamanan.
  9. Memperhatikan aspek keamanan pada aplikasi dan jaringan.

Perusahaan atau korporat besar dan ternama biasanya lebih spesifik dalam memilih network engineer untuk menangani jaringan komputerisasi ditempat mereka. Perusahaan-perusahaan seperti ini mengharuskan setiap network engineer untuk memiliki kemampuan teknis dan requirement tertentu, misalnya :

  1. Memiliki sertifikasi training CCNA, MCSE, CCNP, CCIE, CNE (Cisco), MTCNA (MikroTik), atau JNCIA (Juniper) dan sejenisnya.
  2. Memiliki pendidikan setara sarjana atau D3 untuk bidang pengetahuan komputer, informasi teknologi, atau sejenisnya.
  3. Memiliki pengetahuan baik untuk sistem berbasis Windows, Cisco, Unix, Linux atau Novell
  4. Memiliki kemampuan dalam mengoperasikan dan menggunakan perangkat jaringan seperti switch, router, hub, kabel, firewall, dan lain-lainnya.


Ada beberapa kiat sukses menjadi seorang network engineer yang dapat saya sampaikan, dan anda dapat menyimaknya dibagian ini.

1 | Pertama

Untuk menjadi seorang network engineer yang sukses, anda wajib untuk memiliki pengetahuan dasar tentang konsep dan implementasi jaringan komputer serta memiliki kemampuan analisis dan pengalaman yang memadai.

Anda dapat mengikuti training komputer atau kursus komputer yang berhubungan spesifik dengan jaringan komputer pada lembaga-lembaga tertentu yang terakreditasi untuk mengimprovisasi pengetahuan dan kemampuan analisis anda dibidang jaringan.

Sedangkan untuk mengembangkan kemampuan dan pengetahuan teknis, anda juga dapat mengikuti sertifikasi dan training Cisco, training mikrotik, atau sejenisnya di lembaga yang memang memiliki otorisasi untuk melakukan sertifikasi dan training tersebut. Salah satu lembaga training dan sertifikasi yang direkomendasikan adalah NetCampus Training Center.

NetCampus Training Center sendiri adalah penyelenggara layanan training dan sertifikasi IT, komputer dan networking terbaik di Indonesia. Selain training CCNA, Netcampus juga membuka kesempatan anda untuk mengasah kemampuan dibidang komputer secara umum dengan mengadakan training komputer dan kursus komputer.

2 | Kedua

Network engineer mengemban peranan penting yakni memastikan kelancaran operasional dan komunikasi didalam jaringan dengan tujuan menciptakan kinerja maksimum pada jaringan komputer dalam sebuah perusahaan sehingga perusahaan dapat lebih efektif dalam pencapaian target atau pencapaian Return of Investment (ROI).

Tingkat kesulitan tugas seorang network engineer sangat dipengaruhi oleh cakupan lingkungan kerja – semakin besar perusahaan tempat anda bekerja, maka semakin banyak kesulitan yang akan anda temui. Dan oleh sebab itu, kiat sukses untuk menjadi seorang network engineer selanjutnya adalah terus belajar dari pengalaman yang anda dapatkan serta dapat melakukan budgeting yang efisien (cost efficients) sehingga pengeluaran untuk IT dapat ditekan.

3 | Ketiga

Seorang network engineer yang baik dapat mengaplikasikan seluruh kemampuan (skills) yang ada pada dirinya, baik kemampuan teknis, kemampuan bernegosiasi dan berkomunikasi, melakukan managemen waktu yang baik, menerapkan profesionalisme dalam bertugas, dan lain-lain. Hal ini akan menjadi nilai plus dan merupakan salah satu kiat sukses menjadi seorang network engineer yang dapat anda lakukan.

4 | Keempat

Adalah kesabaran. Tidak jarang seorang staf IT memiliki jadwal kerja yang “berbeda” jika dibandingkan dengan staf lainnya. Network engineer kadang bisa bekerja sampai larut atau bahkan masuk di shift malam saat staff lain sudah pulang.

Tujuannya tidak lain adalah agar dapat melakukan problem solving didalam jaringan. Hal ini dilakukan agar tidak menjadi kendala dalam kegiatan operasional secara umum. Oleh karena itu kesabaran adalah kunci penting agar menjadi sukses sebagai seorang network engineer.


  • Network engineer memiliki peran penting dalam melakukan dan memberikan dukungan untuk kegiatan yang berhubungan dengan jaringan komputer di sebuah perusahaan.
  • Profesi network engineer dapat dibagi menjadi beberapa golongan sesuai dengan cakupan tugas yang dilakukan.
  • Ada beberapa kiat sukses menjadi seorang network engineer antara lain dengan mengikuti pelatihan tambahan untuk memperkaya pengetahuan seputar dunia networking.

Demikian gambaran kerja (job description) dan beberapa kiat sukses menjadi seorang network engineer yang dapat saya jabarkan disini. Semoga bermanfaat untuk anda, dan salam sukses! 🙂



Network Planning and Design


From Wikipedia, the free encyclopedia

Network planning and design is an iterative process, encompassing topological design, network-synthesis, and network-realization, and is aimed at ensuring that a new telecommunications network or service meets the needs of the subscriber and operator. The process can be tailored according to each new network or service.


1 | A Network Planning Methodology
2 | The Role of Forecasting
3 | Dimensioning
4 | Traffic Engineering
5 | Survivability
6 | Tools

1 | A Network Planning Methodology

A traditional network planning methodology in the context of business decisions involves five layers of planning, namely:

  • Need Assessment and Resource Assessment
  • Short-term Network Planning
  • IT Resource
  • Long-term and Medium-term Network Planning
  • Operations and Maintenance.

Each of these layers incorporates plans for different time horizons, i.e. the business planning layer determines the planning that the operator must perform to ensure that the network will perform as required for its intended life-span. The Operations and Maintenance layer, however, examines how the network will run on a day-to-day basis.

The network planning process begins with the acquisition of external information. This includes:

  • Forecasts of how the new network/service will operate;
  • The economic information concerning costs; and
  • The technical details of the network’s capabilities.

Planning a new network/service involves implementing the new system across the first four layers of the OSI Reference Model. Choices must be made for the protocols and transmission technologies.

Network planning process involves three main steps:

  • Topological Design: This stage involves determining where to place the components and how to connect them. The (topological) optimisation methods that can be used in this stage come from an area of mathematics called Graph Theory. These methods involve determining the costs of transmission and the cost of switching, and thereby determining the optimum connection matrix and location of switches and concentrators.
  • Network-Synthesis: This stage involves determining the size of the components used, subject to performance criteria such as the Grade of Service (GOS). The method used is known as “Nonlinear Optimisation”, and involves determining the topology, required GoS, cost of transmission, etc., and using this information to calculate a routing plan, and the size of the components.
  • Network Realization: This stage involves determining how to meet capacity requirements, and ensure reliability within the network. The method used is known as “Multicommodity Flow Optimisation”, and involves determining all information relating to demand, costs and reliability, and then using this information to calculate an actual physical circuit plan.

These steps are performed iteratively in parallel with one another.

2 | The Role of Forecasting

During the process of Network Planning and Design, estimates are made of the expected traffic intensity and traffic load that the network must support. If a network of a similar nature already exists, traffic measurements of such a network can be used to calculate the exact traffic load. If there are no similar networks, then the network planner must use telecommunications forecasting methods to estimate the expected traffic intensity.

The forecasting process involves several steps:

  • Definition of problem;
  • Data acquisition;
  • Choice of forecasting method;
  • Analysis/Forecasting;
  • Documentation and analysis of results.

3 | Dimensioning

Dimensioning a new network determines the minimum capacity requirements that will still allow the Teletraffic Grade of Service (GoS) requirements to be met. To do this, dimensioning involves planning for peak-hour traffic, i.e. that hour during the day during which traffic intensity is at its peak.

The dimensioning process involves determining the network’s topology, routing plan, traffic matrix, and GoS requirements, and using this information to determine the maximum call handling capacity of the switches, and the maximum number of channels required between the switches. This process requires a complex model that simulates the behavior of the network equipment and routing protocols.

A dimensioning rule is that the planner must ensure that the traffic load should never approach a load of 100 percent. To calculate the correct dimensioning to comply with the above rule, the planner must take on-going measurements of the network’s traffic, and continuously maintain and upgrade resources to meet the changing requirements. Another reason for overprovisioning is to make sure that traffic can be rerouted in case a failure occurs in the network.

Because of the complexity of network dimensioning, this is typically done using specialized software tools. Whereas researchers typically develop custom software to study a particular problem, network operators typically make use of commercial network planning software.

4 | Traffic Engineering

Compared to network engineering, which adds resources such as links, routers and switches into the network, traffic engineering targets changing traffic paths on the existing network to alleviate traffic congestion or accommodate more traffic demand.
This technology is critical when the cost of network expansion is prohibitively high and network load is not optimally balanced. The first part provides financial motivation for traffic engineering while the second part grants the possibility of deploying this technology.

5 | Survivability

Network survivability enables the network to maintain maximum network connectivity and quality of service under failure conditions. It has been one of the critical requirements in network planning and design. It involves design requirements on topology, protocol, bandwidth allocation, etc.. Topology requirement can be maintaining a minimum two-connected network against any failure of a single link or node. Protocol requirements include using dynamic routing protocol to reroute traffic against network dynamics during the transition of network dimensioning or equipment failures. Bandwidth allocation requirements pro-actively allocate extra bandwidth to avoid traffic loss under failure conditions. This topic has been actively studied in conferences, such as the International Workshop on Design of Reliable Communication Networks.

6 | Tools

There are a wide variety of tools available for network planning and design depending on the technologies being used. These include:

  • NetSim.


OPNET Technologies, Inc. was a software business that provided performance management for computer networks and applications.

OPNET Technologies

The company was founded in 1986 and went public in 2000. In October 2012, OPNET was acquired by Riverbed Technology, for about $1 billion US dollars.

Prior to Riverbed, OPNET was headquartered in Bethesda, Maryland and had U.S. offices in Cary, North Carolina; Nashua, New Hampshire; Dallas, Texas; and Santa Clara, California. It had international offices in Slough, United Kingdom; Paris, France; Ghent, Belgium; Frankfurt, Germany; and Singapore, with staff and consultants in multiple locations in Asia and Latin America.

Corporate History

“OPNET” was Alain Cohen’s (co-founder, CTO & President) graduate project for a networking course while he was at MIT. OPNET stood for Optimized Network Engineering Tools. Alain, along with brother Marc (co-founder, CEO & Chairman) and classmate Steven Baraniuk, decided to commercialize the software. The company’s first product was OPNET Modeler, a software tool for computer network modeling and simulation.

Since becoming a public company in August 2000, OPNET executed the following acquisitions:

  • March 2001: NetMaker Division of Make Systems
  • January 2002: WDM NetDesign B.V.B.A
  • October 2004: Altaworks Corporation
  • October 2007: substantially all of the assets of Network Physics, Inc.
  • August 2010: DSAuditor product line from Embarcadero Technologies
  • May 2012: Clarus Systems, Inc.

As an independent company, OPNET grew profitably throughout its history. SEC filings are available with further information about its IPO, annual reports, and quarterly reports.

OPNET Solutions (prior to acquisition by Riverbed)

  • Application performance management, see AppTransaction Xpert in Comparison of packet analyzers
  • Network performance management


NetSim is a network simulation and network emulation tool used for network design & planning, defense applications and network R & D. Various technologies such as Cognitive Radio, Wireless Sensor Networks, Wireless LAN, Wi Max, MANETs, Wireless Sensor Networks, LTE, etc. are covered in NetSim.


NetSim is a stochastic discrete event simulator developed by Tetcos, in association with Indian Institute of Science, with the first release in June 2004.

Model Libraries in NetSim

  • Modeling and simulation are supported for the below mentioned technologies. Protocol libraries are available with C source code
  • Inter-Networks:Ethernet – Fast & Gigabit, ARP, WLAN – IEEE 802.11 a/ b / g / n / ac and e. Propagation models – Free space, Log-normal, Rayleigh Fading. Routing – RIP, OSPF. Queuing – Round Robin, FIFO, Priority TCP – Tahoe, Reno, New Reno, BIC and CUBIC, UDP
  • Common Modules with Internetworks: Applications (Traffic Generator): Voice, Video, FTP, Database, HTTP, Email, Peer-to-peer and Custom. Encryption: AES, DES. Virtual Network Stack, Simulation Kernel, Command Line Interface, Wireshark Interface, Metrics Engine with Packet Trace and Event Trace, Packet Animator
  • Legacy Networks – Aloha, Slotted Aloha, Token Ring, Token Bus, CSMA/CD
    Advanced Wireless Networks – Wi-Max, MANET covering DSR, AODV, ZRP, OLSR etc. with sinkhole / black hole attacks and intrusion detection
  • Cellular Networks – GSM and CDMA
  • Sensor Networks – Wireless Sensor Network with LEACH etc., Zigbee
  • Internet of Things (IOT) with Routing Protocol for Low Power and Loss Networks (RPL)
  • Cognitive radio Networks
  • LTE Networks, LTE Advanced Networks – SU / MU MIMO with Carrier aggregation and Relays, LTE D2D, LTE Femto Cell
  • VANETs with interfacing to SUMO through TraCI API’s
  • Military Radios – Tactical and Airborne radios in HF, VHF, UHF bands with crypto and frequency hopping,. Tactical data links, TDMA Link 16, Dynamic TDMA

In addition modules are available for sink hole attack, intrusion detection, packet encryption, packet capture using Wireshark etc.

NetSim Emulator

The Network Emulator Add on allows users to link NetSim to live applications running on real devices. This allows for real traffic to flow via the emulator and experience network effects. In this virtual network, numerous test scenarios, involving real devices and application, can be constructed and executed repetitively for normal operation as well as perturbed operation. Impairment scenarios can studied which included escalating latency, bandwidth constriction at various points, jitter tolerance, packet loss, packet reordering, route loss, failovers and single point of failure identification.

External Interfacing

NetSim can interface externally with MATLAB, Wireshark, LabVIEW and SUMO for VANETs. NetSim can also interface with live PC’s / Sensors using the emulation add-on module.

Academic Version

A deeply discounted academic version is available to universities for teaching and conducting network lab practicals. No student version is available as of date.


NetSim is widely used for

  • Network R & D including custom protocol development
  • Network lab experimentation in universities
  • Defense applications
  • Railway communication networks
  • Utilities transmission and distribution – SCADA Communication Networks.
  • Water/Waste Water, Electric Grid and Oil & Gas
  • Wireless / Satellite link emulation

Custom Code Development

NetSim comes with an in-built development environment, which serves as the interface between User’s code and NetSim’s protocol libraries and simulation kernel. Protocol libraries are available as open C code for user modification. De-bugging custom code during simulation is an advanced feature: i.e. a simulation can be started and then at user determined breakpoints in the code, users can perform single-step, step-in, step over etc. This can be carried out at various levels (depending on where the user code links) including at a per-packet interval.


Over 300 customers across 15 countries use NetSim, including premier enterprises like Philips, Hindustan Aeronautics, Indonesian Aerospace, BSNL etc. and several defense agencies like DRDO labs and space agencies like ISRO use NetSim for modeling the unique requirements of space, defense R & D and Network-centric warfare.

Hundreds of academic institutions such as Ingolstadt University – Germany, De Montfort University – UK, INTI – Malaysia, Barry University – US, Indian_Institutes_of_Technology, Dar Al Hekma – Saudi Arabia etc also use NetSim for teaching / lab experimentation and for network R & D.


5 Hal Dasar dari ‘Networking’ yang Penting Untuk Diketahui


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:

  • Jenis slot
  • Kecepatan tertinggi sebuah NIC adalah 1000 Megabit per detik
  • Kompatibilitas

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:

  • Kecepatan Transfer
  • 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.