Tag Archives: Technology

Thick Coaxial dan Thin Coaxial Cable

Thick Coaxial Cable


thick

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


thinn

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

NETWORKING

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.

ieee802.3_1

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.

10base5_Vampire_connector_aiu_dix

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.

10base5_bnc_connector_aiu_dix

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.

linear_topology

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.

spine

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

tree_topology

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

segmented_topology

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.

Summary

  • 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.

manchester_coding1

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.

802.3_mac_sublayer_protocol1

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

ethernet_performance_1

where
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

ethernet_performance_2

is the probability that the contention window is j slots

Mean number of slots per contention is:

ethernet_performance_3

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

ethernet_performance_4

Let P be the mean transmission time / frame

ethernet_performance_5

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

P = F/B

and

ethernet_performance_6

As BL increases, efficiency decreases

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

802_3_channel_effeciency

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.

Grounding

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.

Grounding

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.

Grounding

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.

Preamble

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.

Pad

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.

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.

Contents


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:

  • OPNET
  • NetSim.

OPNET

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

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.

History


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.

Applications


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.

Customers


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

NETWORKING

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.

Network Fundamentals

Network Fundamentals Checklist


  1. Webopedia Study Guide SectionGetting Started: Key Terms to Know
  2. Webopedia Study Guide SectionDefining a Network
  3. Webopedia Study Guide SectionDifferent Types of Networks
  4. Webopedia Study Guide SectionThe Importance of Network Standards
  5. Webopedia Study Guide SectionNetwork Components, Devices and Functions
  6. Webopedia Study Guide SectionNetwork Models
  7. Webopedia Study Guide SectionThe 7 Layers of the OSI Model
  8. Webopedia Study Guide SectionThe TCP/IP model
  9. Webopedia Study Guide SectionNetwork Topologies

1 | Getting Started: Key Terms to Know


The following definitions will help you to better understand computer networks:

  • Network
  • Networking
  • Stub Network
  • Star Network
  • Ring Network
  • Bus Network
  • Network Map

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.

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Physical Layer

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.

Network Layer

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.

Transport Layer

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.

Session Layer

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.

Presentation Layer

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.

Application Layer

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.

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Application

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.

Transport

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.

Internet

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.

Network Interface

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.

Bus Topology

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.

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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.

Advantages

  • 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.

Disadvantages

  • 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.

Ring Topology

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.

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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

  1. An orderly network where every device has access to the token and the opportunity to transmit
  2. Under heavy network load performs better than a start topology.
  3. 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

  1. One malfunctioning workstation can throw away the entire network.
  2. Moves, adds and changes of devices can affect the entire network .
  3. 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.

Star Topology

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.

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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.

Disadvantages

  • Compared to the bus topology, a star network usually requires more cable.
  • If the Hub fails, the whole network fails.

Advantages

  • 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:

  1. 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.
  2. 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.
  3. 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.

Tree Topology

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.

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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.

Advantages

  • 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.

Disadvantages

  • 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.

Wi-Fi – Sejarah & Penggunaan

Dari Wikipedia bahasa Indonesia, ensiklopedia bebas

Ini adalah versi yang telah diperiksa dari halaman initampilkan/sembunyikan detail

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Logo Wi-Fi

Wi-Fi (/[unsupported input]ˈwaɪfaɪ/, juga ditulis Wifi atau WiFi) adalah sebuah teknologi yang memanfaatkan peralatan elektronik untuk bertukar data secara nirkabel (menggunakan gelombang radio) melalui sebuah jaringan komputer, termasuk koneksi Internet berkecepatan tinggi. Wi-Fi Alliance mendefinisikan Wi-Fi sebagai “produk jaringan wilayah lokal nirkabel (WLAN) apapun yang didasarkan pada standar Institute of Electrical and Electronics Engineers (IEEE) 802.11″. Meski begitu, karena kebanyakan WLAN zaman sekarang didasarkan pada standar tersebut, istilah “Wi-Fi” dipakai dalam bahasa Inggris umum sebagai sinonim “WLAN”.

Electrical and Electronics Engineers (IEEE)

IEEE adalah organisasi internasional, beranggotakan para insinyur, dengan tujuan untuk mengembangan teknologi untuk meningkatkan harkat kemanusiaan.

Sebelumnya IEEE memiliki kepanjangan yang dalam Indonesia berarti Institut Insinyur Listrik dan Elektronik (Institute of Electrical and Electronics Engineers). Namun kini kepanjangan itu tak lagi digunakan, selain untuk keperluan legal; sehingga organisasi ini memiliki nama resmi IEEE saja.

IEEE adalah sebuah organisasi profesi nirlaba yang terdiri dari banyak ahli di bidang teknik yang mempromosikan pengembangan standar-standar dan bertindak sebagai pihak yang mempercepat teknologi-teknologi baru dalam semua aspek dalam industri dan rekayasa (engineering), yang mencakup telekomunikasi, jaringan komputer, kelistrikan, antariksa, dan elektronika.

IEEE memiliki lebih dari 415.000 anggota individual yang tersebar dalam lebih dari 150 negara. Aktivitasnya mencakup beberapa panitia pembuat standar, publikasi terhadap standar-standar teknik, serta mengadakan konferensi

Sebuah alat yang dapat memakai Wi-Fi (seperti komputer pribadi, konsol permainan video, telepon pintar, tablet, atau pemutar audio digital) dapat terhubung dengan sumber jaringan seperti Internet melalui sebuah titik akses jaringan nirkabel. Titik akses (atau hotspot) seperti itu mempunyai jangkauan sekitar 20 meter (65 kaki) di dalam ruangan dan lebih luas lagi di luar ruangan. Cakupan hotspot dapat mencakup wilayah seluas kamar dengan dinding yang memblokir gelombang radio atau beberapa mil persegi — ini bisa dilakukan dengan memakai beberapa titik akses yang saling tumpang tindih.

Titik Akses Jaringan Nirkabel

Dalam jaringan komputer, titik akses nirkabel (bahasa Inggris: wireless access point, WAP) adalah suatu peranti yang memungkinkan peranti nirkabel untuk terhubung ke dalam jaringan dengan menggunakan Wi-Fi, Bluetooth, atau standar lain. WAP biasanya tersambung ke suatu router (melalui kabel) sehingga dapat meneruskan data antara berbagai peranti nirkabel (seperti komputer atau pencetak) dengan jaringan berkabel pada suatu jaringan. Standar yang diterapkan untuk WAP ditetapkan oleh IEEE dan sebagian besar menggunakan IEEE 802.11.

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Contoh peranti titik akses nirkabel atau WAP.

“Wi-Fi” adalah merek dagang Wi-Fi Alliance dan nama merek untuk produk-produk yang memakai keluarga standar IEEE 802.11. Hanya produk-produk Wi-Fi yang menyelesaikan uji coba sertifikasi interoperabilitas Wi-Fi Alliance yang boleh memakai nama dan merek dagang “Wi-Fi CERTIFIED”.

IEEE 802.11

IEEE802.11 adalah serangkaian spesifikasi kendali akses medium dan lapisan fisik untuk mengimplementasikan komunikasi komputer wireless local area network di frekuensi 2.4, 3.6, 5, dan 60 GHz. Mereka diciptakan dan dioperasikan oleh Institute of Electrical and Electronics Engineers. Versi dasar dirilis tahun 1997 dan telah melalui serangkaian pembaruan dan menyediakan dasar bagi produk jaringan nirkabel Wi-Fi.

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The Linksys WRT54G memiliki gelombang radio 802.11b/g dengan dua antenna

Wi-Fi mempunyai sejarah keamanan yang berubah-ubah. Sistem enkripsi pertamanya, WEP, terbukti mudah ditembus. Protokol berkualitas lebih tinggi lagi, WPA dan WPA2, kemudian ditambahkan. Tetapi, sebuah fitur opsional yang ditambahkan tahun 2007 bernama Wi-Fi Protected Setup (WPS), memiliki celah yang memungkinkan penyerang mendapatkan kata sandi WPA atau WPA2 router dari jarak jauh dalam beberapa jam saja. Sejumlah perusahaan menyarankan untuk mematikan fitur WPS. Wi-Fi Alliance sejak itu memperbarui rencana pengujian dan program sertifikasinya untuk menjamin semua peralatan yang baru disertifikasi kebal dari serangan AP PIN yang keras.

Sejarah


Sejarah teknologi 802.11 berawal pada putusan Komisi Komunikasi Federal AS tahun 1985 yang merilis pita GSM untuk pemakaian tanpa lisensi. Pada tahun 1991, NCR Corporation bersama AT&T menemukan pendahulu 802.11 yang ditujukan untuk sistem kasir. Produk-produk nirkabel pertama berada di bawah nama WaveLAN.

Vic Hayes dijuluki “Bapak Wi-Fi”. Ia terlibat dalam perancangan standar pertama IEEE.

Sejumlah besar paten oleh banyak perusahaan memakai standar 802.11. Pada tahun 1992 dan 1996, organisasi Australia CSIRO mendapatkan paten untuk sebuah metode yang kelak dipakai di Wi-Fi untuk menghapus gangguan sinyal. Pada bulan April 2009, 14 perusahaan teknologi setuju membayar $250 juta kepada CSIRO karena melanggar paten-paten mereka. Ini mendorong Wi-Fi disebut-sebut sebagai temuan Australia, meski hal ini telah menjadi topik sejumlah kontroversi. CSIRO memenangkan gugatan senilai $220 juta atas pelanggaran paten Wi-Fi tahun 2012 yang meminta firma-firma global di Amerika Serikat membayar hak lisensi kepada CSIRO senilai $1 miliar.

Tahun 1999, Wi-Fi Alliance dibentuk sebagai sebuah asosiasi dagang untuk memegang merek dagang Wi-Fi yang digunakan oleh banyak produk.

Nama

Istilah Wi-Fi, pertama dipakai secara komersial pada bulan Agustus 1999, dicetuskan oleh sebuah firma konsultasi merek bernama Interbrand Corporation. Wi-Fi Alliance mempekerjakan Interbrand untuk menentukan nama yang “lebih mudah diucapkan daripada ‘IEEE 802.11b Direct Sequence'”. Belanger juga mengatakan bahwa Interbrand menciptakan Wi-Fi sebagai plesetan dari Hi-Fi (high fidelity); mereka juga merancang logo Wi-Fi.

Wi-Fi Alliance membuat slogan iklan asal-asalan “The Standard for Wireless Fidelity” dan sempat menggunakannya sesaat setelah merek Wi-Fi diciptakan. Karena slogan tersebut, orang-orang salah mengira bahwa Wi-Fi merupakan singkatan dari “Wireless Fidelity” meski kenyataannya bukan. Logo yin-yang Wi-Fi menandakan sertifikasi interoperabilitas suatu produk.

Teknologi non-Wi-Fi yang dibutuhkan untuk titik-titk tetap seperti Motorola Canopy biasanya disebut nirkabel tetap. Teknologi nirkabel alternatif meliputi standar telepon genggam seperti 2G, 3G, atau 4G.

Sertifikasi Wi-Fi

IEEE tidak menguji peralatan untuk memenuhi standar mereka. Badan nirlaba Wi-Fi Alliance didirikan tahun 1999 untuk mengisi celah ini — untuk menetapkan dan mendorong standar interoperabilitas dan kompatibilitas mundur, serta mempromosikan teknologi jaringan wilayah lokal nirkabel. Hingga 2010, Wi-Fi Alliance terdiri dari lebih dari 375 perusahaan di seluruh dunia. Wi-Fi Alliance mendorong pemakaian merek Wi-Fi kepada teknologi yang didasarkan pada standar IEEE 802.11 dari Institute of Electrical and Electronics Engineers. Ini meliputi koneksi jaringan wilayah lokal nirkabel (WLAN), konektivitas alat-ke-alat (seperti Wi-Fi Peer to Peer atau Wi-Fi Direct), jaringan wilayah pribadi (PAN), jaringan wilayah lokal (LAN), dan bahkan sejumlah koneksi jaringan wilayah luas (WAN) terbatas. Perusahaan manufaktur dengan keanggotaan Wi-Fi Alliance, yang produknya berhasil melewati proses sertifikasi, berhak menandai produk tersebut dengan logo Wi-Fi.

Secara spesifik, proses sertifikasi memerlukan pemenuhan standar radio IEEE 802.11, standdar keamanan WPA dan WPA2, dan standar autentikasi EAP. Sertifikasi opsionalnya meliputi pengujian standar draf IEEE 802.11, interaksi dengan teknologi telepon seluler pada peralatan konvergen, dan fitur-fitur keamanan, multimedia, dan penghematan tenaga.

Tidak semua peralatan Wi-Fi dikirim untuk mendapatkan sertifikasi. Kurangnya sertifikasi Wi-Fi tidak berarti bahwa sebuah alat tidak kompatibel dengan alat Wi-Fi lainnya. Jika alat tersebut memenuhi syarat atau setengah kompatibel, Wi-Fi Alliance tidak perlu berkomentar terhadap penyebutannya sebagai sebuah alat Wi-Fi, butuh rujukan] meskipun secara teknis hanya alat yang bersertifikasi yang disetujui. Istilah seperti Super Wi-Fi, yang dicetuskan oleh Komisi Komunikasi Federal (FCC) AS untuk mendeskripsikan rencana jaringan pita TV UHF di Amerika Serikat, dapat disetujui atau tidak.

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Logo sinyal Wi-Fi

Penggunaan


Agar terhubung dengan LAN Wi-Fi, sebuah komputer perlu dilengkapi dengan pengontrol antarmuka jaringan nirkabel. Gabungan komputer dan pengontrol antarmuka disebut stasiun. Semua stasiun berbagi satu saluran komunikasi frekuensi radio. Transmisi di saluran ini diterima oleh semua stasiun yang berada dalam jangkauan. Perangkat keras tidak memberitahu pengguna bahwa transmisi berhasil diterima dan ini disebut mekanisme pengiriman terbaik. Sebuah gelombang pengangkut dipakai untuk mengirim data dalam bentuk paket, disebut “bingkai Ethernet”. Setiap stasiun terus terhubung dengan saluran komunikasi frekuensi radio untuk mengambil transmisi yang tersedia.

Akses Internet

Sebuah alat Wi-Fi dapat terhubung ke Internet ketika berada dalam jangkauan sebuah jaringan nirkabel yang terhubung ke Internet. Cakupan satu titik akses atau lebih (interkoneksi) — disebut hotspot — dapat mencakup wilayah seluas beberapa kamar hingga beberapa mil persegi. Cakupan di wilayah yang lebih luas membutuhkan beberapa titik akses dengan cakupan yang saling tumpang tindih. Teknologi Wi-Fi umum luar ruangan berhasil diterapkan dalam jaringan mesh nirkabel di London, Britania Raya.

Wi-Fi menyediakan layanan di rumah pribadi, jalanan besar dan pertokoan, serta ruang publik melalui hotspot Wi-Fi yang dipasang gratis atau berbayar. Organisasi dan bisnis, seperti bandara, hotel, dan restoran, biasanya menyediakan hotspot gratis untuk menarik pengunjung. Pengguna yang antusias atau otoritas yang ingin memberi layanan atau bahkan mempromosikan bisnis di tempat-tempat tertentu kadang menyediakan akses Wi-Fi gratis.

Router yang melibatkan modem jalur pelanggan digital atau modem kabel dan titik akses WI-Fi, biasanya dipasang di rumah dan bangunan lain, menyediakan akses Internet dan antarjaringan ke semua peralatan yang terhubung dengan router secara nirkabel atau kabel. Dengan kemunculan MiFi dan WiBro (router Wi-Fi portabel), pengguna bisa dengan mudah membuat hotspot Wi-Fi-nya sendiri yang terhubung ke Internet melalui jaringan seluler. Sekarang, peralatan Android, Bada, iOS (iPhone), dan Symbian mampu menciptakan koneksi nirkabel. Wi-Fi juga menghubungkan tempat-tempat yang biasanya tidak punya akses jaringan, seperti dapur dan rumah kebun.

Wi-Fi Kota

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Titik akses Wi-Fi terbuka

Pada awal 2000-an, banyak kota di seluruh dunia mengumumkan rencana membangun jaringan Wi-Fi sekota. Contoh usaha yang berhasil yaitu Mysore pada tahun 2004 menjadi kota Wi-Fi pertama di India dan kedua di dunia setelah Jerusalem. Perusahaan WiFiyNet mendirikan beberapa hotspot di Mysore, yang mencakup seluruh kota dan desa-desa sekitarnya.

Tahun 2005, Sunnyvale, California, menjadi kota pertama di Amerika Serikat yang menyediakan Wi-Fi gratis dengan cakupan satu kota, dan Minneapolis memperoleh penghasilan $1,2 juta per tahunnya untuk penyedia jasanya.

Pada bulan Mei 2010, Walikota London, Britania Raya, Boris Johnson berjanji akan membangun jaringan Wi-Fi yang mencakup seluruh London tahun 2012. Sejumlah borough, termasuk Westminster dan Islington sudah memiliki cakupan Wi-Fi terbuka yang luas.

Para pejabat di ibu kota Korea Selatan, Seoul, berusaha menyediakan akses Internet gratis di lebih dari 10.000 lokasi di seluruh kota, termasuk ruang terbuka publik, jalan utama, dan kawasan permukiman padat penduduk. Seoul akan menyerahkan pengoperasiannya kepada KT, LG Telecom dan SK Telecom. Perusahaan-perusahaan tersebut akan menginvestasikan $44 juta untuk proyek ini, yang akan rampung tahun 2015.

Wi-Fi Kampus

Banyak kampus tradisional di Amerika Serikat memiliki cakupan Internet Wi-Fi nirkabel yang setengah-setengah. Carnegie Mellon University membangun jaringan Internet sekampus pertama bernama Wireless Andrew di kampus Pittsburgh-nya tahun 1993 sebelum merek Wi-Fi muncul.

Pada tahun 2000, Drexel University di Philadelphia menjadi universitas besar pertama di Amerika Serikat yang memiliki akses Internet nirkabel di seluruh kampusnya.

Komunikasi Langsung Antar Komputer

Wi-Fi juga memungkinkan komunikasi langsung dari satu komputer ke komputer lain tanpa melalui titik akses. Ini disebut transmisi Wi-Fi ad hoc. Mode jaringan ad hoc nirkabel ini dipopulerkan oleh konsol permainan genggam multipemain, seperti Nintendo DS, Playstation Portable, kamera digital, dan peralatan elektronik konsumen lainnya. Sejumlah alat juga dapat berbagi koneksi Internetnya menggunakan ad-hoc, menjadi hotspot atau “router virtual”.

Sama halnya, Wi-Fi Alliance mempromosikan sebuah spesifikasi bernama Wi-Fi Direct untuk transfer berkas dan berbagi media melalui metodologi pencarian dan keamanan yang abru. Wi-Fi Direct diluncurkan bulan Oktober 2010.

Spesifikasi


Wi-Fi dirancang berdasarkan spesifikasi IEEE 802.11. Sekarang ini ada empat variasi dari 802.11, yaitu:

  • 802.11a
  • 802.11b
  • 802.11g
  • 802.11n

Spesifikasi b merupakan produk pertama Wi-Fi. Variasi g dan n merupakan salah satu produk yang memiliki penjualan terbanyak pada 2005.

Spesifikasi Wi-Fi

Di banyak bagian dunia, frekuensi yang digunakan oleh Wi-Fi, pengguna tidak diperlukan untuk mendapatkan izin dari pengatur lokal (misal, Komisi Komunikasi Federal di A.S.). 802.11a menggunakan frekuensi yang lebih tinggi dan oleh sebab itu daya jangkaunya lebih sempit, lainnya sama.

Versi Wi-Fi yang paling luas dalam pasaran AS sekarang ini (berdasarkan dalam IEEE 802.11b/g) beroperasi pada 2.400 GHz sampai 2.483,50 GHz. Dengan begitu mengijinkan operasi dalam 11 channel (masing-masing 5 MHz), berpusat di frekuensi berikut:

  • Channel 1 – 2,412 GHz;
  • Channel 2 – 2,417 GHz;
  • Channel 3 – 2,422 GHz;
  • Channel 4 – 2,427 GHz;
  • Channel 5 – 2,432 GHz;
  • Channel 6 – 2,437 GHz;
  • Channel 7 – 2,442 GHz;
  • Channel 8 – 2,447 GHz;
  • Channel 9 – 2,452 GHz;
  • Channel 10 – 2,457 GHz;
  • Channel 11 – 2,462 GHz

Secara teknis operasional, Wi-Fi merupakan salah satu varian teknologi komunikasi dan informasi yang bekerja pada jaringan dan perangkat WLAN (wireless local area network). Dengan kata lain, Wi-Fi adalah sertifikasi merek dagang yang diberikan pabrikan kepada perangkat telekomunikasi (internet) yang bekerja di jaringan WLAN dan sudah memenuhi kualitas kapasitas interoperasi yang dipersyaratkan.

Teknologi internet berbasis Wi-Fi dibuat dan dikembangkan sekelompok insinyur Amerika Serikat yang bekerja pada Institute of Electrical and Electronis Engineers (IEEE) berdasarkan standar teknis perangkat bernomor 802.11b, 802.11a dan 802.16. Perangkat Wi-Fi sebenarnya tidak hanya mampu bekerja di jaringan WLAN, tetapi juga di jaringan Wireless Metropolitan Area Network (WMAN).

Karena perangkat dengan standar teknis 802.11b diperuntukkan bagi perangkat WLAN yang digunakan di frekuensi 2,4 GHz atau yang lazim disebut frekuensi ISM (Industrial, Scientific dan Medical). Sedang untuk perangkat yang berstandar teknis 802.11a dan 802.16 diperuntukkan bagi perangkat WMAN atau juga disebut Wi-Max, yang bekerja di sekitar pita frekuensi 5 GHz.

Tingginya animo masyarakat—khususnya di kalangan komunitas Internet—menggunakan teknologi Wi-Fi dikarenakan paling tidak dua faktor. Pertama, kemudahan akses. Artinya, para pengguna dalam satu area dapat mengakses Internet secara bersamaan tanpa perlu direpotkan dengan kabel.

Konsekuensinya, pengguna yang ingin melakukan surfing atau browsing berita dan informasi di Internet, cukup membawa PDA (pocket digital assistance) atau laptop berkemampuan Wi-Fi ke tempat di mana terdapat access point atau hotspot.

Menjamurnya hotspot di tempat-tempat tersebut—yang dibangun oleh operator telekomunikasi, penyedia jasa Internet bahkan orang perorangan—dipicu faktor kedua, yakni karena biaya pembangunannya yang relatif murah atau hanya berkisar 300 dollar Amerika Serikat.

Peningkatan kuantitas pengguna Internet berbasis teknologi Wi-Fi yang semakin menggejala di berbagai belahan dunia, telah mendorong Internet service providers (ISP) membangun hotspot yang di kota-kota besar dunia.

Beberapa pengamat bahkan telah memprediksi pada tahun 2006, akan terdapat hotspot sebanyak 800.000 di negara-negara Eropa, 530.000 di Amerika Serikat dan satu juta di negara-negara Asia.

Keseluruhan jumlah penghasilan yang diperoleh Amerika Serikat dan negara-negara Eropa dari bisnis Internet berbasis teknologi Wi-Fi hingga akhir tahun 2003 diperkirakan berjumlah 5.4 trilliun dollar Amerika, atau meningkat sebesar 33 miliar dollar Amerika dari tahun 2002.

Wi-fi Hardware


Wifig

Wi-Fi dalam bentuk PCI

Hardware Wi-Fi yang ada di pasaran saat ini ada berupa :

  • PCI
  • USB
  • PCMCIA
  • Compact Flash
Wifiusbg

Wi-fi dalam bentuk USB

Mode Akses Koneksi Wi-fi


Ada 2 mode akses koneksi Wi-fi, yaitu

Ad-Hoc

Mode koneksi ini adalah mode di mana beberapa komputer terhubung secara langsung, atau lebih dikenal dengan istilah Peer-to-Peer. Keuntungannya, lebih murah dan praktis bila yang terkoneksi hanya 2 atau 3 komputer, tanpa harus membeli access point.

Infrastruktur

Menggunakan Access Point yang berfungsi sebagai pengatur lalu lintas data, sehingga memungkinkan banyak Client dapat saling terhubung melalui jaringan (Network).

Keselamatan


World Health Organization (WHO) menyatakan, “tidak ada risiko setelah terpapar jaringan wi-fi tingkat rendah dan jangka panjang,” dan United Kingdom Health Protection Agency melaporkan bahwa terpapar Wi-Fi selama setahun “sama seperti terpapar radiasi dari panggilan telepon genggam selama 20 menit”.
Sejumlah kecil pengguna Wi-Fi telah melaporkan masalah kesehatan setelah berkali-kali terpapar dan memakai Wi-Fi, meski belum ada publikasi mengenai dampak apapun dalam studi buta rangkap. Sebuah studi yang melibatkan 725 orang penderita hipersensitivitas elektromagnetik mengaku tidak menemukan bukti atas klaim mereka.

Sebuah studi berspekulasi bahwa “laptop (mode Wi-Fi) di pangkuan dekat buah zakar dapat menurunkan fertilitas pria”. Studi lainnya menemukan memori kerja yang menurun di kalangan pria saat terpapar Wi-Fi.

Apa yang dimaksud dengan Jaringan WiFi dan Bagaimana Cara Setup

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Wifi_logo

Di sini Anda akan di terangkan bagaimana cara setup jaringan wifi, bagaimana nirkabel bekerja, keamanan hotspot, server VPN. Wi-Fi atau wireless fidelity agar kita semua dapat menggunakan semua jenis jaringan 802,11, apakah 802.11, 802.11a dan dual band. Setiap produk yang diuji dan disetujui sebagai Wi-Fi bersertifikat oleh aliansi Wi-Fi yang interoperable satu sama lain.

Biasanya, setiap produk WiFi menggunakan frekwensi radio yang sama dan akan bekerja satu sama lain bahkan jika Wi-Fi tersebut tidak bersertifikat. Sebelumnya istilah Wi-Fi hanya digunakan pada frekwensi 2,4 GHz 802.11b standar di Ethernet dengan cara yang sama digunakan.

Wi-fi wireless fidelity pendek mengacu pada seperangkat teknologi jaringan nirkabel dan lebih khusus disebut sebagai 802,11 pada semua jenis jaringan, 802.11b dan 802.11a dan dual band. Kata Wi-Fi dibangun oleh sebuah organisasi ternama sebagai aliansi Wi-Fi. Sebuah produk yang mengalami analisis Wi-Fi aliansi diberi nama Wi-Fi bersertifikat.

Wi-Fi sangat cepat terkenal di Amerika Serikat dengan titik akses. Perangkat ini diuji oleh “Wi-Fi aliansi” digunakan di seluruh dunia dan memungkinkan pengguna untuk memiliki perangkat Wi-Fi seperti PDA atau Laptop untuk menghubungkan peralatan yang menyediakan jalur akses Wi-Fi. Saat ini ada tiga standar yang digunakan untuk menunjukkan kecepatan koneksi. Baik 802.11a dan 802.11b adalah 54 Mbps dimana 802.11a fitur tambahan. Standar yang paling umum adalah 802.11b/second karena dapat mengirimkan data pada kecepatan 11 Mbps.

Semua koneksi Wi-Fi yang cukup cepat memungkinkan untuk koneksi internet broadband. Wireless Fidelity adalah teknologi nirkabel yang tumbuh paling cepat yang mungkin akan sama umumnya seperti saluran telepon dan perangkat listrik. Wi-Fi menambahkan tingkat kenyamanan dan tingkat produksi yang tinggi.

Wireless Fidelity direncanakan akan digunakan seperti perangkat nirkabel tetapi paling sering digunakan untuk akses internet. Dengan Wi-Fi Anda dapat menghubungkan komputer di rumah Anda, kantor atau di mana saja tanpa perlu kabel. Komputer hanya dapat terhubung ke jaringan yang menggunakan gelombang radio.

Bagaimana Wi-Fi Bekerja?

  • Wi-Fi adalah teknologi nirkabel untuk menangani jaringan / komunikasi. Wi-Fi mengalokasikan koneksi internet global dan salurkan melalui gelombang radio.
  • Gelombang Radio adalah akses utama dari Wi-Fi. gelombang radio yang ditransmisikan dari antena dan Wi-Fi akan di tangkap penerima.
  • Bila pengguna menerima sinyal Wi-Fi, koneksi internet nirkabel diproduksi dan pengguna yang diminta untuk memberikan nama dan password yang diperlukan untuk membuat sambungan nirkabel.

Bagaimana Keamanan Wi-Fi?

  • Wi-Fi akan menjaga keamanan tertentu. WEP atau Wired Equivalent Privacy digunakan dalam lapisan data fisik dan link. Ini dikhususkan untuk menyediakan keamanan nirkabel dengan melindungi data, sementara mengirimkan dari satu titik ke titik lain. Wi-Fi jaringan biasanya dilindungi di dalam bangunan gedung.
  • Transmisi data dalam Wi-Fi dilindungi oleh Wireless LAN namun karena fakta bahwa data yang dikirimkan melalui gelombang radio sehingga ada kemungkinan data dapat terbuka dan ditangkap pengguna lain.

Bagaimana Cara mengamankan jaringan WiFi?

Bila Anda membeli router nirkabel akan diberikan CD Instalasi oleh vendor, CD akan membimbing Anda melalui bantuan tentang pengaturan router. Berikut adalah beberapa saran yang dapat Anda lakukan untuk setting keamanan di router tanpa menggunakan aplikasi perangkat lunak lainnya :

  • Buka browser baru
  • Pada browser Anda ketik alamat IP dari router di kotak alamat browser Anda.
  • Langkah ini anda akan masuk ke system menu pengelolaan router. Karena vendor yang berbeda, pada buku panduan akan diberikan nomor IP router biasanya umum digunakan IP 192.168.0.1 dengan User Name: “admin” dan Pasword: “admin
  • Aktifkan keamanan Wireless. Untuk mengaktifkannya lihat pada tab wireless security. Langkah ini perlu Anda menggunakan WPA atau WPA-PSK dan ini akan sesuai jika perangkat pada jaringan Anda mendukungnya. Jika tidak, Anda mensettingnya WEP 128-bit. Untuk WPA atau WPA-PSK, Anda harus menggunakan jenis frase / kata sandi dalam secarik kertas dan transfer ke thumb drive sehingga Anda dapat mengatur password dalam mesin klien.
  • Ubah SSID Anda. Anda tidak harus mengubah SSID ini bisa menggunakan default SSID, biasanya mereka yang tidak mengkonfigurasi SSID akan memiliki nama router mereka seperti “linksys”, “Belkin”, “Teknis” dll Cobalah mengubah dengan nama seseorang atau perusahaan anda, yang akan menjadi pengenal bagi mereka untuk terhubung dengan Wireles.Perlu diingat bahwa Anda harus menggunakan nama SSID ini bila Anda mengakses jaringan dari mesin klien Anda. Anda dapat menemukan pengaturan ini pada bagian Channel atau SSID.
  • Simpan konfigurasi dan pengaturan dengan mengklik tombol Save setting atau tombol simpan pengaturan. Anda akan harus menyimpan setiap perubahan yang akan Anda buat untuk router agar dapat berlaku dan Anda harus mereboot router Anda beberapa kali.

Wi-Fi Hotspot Security: Menggunakan VPNs

Ada banyak masalah keamanan dari penggunaan jaringan nirkabel publik tetapi semua dapat diatasi. Salah satu solusi untuk pengguna, sebagai dasar keamanan Wi-Fi Hotspot, adalah dengan menggunakan VPN (Virtual Private Network) untuk mengamankan lalu lintas real time dari Wi-Fi hot spot pengguna. Banyak perusahaan kecil dan besar menyediakan karyawan mereka dengan akses VPN.

Meskipun akses ini biasanya dimasukkan untuk karyawan agar memiliki akses remote kepada jaringan perusahaan dalam rangka untuk mengakses file dan dokumen dari jarak jauh. Jika Anda tidak memiliki akses ke server VPN maka anda tidak akan dapat terhubung ke Wi-Fi. Dengan melakukan ini, Anda dapat mengakses file dari kantor anda serta perangkat lain seperti kamera video Wi-Fi untuk mengawasi jaringan dari jarak jauh.

Bila menggunakan perangkat lunak berbasis VPN fitur server di Windows XP Pro, PC menjalankan server harus selalu hidup untuk mengakses jaringan dari hotspot Wi-Fi.

VPN router dikenakan biaya sekitar dari $ 70 sampai $ 130 dan dengan yang populer adalah Linksys, WRV200, dan WRV5G.

Cara Memasang Sistem Kamera Pengawas di Rumah

by Wikihow

3 Metode:

  1. Mempersiapkan Rumah Anda
  2. Memasang Kamera
  3. Mengonsolidasikan Sistem Pengawasan

Kalau membayangkan semua dinding yang harus dibor dan kabel yang harus dipasang untuk memasang sistem kamera pengawas di rumah, mungkin Anda langsung berkecil hati. Namun, banyak sistem pengamanan sudah tersedia dalam satu paket sehingga pemasangannya mudah dilakukan. Bacalah artikel ini sebagai panduan membeli dan memasang sistem kamera pengawas di rumah Anda.


Metode 1

Mempersiapkan Rumah Anda

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1. Buat diagram kebutuhan pengawasan rumah Anda. 

Tidak mungkin Anda memasang kamera untuk mengawasi setiap senti isi rumah. Biayanya akan sangat besar dan tidak efisien. Jadi, tentukan area-area yang perlu diprioritaskan. Gambar sketsa diagram atau cetak blueprint rumah Anda dan tandai lokasi yang akan dipasangi kamera. Jika Anda sudah selesai, periksa lokasi-lokasi tersebut untuk memastikan tidak ada sesuatu yang menghalangi kamera. Dengan demikian, Anda bisa mengawasi rumah dengan maksimal. Sebaiknya, kamera dipasang untuk mengawasi:

  • Pintu depan dan belakang.
  • Jendela yang tidak terlihat dari jalan.
  • Ruang-ruang besar di dalam rumah (dapur, ruang tengah, dsb.)
  • Jalan mobil
  • Beranda
  • Tangga
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2. Beli paket yang sesuai dengan kebutuhan. 

Biasanya, sistem pengawasan yang dibundel harganya lebih murah dan mudah diperoleh. Sistem ini paling tidak berisi 1-3 kamera, sebuah DVR (digital video recorder alias perekam video digital), kabel sambungan (siamese atau BNC), dan kabel daya.

Kamera nirkabel yang bisa dipasang di dinding seharusnya sudah memenuhi kebutuhan Anda, kecuali Anda mengawasi area yang besar.

  • Set Pengawasan Rumah Standar: Berisi 2-3 kamera luar ruangan (untuk mengawasi pintu) dan DVR dengan kapasitas rekaman sedikitnya 3 hari.
  • Set Pengawasan Barang Berharga/Anak Kecil: Berisi 1-3 kamera dalam ruangan yang bisa mengawasi ruangan kecil secara efektif dan mengirimkan rekaman langsung ke komputer Anda.
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3. Belilah kamera secara terpisah, jika diperlukan. 

Apabila Anda sudah mengetahui berapa banyak kamera yang diperlukan, tentukan jenis kamera yang dibutuhkan. Sistem pengawasan rumah memakan biaya mulai dari beberapa juta sampai puluhan juta rupiah.

Jadi, pertimbangkan jenis kamera yang akan dibeli. Fitur-fitur di bawah ini harus tercantum jelas di kotak kemasan kamera. Meskipun semua komponen bisa dibeli secara terpisah, harga paket sistem pengawasan jauh lebih terjangkau dan lebih mudah dipasang.

  • Nirkabel atau kabel: Kamera nirkabel bisa dipasang tanpa harus mengebor dinding atau memasang kabel di rumah Anda. Namun, kualitas rekamannya tidak sebagus kamera kabel, terutama jika jarak kamera dan penerimanya cukup jauh. Jika Anda akan mengawasi area besar, sebaiknya pilih kamera kabel, walaupun kebanyakan rumah memilih kamera nirkabel karena lebih mudah dipasang .
  • Luar ruangan atau dalam ruangan: Kamera yang tidak khusus dibuat untuk luar ruangan akan lebih cepat rusak ketika terpapar hujan dan kelembapan. Pastikan Anda memilih kamera yang sesuai.
  • Pendeteksian gerakan: Sebagian kamera hanya merekam jika mendeteksi gerakan. Dengan demikian, kamera ini akan menghemat energi dan ruang penyimpanan data karena perekaman hanya dilakukan ketika ada orang di dalam ruangan.
  • Pengawasan jarak jauh: Banyak kamera berkualitas tinggi yang menawarkan fitur pengaliran (stream) rekaman ke ponsel atau laptop Anda. Dengan demikian, Anda bisa mengecek rumah menggunakan program atau aplikasi di ponsel atau komputer.
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4. Atur monitor dan perangkat perekaman Anda. 

Anda membutuhkan DVR untuk menyimpan dan menonton rekaman Anda. Perangkat ini menerima semua umpan (feed) video dan menyiarkannya ke monitor. DVR memiliki beragam kapasitas memori sehingga mampu menyimpan rekaman video, mulai dari ratusan jam sampai satu hari.

  • Jika Anda membeli paket kamera pengawas lengkap, DVR biasanya sudah disertakan bersama kamera.
  • Anda juga bisa membeli Perekam Video Jaringan (Network Video Recorder alias NVR) atau perekam analog (analog recorder alias VCR) yang cara kerjanya sama dengan DVR. Bedanya, NVR menggunakan sinyal internet dan VCR menggunakan kaset kosong untuk menyimpan rekaman. Kiat-kiat pemasangan berikut juga bisa diterapkan pada kedua perangkat tersebut.
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5. Tes perlengkapan Anda sebelum dipasang. 

Pastikan semua kabel, DVR, kamera, dan monitor berfungsi dengan baik. Sambungkan perlengkapan-perlengkapan Anda dan lakukan pengujian sebelum dipasang di rumah.


Metode 2

Memasang Kamera

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1. Pilihlah sudut kamera yang luas dan tinggi. 

Sudut terbaik untuk mengawasi ruangan adalah menghadap ke bawah dari tempat pertemuan langit-langit dan dinding. Pastikan semua pintu keluar masuk ruangan bisa dilihat dengan jelas dan kamera berada di dekat sumber daya.

  • Jika Anda memasang kamera di luar ruangan, pastikan ketinggiannya di atas 3 meter sehingga tidak mudah dirusak.
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2. Pasang kamera Anda ke dinding. 

Beberapa kamera dilengkapi bantalan perekat untuk melekatkan kamera ke dinding. Namun, sebaiknya kamera dipasang di dinding menggunakan sekrup. Meskipun setiap kamera berbeda-beda, cara pemasangannya tetap sama:

  • Pasang pegangan kamera di lokasi yang diinginkan.
  • Gunakan spidol untuk menandai lokasi pemasangan sekrup di dinding.
  • Lubangi setiap tanda di dinding dengan bor listrik.
  • Pukul molding pin dengan palu.
  • Pasangkan sekrup sehingga pegangan kamera menempel di dinding.
  • Posisikan kamera ke sudut yang diinginkan. 
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3.  Pasangkan kamera pada sumber daya. 

Hampir semua kamera dijual bersama adaptor daya yang dapat dimasukkan ke soket listrik dinding normal. Masukkan ujung adaptor yang berbentuk bulat kecil ke masukan daya di belakang kamera, dan sambungkan ujung satu lagi ke soket listrik.

  • Jika adaptor daya Anda hilang atau rusak, hubungi produsen kamera Anda.
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4. Pasangkan kabel kamera ke DVR.  

Perlengkapan pengawasan rumah dihubungkan menggunakan koneksi BNC (Bayonet Neill–Concelman). Kabel BNC mudah digunakan. Kedua ujung kabel ini berbentuk sama. Anda cukup menyambungkan kabel ke porta yang sesuai, dan memutar baut kecil di ujungnya sehingga kabel terkunci dengan baik.

Sambungkan ujung satu lagi ke porta “Output” (keluaran) kamera dan ujung satu lagi ke porta “Input” (masukan) DVR.

  • Catat masukan yang Anda sambungkan. Inilah masukan yang perlu diset di DVR supaya dapat menampilkan video kamera Anda.
  • Jika kabel tidak memiliki sambungan BNC, belilah adaptor BNC di toko komputer atau toko perangkat keras. Adaptor ini akan diselipkan ke ujung kabel sehingga kompatibel dengan sambungan BNC.
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5. Hubungkan kamera nirkabel dengan komputer Anda. 

Kamera nirkabel biasanya dijual bersama cakram peranti lunak yang harus dipasang untuk dapat menampilkan umpan kamera. Ikuti panduan di layar monitor untuk dapat mengakses kamera pengawas.

  • Beberapa kamera memiliki penerima (receiver) kecil yang dapat disambungkan dengan komputer melalui porta USB. Pastikan penerima terpasang dengan baik.
  • Tuliskan alamat IP kamera (misalnya 192.168.0.5) kalau diberikan. Nomor ini bisa ditik ke semua peramban web untuk menampilkan umpan kamera dalam jarak jauh.
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6. Pasangkan monitor ke DVR. 

Koneksi ini sering kali juga menggunakan kabel BNC, tetapi sebagian DVR bisa dihubungkan menggunakan kabel HDMI atau koaksial (coaxial). Pilihlah koneksi yang diinginkan, masukkan salah satu ujung kabel ke porta “Output” DVR, dan ujung satunya lagi ke porta “Input” monitor.

  • Anda bisa menyambungkan banyak kamera ke masukan DVR Anda. perangkat akan merekam semua kamera yang dipasang secara otomatis.
  • Catat masukan yang Anda sambungkan. Inilah masukan yang perlu dipilih untuk menampilkan umpan kamera Anda.
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7. Atasi semua gangguan koneksi. 

Cek apakah kamera, DVR, dan monitor sudah tersambung dengan sumber daya dan menyala dengan baik. Pastikan semua kabel terpasang kuat dan Anda sudah memilih masukan yang sesuai untuk DVR dan monitor. Beberapa monitor akan menampilkan setiap kamera secara bersamaan. Sebagian lain memiliki tombol “input” yang memungkinkan Anda berpindah-pindah kamera.


Metode 3

Mengonsolidasikan Sistem Pengawasan

 
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1. Buat “pusat pengawasan” sentral Anda. 

Jika Anda memasang banyak kamera, Anda membutuhkan satu tempat sederhana untuk menerima semua umpan secara bersamaan ke DVR. Tempat ini harus mudah diakses dan mudah dipasangi kabel dari berbagi lokasi di rumah Anda. Loteng, kantor, dan ruter internet Anda merupakan lokasi ideal untuk pusat pengawasan rumah Anda.

  • Anda hanya membutuhkan satu DVR untuk menerima semua kamera.

 
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2. Gunakan kabel siamese untuk menghubungkan sistem Anda secara efektif.

Kabel siamese paling sering digunakan untuk sistem pengawasan rumah. Kabel ini berupa dua kabel yang saling merekat. Satu kabel untuk daya, dan satu lagi untuk video. Artinya, Anda hanya perlu menjalankan satu kabel untuk menyambungkan kamera. Umumnya, kabel ini dijual berupa RG59 atau RG6.

  • Kabel bersisi merah dan hitam berfungsi menyalurkan daya. Sisi berwarna merah adalah positif, dan sisi hitam adalah negatif.
  • Kabel silindris tunggal berfungsi menyalurkan video. Setiap ujungnya memiliki sambungan BNC atau kabel koaksial.
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3. Gunakan power box untuk menyalakan beberapa kamera dari satu soket listrik dinding. 

Kotak ini bisa dibeli di toko listrik atau internet dengan harga sekitar Rp2.000.000, dan memungkinkan Anda menyalakan beberapa kamera dari satu soket listrik dinding. Jumlah porta yang tersedia beragam dan alat ini bagus untuk menyalakan kamera yang saling berdekatan, atau jauh dari sumber daya. Namun, Anda harus memasang kabel panjang supaya kamera bisa tersambung dengan alat ini.

  • Kamera harus dipasang terlebih dahulu sebelum disambungkan ke power box.
  • Pastikan Anda membeli power box yang mampu menyalakan semua kamera di rumah. Jumlah soket yang ada pada power box seharusnya tercantum di kotak.
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4. Sambungkan setiap kabel video ke porta DVR terpisah. 

DVR Anda mampu menerima beberapa kamera secara bersamaan sehingga Anda bisa merekam setiap ruangan di rumah hanya menggunakan satu kotak saja. Monitor akan menampilkan umpan setiap kamera, atau Anda perlu mengganti tampilan kamera menggunakan tombol input di DVR.

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5 Sembunyikan kabel Anda. 

Supaya sistem pengawasan rumah Anda terlihat profesional, masukkan kabel Anda ke dinding menuju pusat pengawasan. Pastikan Anda mengetahui tatanan dinding dan lokasi pipa, kabel atau tiang sebelum mulai memasang kabel. Pemasangan kabel dilakukan dengan mengebor dinding, memasukkan kabel ke dinding menuju DVR melalui ruang terbuka di rumah (misalnya loteng).

  • Jika Anda merasa enggan mengebor dinding dan memanjangkan kabel di dalamnya, hubungi jasa profesional untuk memasang kabel Anda.
  • Anda juga bisa memasang kabel ke dinding atau kerangka kayu menggunakan staple gun (pistor stapler).
  • Coba sembunyikan kabel di bawah karpet, tetapi rekatkan dengan selotip supaya orang lain tidak tersandung.
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6. Kalau tidak, hubungi jasa profesional untuk mengatur sistem pengawasan Anda. 

Terdapat banyak jasa yang akan memasang kamera, sensor gerakan, atau panggilan darurat untuk Anda, walau biayanya juga lebih mahal. Namun, jika rumah Anda cukup besar, merasa tidak kompeten untuk memasang sistem pengawasan, atau menginginkan fitur tambahan (misalnya sensor gerakan dan sistem alarm), jasa profesional ini layak dipakai.

  • Di AS, perusahaan yang menyediakan jasa ini di antaranya ADT, LifeShield, Vivint, dan SafeShield.

Tips

  • Sebagian besar paket pengawasan rumah terdiri dari kabel, DVR, dan kamera. Sistem ini lebih praktis daripada membeli komponennya satu per satu.

Peringatan

  • Ketahui batas Anda. Jika Anda tidak kompeten dalam mengebor, bekerja di tangga, atau memasang sambungan listrik, gunakan jasa profesional untuk memasang sistem pengawasan rumah Anda.
  • Merekam orang lain tanpa persetujuan hukumnya ilegal, kecuali mereka sedang berada di properti pribadi Anda.

Arti Fungsi Dan Pengertian Smelter Pertambangan

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Kalian tahu bahwa kita sering mendengar tentang kaharusan seluruh perusahaan tambang membangun smelter, tapi apa itu smelter? untuk apa dan siapa? mari kita bahas satu-persatu.

Dalam industri pertambangan mineral logam, smelter merupakan bagian dari proses sebuah produksi, mineral yang ditambang dari alam biasanya masih tercampur dengan kotoran yaitu material bawaan yang tidak diinginkan. Sementara ini, material bawaan tersebut harus dibersihkan, selain itu juga harus dimurnikan pada smelter.

Smelter itu sendiri adalah sebuah fasilitas pengolahan hasil tambang yang berfungsi meningkatkan kandungan logam seperti timah, nikel, tembaga, emas, dan perak hingga mencapai tingkat yang memenuhi standar sebagai bahan baku produk akhir.

Proses tersebut telah meliputi pembersihan mineral logam dari pengotor dan pemurnian.

Pembangunan Smelter di wajibkan bagi seluruh perusahaan tambang di indonesia. Baik perusahaan besar maupun kecil.

Setidaknya sudah ada 66 perusahan yang sedang melakukan pembangunan smelter saat tulisan ini dibuat.

Menteri Energi dan Sumber Daya Mineral Jero Wacik mengatakan 66 perusahaan tersebut bagian dari 253 perusahaan pemegang izin usaha pertambangan (IUP) yang menandatangani pakta integritas sejak Peraturan Menteri No.7/2012 diterbitkan.

Dari 66 perusahaan yang telah berkomitmen terdapat 25 perusahaan saja yang telah berada di tahap proses akhir pembangunan smelter.

15 perusahaan dicatat pemerintah tengah melakukan ground konstruksi dan 10 perusahaan tengah konstruksi. Sisanya, 16 perusahaan baru mengurus izin analisis mengenai dampak lingkungan.

Selain 66 perusahaan, terdapat 112 perusahaan yang juga telah menandatangani pakta integritas masih dalam proses studi kelayakan. Sisanya sebanyak 75 perusahaan tidak melakukan apapun.

Menurut sumber hmtaupnykcom Pemerintah menyatakan saat ini ada 28 perusahaan pertambangan baru yang berencana membangun smelter untuk pengolahan bauksit, nikel, alumina, dan bijih besi. Dari jumlah itu, 15 di antaranya bakal merampungkan pembangunan smelter sebelum 2015.

“Ada empat perusahaan sudah bangun 10 persen, empat perusahaan lagi 20 persen. Dan yang udah di atas 60-70 persen itu ada 15 perusahaan,” ujar Wakil Menteri Energi dan Sumber Daya Mineral (ESDM) Susilo Siswoutomo, Kamis (7/11/2013).

Menurutnya, waktu yang dibutuhkan untuk membangun satu pabrik pengolahan bijih mineral sekitar 3 tahun.

Pemerintah melalui Undang-undang No.4/2009 tentang Pertambangan Mineral dan Batubara (minerba) mewajibkan perusahaan pertambangan agar membangun pabrik pengolahan bijih mineral (smelter).

Dalam ketentuannya, aturan tersebut sudah harus berlaku pada 2014 mendatang. Namun, hingga saat ini baru beberapa perusahaan tambang yang menaati peraturan.

Begitupun dari artikel alatberatcom, Sejak tahun 2012 pemerintah telah mengabarkan bahwa akan di berlakukanya UU tentang pembangunan Smelter.

Pemerintah menganjurkan agar perusahaan tambang segera membangun smelter, karena ditahun 2014 akan diberlakukan pelarangan ekspor mineral mentah.

Terbukti pada hari Minggu, 12 Januari 2014 pemerintah mulai memberlakukan pelarangan ekspor mineral mentah. Dan diperkirakan 5-6 tahun lagi smelterakan bisa beroprasi

  • Mengapa pemerintah mewajibkan pembangunan Smelter?
  • Menambah Nilai Jual dari Mineral
  • Meningkatkan Investor dalam atau pun luar negri
  • Membuka lapangan kerja baru

Setelah kita membaca sedikit tentang Smelter, timbul bebrapa opini pro dan kontra. Pada dasarnya pengesahan UU tentang Smelter ini adalah upaya baik pemerintah untuk memperbaiki perekonomian bangsa, meningkatkan nilai hidup masyarakat, dan mengembalikan citra pertambangan yang terkadang hanya disebut sebagai perusak alam.

Dilihat dari segi ekoniminya, memang nilai jual mineral akan jauh berbeda jika sudah diolah, bukan lagi berbentuk bijih atau pun konsentrat. Bukan hanya nilai jual yang meningkat, tapi pengotor konsentrat atau bijih tersebut masih bisa di manfaatkan.

“Aturan ini kita terapkan agar bisa dapat nilai tambah. Sudah puluhan tahun ekspor mineral mentah kita lakukan. Ini tak dikehendaki lagi. Sekarang harus ada proses pengolahan dan pemurnian,” kata Jero Wacik di sela menghadiri rapat kerja di Komisi VII DPR, di Kompleks Parlemen Senayan, Senin (27/1).

Namun terdapat banyak kendala dalam pembanguna smelter ini, seperti:

  • Pembebasan tanah atau lahan yang tidak mudah. Sudah menjadi rahasia umum, tanah dimana disitu akan dibangun proyek, pasti harga tanah melambung.
  • Pasokan dan Ketersedian Listrik, dalam Industri listrik menjadi bahan pokok utama agar pabrik tetep memproduksi. Namun kita semua tau bahwa wilayah pertambangan bukanlah wilayah perkotaan.
  • “Ini otomatis saja, smelter dibikin maka PLN bikin pembangkit. Ini kayak telor sama ayam, bikin dulu aja smelternya baru kita buat PLN. Di Jeneponto tidak ada listrik, tapi ada PLTU. Antara listrik sama industri selalu terjadi tarik menarik,” ujar Jero wacik.
  • Perizinan pembangunan smelter yang tidak mudah tentunya, seperti mencari izin IUP itu sendiri tidaklah mudah.
  • Yang terutama adalah keterbatasan biaya juga menjadi hambatan dalam pembangunan smelter.

Hasil tambang antara lain: bauksit, alumina, bijih besi, timah, nikel, tembaga, emas, dan perak.

Bisa dikatakan jika pembangunan tiga pabrik pemurnian bijih tembaga rampung pada 2017, Indonesia bisa menjadi supplier tembaga terbesar di dunia, terlebih lagi banyak perusahaan tambang di Indonesia ini.