Download basic networking concepts

BASIC NETWORKING CONCEPTS
AddressingBandwidth-The amount of data that can be transferred across telephone or network
wires. Larger bandwidth means more information can be transferred at one time.
Status indicators- LED’s used on various electronic components. They indicate the
status (On, Off, Uplink, On-line, etc.) of that particular device.
TCP/IP- Transmission Control Protocol/Internet Protocol: This is a common shorthand
which refers to the suite of application and transport protocols which run over IP. These
include FTP, Telnet, SMTP, and UDP (a transport layer protocol).
Subnet- a range of logical addresses within the address space that is assigned to an
organization.
IPX/SPX- stands for Internetwork Packet Exchange/Sequenced Packet Exchange.
It is a networking protocol used by the Novell NetWare operating systems. Like UDP,
IPX is a datagram protocol used for connectionless communications. IPX and SPX
are derived from Xerox Network Services' IDP and SPP protocols. IPX and SPX both
provide connection services similar to TCP/IP, with the IPX protocol having
similarities to IP, and SPX having similarities to TCP. IPX/SPX was primarily
designed for local area networks (LANs), and is a very efficient protocol for this
purpose (typically its performance exceeds that of TCP/IP on a LAN).
NWLink- is a IPX/SPX-compatible protocol developed by Microsoft and used in its
Windows NT product line. It is a routable protocol. NWLink is Microsoft's version of
Novell's IPX/SPX Protocol. The Microsoft version of NWLink includes the same
level of functionality as the Novell Protocol. NWLink includes a tool for resolving
NetBIOS names.
NETBEUI- (NetBIOS Extended User Interface) is a new, extended version of NetBIOS,
the program that lets computers communicate within a local area network. NetBEUI
(pronounced net-BOO-ee) formalizes the frame format (or arrangement of information in a
data transmission) that was not specified as part of NetBIOS. NetBEUI was developed by
IBM for its LAN Manager product and has been adopted by Microsoft for its Windows
NT, LAN Manager, and Windows for Workgroups products. Hewlett-Packard and DEC
use it in comparable products. Its the best performance choice for communication within
a single LAN. Because, like NetBIOS, it does not support the routing of messages to
other networks, its interface must be adapted to other protocols such as Internetwork
Packet Exchange or TCP/IP. A recommended method is to install both NetBEUI and
TCP/IP in each computer and set the server up to use NetBEUI for communication within
the LAN and TCP/IP for communication beyond the LAN.
NETBIOS- (Network Basic Input/Output System) is a program that allows applications
on different computers to communicate within a local area network (LAN). It was created
by IBM for its early PC Network, was adopted by Microsoft, and has since become a de
facto industry standard. NetBIOS is used in Ethernet and Token Ring networks and,
included as part of NetBIOS Extended User Interface (NetBEUI), in recent Microsoft
Windows operating systems. It does not in itself support a routing mechanism so
applications communicating on a wide area network (WAN) must use another "transport
mechanism" (such as Transmission Control Protocol) rather than or in addition to
NetBIOS. NetBIOS frees the application from having to understand the details of the
network, including error recovery (in session mode). A NetBIOS request is provided in
the form of a Network Control Block (NCB) which, among other things, specifies a
message location and the name of a destination. NetBIOS provides the session and
transport services described in the Open Systems Interconnection (OSI) model. However,
it does not provide a standard frame or data format for transmission. A standard frame
format is provided by NetBUI. NetBIOS provides two communication modes: session or
datagram. Session mode lets two computers establish a connection for a "conversation,"
allows larger messages to be handled, and provides error detection and recovery.
Datagram mode is "connectionless" (each message is sent independently), messages must
be smaller, and the application is responsible for error detection and recovery. Datagram
mode also supports the broadcast of a message to every computer on the LAN.
Full Duplex- Full-duplex data transmission means that data can be transmitted in both
directions on a signal carrier at the same time. For example, on a local area network with
a technology that has full-duplex transmission, one workstation can be sending data on
the line while another workstation is receiving data. Full-duplex transmission necessarily
implies a bidirectional line (one that can move data in both directions).
Half Duplex- Half-duplex data transmission means that data can be transmitted in both
directions on a signal carrier, but not at the same time. For example, on a local area
network using a technology that has half-duplex transmission, one workstation can send
data on the line and then immediately receive data on the line from the same direction in
which data was just transmitted. Like full-duplex transmission, half-duplex transmission
implies a bidirectional line (one that can carry data in both directions).
CABLES
Twisted Pair- Twisted pair is the ordinary copper wire that connects home and many
business computers to the telephone company. To reduce crosstalk or electromagnetic
induction between pairs of wires, two insulated copper wires are twisted around each
other. Each connection on twisted pair requires both wires. Since some telephone sets or
desktop locations require multiple connections, twisted pair is sometimes installed in two
or more pairs, all within a single cable. For some business locations, twisted pair is
enclosed in a shield that functions as a ground. This is known as shielded twisted pair
(STP). Ordinary wire to the home is unshielded twisted pair (UTP).
Coaxial Cable- Widely installed for use in business and corporation Ethernet and other
types of local area network. Coaxial cable is called "coaxial" because it includes one
physical channel that carries the signal surrounded (after a layer of insulation) by another
concentric physical channel, both running along the same axis. The outer channel serves
as a ground. Many of these cables or pairs of coaxial tubes can be placed in a single outer
sheathing and, with repeaters, can carry information for a great distance.
Fiber Optic- (Transmission of information as light impulses along a glass or plastic wire
or fiber.) Fiber optic wire carries much more information than conventional copper wire
and is far less subject to electromagnetic interference. Most telephone company longdistance lines are now fiber optic. Transmission on fiber optic wire requires repeating at
distance intervals. The glass fiber requires more protection within an outer cable than
copper. For these reasons and because the installation of any new wiring is laborintensive, few communities yet have fiber optic wires or cables from the phone
company's branch office to local customers (known as local loop).
RS-232- (Recommended Standard 232) is a standard for serial binary data signals
connecting between a DTE (Data terminal equipment) and a DCE (Data Circuitterminating Equipment). It is commonly used in computer serial ports. A similar ITU-T
standard is V.24 RS-232 is still quite common in point-of-sale (cash drawers, barcode
and magnetic stripe readers), amateur electronics and industrial measurement and remotecontrol devices, so computers made for such applications are still equipped with RS-232
ports. RS-232 was standard for so long that the circuits needed to control a serial port
became very cheap and often exist on a single chip, sometimes also with circuitry for a
parallel port. Many motherboards and desktop systems provide these ports even though
they may not be used, simply because it costs the manufacturer very little to include
them. Small-form-factor systems and laptops, however, often do not include them in
order to conserve space.
USB- (Universal Serial Bus) is a plug-and-play interface between a computer and add-on
devices (such as audio players, joysticks, keyboards, telephones, scanners, and printers).
With USB, a new device can be added to your computer without having to add an adapter
card or even having to turn the computer off. The USB peripheral bus standard was
developed by Compaq, IBM, DEC, Intel, Microsoft, NEC, and Northern Telecom USB
supports a data speed of 12 megabits per second. This speed will accommodate a wide
range of devices, including MPEG video devices, data gloves, and digitizers. It is
anticipated that USB will easily accommodate plug-in telephones that use ISDN and
digital PBX.
IEEE1394/FireWire- High Performance Serial Bus, is an electronics standard for
connecting devices to your personal computer. IEEE 1394 provides a single plug-andsocket connection on which up to 63 devices can be attached with data transfer speeds up
to 400 Mbps (megabits per second). The standard describes a serial bus or pathway
between one or more peripheral devices and your computer's microprocessor. Many
peripheral devices now come equipped to meet IEEE 1394. Two popular
implementations of IEEE 1394 are Apple's FireWire and Sony's i.LINK. IEEE 1394
implementations provide:
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A simple common plug-in serial connector on the back of your computer and on
many different types of peripheral devices
A thin serial cable rather than the thicker parallel cable you now use to your
printer, for example
A very high-speed rate of data transfer that will accommodate multimedia
applications (100 and 200 megabits per second today; with much higher rates
later)
Hot-plug and Plug and Play capability without disrupting your computer
The ability to chain devices together in a number of different ways without
terminators or complicated set-up requirement
IEEE 1394 provides two types of data transfer: asynchronous and isochronous.
Asynchronous is for traditional load-and-store applications where data transfer can be
initiated and an application interrupted as a given length of data arrives in a buffer.
Isochronous data transfer ensures that data flows at a pre-set rate so that an application
can handle it in a timed way. For multimedia applications, this kind of data transfer
reduces the need for buffering and helps ensure a continuous presentation for the viewer
Peer-to-Peer- Peer-to-peer is a communications model in which each party has the same
capabilities and either party can initiate a communication session. Other models with
which it might be contrasted include the client/server model and the master/slave model.
In some cases, peer-to-peer communications is implemented by giving each
communication node both server and client capabilities. In recent usage, peer-to-peer has
come to describe applications in which users can use the Internet to exchange files with
each other directly or through a mediating server. The user must first download and
execute a peer-to-peer networking program. (Gnutellanet is currently one of the most
popular of these decentralized P2P programs because it allows users to exchange all types
of files.) After launching the program, the user enters the IP address of another computer
belonging to the network. (Typically, the Web page where the user got the download will
list several IP addresses as places to begin). Once the computer finds another network
member on-line, it will connect to that user's connection (who has gotten their IP address
from another user's connection and so on).
Client/Server- Client/server describes the relationship between two computer programs
in which one program, the client, makes a service request from another program, the
server, which fulfills the request. Although the client/server idea can be used by programs
within a single computer, it is a more important idea in a network. In a network, the
client/server model provides a convenient way to interconnect programs that are
distributed efficiently across different locations. Computer transactions using the
client/server model are very common. For example, to check your bank account from
your computer, a client program in your computer forwards your request to a server
program at the bank. That program may in turn forward the request to its own client
program that sends a request to a database server at another bank computer to retrieve
your account balance. The balance is returned back to the bank data client, which in turn
serves it back to the client in your personal computer, which displays the information for
you. The client/server model has become one of the central ideas of network computing.
Most business applications being written today use the client/server model. So does the
Internet's main program, TCP/IP. In marketing, the term has been used to distinguish
distributed computing by smaller dispersed computers from the "monolithic" centralized
computing of mainframe computers. But this distinction has largely disappeared as
mainframes and their applications have also turned to the client/server model and become
part of network computing. In the usual client/server model, one server, sometimes called
a daemon, is activated and awaits client requests. Typically, multiple client programs
share the services of a common server program. Both client programs and server
programs are often part of a larger program or application. Relative to the Internet, your
Web browser is a client program that requests services (the sending of Web pages or
files) from a Web server (which technically is called a Hypertext Transport Protocol or
HTTP server) in another computer somewhere on the Internet. Similarly, your computer
with TCP/IP installed allows you to make client requests for files from File Transfer
Protocol (FTP) servers in other computers on the Internet.
Plenum- Typical plenum cable sizes are American Wire Gauge (AWG) sizes 22 and 24.
Plenum cabling is often made of Teflon and is more expensive than ordinary cabling. In
the event of fire, its outer material is more resistant to flames and, when burning,
produces less smoke than ordinary cabling. Both twisted pair and coaxial cable are made
in plenum cable versions. In construction, iis a separate space provided for air circulation
for heating, ventilation, and air-conditioning (sometimes referred to as HVAC) and
typically provided in the space between the structural ceiling and a drop-down ceiling. A
plenum may also be under a raised floor. In buildings with computer installations, the
plenum space is often used to house connecting communication cables. Because ordinary
cable introduces a toxic hazard in the event of fire, special plenum cabling is required in
plenum areas.
PVC- PVC is commonly used as the insulation on electric wires; the plastic used for this
purpose needs to be plasticized. In a fire, PVC-coated wires can form HCl fumes; the
chlorine serves to scavenge free radicals and is the source of the material's fire
retardance. While HCl fumes can also pose a health hazard in their own right, HCl breaks
down on surfaces, particularly in areas where the air is cool enough to breathe, and is not
available for inhalation.[2] Frequently in applications where smoke is a major hazard
(notably in tunnels) PVC-free LSOH (low-smoke, zero-halogen) cable insulation is used.
The applicable building code should be consulted to determine the type of electrical wires
approved for the intended use.
(A permanent virtual circuit (PVC) is a software-defined logical connection in a network
such as a frame relay network. A feature of frame relay that makes it a highly flexible
network technology is that users (companies or clients of network providers) can define
logical connections and required bandwidth between end points and let the frame relay
network technology worry about how the physical network is used to achieve the defined
connections and manage the traffic. In frame relay, the end points and a stated bandwidth
called a Committed Information Rate (CIR) constitute a PVC, which is defined to the
frame relay network devices. The bandwidth may not exceed the possible physical
bandwidth. Typically, multiple PVCs share the same physical paths at the same time. To
manage the variation in bandwidth requirements expressed in the CIRs, the frame relay
devices use a technique called statistical multiplexing)
UTP- Unshielded twisted pair is the most common kind of copper telephone wiring.
Category
Maximum data rate
Usual application
CAT 1
Up to 1 Mbps (1 MHz)
analog voice (POTS)
Integrated Services Digital Network
Basic Rate Interface in ISDN
Doorbell wiring
CAT 2
4 Mbps
Mainly used in the IBM Cabling
System for Token Ring networks
CAT 3
16 Mbps
Voice and data on 10BASE-T
Ethernet
CAT 4
20 Mbps
Used in 16 Mbps Token Ring
Otherwise not used much
100 Mbps
1000 Mbps (4 pair)
100 Mbps TPDDI
155 Mbps ATM
No longer supported; replaced by 5E
CAT 5E
1000 Mbps
(10000 Mbps prototype)
100 Mbps TPDDI
155 Mbps ATM
Gigabit Ethernet
Offers better near-end crosstalk than
CAT 5
CAT 6
Up to 400 MHz
Super-fast broadband applications
Most popular cabling for new installs
CAT 6E
Up to 625 MHz
(field-tested to 500
MHz)
Support for 10 Gigabit Ethernet
(10GBASE-T)
CAT 7
(ISO Class
F)
600-700 MHz
1.2 GHz in pairs with
Siemon connector
Full-motion video
Teleradiology
Government and manufacturing
environments
Shielded system
CAT 5
STP- Shielded Twisted Pair- metal shielding over each individual pair of copper wires.
This type of shielding protects cable from external EMI (electromagnetic interferences).
e.g. the 150 ohm shielded twisted pair cables defined by the IBM Cabling System
specifications and used with token ring networks.
Single-Mode Fiber- Optical fiber that is designed for the transmission of a single ray or
mode of light as a carrier and is used for long-distance signal transmission. For short
distances, multimode fiber is used. Single mode fiber has a much smaller core than
multimode fiber. Single-mode optical fibers are also called monomode optical fibers,
single-mode optical waveguides, or unimode fibers. single mode fibers do not exhibit
dispersion resulting from multiple spatial modes. Single mode fibers are also better at
retaining the fidelity of each light pulse over long distances than are multi-mode fibers.
For these reasons, single-mode fibers can have a higher bandwidth than multi-mode
fibers. Equipment for single mode fiber is more expensive than equipment for multimode optical fiber, but the single mode fiber itself is usually cheaper in bulk
Multi-Mode Fiber- Multi-mode fibers support applications from 10 Mbit/s to 10 Gbit/s
over link lengths of up to 550 meters, more than sufficient for the majority of premises
applications Optical fiber that is designed to carry multiple light rays or modes
concurrently, each at a slightly different reflection angle within the optical fiber core.
Multimode fiber transmission is used for relatively short distances because the modes
tend to disperse over longer lengths (this is called modal dispersion) . For longer
distances, single mode fiber (sometimes called monomode) fiber is used. Multimode fiber
has a larger core than single mode. Because of its high capacity and reliability, multimode optical fiber generally is used for backbone applications in buildings
RJ45- 8 pin, used mainly in Cat 5/6 ethernet cables.
RJ11- 4 pin used mainly in regular telephone wires.