Lmt 2 Network Design Essentials

8/14/2019 Lmt 2 Network Design Essentials

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Network Design Essentials

By

Amit Kr. Bhardwaj


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Examining the basics ofNetwork layout


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Understanding standardtopologies

Physical bus topology

Logical bus topology

Physical Ring topology Logical Ring topology

Physical Star topology

Wireless topology Mesh


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Topology based networktypes

Bus network

Star network

Ring network Mesh network

Star-bus network

Tree or Hierarchical topologynetwork, etc.


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Bus Topology Linear Bus - The type of

network topology in which

all of the nodes of thenetwork are connected toa common transmissionmedium which has exactlytwo endpoints.

Distributed bus - Thetype of network topologyin which all of the nodesof the network areconnected to a commontransmission medium

which has more than twoendpoints


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Signal propagation In any n/w topology, computers communicate with each

other by sending information across the media as series

of signals, when copper wire is the medium, as in atypical physical bus, those signals are sent as electricalpulses. When a computer transmits data as a series ofelectrical pulses, those signal travel along the length ofcable in all directions. The signal continue to travel

along the cable and through any connecting devicesuntil they weaken enough so as not to be detectable oruntil they encounter a device that absorbs them. Thistravelling along the length of medium is called signalpropagation.

It means that even if a signal encounters the end of acable it become, it bounce back and travels the otherdirection.


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Cable termination

A terminator attached to each end ofa cable prevents signals frombouncing on a physical bus. This

terminal absorb all signals thatreach it

Cable failure : A cable break in a bus

n/w occurs when the cablephysically cut or one end becomesdisconneted.


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Logical Bus topology

Logical topologies describe thepath that travels fromcomputer to computer.


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Bus topology con.

Advantages of a Linear Bus Topology

Easy to connect a computer or peripheral to a linear bus.

Requires less cable length than a star topology.Disadvantages of a Linear Bus Topology

Entire network shuts down if there is a break in the maincable.

Terminators are required at both ends of the backbonecable.

Difficult to identify the problem if the entire networkshuts down.

Not meant to be used as a stand-alone solution in a largebuilding.

Security


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A logical Bus as a Physicalstar


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star topology A star topology is designed with

each node (file server,

workstations, and peripherals)connected directly to a centralnetwork hub or concentrator

All data that is transmittedbetween nodes in the network is

transmitted to this central node,which is usually some type ofdevice that then retransmits thedata to some or all of the othernodes in the network, although

the central node may also be asimple common connectionpoint without any active deviceto repeat the signals.


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Star topology

Extended star - A type of network topology inwhich a network that is based upon the physicalstar topology has one or more repeaters betweenthe central node (the 'hub' of the star) and the

peripheral or 'spoke' nodes, the repeaters beingused to extend the maximum transmissiondistance of the point-to-point links between thecentral node and the peripheral nodes beyondthat which is supported by the transmitter power

of the central node or beyond that which issupported by the standard upon which thephysical layer of the physical star network isbased.


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Star topology

Distributed Star -A type of networktopology that is composed ofindividual networks that are based

upon the physical star topologyconnected together in a linearfashion (e.g., two or more 'stacked'

hubs, along with their associated starconnected nodes )


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Star topologyAdvantages of a Star Topology

Easy to install and wire. No disruptions to the network then

connecting or removing devices. Easy to detect faults and to remove parts.

Disadvantages of a Star Topology Requires more cable length than a linear

topology. If the hub or concentrator fails, nodes

attached are disabled. More expensive than linear bus topologies

because of the cost of the concentrators.

Ri l


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Ring topology The type of network topology in which

each of the nodes of the network is

connected to two other nodes in thenetwork and with the first and lastnodes being connected to each other,forming a ring all data that istransmitted between nodes in thenetwork travels from one node to thenext node in a circular manner and thedata generally flows in a singledirection only.

Each packet is sent around the ringuntil it reaches its final destination.

Today, the ring topology is seldomused.


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Ring topology ..

Advantages

Very orderly network where every device has access to thetoken and the opportunity to transmit Performs better than a star topology under heavy network

load Can create much larger network using Token Ring Does not require network server to manage the

connectivity between the computers

Disadvantages One malfunctioning workstation or bad port in the MAU can

create problems for the entire network

Moves, adds and changes of devices can affect the network Network adapter cards and MAU's are much more

expensive than Ethernet cards and hubs Much slower than an Ethernet network under normal load


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Mesh Topology

The value of fullymeshed networks isproportional to theexponent of the

number ofsubscribers, assumingthat communicatinggroups of any two

endpoints, up to andincluding all theendpoints


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Tree

A tree topology combinescharacteristics of linear busand star topologies. Itconsists of groups of star-configured workstationsconnected to a linear busbackbone cable .Treetopologies allow for theexpansion of an existingnetwork, and enable schoolsto configure a network tomeet their needs.


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Tree..

Advantages of a Tree Topology Point-to-point wiring for individual segments. Supported by several hardware and software

venders.

Disadvantages of a Tree Topology Overall length of each segment is limited by

the type of cabling used. If the backbone line breaks, the entire

segment goes down. More difficult to configure and wire than other

topologies.

H b id t k t l i


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Hybrid network topologiesThe hybrid topology is a type of network topology that is composed ofone or more interconnections of two or more networks that are basedupon different physical topologies or a type of network topology thatis composed of one or more interconnections of two or more networks

that are based upon the same physical topology, but where thephysical topology of the network resulting from such aninterconnection does not meet the definition of the original physicaltopology of the interconnected networks (e.g., the physical topologyof a network that would result from an interconnection of two or morenetworks that are based upon the physical star topology might createa hybrid topology which resembles a mixture of the physical star andphysical bus topologies or a mixture of the physical star and the

physical tree topologies, depending upon how the individual networksare interconnected, while the physical topology of a network thatwould result from an interconnection of two or more networks that arebased upon the physical distributed bus network retains the topologyof a physical distributed bus network).


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Star-busA type of network topology in which the central nodes ofone or more individual networks that are based upon

the physical star topology are connected together usinga common 'bus' network whose physical topology isbased upon the physical linear bus topology, theendpoints of the common 'bus' being terminated withthe characteristic impedance of the transmissionmedium where required e.g., two or more hubs

connected to a common backbone with drop cablesthrough the port on the hub that is provided for thatpurpose (e.g., a properly configured 'uplink' port) wouldcomprise the physical bus portion of the physical star-bus topology, while each of the individual hubs,

combined with the individual nodes which areconnected to them, would comprise the physical starportion of the physical star-bus topology.


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Star-of-stars

A type of network topology that is composed ofan interconnection of individual networks thatare based upon the physical star topologyconnected together in a hierarchical fashion to

form a more complex network e.g., a top levelcentral node which is the 'hub' of the top levelphysical star topology and to which other secondlevel central nodes are attached as the 'spoke'nodes, each of which, in turn, may also become

the central nodes of a third level physical startopology.


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Star-wired ring

A type of hybrid physical network topology that is acombination of the physical star topology and thephysical ring topology, the physical star portion ofthe topology consisting of a network in which eachof the nodes of which the network is composed are

connected to a central node with a point-to-pointlink in a 'hub' and 'spoke' fashion, the central nodebeing the 'hub' and the nodes that are attached tothe central node being the 'spokes' (e.g., acollection of point-to-point links from the peripheralnodes that converge at a central node) in a fashion

that is identical to the physical star topology, whilethe physical ring portion of the topology consists ofcircuitry within the central node which routes thesignals on the network to each of the connectednodes sequentially, in a circular fashion.


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Hybrid mesh

A type of hybrid physical networktopology that is a combination of thephysical partially connected topologyand one or more other physicaltopologies the mesh portion of thetopology consisting of redundant oralternate connections between some ofthe nodes in the network the physicalhybrid mesh topology is commonly usedin networks which require a high degreeof availability..


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Hub and Switch


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Constructing a NetworkLayout

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Lmt 2 Network Design Essentials