Lesson 2 Intro to Network Revised

8/10/2019 Lesson 2 Intro to Network Revised

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Lesson 2


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Network Topology

The network topologydefines the way inwhich computers,printers, and other

devices are connected.A network topologydescribes the layout ofthe wire and devices aswell as the paths used

by data transmissionsThe network topologydescribes the methodused to do the physicalwiring of the network.

Introduction to Computer Networks


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Bus Topology

Commonly referred toas a linear bus, all thedevices on a bus

topology are connectedby one single cable.



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Ring TopologyIntroduction to Computer Networks

A frame travels around thering, stopping at each node.If a node wants to transmitdata, it adds the data as wellas the destination address to

the frame.The frame then continuesaround the ring until it findsthe destination node, whichtakes the data out of theframe.

Single ring All the devices on thenetwork share a single cable

Dual ring The dual ring topologyallows data to be sent in bothdirections.


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When node # 1 receives the empty frame, it inserts atoken in the token bit part of the frame. This operationmay just be an insertion of a 1 bit

The node then inserts the message it wants to send

as well as the address of the receiving node in theframe

The frame is then successively received andexamined by each node in the network. First it is sentto node #2. Node #2 examines the frame andcompares the address in the frame to its ownaddress. Since addresses do not match, it passes theframe onto node #3, which does the same thing

When the frame is received by node #4, the addressof the node matches the destination address withinthe frame. The node copies the message andchanges the token bit in the frame to 0

The frame is then sent over to node #5. This node

also compares addresses and sends it to node #6which does the same procedure

When node #1 receives the frame, it examines thetoken bit and recognizes that it has been changed to0. Node #1 then concludes that the message hasbeen received by the intended node: node #4. Node

#1 then empties the frame and releases the emptyframe back into the network for circulation


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Mesh Topology

The mesh topologyconnects all devices(nodes) to each otherfor redundancy andfault tolerance.

It is used in WANs tointerconnect LANs andfor mission critical

networks like thoseused by banks andfinancial institutions.

Implementing the meshtopology is expensive

and difficult.



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HYBRID Topology

In a hybrid topology, two or

more topologies are combined

to form a complete network

design. Networks are rarely

designed using only one type

of topology. For example, you

may want to combine a star

with a bus topology to benefit

from the advantages of each.

Two types of hybrid topologies

are commonly in use: star-bustopology and star-ring

topology.

Star-Bus

Star-Ring

Next: network cables


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Network Components


Physical Media

Interconnecting Devices

ComputersNetworking Software

Applications


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Networking Media

Networking media canbe defined simply asthe means by which

signals (data) are sentfrom one computer toanother (either by cableor wireless means).



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NETWORK CABLESA cable that connects two computers

or network components is called a

segment. Cables differ in their capabilities

and are categorized according to their

ability to transmit data at varying speeds,with different error rates. The three major

categories of cables that connect most

networks are:


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UNSHILEDED TWISTED PAIR

(UTP)

Twisted pair cabling comes in two varieties:

shielded and unshielded. Unshielded twisted pair

(UTP) is the most popular and is generally the best

option for school networks

The quality of UTP may vary from telephone-grade

wire to extremely high-speed cable.

The cable has four pairs of wires inside the jacket.Each pair is twisted with a different number of

twists per inch to help eliminate interference from

adjacent pairs and other electrical devices.


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UTP

The following summarizes the features of

UTP cable: Speed and throughput10 to 1000 Mbps

Average cost per nodeLeast expensive

Media and connector sizeSmall Maximum cable length100 m (short)


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Commonly used types of UTP cabling are as

follows:

Category 1 Used for telephone communications. Not suitable

for transmitting data.

Category 2 Capable of transmitting data at speeds up to 4

megabits per second (Mbps).

Category 3 Used in 10BASE-T networks. Can transmit data at

speeds up to 10 Mbps.

Category 4 Used in Token Ring networks. Can transmit data

at speeds up to 16 Mbps.

Category 5 Can transmit data at speeds up to 100 Mbps.Category 5e Used in networks running at speeds up to 1000

Mbps (1 gigabit per second [Gbps]).

Category 6 Used in networks running at speeds up to 1000

Mbps (1 gigabit per second [Gbps]).


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STRAIGHT


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CROSS OVER

1-3

2-63-1

4-7

5-8

6-2

7-4

8-5

1-3

2-63-1

4-4

5-5

6-2

7-7

8-8


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STRAIGHT VS CROSS OVER


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UTP


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Shielded Twisted Pair (STP)The following summarizes the

features of STP cable:

Speed and throughput10 to100 Mbps

Average cost per nodeModerately expensive

Media and connector sizeMedium to large

Maximum cable length100m (short)

Although UTP cable is the least expensive cable, it may be susceptible to radioand electrical frequency interference (it should not be too close to electric

motors, fluorescent lights, etc.). If you must place cable in environments with

lots of potential interference, or if you must place cable in extremely sensitive

environments that may be susceptible to the electrical current in the UTP,

shielded twisted pair may be the solution. Shielded cables can also help to

extend the maximum distance of the cables.


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Coaxial Cable
http://en.wikipedia.org/wiki/Image:RG-59.jpg


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Coaxial Cable

Coaxial cable supports 10 to 100 Mbps and isrelatively inexpensive,

although it is more costly than UTP on a per-unitlength. However, coaxial cable can be cheaper

for a physical bus topology because less cablewill be needed.

Coaxial cable can be cabled over longerdistances than twisted-pair cable. For example,

Ethernet can run approximately 100 meters (328feet) using twisted-pair cabling. Using coaxialcable increases this distance to 500m (1640.4feet).


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Coaxial

The two types of coaxial cabling are thick coaxial

and thin coaxial.

Thin coaxial cable is also referred to as thinnet.

10Base2 refers to the specifications for thin coaxialcable carrying Ethernet signals.

The 2 refers to the approximate maximum segment

length being 200 meters. In actual fact the maximum

segment length is 185 meters. Thin coaxial cable ispopular in school networks, especially linear bus

networks.


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Coaxial Cable

Thick coaxial cable is also referred to asthicknet.

10Base5 refers to the specifications for thick coaxial

cable carrying Ethernet signals. The 5 refers to the

maximum segment length being 500 meters. Thick coaxial cable has an extra protective plastic

cover that helps keep moisture away from the center

conductor. This makes thick coaxial a great choice

when running longer lengths in a linear bus network. One disadvantage of thick coaxial is that it does not

bend easily and is difficult to install.


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Coaxial Cable

The following summarizes the features of

coaxial cables:

Speed and throughput10 to 100 Mbps

Average cost per nodeInexpensive

Media and connector sizeMedium

Maximum cable length500 m (medium)


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Coaxial Cable Connectors

The most common type of connectorused with coaxial cables is the Bayone-Neill-Concelman (BNC) connector.

Different types of adapters are availablefor BNC connectors,

including a T-connector,

barrel connector and terminator.


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Connectors

BNCTerminator
http://www.hyperlinktech.com/web/connectors/connector_information.php?SKU=ANM-TERM1http://www.hyperlinktech.com/web/connectors/connectors_bnc.php


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BNC

British Naval Connector

Bayone-Neill Concelman

Thinnet cable


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Fiber Optic Connectors

ST Connector

Straight (ST)

SC Connector

Standard Connector (SC)
http://en.wikipedia.org/wiki/Image:OFC_SC.JPGhttp://en.wikipedia.org/wiki/Image:OFC_ST.JPG


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WIRELESS STANDARDS AND


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WIRELESS STANDARDS ANDSPEED

The Wi-Fi Alliance is a global, non-profit organization that

helps to ensure standards and interoperability for

wireless networks, and wireless networks are often

referred to as WiFi. The original Wi-Fi standard (IEEE802.11) was adopted in 1997. Since then many

variations have emerged (and will continue to emerge).

Wi-Fi networks use the Ethernet protocol.


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Network Adapter

A network card, network adapteror NIC

(network interface controller)

is a piece of computer hardwaredesigned

to allow computers to communicate over a

computer network.
http://en.wikipedia.org/wiki/Computer_hardwarehttp://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Computer_hardware


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Network Adapater

A network adapterinterfaces a computer to anetwork. The term "adapter" was popularizedoriginally by Ethernetadd-in cards for PCs.

Ethernet

is a physical and data link layer technologyfor local area networks (LANs). Ethernet wasinvented by engineer Robert Metcalfe.

Every common adapter supports either Wi-Fi(wireless) or Ethernet (wired) standards.
http://compnetworking.about.com/cs/ethernet1/g/bldef_ethernet.htmhttp://compnetworking.about.com/cs/lanvlanwan/g/bldef_lan.htmhttp://wireless.about.com/cs/wireless80211/g/bldef_wifi.htmhttp://wireless.about.com/cs/ethernet1/g/bldef_ethernet.htmhttp://wireless.about.com/cs/ethernet1/g/bldef_ethernet.htmhttp://wireless.about.com/cs/wireless80211/g/bldef_wifi.htmhttp://wireless.about.com/cs/wireless80211/g/bldef_wifi.htmhttp://wireless.about.com/cs/wireless80211/g/bldef_wifi.htmhttp://compnetworking.about.com/cs/lanvlanwan/g/bldef_lan.htmhttp://compnetworking.about.com/cs/ethernet1/g/bldef_ethernet.htm


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Network Adapter

As the data passes through the cable to

the network adapter, it is formatted into

packets.

A packet is a logical grouping of

information that includes a header, which

contains location information and user

data.


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Network Adapter

Each network adapter has a unique address that is

incorporated into chips on the card. This address is

called the physical, or media access control (MAC),

address.

The network adapter reads the destination address todetermine if the packet is to be delivered to this

computer. If it is, the network adapter then passes

the packet on to the operating system for processing.

If not, the network adapter discards the packet.


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The network adapter performs

the following functions: Receives data from the computer's operating

system and converts it into electrical signals that

are transmitted onto the cable.

Receives electrical signals from the cable andtranslates them into data that the computer's

operating system can understand

Determines whether data received from the

cable is intended for the computer

Controls the flow of data between the computer

and the cabling system


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Network Adapters

Wired
http://en.wikipedia.org/wiki/Image:32-bit_PCI_card.JPGhttp://en.wikipedia.org/wiki/Image:Network_card.jpg


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Network Adapters

ROUTER/SWITCH/BROUTER


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ROUTER/SWITCH/BROUTERRouters: Routers filter out network traffic by specific protocol

rather than by packet address. Routers also divide

networks logically instead of physically. An IP router can

divide a network into various subnets so that only traffic

destined for particular IP addresses can pass between

segments. Network speed often decreases due to this

type of intelligent forwarding. Such filtering takes moretime than that exercised in a switch or bridge, which only

looks at the Ethernet address. However, in more

complex networks, overall efficiency is improved by

using routers.

The IP address192.168.1.1is the default for Linksys brand home broadband routers.This address is set by the manufacturer at the factory, but you can change it at any time

using the network router's administrative console.

If you have forgotten your LinkSys router password, the easiest thing to do is to

reset your router to the factory default settings.

To restore the router configuration to factory defaults, hold the reset button on theunit for 30 seconds.
http://compnetworking.about.com/library/glossary/bldef-ipaddress.htmhttp://compnetworking.about.com/cs/dslcablerouters/g/bldef_bbrouter.htmhttp://compnetworking.about.com/cs/dslcablerouters/g/bldef_bbrouter.htmhttp://compnetworking.about.com/library/glossary/bldef-ipaddress.htm


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SWITCH

Ethernet switches are an expansion of the

concept in Ethernet bridging. LAN

switches can link four, six, ten or more

networks together.

Switches are sometimes called "multi-port

bridges" for this reason.


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BRIDGE

A bridgedevice filters data traffic at anetwork boundary. Bridges reduce the

amount of traffic on a LAN by dividing it

into two segments.


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WIRELESS BRIDGE


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ACCESS POINT

Wireless access points(APs or WAPs) arespecially configured nodes on wireless local

area networks (WLANs).

Access points act as a central transmitter and

receiver of WLAN radio signals.

Access points used in home or small business

networks are generally small, dedicated

hardware devices featuring a built-in networkadapter, antenna, and radio transmitter.

Access points support Wi-Fi wireless

communication standards.


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Access point


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Reminders

Nov. 23/24 Thursday/ Friday Seatwork3

Nov. 26/27 Monday/Tuesday Quiz 1

Lesson 3. Assignment No. 3

What is static and dynamic IP address?

What is public and private IP address?

IP Classes and its range of IPs.

What is the use of the IP address 127.0.0.0?

Differentiate network ID and host ID?

Lesson 2 Intro to Network Revised

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