CIM 2465 Network Connectivity1 Network Connectivity (Topic 2) Textbook: Networking Basics, CCNA 1...

CIM 2465 Network Connectivity 1

Network Connectivity(Topic 2)

Textbook:

Networking Basics, CCNA 1 Companion Guide, Cisco Press

Cisco Networking Academy Program, CCNA 1 and 2, Companion Guide, Cisco Press, Latest Edition


Analog Signal Vs Digital Signal

• Analog data is continuous data• The world we live in is mainly an analog

world. E.g. light, video, voice • Digital data is discrete, values are distinct

from one another.• Digital computers process data in digital

form (0 or 1)• A/D D/A conversion (e.g. modem)


Analog Signal Vs Digital Signal


Properties of an Analog Signal

• Amplitude

• Frequency

• Phase

• Modulation and Demondulation


Factors AffectingTransmission of Signals

• Noise– Refers to any interference on the physical medium that makes it

difficult for the receiver to detect the data signal– Crosstalk

• Noise created on one wire as a result of current flowing over a nearby wire

• Attenuation– Attenuation in an electrical signal is a decrease in voltage as the

signal crosses the wire– Can be caused by

• Resistance of wires• Energy loss• Frequency of signal


Digital Transmission

• Digital Transmission is a general term that refers to how computing devices transmit the binary bits from one to another

• Can be done by (Modulation)– Varying (modulating) an electrical signal as it

passes over a copper wire– Varying the power of light as sent over an

optical fiber– Varying the radio waves sent through space,

wireless communications


Transmission Media

• Major types– Copper Wires

• Coaxial Cable, Shielded Twisted Pair (STP), Unshielded Twisted Pair (UTP)

– Optical– Wireless

• Considerations– Transmission speed– Digital or Analog transmission– Transmission distance


Coaxial Cable

• Composed of a single copper wire, surrounded by an insulating shell, then a second conductor shield, and a plastic outer shell– Types:

• Thick Coaxial (10Base5)• Thin Coaxial (10Base2)

• Today’s modern LANs no longer use 10BASE5 and 10BASE2


Coaxial Cable

• Advantages– Longer transmission distance than STP and UTP, few

er repeaters needed– Less expensive than fiber-optic, more expensive than

STP and UTP– High bandwidth medium that can carry thousands of

signals, support broadband transmission of cable TV, a single cable is divided into many channels for transmission. Commonly used to deliver cable-television signals and high-speed Internet access


Coaxial Cable


Twisted Pair Wire

• Most commonly used data transmission medium

• Its core consists of pairs of copper wires twisted together to create magnetic field and thus reduce interference

• 2 types: – Shielded Twisted Pair (STP)– Unshielded Twisted Pair (UTP)


Shielded Twisted Pair (STP)


Shielded Twisted Pair (STP)

• Shielding provides a cleaner electrical current by reducing attenuation and noise, thus longer cabling lengths

• More expensive, heavier, and difficult to bend when installing them (compare with UTP)


Unshielded Twisted Pair (UTP)

• Grouped into categories based on quality

• Generally used in LAN

• Cat 5 cable• RJ45

connector


Unshielded Twisted Pair (UTP)

• Adv– Does not require grounding like STP, easier to add co

nnectors– Thinner, more flexible to install– Same data speeds as other copper media

• Disadv– More susceptible to electrical noise and interference– Shorter cabling distance (100m when used for Ethern

et LANs)


Twisted Pair Wire

• Advantages– Commonly available and relative low cost,

especially where telephone lines have already been installed

• Disadvantages– Subject to signal distortion, noise and

interference, and the relatively low transmission rates


Fiber Optic Cable

• Thin wire (usually very pure glass or plastic) surrounded by a reflective cladding that is used to transmit optical signals (light)

• Copper wire cables transmit signals electrically, whereas fiber-optic cables transmit signals by means of light

• More expensive than copper wires, more skill to install


Fiber Optic Cable


Fiber Optic Cable

• Not susceptible to lightning, electromagnetic interference (EMI), or radio frequency interference (RFI), and does not generate EMI or RFI

• Much greater bandwidth• Greater transmission distances• Excellent signal quality


Fiber Optic Cable

• More secure (difficult to tap)

• Thin, requires little space in a conduit

• Lightweight, easy to install

• Better resistance to environment factors, e.g. water

• Generally used to link LANs, WANs, or as backbone of large networks


Fiber Optic Cable

• Fiber Optics Types:– Multi-mode cable

• Less expensive• Less expensive LED transmitters are used• Larger core, multiple angles of entry

– Single-mode cable• More expensive• More expensive laser transmitters are used• Significant longer cabling distances• Skinny core, only one angle of entry


Fiber Optic Cable


Wireless Media (1)

• Infrared

• Radio wave– Bluetooth– Wifi– Mobile Phone network (e.g. GSM, 3G)– Microwave– Satellite


Wireless Media (2)

• WLAN Components– PCs with WLAN NICs– Access Points (APs), which act as a LAN hub for wirel

ess devices

• Infrastructure mode– Uses APs, with the PCs sending and receiving data to

and from the AP

• Ad-hoc mode– Formed by any two wireless devices, find and associa

te with each other


Wireless Media (3)

• To install a WLAN that works with the existing LAN infrastructure– At least one AP– A straight-through cable to connect AP to an e

xisting LAN switch– Wireless NICs in end-user devices to commun

icate with the APs


Wireless Media (4)

• WLAN Organization and Standards– IEEE defines WLAN standards 802.11– Wi-Fi alliance (www.wi-fi.org)

Standard Spectrum Used Max Data Rate

802.11a 5GHz 54Mbps

802.11b 2.4GHz 11Mbps

802.11g 2.4GHz 54Mbps


LAN Cabling

• Considerations– Ethernet Types– Media– Speed– Distance– Connector


LAN UTP Cabling Standards

Category Purpose Comments

1 Telephones Not suitable for data

2 Token Ring Supports 4Mbps Token Ring

3 Telephones and 10BASE-T

4 Token Ring Supports 16Mbps Token Ring

5 Ethernet 10BASE-T and 100BASE-T

5e Ethernet Supports Gigabit Ethernet

6 Ehernet Officially supports 1Gbps, working for 10Gbps support


Ethernet LAN Media and Connectors

Ethernet Types Media Max Segment Length

Connector

10BASE2 50-ohm coax(Thinnet)

185m BNC

10BASE5 50-ohm coax

(Thicknet)

500m Attachment unit interface (AUI)

10BASE-T Cat 3,4,5 UTP 100m RJ45

100BASE-TX Cat 5 UTP 100m RJ45

100BASE-FX 62.5/125 micron multimode fiber

400m Duplex media interface connector (MIC), ST, or SC

1000BASE-T Cat 5 UTP 100m RJ45


UTP Cable Pinouts

• Key concepts– Ethernet devices (at 10 and 100Mbps Ethenet) use on

e pair of wires to transmit data– Ethernet devices (at 10 and 100Mbps Ethenet) use a

nother pair of wires to receive data– Two pairs of wires are required

• Types– Straight-Through Cable– Crossover Cable– Console Connection and Rollover Cable


Straight-Through Cable

• To connect an end-user device and a LAN hub or switch

• PC’s NIC uses– Pin 1, 2 to transmit– Pin 3, 6 to receive

• LAN hubs, switches (the other end)– Pin 3, 6 to transmit– Pin 1, 2 to receive


Straight-Through Cable• TIA/EIA-T568-B or A on BOTH ends of the cable


TIA/EIA 568-A


Crossover Cable

• To connect two devices that both want to send on the same pins (two devices of similar ‘type’, e.g. two PCs)

• BOTH sides use– Pin 1, 2 to transmit– Pin 3, 6 to receive


Crossover Cable• One side is T568-A and T568-B one the other (10BaseT,

100BaseT)• Special arrangement for 1000BaseT


How to choose?

• Two groups of devices– PC, router, server, AP (use pins 1 and 2 to transmit)– Switch, hub, bridge, repeater (use pins 3 and 6 to transmit)

• When connecting two devices that are similar in regard to which pins they use to transmit, use a crossover cable– e.g. Switch to Switch, Switch to Hub, Hub to Hub, Router to Rout

er, PC to PC, Router to PC

• When connecting two devices that differ in regard to which pins they use to transmit, use a straight-through cable– e.g Switch to Router, Switch to PC, Hub to PC


Basic Models for PC Communications (1)

• Peer-to-peer– A computer acts as a peer with other computer by acti

ng both as a client and a server– E.g. Sharing a folder in a Windows workgroup– Adv

• Simple to install• No special hardware required• Most OS support peer-to-peer networking• No network administrators required

– Disadv• Security• Loss control


Basic Models for PC Communications (2)

• Client/Server– A computer acts as either a client or a server– Server usually is more powerful, and requires a more

expensive network operating system (NOS)– Adv

• Centralized control• Security control• Easier data backup

– Disadv• Cost• Network administrators required• If server fails, ….


Comparing Peer-to-Peer and Client/Server

Comparison Point P-to-P C/S

Requires a dedicated server

Requires a more expensive NOS

Requires a dedicated network administrator

End users must be trained in network administration

More secure

Easier to back up data

Scales well

Single point of failure

CIM 2465 Network Connectivity1 Network Connectivity (Topic 2) Textbook: Networking Basics, CCNA 1...

Documents

Transcript of CIM 2465 Network Connectivity1 Network Connectivity (Topic 2) Textbook: Networking Basics, CCNA 1...