Chapter 5 - PowerPoint Presentation

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Chapter 5 - PPT Presentation

Wired Ethernet LANs Chapter 5 2 Ethernet 2013 Pearson Four Introductory Chapters Gave you the concepts and principles to apply for the rest of the term Chapter 1 Core concepts Chapter 2 Standards concepts ID: 417960

pearson 2013 switches ethernet 2013 pearson ethernet switches fiber network optical switch lan area 802 frame core poe lans

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Slide1

Chapter 5

Wired Ethernet LANs

Chapter 5Slide2

Ethernet

Four Introductory ChaptersGave you the concepts and principles to apply for the rest of the term

Chapter 1: Core conceptsChapter 2: Standards concepts

Chapter 3: Security principlesChapter 4: Network management

Three Chapters on Local Area NetworksChapter 5: Wired Ethernet LANsChapters 6 and 7: Wireless LANs

Governed by Layer 1 and Layer 2 StandardsRemaining ChaptersChapters 8 and 9: TCP/IP Internetworking

Chapter 10: Wide Area NetworksChapter 11: Applications

Characteristic

Local Area Network (LAN)

Wide Area Network (WAN)

LocationLocated entirely on customer’s premisesMust carry transmissions beyond customer’s premisesConsequence of Location

Owning company operates the LAN

User must contract with a carrier that has rights of way to carry wires between premises

5.1: LANs versus WANs

Characteristic

Local Area Network (LAN)

Wide Area Network (WAN)

Technology and Service Consequence of Corporate versus Carrier OwnershipOwner can use any technology and service options it wishesCustomer is limited to technologies and service options offered by available carriers

5.1: LANs versus WANs

Characteristic

Local Area Network (LAN)

Wide Area Network (WAN)

Labor Consequences of Corporate versus Carrier OwnershipOwner must do all operation and maintenance workOperational and maintenance work is done by the carrier

5.1: LANs versus WANs

Characteristic

Local Area Network (LAN)

Wide Area Network (WAN)

EconomicsTransmission distances are short, so the cost per bit carried is lowTransmission distances are long, so the cost per bit carried is high

5.1: LANs versus WANs

Characteristic

Local Area Network (LAN)

Wide Area Network (WAN)

Speed Consequences of EconomicsVery high speeds are affordableCustomers are content with lower speedsDesign Consequences of Economics

Optimization of transmission capacity is not pressing

Optimization of transmission capacity is critical

5.1: LANs versus WANs

5.2: Workgroup and Core Switches

Workgroup Switches Connect Hosts to the Network

5.2: Workgroup and Core Switches

Core Switches Connect Switches to Other Switches

5.2: Workgroup and Core Switches

Hosts Normally Connect to Workgroup Switches Through UTP Copper Wiring

5.2: Workgroup and Core Switches

Switches Often Connect to Other Switches Through Optical Fiber

5.3 Ethernet Workgroup Switch

5.4: UTP and Optical Fiber

Characteristic

Unshielded Twisted Pair

Optical FiberMediumCopper wireGlass

Signal

Electrical

Light

Maximum Distance in LANs

Usually 100 meters

Usually 200 to 500 meters

Speed

Similar

Cost

Lower

Higher

5.5: Ethernet Standards Development

Ethernet

5.6: Binary and Digital

5.7: Binary Resistance to Error

5.8: UTP Cord

5.9: RJ-45 Connector and Jack

5.10: Serial versus Parallel Transmission

NOT just 4 pairs!

5.11: Propagation Effects

Propagation Effect(s)

Impact

Installation DisciplineAttenuationSignal may become too low to be received properly.Limit cord distance to 100 m

Noise

Random electromagnet energy

the wire

(noise)

adds to the signal and may produce errors.

Terminal crosstalk interference

Interference

by other wire pairs

the cord is

crosstalk interference.

Crosstalk interference at the two ends where the wires are untwisted

terminal crosstalk interference

. Major problem

Limit

untwisting

of the wires

1.25 cm (0.5 in

)

5.12: Internet Signaling Standards and UTP Quality Levels

Ethernet Signaling Standard

Transmission Speed

UTP Quality CategoryMaximum Cord Length100BASE-TX100 Mbps

Category 5e, 6, or higher

100 meters

1000BASE-T

1 Gbps

Category 5e, 6, or higher

100 meters

10GBASE-T

10 Gbps

Category 6

55 meters

10GBASE-T

10 Gbps

Category 6A

100 meters

Category is a measure of UTP QUALITY

5.13: Optical Fiber Transmission

When modes arrive at different times, this is called modal dispersion.If light rays from different clock cycles overlap, modal dispersion may make the signal unreadable.

5.13: Optical Fiber Transmission

5.14: Optical Fiber Cord and Connections

5.15: Modal Bandwidth

Wavelength

Core Diameter

Modal BandwidthMaximum Propagation Distance850 nm62.5 microns

160 MHz-km

220 m

850 nm

62.5 microns

200 MHz-km

270 m

850 nm

50 microns

500 MHz-km

500 m

Medium Quality

UTP

Optical Fiber

UTP wire quality is indicated by a cord’s category number (5e, 6, etc.).Multimode optical fiber quality is indicated by a cord’s modal bandwidth.33

5.16: Wavelength

Wavelength is the physical distance between comparable points on adjacent cycles.Optical fiber transmission is described in terms of wavelength.

Wavelengths for optical fiber are measured in nanometers (nm).For LANs, 850 nm light is used almost exclusively.

5.16: Wavelength

5.17: LAN versus Carrier Fiber

Characteristic

LAN Fiber

Carrier WAN FiberRequired Distance Span200 to 300 m1 to 40 m

Light Wavelength

850 nm

1,310 or 1,550 nm

Type of Fiber

Multimode (Thick Core)

Single-Mode (Thin Core)

Core Diameter

50 or 62.5 microns

8.3 microns

5.17: LAN versus Carrier Fiber

Characteristic

LAN Fiber

Carrier WAN FiberPrimary Distance LimitationModal DispersionAbsorptive Attenuation

Quality Metric

Modal Bandwidth (MHz-km)

Not Applicable

5.18: Link Aggregation

5.19: Data Link Using Multiple Switches

The first physical link is 100BASE-TX,so the maximum physical span is 100 meters.Slide40

5.19: Data Link Using Multiple

SwitchesThe switch regenerates the received signal.On a 1000BASE-SX link, the clean new signalcan travel up to another 220 meters.Slide41

5.19: Data Link Using Multiple

Switches

5.19: Regeneration

Ethernet

5.20: The Ethernet Frame

5.21: Hexadecimal Notation

4 Bits

Decimal(Base 10)Hexadecimal(Base 16)

0000

0 hex

0001

1 hex

0010

2 hex

0011

3 hex

0100

4 hex

0101

5 hex

0110

6 hex

0111

7 hex

What is 0101 in hex?

What is 0000 in hex?

5.21: Hexadecimal Notation

What is 1001 in hex?

What is 1111 in hex?4 Bits*Decimal(Base 10)

Hexadecimal

(Base 16)

1000

8 hex

1001

9 hex

1010

A hex

1011

B hex

1100

C hex

1101

D hex

1110

E hex

1111

F hex

Converting a 48-bit MAC address to hexWrite down the 48-bit address in 12 four-bit nibbles.

Represent each nibble as a hex symbol.Pair the hex symbols and put a dash between the 6 pairs.Try these four nibbles: 0000111101011010

5.20: The Ethernet Frame

50Slide51

5.20: The Ethernet Frame

5.22:

Multiswitch Ethernet LANA packet from A1… to E5… must pass through Switches 1, 2, and 3.Slide55

5.22:

Multiswitch Ethernet LAN

Switch 1 sees that it should send the frame to E5 out Port 5.Slide56

5.22:

Multiswitch Ethernet LAN

Switch 2 sees that it should send the frame to E5 out Port 7.Slide57

5.22:

Multiswitch Ethernet LAN

Switch 3 sees that it should send the frame to E5 out Port 6.Slide58

5-23: Hierarchical LAN

5.24: Single Points of Failure

5.25: Rapid Spanning Tree Protocol

Loops are not allowed in Ethernet.

5.26: Rapid Spanning Tree Protocol

5.27: Virtual LANs (VLANs)

Tag Control Information (TCI) FieldThere are 12 bits for VLAN addresses.

There are 3 bits for frame priority.This permits 23 = 8 different priority values.

5.29: Managed Switches

Ethernet

Power over Ethernet (POE)Switches can supply power to devices via UTP.

(Wired telephone systems and USB ports already do this.)Less expensive thansupplying power

separately.

Latest POE StandardProvides up to 25 Watts to attached devices

Sufficient for most wireless access pointsSufficient for VoIP phonesSufficient for surveillance camerasSufficient for tablets

Not sufficient for desktop or notebook PCs

The Future

Nonstandard products now supply 60 Watts of power.

May become a future standard.

Still will not be enough for desktop or notebook PCs.POE switchesNew switches can be purchased with POE.Companies can also add POE equipment to an existing non-POE switch.685.30: Power over Ethernet (POE)

The Problem

Anyone can enter the building and plug their computer into a switch or into a wall RJ-45 port, which connects to a switch.

This usually gives the attacker access to the network without going through a firewall.

Solution: access control at switch ports.802.1X Port Based Access Control can do this.Created by the 802.1 WG, not the 802.3 WG.802.1 WG creates general standards, such as security standards.69

5.31: Ethernet 802.1X Security

Advantages of a Central Authentication Server

Consistency: Attacker cannot find a misconfigured switch.

Rapid changes: When someone leaves, is hired, or needs credential changes.

802.3ba governs Ethernet for both 40 Gbps and 100 GbpsVirtual LaneEntire 40 Gbps or 100 Gbps

Media LanePhysical connectionThere may be several per virtual laneEssentially, built-in bonding

73802.3baBoxSlide74

Example: 100GBASE-SR10100 Gbps virtual lane

S = 850 nm lightR = How bits are processed10 = 10 Gbps media lane

Media Lanes10 Mbps optical fiber pairs2 extra pairs