Wired Ethernet LANs Chapter 5 Ethernet Basics Physical

Wired Ethernet LANs Chapter 5

Ethernet Basics Physical Layer Ethernet Standards Data Link Layer Ethernet Standards Ethernet Security ©

Where We’ve Been 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 ◦ Chapter 3: Security principles ◦ Chapter 4: Network management © 2013 Pearson 3

Where We Are Going Three Chapters on Local Area Networks ◦ Chapter 5: Wired Ethernet LANs ◦ Chapters 6 and 7: Wireless LANs ◦ Governed by Layer 1 and Layer 2 Standards Remaining Chapters ◦ Chapters 8 and 9: TCP/IP Internetworking ◦ Chapter 10: Wide Area Networks ◦ Chapter 11: Applications © 2013 Pearson 4

5. 1: LANs versus WANs Characteristic Location Consequence of Location © 2013 Pearson Local Area Network (LAN) Located entirely on customer’s premises Wide Area Network (WAN) Must carry transmissions beyond customer’s premises Owning User must contract company with a carrier that operates the LAN has rights of way to carry wires between premises 5

5. 1: LANs versus WANs Characteristic Technology and Service Consequence of Corporate versus Carrier Ownership © 2013 Pearson Local Area Network (LAN) Owner can use any technology and service options it wishes Wide Area Network (WAN) Customer is limited to technologies and service options offered by available carriers 6

5. 1: LANs versus WANs Characteristic Local Area Network (LAN) Labor Owner must do Consequences all operation and of Corporate maintenance versus Carrier work Ownership © 2013 Pearson Wide Area Network (WAN) Operational and maintenance work is done by the carrier 7

5. 1: LANs versus WANs Characteristic Economics © 2013 Pearson Local Area Network (LAN) Transmission distances are short, so the cost per bit carried is low Wide Area Network (WAN) Transmission distances are long, so the cost per bit carried is high 8

5. 1: LANs versus WANs Characteristic Local Area Network (LAN) Wide Area Network (WAN) Speed Very high speeds Customers are Consequences are affordable content with lower of Economics speeds Design Optimization of Consequences transmission of Economics capacity is not pressing © 2013 Pearson Optimization of transmission capacity is critical 9

5. 2: Workgroup and Core Switches Workgroup Switches Connect Hosts to the Network ©

5. 2: Workgroup and Core Switches Connect Switches to Other Switches © 2013 Pearson

5. 2: Workgroup and Core Switches Hosts Normally Connect to Workgroup Switches Through UTP

5. 2: Workgroup and Core Switches Often Connect to Other Switches Through Optical Fiber

5. 3 Ethernet Workgroup Switch © 2013 Pearson 14

5. 4: UTP and Optical Fiber Characteristic Unshielded Twisted Pair Optical Fiber Medium Copper wire Glass Signal Electrical Light Maximum Usually 100 Distance in LANs meters Usually 200 to 500 meters Speed Similar Cost Lower Higher © 2013 Pearson 15

5. 5: Ethernet Standards Development © 2013 Pearson 16

5. 5: Ethernet Standards Development © 2013 Pearson 17

5. 6: Binary and Digital © 2013 Pearson 19

5. 6: Binary and Digital © 2013 Pearson 20

5. 7: Binary Resistance to Error © 2013 Pearson 21

5. 7: Binary Resistance to Error © 2013 Pearson 22

5. 9: RJ-45 Connector and Jack © 2013 Pearson 24

5. 10: Serial versus Parallel Transmission NOT just 4 pairs! 25 © 2013 Pearson

5. 11: Propagation Effects Propagation Effect(s) Impact Installation Discipline Attenuation Signal may become too low to be received properly. Limit cord distance to 100 m Noise Random electromagnet energy in the wire (noise) adds to the signal and may produce errors. Terminal crosstalk interference Interference by other wire pairs Limit untwisting of in the cord is crosstalk the wires to interference. 1. 25 cm (0. 5 in) Crosstalk interference at the two ends where the wires are untwisted is terminal crosstalk interference. Major problem © 2013 Pearson 26

5. 12: Internet Signaling Standards and UTP Quality Levels Ethernet Signaling Standard Transmission Speed UTP Quality Category Maximum Cord Length 100 BASE-TX 100 Mbps Category 5 e, 6, or higher 100 meters 1000 BASE-T 1 Gbps Category 5 e, 6, or higher 100 meters 10 GBASE-T 10 Gbps Category 6 55 meters 10 GBASE-T 10 Gbps Category 6 A 100 meters Category is a measure of UTP QUALITY © 2013 Pearson 27

5. 13: Optical Fiber Transmission © 2013 Pearson 28

5. 13: Optical Fiber Transmission © 2013 Pearson 29

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. © 2013 Pearson 30

5. 14: Optical Fiber Cord and Connections © 2013 Pearson 31

5. 15: Modal Bandwidth Wavelength Core Diameter 850 nm 62. 5 microns 160 MHz-km 220 m 850 nm 62. 5 microns 200 MHz-km 270 m 850 nm 50 microns © 2013 Pearson Modal Bandwidth Maximum Propagation Distance 500 MHz-km 500 m 32

Medium Quality UTP Optical Fiber UTP wire quality is indicated by a cord’s category

5. 16: 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. © 2013 Pearson 35

5. 17: LAN versus Carrier Fiber Characteristic LAN Fiber Carrier WAN Fiber Required Distance Span 200 to 300 m 1 to 40 m Light Wavelength 850 nm 1, 310 or 1, 550 nm Type of Fiber Multimode (Thick Single-Mode Core) (Thin Core) Core Diameter 50 or 62. 5 microns © 2013 Pearson 8. 3 microns 36

5. 17: LAN versus Carrier Fiber Characteristic LAN Fiber Carrier WAN Fiber Primary Distance Modal Dispersion Absorptive Limitation Attenuation Quality Metric © 2013 Pearson Modal Bandwidth Not Applicable (MHz-km) 37

5. 18: Link Aggregation © 2013 Pearson 38

5. 19: Data Link Using Multiple Switches The first physical link is 100 BASE-TX,

5. 19: Data Link Using Multiple Switches The switch regenerates the received signal. On

5. 19: Data Link Using Multiple Switches The second switch also regenerates the signal.

5. 20: The Ethernet Frame © 2013 Pearson 44

5. 20: The Ethernet Frame © 2013 Pearson 45

5. 21: Hexadecimal Notation 4 Bits 0000 0001 0010 0011 0100 0101 0110 0111 Decimal (Base 10) 0 1 2 3 4 5 6 7 Hexadecimal (Base 16) 0 hex 1 hex 2 hex 3 hex 4 hex 5 hex 6 hex 7 hex What is 0101 in hex? What is 0000 in hex? © 2013 Pearson 46

5. 21: Hexadecimal Notation 4 Bits* 1000 1001 1010 1011 1100 1101 1110 Decimal (Base 10) 8 9 10 11 12 13 14 Hexadecimal (Base 16) 8 hex 9 hex A hex B hex C hex D hex E hex 1111 15 F hex © 2013 Pearson What is 1001 in hex? What is 1111 in hex? 47

5. 21: Hexadecimal Notation Converting a 48 -bit MAC address to hex ◦ Write 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: 00001111010 © 2013 Pearson 48

5. 20: The Ethernet Frame © 2013 Pearson 49

5. 20: The Ethernet Frame © 2013 Pearson 50

5. 20: The Ethernet Frame © 2013 Pearson 51

5. 20: The Ethernet Frame © 2013 Pearson 52

5. 20: The Ethernet Frame © 2013 Pearson 53

5. 22: Multiswitch Ethernet LAN A packet from A 1… to E 5… must

Switch 1 sees that it should send the frame to E 5 out Port

Switch 2 sees that it should send the frame to E 5 out Port

5. 22: Multiswitch Ethernet LAN Switch 3 sees that it should send the frame

5 -23: Hierarchical LAN © 2013 Pearson 58

5. 24: Single Points of Failure © 2013 Pearson 59

5. 25: Rapid Spanning Tree Protocol Loops are not allowed in Ethernet. A strict

5. 26: Rapid Spanning Tree Protocol © 2013 Pearson 61

5. 27: Virtual LANs (VLANs) © 2013 Pearson 62

5. 28: Priority and Overprovisioning Tag Control Information (TCI) Field ◦ There are 12 bits for VLAN addresses. ◦ There are 3 bits for frame priority. ◦ This permits 23 = 8 different priority values. © 2013 Pearson 63

5. 29: Managed Switches © 2013 Pearson 64

5. 30: Power over Ethernet (POE) ◦ Switches can supply power to devices via UTP. ◦ (Wired telephone systems and USB ports already do this. ) ◦ Less expensive than supplying power separately. © 2013 Pearson 66

5. 30: Power over Ethernet (POE) Latest POE Standard ◦ Provides up to 25 Watts to attached devices ◦ Sufficient for most wireless access points ◦ Sufficient for Vo. IP phones ◦ Sufficient for surveillance cameras ◦ Sufficient for tablets Not sufficient for desktop or notebook PCs © 2013 Pearson 67

5. 30: Power over Ethernet (POE) � 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 switches ◦ New switches can be purchased with POE. ◦ Companies can also add POE equipment to an existing non-POE switch. © 2013 Pearson 68

5. 31: Ethernet 802. 1 X Security � 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. 1 X 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. © 2013 Pearson 69

5. 31: Ethernet 802. 1 X Security © 2013 Pearson 70

5. 31: Ethernet 802. 1 X Security © 2013 Pearson 71

5. 21: Ethernet 802. 1 X Security � Advantages Server of a Central Authentication ◦ Consistency: Attacker cannot find a misconfigured switch. ◦ Rapid changes: When someone leaves, is hired, or needs credential changes. ◦ Switch cost: Authentication server does heavy work. ◦ Reduced management cost: Only one authentication database to maintain. © 2013 Pearson 72

802. 3 ba Box 802. 3 ba governs Ethernet for both 40 Gbps and 100 Gbps Virtual Lane ◦ Entire 40 Gbps or 100 Gbps Media Lane ◦ Physical connection ◦ There may be several per virtual lane ◦ Essentially, built-in bonding © 2013 Pearson 73

802. 3 ba Example: 100 GBASE-SR 10 ◦ ◦ Box 100 Gbps virtual lane S = 850 nm light R = How bits are processed 10 = 10 Gbps media lane Media Lanes ◦ 10 Mbps optical fiber pairs ◦ 2 extra pairs ◦ 24 optical fiber strands in total © 2013 Pearson 74