ETHERNETChapter 4

OBJECTIVES Upon completion of this chapter, you

should be able to:Describe how data accesses the media on

EthernetSelect the correct network device for an

Ethernet networkConnect the proper media for an Ethernet

networkSelect the correct cable type for connecting

devicesTroubleshoot & resolve network connectivity

ETHERNET

4.1

TOPOLOGY What was the old, original Ethernet

physical topology? Bus

What is the current Ethernet physical topology? Star or Extended Star

What is the logical topology for current Ethernet using a hub? Bus/broadcast (sent to all on segment)

What is the logical topology for current Ethernet using a switch? Star (sent only to destination device)

ETHERNET ACCESS METHOD Data on Ethernet networks shares the

cable

How can all devices communicate on this shared media?

CSMA Ethernet is contention-based/non-deterministic

Data contends or shares for a spot on the media Doesn’t know when it’ll get access to it

Listens for signal on media No signal = transmit data Transmit at same time= collision

Devices do not keep track of whose turn it is

More collisions= less throughput SOLUTION: CSMA/CD

CSMA/CD ON ETHERNET NETWORKS Listens for silence

Silence= transmit data

If devices transmit at same time, collisionThey send a jam signalBackoff random time, listen for silence,

retransmit

Collisions not a problem much anymoreUsing switches & full-duplex, this is not a

problem anymore

CURRENT SWITCHED NETWORK

DUPLEXING Hubs

Send data out all portsAre dumb & can’t handle in/outHALF DUPLEX ONLY

Switch IntelligentFULL DUPLEXSends & receives at the same time

FRAME SIZE Min. frame size is 64 bytes; max is 1518

bytesData is 46-1500 bytes

> 64 bytes is considered a collision fragment & will be dropped

ACTIVITY TestOut 4.1

4.1.14.1.2- Fact Sheet4.1.3- Quiz (4Q)

REVIEW- 4Q What important addresses are

encapsulated into a frame?Source & destination MAC

What does the preamble used for?Timing/synchronization

What is the minimum frame size?64 bytes

What happens if a frame is less than 64 bytes?Considered a fragment & dropped

ETHERNET SPECIFICATIONS

4.2

ETHERNET STANDARDS FOR COPPER

Speed; Baseband; Twisted Pair 100Base-T Fast Ethernet (Cat 5 or

higher) 1000Base-T (Cat 5e or higher) 1000Base-TX (Cat 6 or higher) 100m max; Cat 6 less than 100m; Cat6a

100m

ETHERNET STANDARDS FOR FIBER L= LONG; S= SHORT; Ex= EXTENDED

REACHL & Ex are Single Mode (long distance)S is Multimode (shorter distance)

OTHER ETHERNET STANDARDS SONET

Uses fiber to multiplex signals over a cable over MUCH longer distances for a WAN

Ethernet over HDMIData shared over an Ethernet Channel

(HEC) without using extra cables

Ethernet over Power LineSends data over AC lines on different

frequencyUse instead of running cable

ACTIVITY Review 4.2.2 Fact Sheet

Lab 4.2.3 Reconnect to an Ethernet Network

4.2.4 Quiz (15 questions)

REVIEW- 3Q If a fiber cable has an L or Ex, which

type of fiber cable is it?Single mode

1000Base-Tx is what category of Ethernet?Cat 6

You need to use PoE to some switches. Which of these Ethernet standards will work; 100Base-Fx, 1000Base-T, 10GBase-LR, 1000Base-Lx?1000Base-T (all the others are fiber)

CONNECTING NETWORK DEVICES

4.3

WHICH CABLE? Choose the correct cable:

UPLINK PORT Uplink Port (Internet Port)

Allows you to connect one device to another, like switch to switch or hub to hub for when you run out of ports

Uplink port on switch 1 to regular port on other switch using a straight through cable

ACTIVITY Lab 4.3.3 Connect Network Devices

4.3.4 Quiz (10 Questions)

REVIEW- 3Q What happens when the CSMA/CD

network detects a collision?Signals a collision, waits to check for

silence, retransmits The data part of an Ethernet frame is 36

bytes. What needs to be added to the frame and how many bytes will the data need to be?Padding; 46 bytes

A port on a switch is labeled Auto-MDIX. What does that mean? It will autosense the cable

TROUBLESHOOTING PHYSICAL CONNECTIVITY

4.4

TROUBLESHOOTING THE LINK STATUS Usually 2 lights on NIC/port

Link Green- getting full 1Gbps Orange- only getting 100Mbps Red- possibly using wrong cable None- no connection

Activity Flashing- data being sent/received

Speed

ACTIVITY Watch 4.4.1- Troubleshooting the Fault Domain

Lab 4.4.5- Exploring Physical Connectivity

Lab 4.4.6- Troubleshoot Physical Connectivity 1

Lab 4.4.7- Troubleshoot Physical Connectivity 2

Lab 4.4.8- Troubleshoot Physical Connectivity 3

Lab 4.4.9- Troubleshoot Physical Connectivity 4

4.4.10 Quiz (15 questions)

REVIEW- 3Q If you connect a cable from a switch’s

uplink to port 1 on another switch, which cable should you use?Straight through

What does it mean if the NIC’s activity light is flashing?Data is being sent/received

If you need to connect a laptop to a router to configure it, what do you need?Rollover/console cable & terminal emulation

software

ETHERNETChapter 4