1. ethernet
Chapter 4

2. objectives Upon completion of this chapter, you should be able to:
Describe how data accesses the media on Ethernet
Select the correct network device for an Ethernet network
Connect the proper media for an Ethernet network
Select the correct cable type for connecting devices
Troubleshoot & resolve network connectivity

3. 4.1
ethernet

4. 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 can use copper twisted pair or fiber cabling.

5. Ethernet access method
Data on Ethernet networks shares the cable
How can all devices communicate on this shared media?

6. 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
Deterministic takes turns. Non-deterministic does not take turns.

7. Csma/cd on ethernet networks
Listens for silence
Silence= transmit data
If devices transmit at same time, collision
They send a jam signal
Backoff random time, listen for silence, retransmit
Collisions not a problem much anymore
Using switches & full-duplex, this is not a problem anymore
This is like using walkie-talkies. If no one is talking, you press the button to speak.
Collisions are a naturally occurring event. Your goal is to keep collisions to a minimum. To do that you have to keep network segments small and use a switch.

8. Current switched network
1st picture: NO COLLISIONS
2nd picture: SOME COLLISIONS because of the hub

9. duplexing Hubs Switch Send data out all ports
Are dumb & can’t handle in/out
HALF DUPLEX ONLY
Switch
Intelligent
FULL DUPLEX
Sends & receives at the same time

10. Frame size Min. frame size is 64 bytes; max is 1518 bytes
Data is bytes
> 64 bytes is considered a collision fragment & will be dropped
Note there are different types/speeds of Ethernet. The frame structure for each is nearly identical.
Ethernet II is used in TCP/IP networks.
Padding can be added to make sure the data part is at least 46 bytes.
PREAMBLE- used timing/synchronization of the frame between send & receiver. Basically saying., “Here comes a frame!”
FCS or CRC- must match on destination NIC to show it received a complete frame

11. activity
TestOut 4.1
4.1.1
Fact Sheet
Quiz (4Q)

12. 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

13. Ethernet specifications
4.2
Ethernet specifications

14. 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
Cx= using STP cable

15. Ethernet standards for fiber
L= LONG; S= SHORT; Ex= EXTENDED REACH
L & Ex are Single Mode (long distance)
S is Multimode (shorter distance)
Over 2000m, you must use single mode cable.
W= compatible with SONET

16. Other ethernet standards
SONET
Uses fiber to multiplex signals over a cable over MUCH longer distances for a WAN
Ethernet over HDMI
Data shared over an Ethernet Channel (HEC) without using extra cables
Ethernet over Power Line
Sends data over AC lines on different frequency
Use instead of running cable
PoE requires Cat5 or better and devices that support it.

17. activity Review 4.2.2 Fact Sheet
Lab Reconnect to an Ethernet Network
4.2.4 Quiz (15 questions)

18. 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)

19. Connecting network devices
4.3
Connecting network devices

20. Which cable? Choose the correct cable:
Crossover cable used to connect two switches/hubs using a regular port.
Rollover & terminal emulation software.
Auto MDI or MDIX means it will autosense & use whichever cable you plug in.

21. 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
Show the hub with uplink port switch.
Uplink to uplink port needs a crossover cable. Proper hookup would be uplink to regular port using a straight through cable.

22. activity
Lab Connect Network Devices
4.3.4 Quiz (10 Questions)

23. 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

24. Troubleshooting physical connectivity
4.4
Troubleshooting physical connectivity

25. 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- even if nothing is being transmitted, a heartbeat signal is sent periodically.

26. activity Watch 4.4.1- Troubleshooting the Fault Domain
Lab Exploring Physical Connectivity
Lab Troubleshoot Physical Connectivity 1
Lab Troubleshoot Physical Connectivity 2
Lab Troubleshoot Physical Connectivity 3
Lab Troubleshoot Physical Connectivity 4
Quiz (15 questions)

27. 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

28. ethernet
Chapter 4