Fundamentals of Ethernet LAN Flashcards Preview

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Flashcards in Fundamentals of Ethernet LAN Deck (51)
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1

Ethernet

Family of LAN standards with standard names that begin with 802.3 that together define the physical and data-link layers of the world’s most popular WIRED LAN technology

2

Wireless LANs

Defined by the IEEE using standards that begin with 802.11, use radio waves to send the bits from one node to the next

3

Unshielded Twisted Pair (UTP)

Transmits data over electrical circuits via the copper wires inside the cable.
Suffix includes T (Twisted pairs)
Up to 100 meters

4

Fiber-optic

Sends light over glass fibers in the center of the cable.
Although more expensive, optical cables typically allow longer cabling distances between nodes.
Suffix includes X

5

Ethernet header and trailer

Bytes of overhead data that Ethernet uses to do its job of sending data over a LAN, with the same format no matter the speed or the medium

6

Ethernet Frame

Refers to the header and trailer of a data-link protocol, plus the data encapsulated inside that header and trailer

7

10BASE-T

Standard Ethernet 10Mbps
2 pairs of wires

8

100BASE-T

Fast Ethernet (FE) 100Mbps
2 pairs of wires

9

1000BASE-T

Gigabit Ethernet (GE)
1000Mbps
4 pairs of wires

10

Electro Magnetic Interference (EMI)

When electrical current passes over any wire, it creates electromagnetic interference that interferes with the electrical signals in nearby wires, including the wires in the same cable.

11

Crosstalk

Electro Magnetic Interference (EMI) between wire pairs in the same cable

12

Ethernet link

Any physical cable between two Ethernet nodes

13

Network Interface Card (NIC)

Standard name for PC network Card

14

Gigabit Ethernet Interface Converter (GBIC)

The original form factor for a removable transceiver for Gigabit interfaces

15

Small Form Pluggable (SFP)

The replacement for GBICs, used on Gigabit interfaces, with a smaller size, taking less space on the side of the networking card or switch

16

Small Form Pluggable Plus (SFP+)

Same size as the SFP, but used on 10-Gbps interfaces.

17

10BASE-T and 100BASE-T Straight-Through Cable Pinout

For transmission, pin 1 and 2 on one end of the cable to pin 1 and 2 at the other end of the cable
For receiving, pin 3 and 6 on one end of the cable to pin 3 and 6 at the other end of the cable

18

10BASE-T and 100BASE-T Crossover Cable Pinout

Pin 1 and 2 on one end of the cable to pin 3 and 6 at the other end of the cable, and viceversa

19

Straight-through vs Crossover cable

Straight-through cable, if the endpoints transmit on different pin pairs
Crossover cable, if the endpoints transmit on the same pin pairs

20

Devices which transmit on Pins 1,2

PC NICs
Routers
Wireless access point (Ethernet interface)

21

Devices which transmit on Pins 3,6

Hubs
Switches

22

Auto mdix

Cisco switches feature that notices when the wrong cable is used and automatically changes its logic to make the link work

23

1000BASE-T Cable Pinout

1,2 > 3,6
4,5 > 7,8

24

Multimode fiber

The cable allows for multiple angles (modes) of light waves emitted by a LED trasmitter entering the core

25

Single mode fiber

To transmit light into a much smaller core, a laser-based transmitter sends light at a single angle (hence the name single-mode)
Smaller-diameter core, around one-fifth the diameter of common multimode cables

26

Fiber transmission between devices

Two cables, one for each direction, like having two electrical circuits with the original UTP Ethernet standards.
Transmit port on one device connects to a cable that connects to a receive port on the other device, and vice versa with the other cable

27

Comparisons Between UTP, MM, and SM

Relative Cost of Cabling Low > Medium > Medium
Relative Cost of a Switch Port Low > Medium > High
Approximate Max Distance 100m > 500m > 40km
Relative Susceptibility to Interference Some > None > None
Relative Risk of Copying from Cable Emissions Some > None > None

28

Ethernet Frame Format

Header
Preamble (7)
SFD (1)
Destination (6)
Source (6)
Type (2)

Data and Pad (46-1500)

Trailer
FCS (4)

29

Ethernet Frame Header - Preamble

Synchronization (7 bytes)

30

Ethernet Frame Header - Start Frame Delimiter (SFD)

Signifies that the next byte begins the Destination MAC Address field (1 byte)