Ethernet LAN Fundamentals

Question 1

Ethernet LANs use….

Answer 1

cables and defines wired LAN technology only

Question 2

These devices work to create LAN itself

Answer 2

LAN switch and Wireless access point

Question 3

This device connects LANs and WANs

Answer 3

Router

Question 4

Char. of 10 Mbps Ethernet

Answer 4

10BASE-T; 802.3; Copper, 100m

Question 5

Char. of 100 Mbps Ethernet

Answer 5

aka Fast Ethernet; 802.3u; Copper 100m

Question 6

Char. of 1000 Mbps Ehternet

Answer 6

aka Gigabit Ethernet; 1000BASE-LX (fiber); 802.3z, 5000 m
1000BASE-T; 802.3ab; Copper, 100m
Both requires four pairs of wires

Question 7

Char. of 10Gbps Ethernet

Answer 7

aka 10 Gig Ethernet; 802.3an; Copper 100m

Question 8

Thing that remains constant over all links using Ethernet DLL

Answer 8

the DLL header and trailer format

Question 9

Ethernet frame…

Answer 9

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

Question 10

Essential definition of Ethernet LAN

Answer 10

a combination of user devices, LAN switches, and different forms of cabling

Question 11

Ethernet Link

Answer 11

refers to any physical cable between two Ethernet nodes

Question 12

Pinout rules

Answer 12

Ethernet NIC transmitters use pins 1 and 2; the NIC receivers use pins 3 and 6; same goes for hubs (orange and green pairs are used)

Question 13

Crossover-cable pinout….

Answer 13

connects two-like devices to an Ethernet link, they both transmit on over the same pairs

Question 14

Transmits on pins 1, 2

Answer 14

PC NICs, routers, wireless access point

Question 15

Transmits on pins 3, 6

Answer 15

hubs, switches

Question 16

Preamble (DLL header)

Answer 16

Synchronization

Question 17

start frame delimiter (SFD)

Answer 17

signals that the next byte begins the Destination MAC address field

Question 18

Type

Answer 18

Defines protocol listed inside the frame; most likely IPv4 or IPv6

Question 19

Organizationally unique identifier (OUI)

Answer 19

IEEE assigns the manufacturer that sells Ethernet products a universally unique 3-byte code (24-bit, 6 hex digit)

Question 20

Types of group addresses

Answer 20

Broadcast: delivers frames to all devices on Ethernet LAN
Multicast: towards certain address within Ethernet LAN

Question 21

Frame Check Sequence

Answer 21

only field in the Ethernet trailer; gives receiving node a way to compare results with the sender, to discover whether errors occurred in the frame; error detection

Question 22

Hubs forward data using…

Answer 22

physical layer standards, are considered Layer 1 devices; repeats any signal it receives to all ports except the incoming port

Question 23

Switches are Layer 2 devices because…

Answer 23

It looks at the data link layer header and trailer and refers to its MAC address table and then use store and forward switching

Question 24

If a collision occurs:

Answer 24

1. All sending nodes send a backoff algorithm indicating a jamming signal to all nodes
2. they independently choose a random time to wait before trying again to avoid unfortunate timing
3. Starts listening to frames again when done.