chapter6

Question 1

why are switches preferred

Answer 1

they limit the collision domain

Question 2

ethernet

Answer 2

standard LAN implementation. IEEE 802.3 specifies standards for physical and data link layers

Question 3

CSMA/CD protocol

Answer 3

• carrier sense multiple access/collison detect. PREVENTS COLLISONS
  1) perform carrier sense
  2) wait a little longer
  3) if wait is interrupted send a jam signal. jam signal causes all hosts to wait for random period of time
  4) host timeout if 15 collisions in a row

Question 4

carrier sense

Answer 4

listen to the wire and wait until the line is clear

Question 5

half-duplex

Answer 5

devices CANNOT send and recieve at same time. only about half of theoretical speed. ethernet coaxial is half-duplex

Question 6

full-duplex ethernet

Answer 6

send data in both direction over two pairs of wires. most ethernet cable support this, especially twisted pair. eliminates data collisons

Question 7

10BASE5

Answer 7

-thicknet, thick coaxial cable

OBSOLETE

Question 8

10BASE2

Answer 8

Thinnet, thinner cable, easier to connect bc of T adapter

Question 9

10BASE-T

Answer 9

most common for 10Mbps networks. star topology. uses twisted pair cabling

Question 10

baseband

Answer 10

transmit signal at single low frequency

Question 11

fast ethernet

Answer 11

100Mbps

Question 12

100BASE-TX

Answer 12

norm for fast ethernet. uses cat 5 cable but only uses 2 pairs.

Question 13

100BASE-FX

Answer 13

fiber optical cabling. supports much longer distances

Question 14

100BASE-SX

Answer 14

fiber optical cable, uses shorter wavelength but is much cheaper. tradeoff is less distance

Question 15

1000BASE-T

Answer 15

able to use cheaper cat5 cables. uses all four pairs.

Question 16

1000BASE-TX

Answer 16

has to use more expensive cat6 or cat7 cables.

Question 17

MAC address

Answer 17

used to route frames on the local level. contains info about device/vendor.

Question 18

data-link frame

Answer 18

contain data from network level, info about sender, reciever, and control

Question 19

logical link control (LLC)

Answer 19

header that contains extra info contained in the data frame

Question 20

MTU

Answer 20

maximum transmission unit. configure the data size in the frame. leave the same on network to avoid unneccesary segmentation

Question 21

channel attenuation

Answer 21

loss of signal strength over distance

Question 22

crosstalk

Answer 22

signal interference between close cables. twisting eliminates this effect.

Question 23

STP

Answer 23

shielded twisted pair. best for industrial applications, shields electromagetism better

Question 24

straight through cable

Answer 24

T568A at both ends. connect sending device to recieving device

Question 25

crossover cable

Answer 25

T568A and one end and T568B on another. connect similar devices

Question 26

rollover cable

Answer 26

invert pinnings (pin 1 becomes pin 8)

Question 27

CSMA/CD back-off algorithm

Answer 27

controls how much time to wait when frame collision occurs