Chapter 7 networks

Question 1

What is a WAN

Answer 1

wide area network, connecting LANs

Question 2

How do LANs and WANs differ?

Answer 2

Layers 1 & 2 of the OSI model, access methods, topologies & media

Question 3

How do WANs transmit data?

Answer 3

public communication networks vs LANs that are internal and owned by a company

Question 4

What is a NSP

Answer 4

network service provider

Question 5

How do organizations get dedicated lines?

Answer 5

they lease dedicated lines

Question 6

How do dedicated lines differ?

Answer 6

capacity and transmission characteristics differ

Question 7

What is a WAN link?

Answer 7

how WANS are interconnected.

Question 8

How is a LAN topology different from a WAN topology?

Answer 8

same patterns, longer distances.

Question 9

BUS topology

Answer 9

on a line, if one fails the remainder fail, does not grow (scale) well

Question 10

Ring topology

Answer 10

in a ring, if one fails the direction of data travel can be reversed, only practical for 4-5 sites

Question 11

Star topology

Answer 11

Single site is the central connection point, if a site fails only that site loses connectivity, shorter data paths

Question 12

drawback of Star

Answer 12

if the central site is overwhelmed with data, the whole system will fail

Question 13

Mesh topology

Answer 13

interconnected, no site will bring down the whole system. Very expensive

Question 14

Partial mesh

Answer 14

the most important places are interconnected, and the lower level places have a star topology

Question 15

Tiered topology

Answer 15

most flexible, easy to expand, hierarchical

Question 16

PSTN?

Answer 16

Public Switched Telephone network. Sometimes POTS plain old telephone service

Question 17

What is dial-up?

Answer 17

using the telephone lines, fixed connection time

Question 18

What kind of line does dial-up use>

Answer 18

PSTN Public switched telephone.

Question 19

Why is a modem usually necessary in dial up?

Answer 19

Because PSTN is analog and the modem switches signals to digital

Question 20

What is PON

Answer 20

passive optical network

Question 21

what is FTTP

Answer 21

Fiber to premises

Question 22

What is FTTH

Answer 22

Fiber to home

Question 23

What is OLT

Answer 23

Optical line terminal that splits a signal into 32 channels

Question 24

Where does a fiber optic network end?

Answer 24

ONU optical network unit

Question 25

What is ISDN?

Answer 25

Integrated Services Digital Network that transmits over PSTN , used to connect data and voice signals 1992

Question 26

On which layers does ISDN work?

Answer 26

physical, data link, and transport layers

Question 27

How is ISDN unique?

Answer 27

can carry two voice calls and one data line at one time, does not covert to analog

Question 28

What are BRI & PRI?

Answer 28

the two types of ISDN available in N. America. Basic Rate Interface & Primary Rate Interface

Question 29

What does BRI have?

Answer 29

two B channels and one D channel 2B+D

Question 30

How much throughput does BRI Have?

Answer 30

Two 64 Kbps channels combine to make 128Kbps and 16-64 on the D channel

Question 31

How is PRI better than BRI?

Answer 31

23 B channels, 64 Kbps D channel 23B+D = ma of 1.544 Mbps

Question 32

What is T carrier technology?

Answer 32

for high data transmission

Question 33

what is a T1 channel?

Answer 33

each circuit has 24 channels, each with 64 Kbps, so one T1 Channel has 1.544 Mbps speed

Question 34

Why is shielded cable preferable for T1 lines?

Answer 34

the signal is digital, so the less interference the better

Question 35

Why is fiber optic cable preferred.

Answer 35

b/c coper wires need repeaters every 6000 feet

Question 36

What is a smart jack?

Answer 36

the end point for a t1 line with lights to show connectivity

Question 37

What is CSU

Answer 37

channel service unit

Question 38

what is DSU

Answer 38

data service unit

Question 39

What does a CSU/DSU do?

Answer 39

terminates the digital signal, ensures connection integrity and converts the t-frames to frames the LAN understands

Question 40

What does a DSU also have?

Answer 40

a multiplexer

Question 41

what is terminal equipment?

Answer 41

equipment that is at the end of a T1 connection, usually router or layer 3 higher

Question 42

What is DSL

Answer 42

Digital subscriber line

Question 43

How does DSL use current cables?

Answer 43

goes over the telephone wires at a different frequency

Question 44

What layer does DSL work at?

Answer 44

Physical layer

Question 45

How many types of DSL are there

Answer 45

8

Question 46

What is downstream/upstream

Answer 46

down loading to customer and uploading to service provider

Question 47

What is asymmetrical DSL

Answer 47

you have more download power than upload power

Question 48

What is different about HDSL and SDSL

Answer 48

they don't use the telephone line, but use a wire that is inside the telephone wire (not typically used part of the same wire)

Question 49

What is broadband cable?

Answer 49

Cable TV companies who use their coaxial cable lines for internet service

Question 50

on what layer do cable modems operate?

Answer 50

the physical and data link layer

Question 51

What must cable companies have upgraded to be able to offer this service?

Answer 51

HFC hybrid-fiber-coax cables to allow uploading not just downloading

Question 52

What is the head end?

Answer 52

the cable companies central office, which then connects to the internet

Question 53

What is BPL?

Answer 53

Broadband over power line.

Question 54

Why was BPL not well used?

Answer 54

too much interference, interfered with radio signals, more repeaters needed

Question 55

What is ATM?

Answer 55

Asynchronous transfer mode

Question 56

On what layer does ATM Work?

Answer 56

the data link layer, packet size is fixed 53 byte, so network performance is predictable.

Question 57

What is SONET

Answer 57

synchronous optical network

Question 58

What are the 4 benefits of SONET?

Answer 58

1. integrates with other WAN technology, 2. fast data transfers, 3. uses time.clock for transmissions, 4. high fault tollerance

Question 59

What is SONET known as in other countries?

Answer 59

SDH Synchronous Digital Hierarchy

Question 60

How does SONETS double ring topology help

Answer 60

Self-Healing: if one ring goes down, it automatically switches to the other ring.

Question 61

How is the data rate of SONET shown

Answer 61

OC optical carrier level