Chapter 4 - Fundamentals Of Wans

Front 1

T/F: The division between LAN and WAN is often unclear.

Back 1

True

Front 2

What does MAN stand for?

Back 2

Metropolitan-Area Network

Front 3

What does the PTT in PTT company stand for?

Back 3

Public Telephone and Telegraph

Front 4

Since operators of a WAN cannot own all the cables connecting the network links, they use _______.

Back 4

leased lines

Front 5

A crossover cable connects one device's ______ pair to another device's ______ pair.

Back 5

Transmit, Receive

Front 6

A company that provides any form of WAN connectivity can generically be called a ________.

Back 6

service provider

Front 7

Why is it that, whenever you see a LAN connected to some other site using a WAN connection, you will see a router connected to each LAN?

Back 7

Unlike switches, routers can connect to non-Ethernet devices.

Front 8

CSU/DSU stands for?

Back 8

Channel Service Unit / Digital Service Unit

Front 9

The CSU/DSU forms the connection between ______.

Back 9

The customer's router and the telco's CO.

Front 10

CO stands for, and means what?

Back 10

Central Office, the building where the telco puts its equipment.

Front 11

T/F: The technologies used to transmit data beyond the Central Office are beyond the scope of the CCNA test.

Back 11

True

Front 12

T/F: Typically, the CSU/DSU is owned by the telco.

Back 12

False, typically it is owned by the client company.

Front 13

The term demarc refers to what?

Back 13

The point at which the telco's responsibility is one one side and the customer's responsibility is on the other.

Front 14

In the United States, the demarc is typically where?

Back 14

Where the telco physically terminates their (four-wire) cables inside the customer's building.

Front 15

CPE stands for what?

Back 15

Customer Premises Equipment

Front 16

What does CPE mean? (not what stands for)

Back 16

Devices that are at the customer site, from the telco's perspective.

Front 17

What are two common CPE devices?

Back 17

CSU/DSU and router

Front 18

If the telco owned the CSU/DSU, where would the demarc be?

Back 18

On the router side of the CSU/DSU.

Front 19

T/F: Regardless of where the demarc sits, the term CPE still refers to the equipment at the telco customer's location

Back 19

True

Front 20

The telco CO typically uses an _____ connector to connect to the CSU/DSU.

Back 20

RJ-48

Front 21

The RJ in RJ-11, RJ-45, and similar standards stands for?

Back 21

Registered Jack

Front 22

T/F: Many Cisco routers have an integrated CSU/DSU.

Back 22

True

Front 23

In the case of a router with integrated CSU/DSU, the line from the telco would typically be connected to a _____ port on the router's ______.

Back 23

RJ-48, serial interface card

Front 24

The CSU/DSU provides a _______ to the router so that it may send and receive at the correct rate.

Back 24

clocking signal

Front 25

Along with clock rate and bandwidth, what is another term relating to the speed of a WAN connection?

Back 25

link speed

Front 26

DCE stands for?

Back 26

data communications equipment

Front 27

DTE stands for?

Back 27

data terminal equipment

Front 28

What is the meaning of DCE? (not what it stands for)

Back 28

The device that provides clocking.

Front 29

What is the meaning of DTE? (not what it stands for)

Back 29

The device that receives clocking.

Front 30

T/F: It is possible for a router to clock a CSU/DSU and thus act as a DCE.

Back 30

True (but uncommon)

Front 31

Since using a router as a DCE is uncommon, what is the practical use of DCE cables?

Back 31

Setting up a back-to-back serial connection, an imitation WAN, in an educational setting to study WANs.

Front 32

The difference between a DCE and DTE cable is similar the difference between ______ and ______ cables.

Back 32

straght-through
AND
crossover

Front 33

Between DCE and DTE cables, which is much more commonly used in the real world?

Back 33

DTE

Front 34

What does PCM stand for?

Back 34

pulse code modulation

Front 35

The original standard for converting analog voice to a digital signal is called?

Back 35

PCM

Front 36

The term DS0 stands for?

Back 36

digital signal level 0

Front 37

DS0 operates at 64-kbps, why?

Back 37

Because that was the original data rate considered acceptable to transmit voice.

Front 38

Why were many data services offered over DS0 only 56kbps instead of 64kbps?

Back 38

1/8 of the bandwidth was reserved for network overhead.

Front 39

What is the definition of DS1? (not what it stands for)

Back 39

A single line that supports 24 DS0s and an 8-kbps overhead channel.

Front 40

DS1 and DS3 stand for?

Back 40

digital signal level 1 and digital signal level 3

Front 41

What signaling type does a T1 line use?

Back 41

DS1

Front 42

What signaling type does a E1 line use?

Back 42

ZM

Front 43

What bitrate does a T1 line operate at?

Back 43

1.544 Mbps (24 DS0s, plus 8 kbps overhead)

Front 44

What bitrate does an E1 line use?

Back 44

2.048 Mbps (32 DS0s)

Front 45

What does SONET stand for?

Back 45

Synchronous Optical Network

Front 46

The two most popular data-link protocols used on point-to-point links are?

Back 46

HDLC and PPP

Front 47

HDLC stands for?

Back 47

High-Level Data Link Control

Front 48

PPP stands for?

Back 48

Point-to-Point Protocol

Front 49

T/F: The address field in the HDLC frame is usually unnecessary.

Back 49

True

Front 50

Why does HDLC include an address field if it's not used?

Back 50

Because of multidrop circuits. (research this - multiple on your end or the telco's?)

Front 51

HDLC defined the address field to _________?

Back 51

To identify the diferent remote sites on a multidrop link.

Front 52

True/False: Unlike Ethernet, HDLC is unable to determine the type of packet inside a frame.

Back 52

False

Front 53

The version of HDLC used by Cisco is (universal / proprietary)

Back 53

proprietary

Front 54

PPP LCP stands for?

Back 54

PPP Link Control Protocol

Front 55

IPCP stands for?

Back 55

IP Control Protocol

Front 56

What is the purpose of IPCP?

Back 56

It allows for IP address assignment over a PPP link.

Front 57

PPP CP Stands for?

Back 57

PPP Control Protocol

Front 58

Each link that uses PPP has one ___ per link and one ____ per _____ protocol defined on the link.

Back 58

LCP, CP, Layer 3

Front 59

LCP focuses on features that apply (depending on / regardless of) the Layer 3 protocol used.

Back 59

regardless of

Front 60

PPP also defines several control protocols (CPs), which are used for any special purposes for a particular _____________.

Back 60

Layer 3 protocol

Front 61

LQM stands for?

Back 61

Link quality monitoring

Front 62

LQM is a function of _______, which is a component of the _________ protocol

Back 62

LCP, PPP

Front 63

The "magic number" features of LCP is used to detect ________.

Back 63

looped link

Front 64

Multilink PPP allows what?

Back 64

multiple parallel serial links to be connected between the same two routers

Front 65

PAP and CHAP are functions of ______, which is a component of the ________ protocol

Back 65

LCP, PPP

Front 66

The protocols used by PPP for authentication are?

Back 66

PAP and CHAP

Front 67

Recent WAN data-link protocols (expect a higher-layer protocol to perform error recovery / perform error recovery themselves by causing corrupted frames to be resent)

Back 67

expect a higher-layer protocol to perform error recovery

Front 68

The default data-link protocol over serial links used by Cisco?

Back 68

HDLC

Front 69

T/F: Cisco's implementation of LAPB and HDLC includes a proprietary Protocol Type field

Back 69

True

Front 70

HDLC and PPP are (synchronous / asynchronous)

Back 70

synchronous

Front 71

Define clock source

Back 71

The device to which other devices on the link adjust their speed when using synchronous links.

Front 72

What are the two most popular packet-switching services today?

Back 72

Frame Relay and ATM

Front 73

Frame Relay nentworks are multiaccess networks, meaning that?

Back 73

more than two devices can attach to the network

Front 74

DLCI stands for?

Back 74

Data-link connection identifier

Front 75

Where is DLCI located and what does it do?

Back 75

Located in a Frame Relay frame header, it tells where the frame is supposed to go. This is necessary as Frame Relay is a multiaccess network.

Front 76

In the context of Frame Relay, the Frame Relay switches are called ____ and the customer equipment, such as routers, are called _____.

Back 76

DCE,DTE

Front 77

VC and PVC stand for?

Back 77

virtual circuit and permanent virtual circuit

Front 78

Frame Relay is designed with the concept of a CIR. What does that stand for/mean?

Back 78

committed information rate, it's a guranteed minimum data rate

Front 79

ATM provides Layer ___ features over the the layer ___ featuers of ______?

Back 79

2,1,SONET

Front 80

One of the motivations in creating ATM was the ability to _________

Back 80

Transfer voice and data over the same core infrastructure

Front 81

SONET stands for?

Back 81

Synchronous Optical Network

Front 82

ATM stands for?

Back 82

Asynchronous Transfer Mode

Front 83

T/F: ATM and Frame Relay both use the same unit of data

Back 83

False. Frame Relay uses frames, ATM uses cells

Front 84

VPI stands for?

Back 84

Virtual Path Identifier

Front 85

VPI and VCI are used by ______ for ______

Back 85

ATM, identifying the VC, basically information as to where to send the cell

Front 86

SAR stands for, and refers to?

Back 86

segmentation and reassembly. it refers to how ATM converts ethernet frames to and from ATM cells

Front 87

Although ATM is considered a type of packet-switching service, it may more accurately be called a ________ service.

Back 87

cell-switching

Front 88

Although Frame Relay is considered a type of packet-switching service, it is also known as a _______ service.

Back 88

frame-switching

Front 89

Circuit-switching refers to?

Back 89

dialing, setting up a circuit, and then hanging up. in other words, switching a circuit on and off.

Front 90

T/F: circuit-switching refers to a single connection between two devices

Back 90

True