Chapter 3 Flashcards - Sheet1

Question 1

Name the different terms for a leased line

Answer 1

Leased circuit, serial link/line, point-to-point link/line, T1, WAN link, private line

Question 2

T1

Answer 2

Type of leased line that transmits at 1.545Mbps

Question 3

CO

Answer 3

Central Office - Location of equipment for telcos providing leased lines

Question 4

CSU/DSU

Answer 4

Channel Service Unit / Data Service Unit (Modem / Connection equipment to a WAN)

Question 5

CPE

Answer 5

Customer Presmises Equipment

Question 6

Examples of CPE:

Answer 6

Router, serial interface card, CSU/DSU. The CSU/DSU may be integrated into the serial interface card in the router.

Question 7

Typical connection from a telco to the CSU/DSU

Answer 7

RJ-48

Question 8

DTE Cables

Answer 8

Data terminal equipment cables. Serial cables normally used between a router and an external CSU/DSU

Question 9

DTE Cable equivalent of a crossover cable

Answer 9

DCE - Data Communications Equipment Cable

Question 10

Clocking

Answer 10

Function of the CSU/DSU that tells the router when to send each bit through signaling over a serial cable.

Question 11

Two most popular data link layer protocols used for leased lines (WANs) are

Answer 11

HDLC (High Level Data Link Control) and PPP (Point to Point Protocol), Ethernet WANs(!)

Question 12

All data link protocols perform this similar role

Answer 12

Control correct delivery of data over a physical link of a particular type.

Question 13

HDLC frames have less work to do than Ethernet because –

Answer 13

The source and destination are implied. There are only two endpoints. Despite this, HDLC still has an address field, b/c telcos used to offer multidrop circuits w/more than 2 devices

Question 14

Lists the HDLC fields and their Ethernet equiv

Answer 14

Flag (Preamble), Address (Destination Address), Type (Type), Data (Data), FCS (FCS)

Question 15

Size of the HDLC’s flag

Answer 15

1 byte

Question 16

Size of the HDLC’s Address

Answer 16

1 byte

Question 17

Size of the HDLC’s type

Answer 17

2 bytes

Question 18

Size of the HDLC’s FCS

Answer 18

2 bytes

Question 19

Size of the HDLC’s control

Answer 19

1 byte

Question 20

EoMPLS

Answer 20

Ethernet Over MPLS. AKA Ethernet Emulation. An Ethernet WAN service.

Question 21

DSLAM

Answer 21

DSL Access Multiplexer - Housed at the TelCo’s central office, splits phone from data traffic. Sends phone traffic through PSTN, sends data through a router.

Question 22

DSL speeds are ______, meaning the down speed is different than the up speed

Answer 22

Asymmetric

Question 23

Telco

Answer 23

Telephone Company

Question 24

Leased Line

Answer 24

A serial communications circuit between two points, provided by some service provider,
typically a telephone company (telco)

Question 25

Serial Interface

Answer 25

A type of interface on a router, used to connect to some types of WAN links, particularly leased lines and Frame Relay access links.