Chapter 1

Question 1

Purpose of WANs

Answer 1

• Operate beyond the scope of LANs
• Interconnect enterprise LAN to remote LANs
• Owned by service providers
• Organizations must pay fee for using provider service to connect to sites

Question 2

WANs in the OSI Model

Answer 2

Physical and Data Link

Question 3

WAN Devices

Answer 3

Dial-up Modem, Access Server, Broadband Modem, CSU/DSU, WAN Switch, Router, Core Router/Multi-layer Switch

Question 4

WAN Operations

Answer 4

Can operate as circuit-switched or packet-switched

networks

Question 5

Circuit-Switched Networks

Answer 5

Establish a dedicated circuit between source and destination before the users may communicate, such as making a telephone call

Question 6

Packet-Switched Networks

Answer 6

Split traffic into packets that are routed over a shared network and do not require a dedicated circuit between source and destination

Question 7

What are two ways to get WAN access?

Answer 7

Private WAN Infrastructure or Public WAN Infrastructure

Question 8

Private WAN

Answer 8

Negotiated dedicated/switched WAN access with a service provider

Question 9

Public WAN

Answer 9

WAN access is achieved through the Internet using broadband connections. VPNs secure the connections.

Question 10

Advantages and Disadvantages of Leased Lines (Private WAN)

Answer 10

Adv: Simplicity, Quality, Availability
Disadv: Cost, Limited Flexibility

Question 11

ATM (Private WAN)

Answer 11

Built on a cell-based architecture, rather than on a frame-based architecture. ATM cells are always a fixed length of 53 bytes

Question 12

Multiprotocol Label Switching (MPLS) (Private WAN)

Answer 12

A multiprotocol high-performance WAN technology that directs data from one router to the next, based on
short path labels rather than IP network addresses

Question 13

Very small aperture terminal (VSAT) (Private WAN)

Answer 13

A solution that creates a private WAN using satellite communications

Question 14

DSL (Public WAN)

Answer 14

Always-on connection technology that uses existing twisted-pair telephone lines to transport high-bandwidth data, and provides IP services to
subscribers. DSL modems convert an Ethernet signal from the user device to a DSL signal, which is transmitted to the central office

Question 15

Cable (Public WAN)

Answer 15

Network access is available from some cable
television networks. Cable modems provide an always-on connection and a simple
installation

Question 16

Wireless (Public WAN)

Answer 16

Municipal Wi-Fi, WiMAX, Satellite Internet

Question 17

Municipal Wi-Fi (Public WAN)

Answer 17

Many cities have begun setting up municipal wireless

Question 18

WiMAX (Public WAN)

Answer 18

Worldwide Inter-operability for Microwave Access

Question 19

Satellite Internet (Public WAN)

Answer 19

Typically used by rural users where cable and DSL are not available

Question 20

WAN Access Standards are defined and managed by who?

Answer 20

TIA, EIA, ISO, IEEE

Question 21

Customer Premises Equipment (CPE)

Answer 21

Devices and inside wiring located on enterprise edge that the customer either owns or leases from the service provider

Question 22

Data Communications Equipment (DCE)

Answer 22

An EIA term, consists of devices that put data on the local loop. Primarily provides an interface to connect customers to a commmunication link on the WAN cloud

Question 23

Data Terminal Equipment (DTE)

Answer 23

Devices that pass data from a customer network or host for transmission over WAN. DTE connects to the local loop through the DCE

Question 24

Demarcation Point

Answer 24

Established in a building or complex to separate customer equipment from service provider equipment. The cabling junction box that connects the CPE wiring to local loop

Question 25

Local Loop (AKA Last-Mile)

Answer 25

The cable that connects the CPE to the CO of the service provider

Question 26

Central Office (CO)

Answer 26

The local service provider facility/building that connects the CPE to the provider network