WAN Technologies Chapter 3

Questions and Answers

Which layer of the OSI model do WAN technologies primarily operate at?

Upper three layers

Only the application layer

All seven layers

Lower three layers (correct)

What is a primary function of common carriers in WAN environments?

Supply transmission facilities (correct)

Provide security protocols

Manage local area networks

Create software applications

Which of the following is NOT a type of WAN service mentioned in the chapter?

Point-to-point links

Virtual circuits

Circuit switching

Broadband local area network (correct)

What is the distinction between circuit switching and packet switching in WAN technologies?

Packet switching is more efficient for bursty data communication than circuit switching. Signup and view all the answers

Which statement best defines a WAN?

A broad geographic data communications network utilizing common carrier facilities. Signup and view all the answers

Which aspect of WAN technologies emphasizes their relationship with the OSI reference model?

They typically engage with the physical, data link, and network layers. Signup and view all the answers

What is a characteristic of switched virtual circuits (SVCs)?

SVCs are terminated once data transmission is complete. Signup and view all the answers

What does the term 'virtual circuit' refer to in packet switching?

A logical circuit within a shared network. Signup and view all the answers

Which of the following is NOT a type of virtual circuit?

Dynamic virtual circuits (DVCs) Signup and view all the answers

What is the first phase of communication over a switched virtual circuit?

Circuit establishment Signup and view all the answers

Which network technologies are examples of packet-switching networks?

Asynchronous Transfer Mode (ATM) and Frame Relay Signup and view all the answers

What happens during the circuit termination phase of an SVC?

The virtual circuit connection is removed. Signup and view all the answers

Which statement about permanent virtual circuits (PVCs) is true?

PVCs provide a constant virtual connection between two endpoints. Signup and view all the answers

What is an essential component in the communication process over SVCs?

Three distinct phases: establishment, transfer, termination. Signup and view all the answers

What is the primary function of a Switched Virtual Circuit (SVC)?

To allow for sporadic data transmission between devices. Signup and view all the answers

How do Permanent Virtual Circuits (PVCs) affect bandwidth usage?

They decrease bandwidth usage by eliminating establishment phases. Signup and view all the answers

Why might a service provider configure a PVC for a customer?

To meet the constant data transfer requirement of the customer. Signup and view all the answers

What occurs during dial-on-demand routing (DDR)?

A router establishes a connection based on the traffic needs. Signup and view all the answers

Which statement best describes a drawback of PVCs compared to SVCs?

PVCs incur higher costs due to their constant availability. Signup and view all the answers

What is a significant characteristic of SVCs compared to PVCs?

SVCs provide more cost-effective solutions for temporary connections. Signup and view all the answers

Which scenario is most suitable for using a PVC?

An organization needs a dedicated line for continuous video streaming. Signup and view all the answers

What could be a potential limitation of using DDR in a network?

It initiates connections only based on predefined criteria. Signup and view all the answers

What is the primary function of an idle timer in router configuration?

To drop the connection if the circuit is idle for a specified time Signup and view all the answers

How does dial backup function in a WAN environment?

It provides a backup service for a primary circuit when failure is detected Signup and view all the answers

In terms of OSI model layers, at which layer do WAN switches primarily operate?

Data link layer Signup and view all the answers

Which of the following devices is NOT typically associated with WAN environments?

Network interface cards Signup and view all the answers

What happens to the dial backup connection when the primary circuit is restored?

It is terminated as the primary circuit is restored Signup and view all the answers

Which type of traffic do WAN switches typically switch in carrier networks?

Frame Relay, X.25, and SMDS Signup and view all the answers

Which type of WAN circuit is characterized by dedicated connections between two endpoints?

Point-to-point Signup and view all the answers

What is the primary function of a CSU/DSU in a WAN setup?

To interface a router with a digital line Signup and view all the answers

How does dial-on-demand routing (DDR) function compared to dial backup?

DDR initiates a dial connection only when needed, while dial backup is always on Signup and view all the answers

What distinguishes an ISDN terminal adapter from a traditional modem?

ISDN terminal adapters handle digital signals natively Signup and view all the answers

In which scenario would dial backup be initiated?

When the primary circuit fails Signup and view all the answers

Which of these WAN circuit types does NOT require a dedicated connection?

Packet-switched Signup and view all the answers

What aspect makes DDR particularly useful for WAN connectivity?

It conserves bandwidth by activating connections as needed Signup and view all the answers

What type of service does a modem specifically provide?

Converting digital to analog signals for transmission Signup and view all the answers

Study Notes

WAN Fundamentals

A Wide Area Network (WAN) covers broad geographic areas, utilizing transmission facilities from common carriers like telephone companies.
WAN technologies operate primarily at the physical, data link, and network layers of the OSI model.
The shared section of a carrier's network is often depicted as a cloud.

Types of WAN Technologies

Includes several protocols such as:
- Asynchronous Transfer Mode (ATM)
- Frame Relay
- Switched Multimegabit Data Services (SMDS)
- X.25
Packet-switching networks transfer data in packets across carriers, with virtual connections called virtual circuits.

Virtual Circuits

Virtual Circuit: A logical connection between two devices in a shared network.
- Switched Virtual Circuits (SVCs): Established on demand and terminated after data transmission, ideal for sporadic communication.
- Permanent Virtual Circuits (PVCs): Always available, suitable for constant data transfer, configured by service providers.

Dialup Services

Dialup services offer economical WAN connectivity, with key implementations being:
- Dial-on-Demand Routing (DDR): Dynamically initiates connections based on specific traffic criteria, with an idle timer for disconnection.
- Dial Backup: Provides alternative connectivity in case of primary circuit failure, automatically activated upon failure.

WAN Equipment

Various devices are utilized in WAN environments:
- WAN Switches: Multiport devices operating at the data link layer, suited for traffic like Frame Relay and X.25.
- Access Servers
- Modems
- Channel Service Units/Data Service Units (CSU/DSU): Interface digital lines (e.g., T1) with routers.
- ISDN Terminal Adapters
- Other devices include routers and multiplexers, integral to WAN operations.

Key Comparisons

Point-to-Point Circuits: Direct connections between two points.
Packet-Switched Circuits: Data is sent in packets across a shared network.
Circuit-Switched Circuits: Established paths that are maintained throughout transmission.

Differences in Technologies

Modems convert digital signals to analog for transmission, whereas ISDN terminal adapters connect digital signals directly with no conversion necessary.

Review Questions Highlights

Types of WAN circuits include point-to-point, packet-switched, and circuit-switched.
The distinction between DDR and dial backup lies in their application—DDR initiates connections for active traffic, while dial backup activates upon primary circuit failure.
CSU/DSU functions to interface routers with digital lines.

These notes provide a comprehensive understanding of WAN technologies, circuits, and equipment necessary for effective network management.

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Description

This chapter provides an overview of wide-area network (WAN) technologies. It covers terminology, types of WAN connections, and various WAN equipment. Students will learn about protocols including circuit switching and packet switching.