Сетевые устройства. Сетевое соединительное оборудование. Сетевая интерфейсная плата, страница 9

Устройства обслуживания канала и данных DSU/CSU

Channel Service Unit/Digital Service Unit

Эти устройства позволяют преобразовать электрический сигнал для передачи по носителю глобальных сетей. Они проверяют достаточно ли силен сигнал и соответствует ли он требуемому формату. Эти устройства защищают пользователя и сеть от нежелательных электрических шумов или скачков высокого напряжения. К тому же они преобразуют поступающие данные в соответствии с накладываемыми другой сетью правилами.

Работа DSU/CSU похожа на работу модема, отличие заключается в том, что модемы работают с аналоговой средой передачи сигнала, а DSU/CSU – с цифровой.

Шлюзы

Шлюз – это аппаратно-программный комплекс, осуществляющий преобразование протоколов. В стеке TCP/IP термин «шлюз» может обозначать маршрутизатор. Шлюзом может быть и устройство, и программа, и их комбинация. Подробнее шлюзы будут рассматриваться на сетевом уровне.

Контрольный тест

1. If a 10BaseT network has been installed and one of the segments exceeds 150 meters, which type of device can help to prevent signal attenuation? (Выберите лучший вариант)

A. Tuner

B. Receiver

C. Amplifier

D. Repeater

2. Your network is experiencing heavy traffic and signal attenuation due to long cable distances between computers.

Required Result:

Correct the signal attenuation problem.

Optional Desired Results:

Reduce the broadcast traffic is present on you network.

Filter the network traffic to reduce the number of frames transferred across the network.

Proposed Solution:

Install repeaters between distant segments.

Which results does the proposed solution produce?

A. The proposed solution produces the required result and produces both of the optional desired results.

B. The proposed solution produces the required result and produces only one of the optional results.

C. The proposed solution produces the required result, but does not produce any of the optional desired results.

D. The proposed solution does not produce the required result.

3. Your network is experiencing heavy traffic and signal attenuation due to long cable distances between computers.

Required Result:

Correct the signal attenuation problem.

Optional Desired Results:

Reduce the broadcast traffic that is present on you network.

Route the network traffic.

Proposed Solution:

Install repeaters between distant segments. Install routers and configure them to filter broadcast traffic.

Which results does the proposed solution produce?

A. The proposed solution produces the required result and produces both of the optional desired results.

B. The proposed solution produces the required result and produces only one of the optional desired results.

C. The proposed solution produces the required result, but does not produce any of the optional desired results.

D. The proposed solution does not produce the required result

4. Which of the following network devices functions at the Network layer of the OSI model?

A. Bridge

B. Repeater

C. Router

D. Gateway

5. You are installing the network card in a computer that has several devices configured. There is a printer on LPT 1, a mouse on COM 1, a modem on COM 2, and a SCSI host adapter occupying IRQ 10. The computer also has a sound card using IRQ 5. If you network card supports IRQs 3 through 5 and 9 through 11, which of the following IRQs could you set it forin this computer? (Check all correct answers.)

q  A. IRQ 3

q  B. IRQ 4

q  C. IRQ 10

q  D. IRQ 11

6. Your company has two LANs that use different protocols. You need to connect the two LANs, but you do not want to configure additional protocols on either network. Which device could you use to perform this task?

A. Bridge

B. Router

C. Brouter

D. Gateway