Networking Models, Traffic and Devices

1. Describe the three modes of communication available on a network. (Minimum word count: 60)

Simplex – Data travels in only one direction, similar to a public address (PA) system

Half-duplex – Data travels in two directions, but in only one direction at a time, similar to a walkie-talkie. Traditional shared Ethernet uses half-duplex transmissions.

Full-duplex – Data travels in two directions simultaneously, similar to a phone conversation. Full-duplex Ethernet (or switched Ethernet) supports full-duplex transmissions in a switched environment 2. List the seven layers of the OSI model, including both layer number and name for each. (Minimum word count: 20) THE 7 LAYERS OF OSI

Sender

Receiver
Receive

Application
LAYER 7
Application

Presentation
LAYER 6
Presentation

Session
LAYER 5
Session

Transport
LAYER 4
Transport

Network
LAYER 3
Network

Data link
LAYER 2
Data link

Physical
LAYER 1
Physical

3. Describe a protocol data unit (PDU). (Minimum word count: 30) A protocol data unit (PDU) is an open-system interconnection (OSI) term used in telecommunications that refers to a group of information added or removed by a layer of the OSI model. Each layer in the model uses the PDU to communicate and exchange information, which can only be read by the peer layer on the receiving device and is then handed over to next upper layer after stripping.

4. List three practical functions of the OSI model. (Minimum word count: 60) The OSI/RM has three practical functions, as follows:

It gives developers necessary, universal concepts so they can develop and perfect protocols that can work with operating systems and network products developed by other vendors.

It explains the framework used to connect heterogeneous systems. In other words, it allows clients and servers to communicate even if they are using different applications and operating systems; all they need is a common protocol, such as TCP/IP or IPX/SPX.

It describes the process of packet creation. You will learn more about packet creation shortly.

5. Describe a collision domain. (Minimum word count: 70)
A collision domain is a networking segment where two signals can collide.

For example two computes connected to a hub are considered to be on the same collision domain, because a hub does not do any decision making when sending packets down the pipe. When a hub receives a packet or stream of electronic voltages, it just forwards that stream out on all other ports in the hub, hence tying up the lines. So when the two computers send packets at the same time…their signals will collide, causing the information to be corrupted. All devices connected to a hub are considered on the same collision domain.

6. Match each term below with the correct definition.

Answer: 7 – A6 -F 5 – D4 – E 3 – G2 – C 1 – B

(Please do not change the order of the answer numbers – just fill-in the appropriate character)

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