Ch 2 - Communicating over the Network

Question 1

Three Elements of Communication

Answer 1

1. Sender (source)
2. Receiver (destination)
3. Channel (the media that provides the pathway over which the message can travel)

Question 2

The Theory of Communication

Answer 2

A single communication such as music video or email could be sent across a network from source to destination as one massive continuous stream of bits but that would mean:

• No other device could send/receive messages on that same network while this data transfers.
• Large streams of data would result in significant delays.
• If the link sending failed during the transmission, the complete message would be lost and have to be retransmitted in full.

Question 3

A better approach is to divide the data into smaller, more manageable pieces to send over the network.

Answer 3

Segmentation – the division of the data stream into smaller pieces.

Question 4

Benefits of Segmentation

Answer 4

• Sending smaller individual pieces over the network means we can now send many different conversations over the network by interleaving the packets.** Multiplexing** – A process where multiple digital data streams are combined into one signal.
• Increases the reliability of network communications because separate pieces of each message does not need to travel the same pathway across the network from source to destination.

Question 5

Down side of using Segmentation and Multiplexing

Answer 5

Complexity – very packet would go through the process of encapsulation/decapsulation to ensure that it gets to the correct destination.

Question 6

End Devices

Answer 6

These end devices are interfaces between the human network and the communication network, and are sometimes referred to “hosts or clients”:

• Computers
• Printers
• VoIP phones
• Security Cameras

Question 7

Intermediary Devices and their Role in the Network

Answer 7

• Networks rely on intermediary devices to provide connectivity and to work behind the scenes to ensure that data flows across the network.
• The management of data as it flows trough the network is also a role of the intermediary devices.
• They use the destination host address, in conjunction with info about the network interconnections, to determine the path the message should take through the network.

Question 8

Some Intermediary Devices are:

Answer 8

• Network Access Devices (hubs, switches, wireless access points)
• Internetworking Devices (routers)
• Communication Servers and Modems
• Security Devices (firewalls ASA)

Question 9

Network Media

Answer 9

Communication across a network is carried on a medium.
The medium provides the channel over which the message travels from source to destination.

Question 10

Three Primary Types of Media to interconnect devices and to provide the pathway over which data can be transmitted.

Answer 10

1. Copper Wires - Metallic wires within cables
2. Fiber Optic Cable - Glass or Plastic Fiber
3. Wireless Transmission

Question 11

Each Media types Signal Encoding

Answer 11

1. Copper Wires - Metallic wires within cables uses Electric impulses.
2. Fiber Optic Cable - Glass or Plastic Fiber uses Light impulses, within either infrared or visible light ranges.
3. Wireless Transmission - uses Patterns of electromagnetic waves depict the various bit values.

Question 12

Rules that Govern Communications

Answer 12

All communication over a network is governed by predetermined rules called protocols.

• Protocols are specific to the characteristics of the conversation.
• Successful communication between hosts on a network requires the interaction of many different protocols.
• A group of inter-related protocols that are necessary to perform a communication function is called a protocol suite.

Question 13

Network Protocols

Answer 13

Networking protocol suites describe processes such as:

• The format or structure of the message.
• The method by which networking devices share information about pathways with other networks.
• How and when error and system messages are passed between devices.
• The setup and termination of data transfer sessions.

Question 14

Application Protocol:

Answer 14

Hypertext Transfer Protocol (HTTP) is a common protocol that governs the way that a web server and a web client interact.

HTTP defines the content and formatting of the requests and responses exchanged between the client and server.

Both the client and the web server software implement HTTP as part of the application.