Communicating over the Network

 V 4.0




What are the five aspects of the information network we will focus on in this course?

Devices that make up the network

Media that connect the devices

Messages that are carried across the network

Rules and processes that govern network communications

Tools and commands for constructing and maintaining networks


What are the three elements of communication?

Sender, Receiver, Chanell


What is the definition of the term network for this course?

data or information networks capable of carrying many different types of communications, including traditional computer data, interactive voice, video, and entertainment products.


What would happen to the network if a message was sent as one massive continuous stream of bits?

no other device would be able to send or receive messages on the same network while this data transfer was in progress


Define segmentation of messages

division of the data stream into smaller pieces


What are the 2 advantages of segmentation?

many different conversations can be interleaved on the network

segmentation can increase the reliability of network communications


What is multiplexing?

process used to interleave the pieces of separate conversations together on the network


What is hardware on a network?

the visible components of the network platform


What are end devices on a network?

Computers (work stations, laptops, file servers, web servers)

Network printers

VoIP phones

Security cameras

Mobile handheld devices (such as wireless barcode scanners, PDAs)


What is the definition of a host?

either the source or destination of a message transmitted over the network


What is the definition of a server?

hosts that have software installed that enables them to provide information and services


What is the definition of a client?

hosts that have software installed that enables them to request and display the information obtained from the server


List examples of intermediary devices.

Network Access Devices (Hubs, switches, and wireless access points)

Internetworking Devices (routers)

Communication Servers and Modems

Security Devices (firewalls)


List examples of process that intermediary devices perform.

Regenerate and retransmit data signals

Maintain information about what pathways exist through the network and internetwork

Notify other devices of errors and communication failures

Direct data along alternate pathways when there is a link failure

Classify and direct messages according to QoS priorities

Permit or deny the flow of data, based on security settings


What are the 3 primary types of media used in modern networks?

Metallic wires within cables

Glass or plastic fibers (fiber optic cable)

Wireless transmission


What criteria should be used to select network media?

The distance the media can successfully carry a signal.

The environment in which the media is to be installed.

The amount of data and the speed at which it must be transmitted.

The cost of the media and installation


What are the ways in which network infrastructure can vary?

The size of the area covered

The number of users connected

The number and types of services available


What is the definition of a LAN?

individual network usually spans a single geographical area, providing services and applications to people within a common organizational structure


What is the definition of a WAN?

networks that connect LANs in geographically separated locations


What is an internetwork?

A global mesh of interconnected networks (internetworks) meets these human communication needs.


What is an intranetwork?

a private connection of LANs and WANs that belongs to an organization, and is designed to be accessible only by the organization's members, employees, or others with authorization

Define a NIC

provides the physical connection to the network at the PC or other host device.


Define a physical port

A connector or outlet on a networking device where the media is connected to a host or other networking device.


Define an interface

Specialized ports on an internetworking device that connect to individual networks.

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What are the 3 layers of protocols described?

Content Layer, Rules Layer, Physical Layer


What process do networking layer protocol suites describe?

The format or structure of the message

The process 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


What is proprietary?

one company or vendor controls the definition of the protocol and how it functions


What does the use of standards and protocols provide?

products from different manufacturers can work together for efficient communications


What is an application protocol?

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


What is a Transport Protocol?

manages the individual conversations between web servers and web clients


What is the Internetwork Protocol

responsible for taking the formatted segments from TCP, encapsulating them into packets, assigning the appropriate addresses, and selecting the best path to the destination host.


What is the Network Access Protocol?

Network access protocols describe two primary functions, data link management and the physical transmission of data on the media.


What do networking protocols describe?

the functions that occur during network communications


What are the benefits of using a layered model to describe networking?

Assists in protocol design, because protocols that operate at a specific layer have defined information that they act upon and a defined interface to the layers above and below.

Fosters competition because products from different vendors can work together.

Prevents technology or capability changes in one layer from affecting other layers above and below.

Provides a common language to describe networking functions and capabilities.


What are the two basic types of networking models?

protocol models and reference models


What are the two primary models used when describing networking?



What is done at the Application Layer?

Represents the data to the user plus encoding and dialog control


What is done at the Transport Layer?

Supports communication between diverse devices across diverse neworks


What is done at the Internet Layer?

Determines the best path through the network


What is done at the Network Access Layer?

Controls the hardware devices and media that make up the network


What are the seven steps in a complete communication process?

1. Creation of data at the application layer of the originating source end device


2. Segmentation and encapsulation of data as it passes down the protocol stack in the source end device


3. Generation of the data onto the media at the network access layer of the stack


4. Transportation of the data through the internetwork, which consists of media and any intermediary devices


5. Reception of the data at the network access layer of the destination end device


6. Decapsulation and reassembly of the data as it passes up the stack in the destination device


7. Passing this data to the destination application at the Application layer of the destination end device


What is the PDU for the application layer?



What is the Transport Layer PDU?



What is the PDU for the Internet Layer?



What is the PDU for the Network Access Layer?



What PDU is used when physically transporting the information over the medium?


How is the protocol stack processed when sending information?

Top to bottom

What is the process use at the receiving end called?



What are the seven layers of the OSI Model?

Application, Presentation, Session, Transport, Network, Data Link, Physical


Which Layers of the OSI Model parallel with the TCP/IP Model?

Application, Presentation, Session-Application



Data Link, Physical-Network Access


What does the physical layer do?

Timing and synchronization of bits


What addresses does the data link layer use?

Destination and source physical address


What address does the network layer use?

Destination and source logical address


What does the transport layer use?

Destination and source process number (ports)


What do the upper layers use?

Encoded application data


What is the PDU for Layer 2 called



What is the layer 2 address called?

MAC address


What happens after the frame has reached its’ destination?

the Layer 2 address information is removed as the data is decapsulated and moved up the protocol stack to Layer 3


What are layer 3 devices primarily designed for?

to move data from one local network to another local network within an internetwork


What address is used at Layer 3?

IP address


What is the PDU of the Layer 3 information?



Which device decapsulates the frame at the edge of a network?



What does a router do?

use the network identifier portion of this address to determine which path to use to reach the destination host


What happens when the frame reaches the end device?

the frame and packet headers are removed and the data moved up to Layer 4


What does the information in the frame provide at Layer 4?

identifies the specific process or service running on the destination host device that will act on the data being delivered


How is each application or service represented at Layer 4?

Port number


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Complete the Packet Tracer Lab and save your network when completed. E-mail the file



Complete the Packet Tracer Lab and save your network when completed. E-mail the file

**Extra Credit***

Complete this Packet Tracer Lab, save the file, and email it to me.