Chapter 1

When you design a network you often think of the network design into terms of three groups:

1) Hardware (physical and data link) 2) Internetwork (network and transport) 3) Application

Wireless Local Area Networks (WLAN)

A LAN that uses wireless circuits

Telecommunications

A broader term and includes the transmission of voice and video (images and graphics) as well as data and usually implies longer distances

Server

A device that stores and transmits data to a client; usually a personal computer (often more powerful than other computers on the network) but it can also be minicomputers or mainframes

Local Area Network (LAN)

A group of computers located in the same general area; it only covers a clearly defined small area; support high speed data transmission

Client

A input-output user device that provides users with access to the network and receives data from server

Backbone Network (BN)

A larger central network connecting several LANs, other BNs, MANs, and WANs; typically span from 100s of feet to several miles and provide very-high speed data transmission

Intranet

A network (often a LAN) that uses the Internet technologies to share information within an organization; open only those inside the organization

Extranet

A network that uses the Internet technologies to share information between organizations; open only those invited users outside the organization; accessible through the Internet and access gained through passwords, smart cards, or special software

Circuit

A pathway or connection between client and server through which the messages travel; switches and cables are included in this

Standards

A set of rules, also known as protocols; ensure that hardware and software from different vendors work together and speak the same language

Router

A special device that connects two or more networks; enables computers on the network to communicate with other computers (i.e., the Internet)

Protocol Stack

Because the protocols are used at different levels and are stacked on top of one another, the set of software used to understand the different protocols is often called a ______.

Physical layer (OSI layer 1)

Concerned primarily with transmitting data bits (0's and 1's) over a communication circuit; defines the rules by which ones and zeros are transmitted

Print Server

Connected to a printer, it manages all printing requests from the clients on the network

Acceptance Stage

Considered to be the most difficult stage; consists of defining the solution and getting recognized industry leaders to agree on a single uniform solution

Open Systems Interconnection Reference model

Consists of 7 layers; helped change the face of network computing

Examples of Circuits

Copper wire, Fiber Optic Cable, Wireless

The two types of standards:

De Jure and De Facto

Examples of Client

Desktops, laptops, tablets, cell phones

Network Models

Divide communication functions into layers; allow functions to be addressed separately

Requests for Comments

During the process of making network protocols become standards, if the report is favorable the IETF issues this, which describes the proposed standard and solicits comments from the entire world

Examples of Intranet

Employees accessing budgets, calendars, and payroll information available through the organization

Example of Data Link Layer

Ethernet

Data communication networks

Generally collect data from personal computers and other devices and transmit those to a central server that is a more powerful personal computer, minicomputer, or mainframe, or they perform the reverse process, or a combination of the two; provide faster information flow

Example of Application Layer

HTTP

Examples of De Jure

HTTP, IEEE, 802.3, 802.11n

Example of Network Layer

IP

Identification of Choices stage

In this stage those working on the standard identify the various solutions and choose an optimum solution from among the alternatives

Disadvantages of Using Layers

Inefficient because the encapsulation/de-encapsulation at each layer requires processing; Inefficient because encapsulation in a PDU increases overhead at each layer

Wide Area Networks (WAN)

Largest geographic scope; often composed of leased circuits as organizations do not tend to build their own; May span 100s or 1000s of miles; connect BNs and MANs

Example of Physical Layer

Network Cable

Advantages to Using Layers

Networking functionality is modular and the software/hardware at any layer can be more easily substituted (E.g., substitute wired for wireless at the physical layer); Easier to troubleshoot or make changes to one layer at a time; Application developers only need to worry about the application layer in their programs

Peer-to-Peer Networks

Networks designed to connect a set of similar computers that share their data and software with each other; the computers in this function as equals rather than relying on a central server to store data/software

Examples of LAN

One floor or work area, a single building, or a group of buildings

The two most important types of Network Models:

Open Systems Interconnection Reference (OSI) model and the Internet model

The 7 layers of OSI:

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

The 5 layers of the Internet Model:

Physical, Data, Network, Transport, and Application

Native Apps

Require an app to be developed for each application that the employee might be using for every potential device that the employee might use; one of the main approaches to managing access to companies applications for BYOD

Browser-Based

Requires employees to access application through a web browser instead of creating an app; one of the main approaches to managing access to companies applications for BYOD

Data Link layer (Internet 2)

Responsible for moving a message from one computer to the next computer in the network path from the sender to the receiver; performs the same three functions as the data link in the OSI layer

What are the three stages of the De Jure Standardization process?

Specification, identification of choices, and acceptance

File Server

Stores data and software that can be used by computers on the network

Web Server

Stores documents and graphics that can be accessed from any Web browser; can respond to requests from computers on this network or any computer on the Internet

Examples of Extranet

Suppliers and customers accessing the inventory information of a company

Example of Transport Layer

TCP

Application Layer (OSI layer 7)

The end user's access to the network; primarily provides a set of utilities for application programs; user programs determine the set of messages and any actions it might take on receipt of that message

Physical Layer (Internet 1)

The physical connection between the sender and the receiver; transfers a series of signals through a circuit; includes all hardware devices and physical media

Examples of Servers

Web server, File server, Print server

De Facto standard

Widely accepted, but has no official standing; in communications industry, this standard typically becomes de jure once widely accepted

Hardware Layers

a group of layers that people refer to when grouping the physical and the data link layers, which is based off the two layers' similarities

Institute of Electrical and Electronics Engineers (IEEE)

a professional society in the United States to standards association develop standards; most known for its standards in LANs

Protocol Data Unit (PDU)

all layers except the physical layer create a new ______; act like nested envelopes; contains information that is needed to transmit the message through the network; also referred to as a packet by some professionals

Specification stage

consists of developing a nomenclature and identifying the problems to be addressed

Transport Layer (OSI layer 4)

deals with end-to-end issues, such as procedures for entering and departing from the networks; it establishes, maintains, and terminates logical connections for the transfer of data between the original sender and the destination of the message; breaks large data into smaller packets of data; can also perform error checking

De Jure standardization

developed by an official industry or a government body and is often called a formal standard

Presentation Layer (OSI layer 6)

formats the data for presentation to the user; to accommodate different interfaces on different computers so the application program don't need to worry about them; concerned with displaying, formatting and editing user inputs and outputs

Data Link (OSI layer 2)

manages the physical transmission circuit in layer 1 and transforms it into a circuit that is free of transmission errors; this layer must create and recognize message boundaries (where the message begins and ends) and solve the problems caused by the damage, lost or duplicated messages so other layers are shielded from transmission errors

Encapsulation

occurs when a higher level PDU is placed inside of a lower level PDU

International Organization for Standardization (ISO)

one of the most important standards making bodies, this group makes technical recommendations about data communication interfaces

Internetwork Layers

people refer to this group when grouping the transport and network layers together

Network Layer (Internet 3)

performs routing; determines the next computer to which the message should be sent so it can follow the best route

Network Layer (OSI layer 3)

performs routing; determines the next computer to which the message should be sent so it can follow the best route

Session Layer (OSI layer 5)

responsible for managing and structuring all sessions; session initiation must arrange for all the desired and required services between session participants; session termination provides orderly way to end the session or prematurely abort it

Internet Engineering Task Force (IETF)

sets the standards that govern how much the Internet will operate; is unique in that it doesn't really have official memberships

Protocol

simply a set of rules that define what the layer will do and provides a clearly defined set of messages that software at the layer needs to understand

Application Layer (Internet 5)

the application software network user and includes much of what the OSI model contains in the application, presentation, and session layers. It's the user's access to the network.

American National Standards Institute (ANSI)

the coordinating organization for the US national system of standards for both technology and nontechnology; it's a standardization organization, not a standards making body, in that it accepts standards developed by other organizations and publishes them as American standards; its role is to coordinate the development of voluntary national standards and interact with ISO to develop national standards that comply with ISO's international recommendations

Data communications

the movement of computer information from one point to another by means of electrical or optical transmission systems

International Telecommunications Union (ITU-T)

the technical standard setting organization of the United States international telecommunications Union

Internet Model

this simpler 5 layer network model evolved from the work of thousands of people who developed pieces of the internet; never formally defined so it has to be interpreted from a number of standards. The Internet model collapses the top three OSI layers into one; most commonly used model.

For network to operate, many different standards must be used simultaneously.

true

Transport Layer (Internet 4)

very similar to that of the OSI model - performs two functions: 1) its responsible for linking the application layer software to the network and establishing end to end connections between the sender and receiver when needed, 2) responsible for breaking long messages into several smaller messages to make them easier to transmit and then recombining them back into the original large messages at the receiving end; Can also detect lost messages and request they be resent.