Classnotes_6a - Focus Consulting

puffyyaphankyonkersNetworking and Communications

Oct 26, 2013 (3 years and 9 months ago)

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Week
6 (Chapter 3)

Networking

Spring Term 2013

Washington College

Professor Suydam

Basics of Computing


PowerPoint Primer


Basics of
Networking


Debugging


MP3 Setup & Submission Preparation

6a
-
2


G
ood templates and/or Design Themes


H
igh
-
contrast colors (but not intense)


S
ans serif fonts


E
fficient text


W
isely chosen images


A
ppropriate “build” effects (animation)


V
isual balance of slide elements

6a
-
3

Try to avoid “moving” or slow
effects like:

Opt instead

for “in
-
place” effects like:



spiral



swivel



crawl

wipe

random bars

blinds

peek

split

stretch

dissolve

6a
-
4

Links to Microsoft tutorials


click on link, it will open a new browser page,
when completed, simply close browser to return to this slide



Choose the right colors for your PowerPoint presentation


About design templates


Tips for giving better presentations


MP3 includes a self
-
paced exercise accessed at link below:


Presentation Concepts

Starter File


6a
-
5

Tell whether a communication technology (Internet, radio,
LAN, etc.) is synchronous or asynchronous; broadcast or point
-
to
-
point

Explain the roles of Internet addresses, domain names, and
DNS servers in networking

Distinguish between types of protocols (TCP/IP and Ethernet)

Describe how computers are interconnected by an ISP and by a
LAN

Distinguish between the Internet and the World Wide Web

How long does it take for a 1MB picture to download with a
connection bandwidth of 100 Kbps?


1MB


1,000,000 Bytes


8,000,000 bits

100Kbps


100,000 bits/second


Download = file size/speed of transmission




= 8,000,000 bits/100,000 bits/second




= 80 seconds

6
-
7

6
-
8

When you click link, your computer enters client/server relationship with
web server

Server is the computer that stores the web page

Client is the computer that accesses the web page

Once the page is sent to you, the client/server relationship ends

Server can form many brief relationships so it can serve many clients at the
same time

6
-
9

Computer Addresses

IP addresses: Each computer connected to
the Internet is given a unique numerical
address

Domain Names: Human
-
readable symbolic
names, based on domain hierarchy
--

easier
to read and remember


6
-
10

Internet host knows the IP address of its
nearest DNS server, a computer that
keeps a list of domain names and
corresponding IP addresses

When you use a domain name to send
information, your computer asks the
DNS server to look up the IP address

If the DNS server doesn't know the IP
address, it asks a Root name server,
which keeps the master

list of name
-
to
-
address relationships

The Domain Name System translates the human
-
readable names into IP addresses

6
-
11

Web requests use client/server interaction

Requesting a Web page means your browser is a
client

asking for a file from
a Web
server

The file can be found in looking at the
URL

(Universal Resource Locator)

Web browsers and Web servers both “speak”
HTTP

http
://
www.cs.washington.edu
/
homes/snyder/
index.html

The URL has three main parts:


Protocol
.

tells the computers how to handle the file


Server computer’s name

or the name given by the domain hierarchy


Page’s pathname
.

tells the server which file (page) is requested and where to find
it

Servers do not store Web pages in the form seen on our screens

The pages are stored as a
description of how they should appear on the
screen.

The browser receives the description/source file and creates the Web page
image that is
described

Domain

is a related group of networked computers


Top
-
Level Domain name identifies the type of organization

Top
-
level domains appear in the last part of domain name:

.
edu

educational institutions

.org

organizations

.net

networks

.mil

military

.
gov

government agencies


http://www.eds.com/home/eds_home.html

Top
-
level Domain

1 Type of connection

2 Domain

3a Path or Directory

3b File name

Email addresses


msuydam2@washcoll.edu

6
-
14

The top
-
level domains were expanded to include biz, info, name, travel,
and others

The full list can be found at
www.icann.org

(ICAAN is
I
nternet
C
orporation for
A
ssigned
N
ames and
N
umbers)

The original top
-
level domains listed all apply to organizations in the United
States.

There is also a set of two
-
letter country designators (
ca

(Canada),
uk

(United Kingdom),
fr

(France), de (Germany, as in Deutschland), etc.)

These allow domain names to be grouped by their country of origin
.

6
-
16

Protocol is how the information is actually sent

TCP/IP (Transmission Control Protocol/Internet Protocol)

TCP/IP Postcard Analogy

The Internet is like sending a novel to your publisher using postcards

The novel is broken into small units that fit on a postcard

The “postcards” are numbered to indicate where each belongs in the
novel

As each postcard is completed, it is mailed

Sooner
or later, your publisher received the postcards, but not
necessarily in sequential order

Nor do they take the same route

The cards are finally arranged in order

These “postcards” are
really
IP
packets

IP Packets:
one unit of information, the destination IP, and their
sequence number
(
which packet they are
)

Internet uses electrical, electronic, and optical communication means

Telephone lines, dedicated fiber optic lines, etc.

The technology used to move the packet is independent from the protocol;
transmission of a single file may use multiple technologies

6
-
18

WAN


Wide Area Network

LAN


Local Area Network

BSS 1

BSS 2

Internet

hub, switch

or router

AP

AP

6
-
19

Source:
http://
en.wikipedia.org/wiki/OSI_model


6
-
20

Source: http
://www.youtube.com/watch?v=reXS_e3fTAk&feature=youtu.be

By Internet Service Provider (ISP)

By Enterprise Network Connections (LAN):


Large networked organizations such as schools, businesses, or
governmental units


The organization creates a LAN or intranet


The intranet connects to the Internet by a gateway


Information from a Web computer is sent across Internet, through
gateway, across LAN to user's computer

Should I know my computer's IP address?


For other IP information on Windows, including the physical address, at
the All
Programs|Accessories|command

prompt, enter:
ipconfig






Or…go
to this link:
http://www.whatismyip.com
/

6
-
21

A variation on the LAN connection

A computer (called the hub) is physically connected to the Internet

The hub broadcasts and receives Radio Frequency (RF) signals

Mobile computers also send and receive signals

The hub relays Internet requests for the networked computers

Washington College Access Points

(Wikipedia: “How it Works”)

6
-
22

Web servers: Computers programmed to send files to browsers running on
other computers connected to the Internet

Web servers and their files make up the World Wide Web

The World Wide Web is a subset of the Internet

Wikipedia: World Wide Web

6
-
23

When is the "www" required and when is it optional?

WWW is just a name; web pages do not have to use it

In order for DNS to work, user must give the exact domain name

To help users reach them, organizations do two things:


Redirection: browser inserts the "www"


Registering multiple domain names


Museum of Modern Art has registered both "moma.org"

and "www.moma.org" to the same IP address

6
-
24

VisualRoute

website/software

Class
Website|Course

Resouces|Supplemental

Materials|Visual

Route


use free
services

6
-
25

A ping is a “please reply” message

Example
:
http://
europa.eu
147.67.136.2

To understand the Internet we need to cover some basic
communication vocabulary:


Synchronous Communication


Asynchronous communication


Broadcast


Multicast


Point
-
to
-
point communication

Most home users connect to the Internet by ISPs


These are companies that sell connections to the Internet

The company places a modem at your house


Modems convert the bits a computer outputs into a form that is
compatible with the carrier

1.
The signals are sent to the carrier’s business

2.
They are converted (via modem) into a form for the server that connects to the Internet
via the Internet Gateway

Digital subscriber line (DSL or ADSL) and cable (TV) are two common
providers

Your smart phone also has a modem for connecting to
network

The other way to connect is as a user of a larger networked organization
(school, business, or governmental unit)

The organization connects to the Internet by a gateway

Variation of a LAN connection

Referred to by its protocol name
802.11

The router is:


Physically connected to an ISP’s modem


Connected to the Internet


Capable of broadcasting and receiving signals, usually radio frequency
(
rf

) signals


Directory Hierarchy


Remember that folders can contain folders as
well as files


This scheme is called the file structure of the
computer and forms the directory hierarchy

Think of any hierarchy as a tree


folders are the branch points


files are the leaves

Directory Hierarchy


All hierarchies have branch points and leaves


Hierarchy trees are often drawn sideways or
upside down


Two terms are standard, however:

1.
Down

in the hierarchy means into
subfolders (towards the leaves)

2.
Up

in the hierarchy means into folders
(toward the root
)

In this chapter we discussed the basics of networking, including
the following:


Basic types of communication: point
-
to
-
point, multicast, broadcast,
synchronous, and asynchronous.


Networking, including IP addresses, domains, IP packets, IP protocol,
WANS and LANS, Ethernet protocol, ISPs, enterprise networks, and
wireless networks.


The difference between the Internet and the World Wide Web.


File hierarchies in preparation for our further study of HTML.