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Introduction to Management Information Systems Chapter 5 Data Communications and Internet Technology

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Title: Introduction to Management Information Systems Chapter 5 Data Communications and Internet Technology


1
Introduction to Management Information
SystemsChapter 5 Data Communications and
Internet Technology
  • HTM 304
  • Fall 07

2
Today The Internet Enterprise Network
  • Internet (Public)
  • Enterprise Network (Private)

3
The Internet
  • Note Capitalized I, the only one, public
    access
  • Also called the Net
  • internet inter-connected networks (LANs or
    WANs) ? there are many.
  • The Internet A global WAN that connects
    approximately 1 million inter organizational
    computer networks in more than 200 countries on
    all continents
  • Origin ARPANET (DoD, 1969)
  • Original purpose ? exchange messages, transfer
    files

4
(No Transcript)
5
Connecting the Internet
  • ISP Internet Service Provider
  • Name several well-known ISPs
  • How to find a local ISP http//www.thelist.com
  • Internet Backbone
  • Providing connectivity in many cities
  • Has many network access points (NAPs)
  • Local ISPs rent NAPs to access
  • the backbone
  • Who owns the backbone?
  • ARPAnet (DoD, 1969 1986)
  • NSFnet educational (1986- now)

6
Domain Name Systems (DNS)
  • To publish on the Internet ? Apply for a public
    domain name
  • Organization ICANN (Internet Corporation for
    Assigned Names and Numbers, www.icann.org ), 13
    root servers maintain lists of IP addresses of
    Internet servers
  • Purpose of Domain Name
  • To get user-friendly names rather than IP
    addresses.
  • Components of a Domain Name
  • www.sina.com.cn
  • From the rightmost Regional code ? top-level
    domains (types of institutes) ? name of the
    institute ? www (or www2, the main server), or a
    specific computer in the domain

7
The Naming System
  • Regional Code
  • E.g. cn, fr, de, it, uk, au, jp,
    etc.
  • What is the regional code for the United States?
  • Top-Level Domains (type of the site)
  • com / edu / gov / net, etc.
  • See page 143 for a complete list (note in some
    country, .com is short as .co, e.g
    www.amazon.co.uk)
  • Name of the institute (e.g. csusm.edu,
    microsoft.com)
  • The leftmost
  • www world wide web generally go to the
    predefined main server of the institute
  • A particular machine or subnet
  • E.g. fangfang.csusm.edu, sandiego.craigslist.org

8
Exercise
  • Based on the following domain name, describe the
    type of the institute.
  • sandiego.craigslist.org
  • www.ebay.com.au
  • www.tsinghua.edu.cn

9
Public IP address
  • Any computer with direct Internet Access needs a
    public IP address.
  • IPv4 and IPv6
  • Some small business/home LANs only obtains one IP
    addresses for the router or server
  • Router has two IP addresses (one public, one
    private)
  • The other computers obtain private IP addresses
    from routers

10
Issues with Domain Name System
  • Use Fake Domain Names to acquire users private
    information
  • Using similar names to gain visits
  • E.g. www.craiglist.com, www.wikipeda.org,
    www.goggle.com, etc.
  • Cybersquatting register domain names in hoping
    companies would want it later gauge for money.
  • Anti-cybersquatting Consumer Protection Act. Nov
    1999.

11
The future of the Internet
  • The current Internet is UNSATISFACTORY
  • Too slow for data intensive applications
  • Unreliable, insecure
  • Article the internet is broken call for a
    complete redesign
  • Three initiatives underway
  • Internet 2
  • Develops and deploys advanced network
    applications such as remote medical diagnosis,
    digital libraries, distance education, online
    simulation and virtual libraries.
    (http//www.Internet2.edu)
  • Next Generation Internet (NGI)
  • Government sponsored initiative aimed at
    creating an Internet that is fast, always on,
    everywhere, natural, intelligent, easy and
    trusted. (http//www.ngi.gov )
  • vBNS
  • high-speed network designed to support the
    academic Internet2 and the NGI. Goal 2.4
    gigabits per second.

12
Enterprise Networks
  • Major Components of Enterprise Networks
  • LANs a small size network in a single location
    (e.g. a building).
  • Small company, home business, a department in a
    big organization (e.g. embedded LAN for large
    enterprise)
  • WANs connects computers (or LANs) located at
    physically separated sites. (see Figure 5-12 on
    page 126)
  • Generally provided by common carriers (e.g.
    Verizon, ATT, etc.)
  • Backbone Networks high-speed
  • central networks which connects
  • multiple smaller networks
  • (e.g. LANs or small WANs)

13
Types of WANs
  • Connecting the PC to an ISP via Modems
  • Home computers, small businesses use
  • Telephone dial up, DSL line, cable TV line
  • Networks of Leased Lines (Mostly PSTN)
  • Lease from telephone companies (a variety of
    lines, speed ranges from 1.544Mbps to 40Gbps)
  • Connecting different sites of the company
  • Expensive, hard to manage,
  • sometimes, managed by specialized 3rd parties
  • Public Switched Data Network (PSDN)
  • PSDN a network of computers and leased lines
    that is developed and maintained by a vendor
  • Lease a line from the vendor that connects to
    PSDN
  • Virtual Private Network (VPN)
  • Uses the public Internet (private internets
    sometimes) to create virtual connections

14
Creating VPN
  • Tunneling Protocol
  • Tunneling encrypts the data packet to be sent,
    and places it inside another packet, which
    provides confidentiality, authentication and
    integrity of the message.
  • Ensure Security software encryption.
  • Offer the benefits of leased lines, but more
    flexible.
  • The connections is established upon user request,
    disconnect at will
  • Good for employees on the go, small sites which
    is too expensive to lease fixed lines, or
    business partners with limited data transfer,
    etc.
  • Microsoft windows supports VPN

15
Criteria for comparing network alternatives
  • Cost
  • Initial setup costs, operational costs, and
    maintenance costs
  • Performance
  • Speed, latency, availability, loss rate,
    transparency, performance guarantees
  • Other
  • Growth potential, commitment periods, management
    time, financial risk, technical risk

16
Extensions of Enterprise Network
  • Intranet vs Extranet
  • Intranet a network designed to serve the
    internal information needs to a single
    organization
  • Extranet connects part of the intranets of
    different organizations and allows for secure
    communications among business partners over the
    Internet using virtual private networks (VPNs)

Extranet Business partners access modules such as
SCM, CRM, and B2B
17
Subnet and Subnet Mask
  • a subnetwork or subnet is a range of logical
    addresses (e.g. IP addresses) that is assigned to
    an organization.
  • Subnet mask is a 32-bit sequence which is used in
    conjunction with IP address to determine whether
    the computer is in the subnet.
  • How? A bitwise and operation

IP address 143.37.100.27 ?
10001111.00100101.01100100.00011011 Subnet mask
255.255.255.0 ? 11111111.11111111.11111111.0000000
0 Bitwise AND operation ?
10001111.00100101.01100100.00000000 143.
37. 100. 0
How many IP addresses can give the same result?
18
Some Other Subnet Masks
  • 11111111.11111111.11111111.00000000
    (255.255.255.0)
  • supports 256 IP addresses
  • 11111111.11111111.11111110.00000000
    (255.255.254.0)
  • supports how many IP addresses?
  • 11111111.11111111.11111111.10000000
    (255.255.255.128)
  • supports how many IP addresses?
  • 255.255.255.254 supports how many IP addresses?
  • If a company has 120 computers, how should the
    network administrator configure the subnet mask?
  • Step1 round up to 2n, (e.g. 27128)
  • Step 2 set all the n digits to be 0 from right
    to left, and the rest digits as 1
  • e.g. 11111111.11111111.11111111.10000000
  • Convert to decimal representation of the network
    address 255.255.255.128

19
Exercises
  • A) what should be the subnet mask if the company
    has 1000 computers?
  • B) Are computer A and B in the same subnet?
  • Computer A 143.37.100.27
  • Computer B 143.37.101.36
  • Subnet Mask 255.255.252.0
  • C) Markstein Hall has both computer labs and
    offices. The network administrator needs to
    separate the computers in the labs and offices
    into two separate subnets. The plan is,
  • Lab computers occupy IP addresses 144.37.2.0127
  • Office computers occupy IP addresses
    144.37.2.128255
  • How should the subnet mask be configured?

20
Assignment the Internet is Broken
  • Read the article and write your thoughts on this
    issue on the blog site.
  • Answer the following questions and email the
    answer to fangfang_at_csusm.edu by Oct 11 before
    class starts
  • What is the basic flaw of the current Internet
    design according to David Clark?
  • Why nowadays, the basic design flaw has become a
    much bigger issue compared to the past?
  • Explain the saying that humans are good at
    ignoring problems use your own words.
  • July 2005, Pew Internet reported ______ of U.S.
    Internet users have reported having spyware or
    adware on their computers merely by visiting
    websites.
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