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					Network Fundamentals
        Part 1

           CS 1
       Rick Graziani
      Cabrillo College
What is
•   Communication!

•   An interconnection of
    computers and other
    devices including:
     – Client computers
     – Servers (computers)
     – Network Devices
        • Hubs and Switches
        • Routers
        • Firewall

Rick Graziani graziani@cabrillo.edu   2
Most successful networking applications?

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What is in a network?

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What is a network?

•   A computer network is a series of computers and other devices
    interconnected by communication paths.
•   Computer networks include: LANs and WANs

Rick Graziani graziani@cabrillo.edu                                      5
Ethernet LANs

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LAN – Local Area Network

•   LAN (Local Area Network) - A network connecting
    computers at a single site

Rick Graziani graziani@cabrillo.edu                   7
LAN – Local Area Network

•   A LAN:
     – Operates within a limited geographical area
     – Controlled by local administration
     – Allows local users to:
        • Share printers
        • Access local file servers with software and data
        • Access the Internet

Rick Graziani graziani@cabrillo.edu                          8
Ethernet LANs

•   The most common LAN technology is Ethernet.
•   Ethernet allows computers, printers, and other devices, “in the same
    network”, to be able to communicate.
•   For devices to be able to communicate with each other over an
    Ethernet network, they must be configured with:
     – IP Address and Subnet Mask on the same network
     – What??? (We will discuss this shortly)

Rick Graziani graziani@cabrillo.edu                                        9
Creating an Ethernet Network
•   To start, your computer must have an Ethernet Network Interface Card
•   Ethernet NICs have an RJ-45 interface or port.

Rick Graziani graziani@cabrillo.edu                                        10
Creating an Ethernet Network

•   Hubs and Switches are used to connect computers,
    printers and other devices in the Ethernet LAN.

Rick Graziani graziani@cabrillo.edu                    11
Creating an Ethernet Network

•   Ethernet cables, i.e. Cat-5 or Cat-6 cables (Category 5,
    Category 6) are used to connect computers to the hubs
    and switches.
•   Cat-5 cable connects computer NIC to hub or switch.

Rick Graziani graziani@cabrillo.edu                            12
Creating an Ethernet Network

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Configuring IP (Internet Protocol)

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IP Configuration

•   To communicate with other computers
    on your network you need to properly
     – IP Address (of your computer)
     – Subnet Mask (of your computer)
•   To communicate with computers
    outside your network you need to
    properly configure:
     – Default Gateway IP Address
•   To be able to use domain names, like
    www.cabrillo.edu, instead of IP
    addresses you need to properly
     – DNS (Domain Name System)
       Server IP Address

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    IP Configuration: IP Address & Mask
                                                I am part of the
•   To communicate with other computers         network!
    on your network you need to properly
     – IP Address (of your computer)
     – Subnet Mask (of your computer)
•   IP – Internet Protocol
•   IP Address is the unique address of your
    computer on your network.
•   Subnet Mask is used by your computer
    to figure out what network it belongs to.
•   Analogy:
     – The Mask tells us which part of
         RICKGRAZIANI is the first name (F)
         and which part is the last name (L).

    Rick Graziani graziani@cabrillo.edu                                        16
IP Configuration: Default Gateway

•   To communicate with computers
    outside your network you need to
    properly configure:
     – Default Gateway IP Address

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 IP Configuration: Default Gateway

 •   Default Gateway or Router: This is the device that connects your
     network to other networks, including the Internet.

DSL or Cable Modem port                Switch ports that connect to
that connects to your                  computers on your LAN
Internet Service Provider
 Rick Graziani graziani@cabrillo.edu                                    18
   IP Configuration: Default Gateway
   •   Any information that needs to be sent to IP Addresses outside your
       network is sent to the Default Gateway or Router.                                              To the Internet


   Rick Graziani graziani@cabrillo.edu                                      19
IP Configuration: DNS

•   To be able to use domain names,
    like www.cabrillo.edu, instead of IP
    addresses you need to properly
      – DNS (Domain Name System)
        Server IP Address


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    IP Configuration: DNS
•    You could use IP Addresses when accessing other computers, but we
     would rather use names (domain names).

    Rick Graziani graziani@cabrillo.edu                                  21
IP Configuration: DNS

•   Computer networks only understand IP Addresses such as:
•   Computer networks do not understand domain names such as:
      – www.yahoo.com
      – A domain name is a name that is entered into a computer (e.g. as
        part of a website or other URL, or an email address) and then
        looked up in the global [Domain Name System] which informs the
        computer of the IP address(es) with that name. (Wikipedia.com)
•   People are better with names than numbers, so we would rather use
    names when:
      – Accessing a web page: www.yahoo.com
      – Emailing a friend: Rick.Graziani@cabrillo.edu
•   DNS (Domain Name System) servers (computers) are used to
    translate domain names to IP Addresses.

Rick Graziani graziani@cabrillo.edu                                        22
IP Configuration: DNS

Hey,, what is the IP
Address for www.yahoo.com?

                              It is

                       please send me your
                       web page.
                                       here is my web page.

 Rick Graziani graziani@cabrillo.edu                          23
IP Configuration: DNS

•   The details of how DNS works.
•   If your DNS server does not know the answer, it will find out for you.

Rick Graziani graziani@cabrillo.edu                                          24
How do I view/edit this information on my computer?

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How do I view/edit this information on my computer?

                                       3. TCP/IP, Properties
                                       Left click

1. Right click

                                  2. Right click
 Rick Graziani graziani@cabrillo.edu                           26
How do I view/edit this information on my computer?

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Setting the IP Configuration Information

•   IP information can be configured:
     – Statically
     – Dynamically
         • Using a DHCP (Dynamic Host Configuration
           Protocol) Server

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IP Configuration: Static Configuration
•   Static configuration is when the user or administrator of the computer
    configures the IP Address, Subnet Mask, Default Gateway and DNS
    Server information.

Rick Graziani graziani@cabrillo.edu                                      29
IP Configuration: Dynamic Configuration

•   Dynamic configuration is when the IP Address, Subnet Mask, Default
    Gateway and DNS Server information is obtained automatically from a
    DHCP (Dynamic Host Configuration Protocol) Server.

Rick Graziani graziani@cabrillo.edu                                   30
IP Configuration: Dynamic Configuration

                                                   I’m booting up, if there is a DHCP
                                                   Server out there, I need my IP
                                                   Configuration Information!


                            Here is your IP
                            Address, Subnet
                            Mask, IP Address for
                            the Default Gateway
                            (router), and IP
                            Address for the DNS

 Rick Graziani graziani@cabrillo.edu                                                    31
The Internet and TCP/IP

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What is the

•   The Internet was originally designed by DARPA (Defense
    Advanced Research Projects Agency) in response to the
    U.S.S.R. launching Sputnik, the first satellite.
•   Out of this came the Internet, a way for computers to
    communicate from different parts of the world.
•   These computers can be any type of computer using any
    type of operating system, as long as they are using the
    protocol TCP/IP.
Rick Graziani graziani@cabrillo.edu                           33
What is TCP/IP? What is a protocol?

                                      The actual letter
                                      (data) is inside
                                      the envelope.

•   A protocol is nothing more than an agreement or rules to
    govern a way of communicating.
•   The sender and receiver, and everyone in between, must
    agree on the rules, the protocol.
Rick Graziani graziani@cabrillo.edu                            34
What is TCP/IP? What is a protocol?

•   Protocol: An agreed form of communications.

Rick Graziani graziani@cabrillo.edu               35
TCP/IP Transmission Control Protocol /
Internet Protocol

    Source IP Address:
                                          Destination IP Address

                                            This is known as
                                            an “IP Packet”

•      TCP/IP is a suite of protocols.
•      IP (Internet Protocol) is used for sender and receiver
•      Every computer on the Internet or a network must have an
       IP address to communicate.
    Rick Graziani graziani@cabrillo.edu                           36
                                       Source IP Address:
                                               Inside envelope:
                                                                     Request for web
                                           Destination IP Address:                     


                                        Source IP Address:
                                                                       Inside envelope:
                                                                       Web page
                                             Destination IP Address:

 Rick Graziani graziani@cabrillo.edu                                                      37
Pinging another computer (FYI)

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Connecting Networks with Routers

•   The Internet, or simply the Net, is the publicly accessible
    worldwide system of interconnected computer networks.
•   Routers are network devices that connect two or more
    networks together.
•   Routers connect networks.
Rick Graziani graziani@cabrillo.edu                               39
Connecting Networks with Routers

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   DSL or Cable Modem: No Router

   •    Routers can help protect your DSL or Cable Modem
                                                  Public Address

Hacker can only get to public
address and not private address

                              DSL or Cable

    Rick Graziani graziani@cabrillo.edu                       41
DSL or Cable Modem: With a Router

•   The router is between your
    computer (LAN) and your DSL
•   The router is between you and
    the Internet.


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   DSL or Cable Modem: With a Router
    When using NAT (Network
    Address Translation, the
    Router helps hide your
    network from attackers.
                                         Private Address
     Public Address


Hackers can only get to public
addresses and not private addresses
   Rick Graziani graziani@cabrillo.edu                     43
Networks: Bandwidth and Connections

•   Local Area Networks
•   DSL
•   Cable Modem
•   Leased Lines
•   Modems

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•   Bandwidth - The amount of information that can flow through a
    network connection in a given period of time.
•   Usually measured in bits per second (bps)
     – bps: bits per second
     – Kbps: thousands of bits per second
     – Mbps: millions of bits per second

Rick Graziani graziani@cabrillo.edu                                 45
LANs: 10 Mbps or 100 Mbps (or more)

Connection to ISP (Internet Service Provider)
Note: Bandwidth depends up provider, location, and service plan.
• DSL:
   – Download: 600 Kbps to 1.5 Mbps (or more)
   – Upload: 256 Kbps (or more)
• Cable Modem:
   – Download: 600 Kbps to 3.0 Mbps (or more)
   – Upload: 256 Kbps (or more)
• Telephone Modem:
   – Up to 53 Kbps
• Leased Lines
   – T1: 1.5 Mbps
   – T3: 44.736 Mbps

Rick Graziani graziani@cabrillo.edu                                46
Connection to ISP: DSL

•   DSL (digital subscriber line) is a
    very high-speed connection that
    uses the same wires as a regular
    telephone line.

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DSL: From HowStuffWorks.com

•   Advantages of DSL:
     – You can leave your Internet connection open and still use the
       phone line for voice calls.
     – The speed is much higher than a regular modem
     – DSL doesn't necessarily require new wiring; it can use the phone
       line you already have.
     – The company that offers DSL will usually provide the modem as
       part of the installation.
•   But there are disadvantages:
     – A DSL connection works better when you are closer to the
       provider's central office.
     – The connection is faster for receiving data than it is for sending
       data over the Internet.
     – The service is not available everywhere.

Rick Graziani graziani@cabrillo.edu                                         48
Connection to ISP: Cable Modem

•   A cable modem is a special type of modem that is
    designed to modulate a data signal over cable television

Rick Graziani graziani@cabrillo.edu                            49
Connection to ISP: Telephone Modem

•   A telephone modem
    is used to modulate
    and demodulate
    (translate) between the
    digital signals of the
    computer and the
    analog signals over
    the telephone line.
•   Maximum bandwidth is
    only 53 Kbps.
•   Need separate phone
    line if you want to use
    the phone while
    connected to the
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IPv4 and IPv6 Addressing

           No handout
• 32 bits or 4 bytes
      • 4,200,000,000 possible addressable nodes
      • 4 billion possible addresses
Who assigns IP Network Addresses?

•    Internet Assigned Numbers Authority (IANA)
     (http://www.iana.net) is the master holder of the IP
•    Today, the remaining IPv4 address space has been
     allocated to various other registries to manage for
     particular purposes or for regional areas.
      – Regional Internet Registries (RIRs)

Regional Internet Registries (RIR)

•    The 5 Regional Internet Registries (RIRs) are:
      – AfriNIC (African Network Information Centre) - Africa Region
      – APNIC (Asia Pacific Network Information Centre) - Asia/Pacific Region
      – ARIN (American Registry for Internet Numbers) - North America Region
      – LACNIC (Regional Latin-American and Caribbean IP Address Registry) -
        Latin America and some Caribbean Islands http://www.lacnic.net
      – RIPE NCC (Reseaux IP Europeans) - Europe, the Middle East, and Central
54      Asia http://www.ripe.net
ISP (Internet Service Providers)

•     Most companies or organizations obtain their IPv4
      address blocks from an ISP (Internet Service
Private IPv4

  •    In early 1990’s IANA and IETF recognized that the we were
       running out of IPv4 addresses.
  •    Long term solution: IPv6
  •    Short Term solution:
        – Private Addresses and Network Address Translation
Private IPv4

  •    Private Addresses
        – to ( /8)
        – to ( /12)
        – to ( /16)
  •    The addresses will not be routed in the Internet
        – Need NAT (Network Address Translation)
NAT – Network Address Translation
PAT – Port Address Translation

  Private Addresses                   Public Address

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•   Monday, January 31, 2011 IANA allocated two blocks of IPv4
    address space to APNIC, the RIR for the Asia Pacific region
    (39/8 and 106/8)
•   IANA has no more IPv4 network addresses to allocate
•   RIR’s Remaining IPv4 addresses
              One Hex digit = 4 bits


   2001 : 0DB8 : AAAA : 1111 : 0000 : 0000 : 0000 : 0100

   16 bits   16 bits   16 bits   16 bits   16 bits   16 bits   16 bits   16 bits

§ IPv6 addresses are 128-bit addresses represented in:
  § Eight 16-bit segments or “hextets” (not a formal term)
  § Hexadecimal (non-case sensitive) between 0000 and
  § Separated by colons
§ How many addresses does 128 bits give us?
 § 340 undecillion addesses or …
 § 340 trillion trillion trillion addresses or …
 § “IPv6 could provide each and every square micrometer of the earth’s
   surface with 5,000 unique addresses. Micrometer = 0.001 mm or
   0.000039 inches” or….
 § “A string of soccer balls would wrap around our universe 200 billion
When will RIR’s run out of IPv4 Addresses?

Rick Graziani graziani@cabrillo.edu      62
Why do we
need to move
to IPv6?

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Network Fundamentals
        Part 1

           CS 1
       Rick Graziani
      Cabrillo College

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