Network Fundamentals Part 1

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Network FundamentalsPart 1

• CS 1
• Rick Graziani
• Cabrillo College

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What is networking?

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

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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

http//www.albany.edu
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Ethernet LANs
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LAN Local Area Network

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

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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

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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)

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Creating an Ethernet Network

• To start, your computer must have an Ethernet
  Network Interface Card (NIC).
• Ethernet NICs have an RJ-45 interface or port.

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Creating an Ethernet Network

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

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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.

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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 configure
• 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 configure
• DNS (Domain Name System) Server IP Address

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IP Configuration IP Address Mask
I am part of the 192.168.1.0 network!

• To communicate with other computers on your
  network you need to properly configure
• 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
• Name RICKGRAZIANI
• Mask FFFFLLLLLLLL
• The Mask tells us which part of RICKGRAZIANI is
  the first name (F) and which part is the last
  name (L).

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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.

Switch ports that connect to computers on your LAN
DSL or Cable Modem port that connects to your
Internet Service Provider
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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
192.168.1.10
192.168.1.1
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IP Configuration DNS

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

207.62.87.54
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IP Configuration DNS

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

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IP Configuration DNS

• Computer networks only understand IP Addresses
  such as
• 66.94.230.47
• 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_at_cabrillo.edu
• DNS (Domain Name System) servers (computers) are
  used to translate domain names to IP Addresses.

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IP Configuration DNS
Hey, 207.62.87.54, what is the IP Address for
www.yahoo.com?
It is 66.94.230.47
Hey, 66.94.230.47, please send me your web page.
Yahoo Web Server
Here, 192.168.1.10, here is my web page.
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IP Configuration DNS

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

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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
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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.

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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.

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IP Configuration Dynamic Configuration
Im booting up, if there is a DHCP Server out
there, I need my IP Configuration Information!
DHCP Server
Here is your IP Address, Subnet Mask, IP Address
for the Default Gateway (router), and IP Address
for the DNS Server!
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The Internet and TCP/IP
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What is the Internet?

• 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.

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What is TCP/IP? What is a protocol?
The actual letter (data) is inside (encapsulated)
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.

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What is TCP/IP? What is a protocol?

• Protocol An agreed form of communications.

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TCP/IP Transmission Control Protocol / Internet
Protocol
Source IP Address 192.168.1.10
Destination IP Address 66.94.230.47
This is known as an IP Packet

• TCP/IP is a suite of protocols.
• IP (Internet Protocol) is used for sender and
  receiver addressing.
• Every computer on the Internet or a network must
  have an IP address to communicate.

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Source IP Address 192.168.1.10
Inside envelope Request for web page
Destination IP Address 66.94.230.47
192.168.1.10
66.94.230.47
Yahoo Web Server
Source IP Address 66.94.230.47
Inside envelope Web page
Destination IP Address 192.168.1.10
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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.

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Connecting Networks with Routers
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DSL or Cable Modem No Router

• Routers can help protect your DSL or Cable Modem
  Network.

204.180.205.1 Public Address
Hacker can only get to public address and not
private address
DSL or Cable Modem
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DSL or Cable Modem With a Router

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

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.
192.168.1.10 Private Address
204.180.205.1 Public Address
Internet
Hackers can only get to public addresses and not
private addresses
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Networks Bandwidth and Connections

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

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Bandwidth

• 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

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Bandwidth

• 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

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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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Ricks IP Packet Analogy

• Routers only need to care about where they send
  the packet next.
• What is the next-hop router I need to send this
  packet to?

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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.

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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 infrastructure.

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Connection to ISP Cable Modem

• From www.linuxports.com
• Cable Modem Advantages
• Fast data transfers, up to 30 Mbps if using a
  100BaseT NIC
• Competitive pricing against competing
  technologies
• Easy to install - home prewired
• Cable Modem Disadvantages
• The available bandwidth depends on the number of
  users on the local cable TV line segment.
• There is an asymmetrical transfer rate. Upstream
  is slower than downstream.
• There can be a bottleneck at the communication
  server at the head end.

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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 Internet

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Connection to ISP Leased Lines

• Many companies and schools use leased lines to
  connect to their ISP.
• These are dedicated circuits between the provider
  and the customer.
• These include
• T1 1.5 Mbps
• T3 44.736 Mbps

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Network FundamentalsPart 1

• CS 1
• Rick Graziani
• Cabrillo College