Network Fundamentals
Part 1
CS 1
Rick Graziani
Cabrillo College
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
• To communicate with other computers
•
•
•
•
I am part of the 192.168.1.0
network!
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.
DSL or Cable Modem port
that connects to your
Internet Service Provider
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Switch ports that connect to
computers on your LAN
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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@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
Rick Graziani graziani@cabrillo.edu
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
I’m 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
192.168.1.10
Inside envelope:
Request for web
page
Destination IP Address:
66.94.230.47
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.
204.180.205.1
Public Address
192.168.1.10
Private 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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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: 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
Rick Graziani graziani@cabrillo.edu
DTE
DCE
digital
analog
PSTN
Dial-up network
Modulation
DTE
DCE
digital
analog
PSTN
Dial-up network
Demodulation
GOLDMAN: DATACOMM
FIG.02-14
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IPv4 and IPv6 Addressing
No handout
IPv4
• 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)
•
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(http://www.iana.net) is the master holder of the IP
addresses.
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)
•
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The 5 Regional Internet Registries (RIRs) are:
– AfriNIC (African Network Information Centre) - Africa Region
http://www.afrinic.net
– APNIC (Asia Pacific Network Information Centre) - Asia/Pacific Region
http://www.apnic.net
– ARIN (American Registry for Internet Numbers) - North America Region
http://www.arin.net
– 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
Asia http://www.ripe.net
ISP (Internet Service Providers)
•
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Most companies or organizations obtain their IPv4
address blocks from an ISP (Internet Service
Provider).
Private IPv4
Addresses
•
•
•
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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
(NAT)
Private IPv4
Addresses
•
•
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Private Addresses
– 10.0.0.0 to 10.255.255.255 (10.0.0.0 /8)
– 172.16.0.0 to 172.31.255.255 (172.16.0.0 /12)
– 192.168.0.0 to 192.168.255.255 (192.168.0.0 /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
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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:1111:0000:0000:0000:0100/64
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
FFFF
 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 times!”
When will RIR’s run out of IPv4 Addresses?
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Why do we
need to move
to IPv6?
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Network Fundamentals
Part 1
CS 1
Rick Graziani
Cabrillo College