computer network fundamentals

• 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... IP Configuration• To c

Computer Network

Fundamentals

CS 1 Rick Graziani Cabrillo College

Most successful networking applications?

What is in a network?

Ethernet LANs

LAN – Local Area Network

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

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

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

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.

Creating an Ethernet Network

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

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.

Creating an Ethernet Network

Configuring IP (Internet Protocol)

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)

IP Configuration: IP Address & Mask

• 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: RICK GRAZIANI

– Mask: FFFF LLLLLLLL

– The Mask tells us which part of

RICKGRAZIANI is the first name (F)

and which part is the last name (L)

I am part of the 192.168.1.0 network!

IP Configuration: Default Gateway

• To communicate with computers

outside your network you need to

properly configure:

– Default Gateway IP Address

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

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

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

IP Configuration: DNS

• You could use IP Addresses when accessing other computers, but

we would rather use names (domain names).

– 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.

IP Configuration: DNS

Hey, 207.62.87.54, what is the IP

Address for www.yahoo.com?

Here, 192.168.1.10, here is my web page.

IP Configuration: DNS

• The details of how DNS works.

• If your DNS server does not know the answer, it will find out for you.

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

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

1 Right click

2 Right click

3 TCP/IP, Properties Left click

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

Setting the IP Configuration Information

• IP information can be configured:

Protocol) Server

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.

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.

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!

The Internet and TCP/IP

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

What is TCP/IP? What is a protocol?

• A protocol is nothing more than an agreement or rules to govern

What is TCP/IP? What is a protocol?

• Protocol: An agreed form of communications.

TCP/IP Transmission Control Protocol /

Internet Protocol

• 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.

Source IP Address: 192.168.1.10

Destination IP Address 66.94.230.47

This is known as

an “IP Packet”

Yahoo Web Server

Pinging another computer (FYI)

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.

Connecting Networks with Routers

DSL or Cable Modem: No Router

204.180.205.1 Public Address

Hacker can only get to public

address and not private address

DSL or Cable Modem

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

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

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 DSL or Cable Modem: With a Router

Internet

Networks: Bandwidth and Connections

• Local Area Networks

• DSL

• Cable Modem

• Leased Lines

• Modems

• 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

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)

Connection to ISP: DSL

• DSL (digital subscriber line) is a

very high-speed connection that

uses the same wires as a regular

telephone line

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

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.

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

GOLDMAN: DATACOMM FIG.02-14

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 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)

• The 5 Regional Internet Registries (RIRs) are:

– AfriNIC (African Network Information Centre) - Africa 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

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

ISP (Internet Service Providers)

Private IPv4

Addresses

• In early 1990’s IANA and IETF recognized that the we were running out of IPv4 addresses.

• Long term solution: IPv6

• Short Term solution:

(NAT)

NAT – Network Address Translation

PAT – Port Address Translation

• 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)

 IPv6 addresses are 128-bit addresses represented in:

 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

When will RIR’s run out of IPv4 Addresses?

Why do we

need to move

to IPv6?

Network Fundamentals

Part 1

CS 1 Rick Graziani Cabrillo College