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Advantages of the Internet
• An Internet connection allows world-wide access to people and
other computers on the network.
• The amount of information available on the Internet is growing
rapidly every day.
• Public servers for various types of work and research are readily
available to those who are connected.
• Public domain files and archives may be downloaded as needed.
• Electronic mail and interactive discussion groups allow users to
communicate and share common interests with other users from
around the world.
• Information is accessible 24 hours a day, 7 days a week.
• Information may be accessed within seconds of release, totally
independent of geographical location and time.
• Personal and dynamic channel of contact with clients, customers,
employees and vendors.
• An established Internet presence gives the user access to the
Internet as a new mass communications medium. By taking the lead
in quickly employing the tools of this new information technology,
your business will gain enormous advantage in the worldwide
marketplace.
Basic Networking Concepts
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What is a network?
What is a Protocol?
Types of Networks
Network Components
What is a Network?
• Two or more computers connected
together
• Communication and sharing
• Hardware and software
• Interoperable
A network is a group of computers
that are able to communicate with
one another and share data, files,
programs, and operations.
• The computers in a network are connected via
hardware and software.
• The hardware is what physically connects the
computers in the network together. For example:
telephone lines, fiber-optic cables, routers and
gateways, and the computers themselves.
• The software is what enables us to use the
hardware for communication and exchanging
information.
• Just as your brain tells your body parts how to
function and work together, the software governs
the way computers in the network communicate
with each other and perform functions.
• Software that enables networking follows a set
of rules that are generally referred to as a
protocol.
• Networks can be interoperable.
This means that different types of computers,
using different operating systems, can be
connected, communicate with each other, and
share information - as long as they follow the
network protocols.
In Summary:
A network is a group of two or more
computers, connected together through a
physical infrastructure, that are able to
communicate and exchange information
because they agree to use software that
observes the same set of rules, or
protocol.
What is a protocol?
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Rules for communication
Description
Format and method
Understood by different types of
computers
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Topics Covered
History of the Internet
Fundamentals
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Packet Routing
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IP, ICMP, UDP, TCP, ARP/RARP;
IP over serial lines: PPP and SLIP
Domain Name Service Overview
User-Level Protocols
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Basic, static, dynamic; Routing protocols; Subnetting
Internet Protocol Suite (TCP/IP)
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Encapsulation and layering; Internet Protocol (IP) layer model; IP addresses
SMTP and electronic mail; NNTP and Usenet News;
FTP and Anonymous FTP; Telnet; Gopher; Archie;
WAIS; HTTP/HTML
The World Wide Web
Service Providers: How to get on board
Internet Culture and "Netiquette"
Future of the Internet
• A protocol is a standard set of rules that
determines how computers communicate
with each other across networks.
• A network is two or more computers that
are physically connected to each other
and able to share information.
• When computers communicate with one
another, they exchange a series of messages.
• To understand and act on these messages,
computers must agree on what a message
means.
• Examples of messages include establishing a
connection to a remote machine; sending or
receiving e-mail; and transferring files and data.
A protocol describes:
– the format that a message must take, and
– the way in which computers must exchange a
message
within the context of a particular activity,
such as sending messages across
networks, exchanging e-mail, establishing
remote connections, or transferring files.
• Think of an electronic mail message. Both
the format of the electronic mail message
and the way that it is transmitted across
the network are described and governed
by a protocol.
• Protocols ensure that electronic mail
messages are correctly formatted and
transmitted from the originating computer
to the destination computer.
• A comparison can be made to the rules that
govern how letters are handled by the post
office:
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• There are different protocols for different types of network services.
For example, the Internet is based on the TCP/IP suite, or family, of
protocols.
• Some of the protocols used on the Internet are:
• Simple Mail Transfer Protocol (SMTP) - to send and receive
electronic mail
• File Transfer Protocol (FTP) - to transfer files between computers
• Hypertext Transfer Protocol (HTTP) - to transmit information on the
World Wide Web
• Network News Transfer Protocol (NNTP) - to transmit network news
In Summary:
• A protocol is a standard set of rules that governs how
computers communicate with each other. Protocols
describe both the format that a message must take and
the way in which messages are exchanged between
computers.
• Different types of computers are able to communicate
with each other - in spite of their differences - when they
agree to use a protocol that offers a standard format and
method for communication. Some of the protocols used
on the Internet are TCP/IP, SMTP, FTP, HTTP, and
NNTP.
Network Types
• Local Area Network
• Metropolitan Area Network
• Wide Area Network
Network Components
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Computer
Server/Gateway
NIC
Ethernet
Hub
Router
DSU/CSU
Server / Gateways
• In client/server architecture, a server is a single, highpowered machine with a large hard disk set aside to
function as a file server for all the client machines in the
network
– A server could function as a file server, Web server, Mail server,
FTP server, News server, and many other applications.
• A Gateway is a computer that performs protocol
conversion between different types of networks or
applications.
– For example, a gateway can connect a personal computer LAN to
a mainframe network. An electronic mail gateway converts
messages from two or more different e-mail standards.
Network Interface Card
• The network interface card (NIC) provides the physical
connection between the network and the computer
workstation.
• Most NICs are internal, with the card fitting into an
expansion slot inside the computer. Some computers,
such as Mac Classics, use external boxes which are
attached to a serial port or a SCSI port. Laptop
computers generally use external LAN adapters
connected to the parallel port or network cards that slip
into a PCMCIA slot.
• Network interface cards are a major factor in determining
the speed and performance of a network. It is a good
idea to use the fastest network card available for the type
of workstation you are using.
•The three most common network interface connections
are
–Ethernet cards,
–LocalTalk connectors, and
–Token Ring cards.
According to a International Data Corporation study,
Ethernet is the most popular, followed by Token Ring and LocalTalk
(Sant'Angelo, R. (1995).
NetWare Unleashed, Indianapolis, IN: Sams Publishing).
The network interface card (NIC) provides the physical connection
between the network and the computer workstation.
Most NICs are internal, with the card fitting into an expansion slot
inside the computer.
Some computers, such as Mac Classics, use external boxes which
are attached to a serial port or a SCSI port. Laptop computers
generally use external LAN adapters connected to the parallel port or
network cards that slip into a PCMCIA slot.
• Network interface cards are a major factor in
determining the speed and performance of a
network. It is a good idea to use the fastest
network card available for the type of
workstation you are using.
• The three most common network interface
connections are Ethernet cards, LocalTalk
connectors, and Token Ring cards. According to
a International Data Corporation study, Ethernet
is the most popular, followed by Token Ring and
LocalTalk (Sant'Angelo, R. (1995). NetWare
Unleashed, Indianapolis, IN: Sams Publishing).
Ethernet
• Local area network (LAN) developed by Xerox, Digital
and Intel.
• It connects up to 1,024 nodes in a bus topology at 10
Mbits per second over twisted pair, coax and optical
fiber.
• Faster Ethernets are coming, including Fast Ethernet,
which runs at 100 Mbits per second, and switched
Ethernet, which gives each user a 10 Mbits/sec
channel.
• Ethernet is the most widely used LAN. Token Ring is
next.
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Standard Ethernet, or "Thick Ethernet" requires a thicker coax cable, but
can run as far as 1,640 feet without using repeaters.
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Attachment is made by clamping a transceiver, which is cabled to the
adapter card, onto the main bus cable.
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Thin Ethernet, also "ThinNet" and "CheaperNet" uses a thinner, lessexpensive coax that is easier to daisy chain together using T-type BNC
connectors. The transceivers are built into the adapter cards.
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Twisted pair Ethernet allows installed telephone wire to be used, and Fiber
Optic Ethernet is impervious to external radiation.
Both use a star topology for easier debugging of failed nodes. Ethernet is a
data link protocol and functions at the data link and physical levels of the
OSI model (1 and 2).
It uses the CSMA/CD access method and conforms to the IEEE 802.3
standard.
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Hub
• Central connecting device for communications lines in a
star topology. "Passive hubs" add nothing to the data
being transmitted.
• "Active hubs" regenerate signals and may monitor traffic
for network management. "Intelligent hubs" are
computers that provide network anagement and may also
include bridging, routing and gateway capabilities.
• The hub's star topology improves troubleshooting over
bus topology, in which all nodes are connected to a
common cable.
• Hubs can be added to Ethernet (bus) networks for
improved network anagement. Both hubs and routers
may be inserted into the middle of a network in order to
improve performance and network management.
Router
• Computer system that routes messages from one LAN
(local area network) to another.
• It is used to internetwork similar and dissimilar networks
and can select the most expedient route based on traffic
load, line speeds and costs and network failures.
• Routers maintain address tables for all nodes in the
network and work at OSI layer 3.
• Routers are used to break apart the LAN into smaller
LANs for improved security, troubleshooting and
performance.
• Routers with high-speed (gigabit) buses may serve as an
internet backbone, connecting all networks in the
enterprise.
DSU/CSU
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(Digital (or Data) Service Unit/Channel Service Unit) Pair of
communications devices that connect an inhouse line to an external
digital circuit (T1, DDS, etc.).
It is similar to a modem, but connects a digital circuit rather than an
analog one.
The CSU terminates the external line at the customer's premises.
It also provides diagnostics and allows for remote testing.
If the customer's communications devices are T1 ready and have
the proper interface, then the CSU is not required, only the DSU.
The DSU does the actual transmission and receiving of the signal
and provides buffering and flow control.
The DSU and CSU are often in the same unit.
The DSU may also be built into the multiplexor, commonly used to
combine digital signals for high-speed lines.
What is TCP/IP?
• A suite of protocols
• Rules for sending and receiving data across
networks
• Addressing
• Management and verification
• TCP/IP stands for Transmission Control
Protocol/Internet Protocol.
TCP/IP is actually a collection of protocols,
or rules, that govern the way data travels
from one machine to another across
networks.
The Internet is based on TCP/IP.
• TCP/IP has two major components: TCP and IP.
• IP:
• envelopes and addresses the data
enables the network to read the envelope and
forward the data to its destination
defines how much data can fit in a single
"envelope" (a packet)
• The relationship between data, IP, and networks
is often compared to the relationship between a
letter, its addressed envelope, and the postal
system.
• TCP:
• breaks data up into packets that the network can
handle efficiently
verifies that all the packets arrive at their destination
"reassembles" the data
• TCP/IP can be compared to moving across country.
• You pack your house in boxes and put your new address
on them.
The moving company picks them up, makes a list of the
boxes, and ships them across country along the most
efficient route - this may mean putting your dishes and
your bedroom furniture on different trucks.
Your belongings arrive at your new address. You consult
your list to make sure that everything you shipped has
arrived (in good shape), then you unpack your boxes
and "reassemble" your house.
In Summary:
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TCP/IP is a suite, or family, of protocols that govern the
way data is transmitted across networks.
TCP/IP protocols work together to break the data into
small pieces that can be efficiently handled by the
network, communicate the destination of the data to the
network, verify the receipt of the data on the other end of
the transmission, and reconstruct the data in its original
form.
What is an IP Address?
• A way to identify machines on the Internet
• A number
• Unique
• Global
• Standardized
• If you want to connect to another computer, transfer files
to or from another computer, or send an e-mail message,
you first need to know where the other computer is - you
need the computer's "address."
An IP (Internet Protocol) address is an identifier for a
particular machine on a particular network; it is part of a
scheme to identify computers on the Internet.
IP addresses are also referred to as IP numbers and
Internet addresses.
• An IP address consists of four sections
separated by periods.
Each section contains a number ranging
from 0 to 256.
Example = 198.41.0.52
• These four sections represent both the machine
itself, or host, and the network that the host is
on.
The network portion of the IP address is
allocated to Internet Service Providers (ISPs) by
the InterNIC, under authority of the Internet
Assigned Numbers Authority (IANA).
ISPs then assign the host portion of the IP
address to the machines on the networks that
they operate.
• Which sections of the IP address represent the network
and which sections represent the machine will depend
on what "class" of IP address is assigned to a network.
There are 5 classes of IP addresses: Class A, Class B,
Class C, Class D, and Class E.
Classes correspond either to the size of the network (the
number of hosts that the network can support) or are
reserved for specific purposes, such as multicasting and
experimentation.
• The diagram below compares Class A, Class B
and Class C IP addresses. The blue numbers
represent the network and the red numbers
represent hosts on the network. Therefore, a
Class A network can support many more hosts
than a Class C network.
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Class A Networks
• Class A networks may have up to 16 million hosts within
the network.
• If the first bit is set to 0, then the next 7 bits are the
network number, and the remaining 24 bits are the host
number.
• This allows up to 127 Class A networks. A value of 127
in the first field is reserved and is called the loopback.
• A loopback refers to an interface that allows a host to
send packets to itself.
• This address is commonly 127.0.0.1.
Class B Networks
• Class B networks may have up to 65,000 hosts.
• If the first two bits are 10, then the next 14 bits
are the network number and the remaining 16
bits are the host number. This allows 16,384
Class B networks.
Class C Networks
• Class C networks may have up to 254 hosts. If
the first 3 bits are 110, then the next 21 bits are
the network number and the remaining 8 bits are
the host number. This allows up to 2,097,152
Class C networks.
In Summary:
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An IP address is a unique, numeric identifier used to
specify a particular host on a particular network, and is
part of a global, standardized scheme for identifying
machines that are connected to the Internet. IP
addresses consist of four numbers between 0 and 256,
separated by periods, which represent both the network
and the host machine.
The InterNIC, under the authority of the Internet
Assigned Numbers Authority (IANA), allocates the
network portions of IP addresses to Internet Service
Providers (ISPs); ISPs are responsible for assigning the
host portion of the IP address to machines within their
local networks.
• IP addresses are unique.
No two machines can have the same IP
number.
IP addresses are also global and standardized.
All machines connected to the Internet agree to
use the same scheme for establishing an
address.
• IP Addresses - An IP address is a unique number
assigned to a host on a network.
• IP addresses are 32 bits, divided into four 8-bit fileds.
• Each 8-bit field, or octet, is represented by a decimal
number between 0 and 255, seperated by periods.
• For example, 129.150.182.31.
• Each IP address identifies a network and a unique host
on that network.
• The value of the first field determines which portion of
the IP address is the network number and which portion
is the host number.
• The network numbers are divided into 4 classes: Class
A, B, C, and D.