Lesson05

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Lesson 5

Networking BASICS

1

Networking BASICS

Protocols and
Network
Software


Unit 2

Lesson 5

Lesson 5

Networking BASICS

2

Objectives


Explain the OSI reference model.


Define protocol.


List and describe the functions of
TCP/IP.


Explain the functions of client and
server network software.

Lesson 5

Networking BASICS

3

OSI Reference Model



It was created by the International
Standards Organization (ISO).



It breaks network functions into seven
layers.


It illustrates how each layer provides
specific services and shares with the
layers above and below.

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Networking BASICS

4

OSI Reference Model



The “flow” between layers goes
down

when data is sent and
up

when data is received.


The function that each layer
performs is to add or remove
network information on a
packet.

Lesson 5

Networking BASICS

5

OSI Reference Model

Lesson 5

Networking BASICS

6

OSI Reference Model



Physical


Data Link


Network


Transport


Session


Presentation


Application


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Networking BASICS

7

Protocol
s


Protocols are rules for communication.


A combination of protocols is called a
protocol stack or protocol suite.


A connectionless protocol assumes that
packets will arrive.


A connection
-
oriented protocol
establishes a link between devices.

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Networking BASICS

8

TCP/IP



Transmission Control
Protocol/Internet Protocol (TCP/IP)


It is the most common protocol
suite used today for LANs as well
as the Internet.


It is composed of several different
protocols.

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Networking BASICS

9

TCP/IP

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Networking BASICS

10

Internet Protocol (IP)



The hosts on a TCP/IP network use a
logical address.


This logical address, called the IP
address, is assigned to each host.


IP is responsible for the addressing of
packets.


Lesson 5

Networking BASICS

11

IP Addressing



An IP address is four bytes (octets).
Each contains eight bits (total of 32
bits in length).


Each octet is a number from 1 to
254.


IP addresses are usually given as
dotted decimal notation.

Lesson 5

Networking BASICS

12

IP Addressing

Lesson 5

Networking BASICS

13

Classes



There are five classes of IP ad
-
dresses, Class A through Class E.


Each class uses a different com
-
bination of octets to indicate the
number of the network and the
number of the host.

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Networking BASICS

14

Class A


The first octet indicates the
number of the network, and the
remaining three octets indicate
the number of the host.


126 network addresses


16 million hosts per network


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Networking BASICS

15

Class A

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Networking BASICS

16

Class B


The first two octets indicate the
network number, and last two
octets indicate the host.


It is intended for organizations that
have more networks, but not as
many hosts per network.


16,384 network addresses


65,534 hosts per network

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Networking BASICS

17

Class B

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Networking BASICS

18

Class C



The first three octets are for the network
number, and last octet is for the host.


It is intended for organizations that have
many networks, but few hosts per
network.



Over

2

million

network

numbers



254

hosts

per

network

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Networking BASICS

19

Class C

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Networking BASICS

20

Other Classes


Class D and Class E
addresses are for special
uses.



Special IP addresses are
known as private addresses.


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Networking BASICS

21

Subnet Mask



A subnet mask

is used to separate
a network number from the host
number in an IP address.


1 represents a network and 0
represents a host.


Subnet masks are also used to
subdivide networks.

Lesson 5

Networking BASICS

22

Transmission Control
Protocol(TCP)



TCP is responsible for the reliable
transmission of data from one host
to another.


It is based on port numbers.


The combination of an IP address
and a port number is called a
socket.

Lesson 5

Networking BASICS

23

IPv6



The current version of the IP protocol is
IPv4.


The next generation of the IP protocol is
called IPv6.


340 trillion, trillion, trillion addresses


It uses a fixed packet header size of 24
bytes so that information always
appears in the same place.


Lesson 5

Networking BASICS

24

Network Software



Software that runs on the client


Software that runs on the server

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Networking BASICS

25

Client Software


Network Driver Interfaces

-

“Middleman” between NIC and client’s
operating system software.


Redirector

-

Sends request to network.


Designator

-

Keeps track of which drive
letter is associated with which network
device.

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Networking BASICS

26

Server Software


Network operating system

-

Manages and coordinates users
and requests across the network.


Directory service

-

Database
stored on the network containing
information about users and
privileges to resources.

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Networking BASICS

27

Summary


The International Standards Organization (ISO) released a set
of specifications that was intended to describe how dissimilar
computers could be connected together on a network. Called
the Open Systems Interconnections (OSI) reference model, it
illustrates how a network device prepares data for delivery over
the network to another device and how data is handled when it
is received. The key to the OSI reference model is layers. The
model breaks networking steps down into a series of seven dif
-
ferent layers. Each layer cooperates with the layer immediately
above and below it by sending and receiving information.

Lesson 5

Networking BASICS

28

Summary (continued)


The rules for communication between network devices are
known as protocols. These protocols are essential for proper
communication to take place between the OSI reference models
on the network devices. Instead of having just one single proto
-
col, computer networks typically employ several different proto
-
cols that function together. This combination of protocols is
known as a protocol stack or a protocol suite. Protocols use one
of two different methods for delivering data through a network:
connectionless protocols, which place the packets on the net
-
work and then assume that they will arrive at the destination,
and connection
-
oriented protocols, which establish a connection
between the two devices before sending any packets. As each
packet is received, an acknowledgment is sent back to the
sender.

Lesson 5

Networking BASICS

29

Summary (continued)


The most common protocol suite used today for LANs as well as
the Internet is Transmission Control Protocol/Internet Protocol
(TCP/IP). Because it is a suite, TCP/IP is composed of several
different protocols that all function together. Although the
TCP/IP suite is composed of several different protocols, the two
major protocols are those that make up its name, TCP and IP.
The IP is responsible for addressing the packets and sending
them on the correct route to the destination. Each device on a
TCP/IP computer network must have a unique number. Com
-
puters on a TCP/IP network use a logical address instead. This
logical address, called an IP address, is assigned to each host
computer.

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Networking BASICS

30

Summary (continued)


IP addresses are also broken down into groups, called classes:
Class A through Class E. In addition, special IP addresses,
known as private addresses, are used when the computer is not
connected to another network. A subnet mask is used to sepa
-
rate the network number from the host number in an IP address.
Subnet masks are also used to subdivide networks. IP uses
Address Resolution Protocol (ARP) to determine a host’s IP
address.


The Transmission Control Protocol (TCP) portion of the TCP/IP
suite is responsible for the reliable transmission of data from
one host to another. TCP is based on port numbers. A port num
-
ber identifies what program or service on the receiving computer
is being accessed.

Lesson 5

Networking BASICS

31

Summary (continued)


Because TCP/IP is a connection
-
oriented protocol, it establishes
a session, or link, between the sending and receiving devices.
This session is created through a three
-
way handshake be
-
tween the devices. The current version of the IP protocol is ver
-
sion 4, called IPv4. Developed in 1981, long before the Internet
was universally popular, IPv4 has begun to show some weak
-
nesses. The next generation of the IP protocol is IPv6. IPv6
provides several significant improvements. IP addresses under
IPv6 will be 16 bytes long or four times the length of IPv4 ad
-
resses. IPv6 also uses a fixed packet header size of 24 bytes,
so information always appears in the same place. This speeds
up finding information in the packet and processing the packet.

Lesson 5

Networking BASICS

32

Summary (continued)


Software that runs on the client computer performs many differ
-
ent functions that enable the device to function effectively on the
network. The Network Device Interface Specifications (NDIS)
and Open Date
-
link Interface (ODI) specifications outline precise
standards regarding NIC network driver interfaces. Drivers that
follow these standards allow multiple protocols to function simul
-
taneously on a single computer. Client software called a redirec
-
tor works closely with the operating system of a client computer.
When the user gives a command to the computer, the computer
goes first to the client operating system. If that command doesn’t
apply to the client computer, the operating system gives the
command to the redirector, which sends it out to the network. A
designator is designed to keep track of which drive letter is
associated with which network device.

Lesson 5

Networking BASICS

33

Summary (continued)


Server software plays a critical role on a computer network. A
network server uses network operating system (NOS) software.
NOS software manages and coordinates all users and their
requests across the network. A directory service is a database
stored on the network. It contains information about users and
network devices. A directory service also keeps track of the
resources on the network and a user’s privileges to those
resources.