INTRODUCTION TO COMPUTER NETWORK

dingdongboomNetworking and Communications

Oct 27, 2013 (3 years and 8 months ago)

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INTRODUCTION TO COMPUTER NETWORK


PTI 2012


2


06 [ATW]


COMMUNICATION BETWEEN COMPUTER??


Human Communication is need when they are
talk, and interact.


How about Computer??


Are they can
interract

each other?


In what subject?


How can computer interact each other?


What kind of language? (Any role or protocol)?

NODE AND LINK


Yes, they can
interract

each other.


File sharing is one example of it.




Nodes

are often general
-
purpose computers,
like a desktop workstation, a multiprocessor,
tablet or a PC.

NODE AND LINK


Network links are implemented on a variety of
different physical media, including :


twisted pair (the wire that your phone connects to),


coaxial cable (the wire that your TV connects to),


optical fiber (the medium most commonly used for
high
-
bandwidth, long
-
distance links), and


space (the stuff that radio waves, microwaves, and
infrared beams propagate through).

NUMBER, AND DISTANCE OF NODES


See the table below, and of course imagine
that the number of node also increase

LOCAL AREA NETWORK


is a network in which computers are
relatively
close together (like the same office or building).


LAN doesn’t imply that the network is small
(
can contain hundreds of computers).


Usually a LAN is contained within a single
building, but a LAN can extend to several
buildings on a campus.

WIDE AREA NETWORK


is a network that
spans a large geographic
territory,


entire city, region, or even an entire country.


typically used to connect two or more LANs that
are relatively far apart.


For example, a WAN may connect an office in
Bandung with an office in Jakarta.

WIDE AREA NETWORKS


Relation between hosts on LANs and the subnet.

WIDE AREA NETWORKS (2)


A stream of packets from sender to receiver.

METROPOLITAN AREA NETWORK


is a network that’s smaller than a typical WAN
but larger than a LAN.


Typically, a MAN connects two or more LANs
within a same city but are far enough apart that
the networks can’t be connected using a
simple cable or wireless connection.

METROPOLITAN AREA NETWORKS


A metropolitan area network based on cable TV.

INTERNETWORK (INTERNET)


The Internet is a global network connecting millions of
computers.


More than 100 countries are linked into exchanges of
data, news and opinions. (Planet space / Earth)


According to Internet World Stats, as of December 31,
2011 there was an estimated 2,267,233,742 Internet
users worldwide.


The Internet is not synonymous with World Wide Web.


The Internet is a massive network of networks, a
networking infrastructure

NETWORK TOPOLOGY


The shape of how the computers and other
network components are connected to each
other.


Terms :


Node : device that is connected to the network.
Computer, IP TV, Smart phone, Server, etc.


Packet : message that is sent over the network
from one node to another node.

BUS TOPOLOGY


nodes are strung together in a line





Every node on the network can see every packet
that’s sent on the cable.


Each node looks at each packet to determine
whether the packet is intended for it.


If the cable in a bus network breaks, the network
is effectively divided into two networks

STAR TOPOLOGY [1]


each network node is
connected to a central
device called a
hub or a
switch,


If a cable in a star network
breaks :


only the node connected to
that cable is isolated from
the network.


The other nodes can
continue to operate without
interruption

STAR TOPOLOGY [2]


Use Switch to get the “True Star”


Hub :


doesn’t know anything about the computers that are
connected to each of its ports.


the hub sends a duplicate copy of the packet to all its
ports.


Switch :


switch knows which computer is connected to each of
its ports.


when a switch receives a packet it sends only to the
port that the recipient is connected to.

EXPANDING STARS


simple bus or star topology is suitable only for
small networks, with a dozen or so computers


For larger networks, it’s common to create
more complicated topologies that combine
stars and buses


Daisy
-
chaining : a hub or switch is connected to
another hub or switch as if it were one of the
nodes on the star.

RING TOPOLOGY


packets are sent around the circle from
computer to computer.


Each computer looks at each packet to decide
whether the packet was intended for it.


If not, the packet is passed on to the next
computer in the ring.

MESH TOPOLOGY


has multiple connections between each of the
nodes on the network.


advantage of a mesh topology is that if one
cable breaks, the network can use an
alternative route to deliver its packets.

NETWORK HARDWARE AND MEDIA


Many hardware and media is used in networks.
They are :


Network Interface Cards,


Network Cable,


Coaxial Cable,


Twisted
-
Pair Cable,


Hubs and Switches,


Repeater,


Bridge,


Routers, etc.

NETWORK INTERFACE CARDS [1]


NIC : usually a separate adapter card that
slides into one of the server’s motherboard
expansion slots.


Some motherboards have a built
-
in NIC.


NIC must have a connector that matches the
type of cable that you use.
E.g

:


thinnet

cable, use BNC connector.


twisted
-
pair wiring, use RJ
-
45 connector.


Some NIC provide two or three connectors

NETWORK INTERFACE CARDS [2]


NIC is a Physical layer and Data Link layer
device.


NIC establishes a network node, and must have a
physical network address (MAC address).


Every NIC ever manufactured has a unique MAC
address.


For server computers, it makes sense to use
more than one NIC (to handle more traffic).


Some server NICs have two or more network
interfaces built into a single card

NETWORK CABLE


Pick one :


coaxial cable, which resembles TV cable, or


twisted
-
pair cable,
which looks like phone cable.
Twisted
-
pair cable is sometimes called
UTP,
or
10BaseT cable


fiber
-
optic cables that span long distances at high
speeds, or


thick twisted
-
pair bundles that carry multiple sets of
twisted
-
pair cable between wiring closets in a large
building.

COAXIAL CABLE


usually called
thinnet

or sometimes BNC cable,


operates only at 10Mbps (rarely used for new networks),


computers connected with point
-
to
-
point in a bus topology,


T connector is used to connect two cables to the network
interface card.


a terminator
is required at each end of a series


The maximum length is 200 meters (actually, 185 meters)
with 30 computers on one segment.


To span a distance greater, use two or more segments with a
repeater to connect each segment.


Although Ethernet coaxial cable resembles TV coaxial cable,
the two types of cable are not interchangeable

TWISTED
-
PAIR CABLE


Twisted
-
pair cable, or unshielded twisted pair (UTP ).


connect the computers in a star arrangement (needs
Hub or Switch),


UTP cable consists of pairs of thin wire twisted around
each other,


is fine for 100Mbps networks,


UTP connectors are officially called
RJ
-
45 connectors,


Maximum allowable cable length between the hub and
the computer is 100 meters

HUBS AND SWITCHES


Both hubs and switches let you connect using
twisted
-
pair network


HUB

SWITCHES

Physical layer device

Data Link layer device

Doesn’t keep track of which
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able to look into the packets and
examine a critical piece of Data
Link layer information

every packet that arrives at the hub

on any of its ports is automatically
sent out on every other port

Only send to node have
correct

MAC address on specific port

Less secure than switches

Improve the security

REPEATERS


gives your network signals a boost so that the
signals can travel farther,


BRIDGES


Connects two networks so that they act as if
they are one network.


You can think of a bridge as a kind of smart
repeater.

REPEATER

BRIDGES

Listen signal come on one
network, amplify them, and

send
themto

the other cable

Listen to the network and automatically figure
out

the address of each computer on both
side,

Doesn’t pay attention to the
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PROTOCOL


Set of rules that enable effective communications to occur.


example of an everyday protocol: making a phone call.


Pick up a phone, listen for a dial tone. If dial tone didn't exist, (1)
someone is talking on the phone, or (2) something is wrong with
the phone.


When dial tone Exist, dial the number you want to reach. If it is in
the same area code, we can ignore the area number. If it is in a
different area code, dial the area code and the number it self.


If a series of long ringing tones exist, wait until the other person
answers the phone.


If no answer on several time, hang up and try again later.


If we get the answer, begin a conversation.


...

STANDARDS


Standard is an agreed
-
upon definition of a protocol


Many organizations are involved in setting standards for
networking.


American National Standards Institute (ANSI): The official standards
organization in the United States.


Institute of Electrical and Electronics Engineers (IEEE): An international
organization that publishes several key networking standards; in
particular, the official standard for the Ethernet networking system.


International Organization for Standardization (ISO): A federation of
more than 100 standards organizations from throughout the world.


Internet Engineering Task Force (IETF): The organization responsible for
the protocols that drive the Internet.


World Wide Web Consortium (W3C): An international organization that
handles the development of standards for the World Wide Web.

OSI LAYER


Open Systems Interconnection Reference Model, affectionately
known as the OSI model,


Layer

Name

Description

1

Physical

Governs the layout of cables and devices such as
repeaters and hubs.

2

Data Link

Provides MAC addresses to uniquely identify network

nodes and a means for data to be sent over the Physical
layer in the form of packets. Bridges and switches are
layer 2 devices.

3

Network

Handles routing of data across network segments.

4

Transport

Provides for reliable delivery of packets.

5

Session

Establishes sessions between network applications.

6

Presentation

Converts data so that systems that use different data

formats can exchange information.

7

Aplication

Allows applications to request network services.

PHYSICAL LAYER


Bottom layer of the OSI model.


Addresses the physical characteristics of the
network, such as the types of cables used to
connect devices, the types of connectors used,
how long the cables can be, and so on,


Example :
repeater, Network Adapter,

DATA LINK LAYER


Data Link layer is the lowest layer at which meaning is
assigned to the
bits that are transmitted over the network.


Address such as :


the size of each data packet to be sent,


a means of addressing each packet so that it’s delivered to the
intended recipient


Way to ensure that two or more nodes don’t try to transmit data
on the network at the same time.


provides basic error detection and correction to ensure that the
data sent is the same as the data received.


network has an address known as the
Media Access Control
address, or MAC address.

NETWORK LAYER


Network layer handles the task of routing
network messages from one
computer to
another.


The two most popular layer 3 protocols are IP
(paired with TCP) and IPX (paired with SPX).


provide two important functions:


logical addressing and routing.

NETWORK LAYER


LOGICAL ADDRESSING


Logical addresses are created and used by
Network layer protocols such as IP or IPX.


The Network layer protocol translates logical
addresses to MAC addresses


Example, if you use IP as the Network layer
protocol, devices on the network are assigned IP
addresses such as 10.14.4.123

NETWORK

LAYER
-

ROUTING


Routing process came from computer on one
network needs to send a packet to a computer
on another network.


Router is used to forward the packet to the
destination network


TRANSPORT

LAYER


Transport layer is concerned with the
transportation of information from one
computer to another


ensure that packets are transported reliably
and without errors,


divides large messages into smaller packets
that can be sent over the network efficiently.


important feature include
name resolution that
map
www.ittelkom.ac.id

into some address.

SESSION LAYER


Session layer establishes conversations known as
sessions between networked
devices


single session can include many exchanges of data
between the two computers involved in the session,


The session layer allows three types of transmission
modes:


Simplex,
in which data flows in only one direction.


Half
-
duplex,
in which data flows in both directions, but only
in one direction at a time.


Full
-
duplex,
in which data flows in both directions at the
same time.

PRESENTATION LAYER


converting data from one code to another,


apply sophisticated compression techniques so
that fewer bytes of data is sent over the
network,


uncompresses

the data.


can also scramble the data before it is
transmitted and unscramble.

APPLICATION LAYER


Application programs such as Microsoft Office
aren’t
a part
of the Application layer.


Application layer represents the programming interfaces that
application programs request network services.


Better
-
known Application layer protocols are


DNS (Domain Name System) for resolving Internet domain
names.


FTP (File Transfer Protocol) for file transfers.


SMTP (Simple Mail Transfer Protocol) for e
-
mail.


SMB (Server Message Block) for file sharing in Windows
networks.


NFS (Network File System) for file sharing in UNIX networks.


Telnet for terminal emulation.

TCP/IP PROTOCOL SUITE