what is a network? wireless/mobile computing need for networking cloud computing evolution of...
TRANSCRIPT
Communication
& Network Concepts
Objectives What is a network? Wireless/Mobile Computing Need for networking Cloud Computing Evolution of Networking Switching Techniques Transmission media Data Communication Technologies Types of Networks Network Topologies Network Devices Communication Protocols
What is a network ??
A network is an
interconnected collection
of autonomous computers.
Need for networking
To share computer filesTo share computer peripheralsTo enable different computers
(different platforms) to communicate with each other
To improve communication speed and accuracy.
To reduce cost of data transfer
ARPANET1969
INTERNET1990
NSFNET1980
ARPANET Advanced
Research
Projects
Agency
Network
National Science Foundation Network
NSFNET
INTERNET
WORLD WIDE NETWORK OF COMPUTER NETWORKS
GATEWAYDevice that connects dissimilar networksBACKBONECentral interconnecting structure that connects one or more networks
RING BUS
TREE
STAR
BACKBONE
G
G G
G
Few terms related to Network
Workstation or Node refers to a computer
that are attached to a network.
Server The master comp is
called server. Facilitates the sharing of
data, s/w and h/w.
NODES - WORK STATIONS
SERVER
Dedicated Non-dedicated
DEDICATED servers - used in
Master - Slave ( large) networks
NON -DEDICATED servers - used in
Peer - to - Peer (small )networks
DEDICATED servers –a computer (server)reserved for server’s job and its only job is to help workstations access data, software and hardware.
NON -DEDICATED servers –the computer (server) works as a workstation as well as a server
NIU NETWORK INTERFACE UNIT
NIU / NIC
.WORK
STATION SERVERNIU
Network Interface Unit (NIU) It is a device attached to each workstation to establish
communication b/w the server and the workstation. Helps to make connections within the network. Each NIU has a unique number identifying it called
node address. (given by the router or parent node) NIU is also called terminal access point (TAP). Also called Network Interface Card (NIC) Each NIC is given a unique physical address (by the
manufacturer )called MAC address (Media Access Control).
SWITCHING TECHNIQUES
CIRCUIT SWITCHING
MESSAGE SWITCHING
PACKET SWITCHING
CIRCUIT SWITCHING· in telecommunications· old and expensive· more reliable than packet-switching· two network nodes establish a dedicated communications channel (circuit) connecting them for the duration of the communication session before the nodes may communicate. ·functions as if the nodes were physically connected with an electrical circuit.
MESSAGE SWITCHING
store-and-forward switching
transmission of messages from node to
node through a network.
message is stored at each node until such
time as a forwarding path is available.
PACKET SWITCHING
Paul Baran in - 1960's (
· dividing of messages into packets before they are
sent, transmitting each packet individually, and then
reassembling them into the original message once all
of them have arrived at the intended destination.
TRANSMISSION MEDIA
( Connecting media / Connecting
cables )
1. GUIDED - Twisted pair, Coaxial, Optic fibre
2. UNGUIDED - Microwaves ,Radio waves,
Satellites , Infra red, Laser
Cables
Following types of cables are used in networks
Unshielded Twisted Pair (UTP) Cable
Shielded Twisted Pair (STP) Cable
Coaxial Cable
Fiber Optic Cable
Wireless LANs
COAXIAL CABLE( GUIDED )
THICKNET -- max 500 M longTHINNET -- max 185 M long
OPTIC FIBRE ( GUIDED )
•Light weight
•High
transmission rate
•No interference
Multimode - 2kms - 100Mbps Singlemode - 100 kms - 2Gbps
**** No interference. High transmission capacity.
Wireless LAN
WIRELESS / MOBILE COMPUTINGWIRELESS
communication without landlines
radio,cellphone device -continuously
connected to the n/w
MOBILE
laptop,PDA ,smartphonesdevice - not continuously
connected to the n/w
Wireless LANs
Not all networks are connected with cabling some networks are wireless .Wireless LANs use high frequency radio signals,infrared light beams, or lasers to communicate
between the workstations and the file server or hubs .
Each workstation and file server on a wireless network has some sort of transceiver/antenna to send and receive the data.
Wireless LAN contd.
For longer distance, wireless communications can also take place through cellular telephone technology, microwave transmission, or by satellite.
Wireless networks are great for allowing laptop computers or remote computers to connect to the LAN.
Wireless networks are also beneficial in older buildings where it may be difficult or
impossible to install cables.
UNGUIDED
Radiowave Microwave Satellite
300KHz - 3GHz Above 3GHz Microwave signals
10 miles range 100kms range spanning large area (16km)
FACTORS TO SELECT A MEDIUM
COST
DATA RATE
BANDWIDTH
DISTANCE
DATA COMMUNICATION -TERMINOLOGIES
Data Channel
Baud (bps)
Bandwidth -- difference between the highest and the lowest
frequencies ( kHz , MHz , GHz , THz ) Data Transfer rates
BITS / BYTES Bps --- Bytes per second
bps --- bits per second
Kbps --- Kilo bytes per second
kbps --- kilo bits per second
Mbps --- Million bytes per second
mbps --- million(mega) bits per second
TYPES OF NETWORKS
LAN - Local Area Network
MAN - Metropolitan Area Network
WAN - Wide Area Network
LAN
MAN
WAN
LAN - WAN Confined to a
small area( 10km)
Data rate - high
Owned by single organization
Low error rates
Span entire countries
Data rate - low
Owned by multiple organizations
High error rates
NETWORK TOPOLOGIES
Pattern of interconnection of nodes in a network
1. Star 2. Bus
3. Ring 4. Tree 5. Graph6. Mesh
Selection of a topology depends on the following factors:
1. Cost
2. Flexibility
3. Reliability
STAR TOPOLOGY
ثراراالالاالتت Ease of service
One device per connection
Centralized control/
problem diagnosis
simple access protocols long cable length difficult to expand central node dependency
short cable length
no wiring space required
suitable for optical fibres
node failure causes network failuredifficult to diagonise faultsn/w reconfiguration is difficult
RING TOPOLOGY
BUS TOPOLOGY
•short cable length and simple wiring•resilient architecture•easy to extend
•difficulty in fault diagnosis , fault isolation•repeater configuration•nodes must be intelligent
TREE TOPOLOGY MESH TOPOLOGY
Considerations When Choosing a Topology:
Money. A linear bus network may be the least expensive way to install a network; you do not have to purchase concentrators.
Length of cable needed. The linear bus network uses shorter lengths of cable.
Future growth. With a star topology, expanding a network is easily done by adding another concentrator.
Cable type. The most common cable in schools is unshielded twisted pair, which is most often used with star topologies.
NETWORK DEVICES•MODEM• RJ-45•ETHERNET CARD•HUB•SWITCH•REPEATER•BRIDGE•ROUTER•GATEWAY
MODEM
MODEM
INTERNAL MODEMEXTERNAL MODEM
RJ -45REGISTERED JACK - 45
Register Jack 45 is an 8 wire connector which is commonly used to connect computers on LAN.
Looks like RJ-11 telephone connector
ETHERNET CARD
ETHERNET CARD
Developed by XEROX
Data transfer rate- 10Mbps
connections for coaxial/twisted pair/fiber optic
HUB
HUB - ( Concentrator )
central connection point from cables from workstations
forward data packets
active hub -- used as repeaters to extend the length of the network
passive hub -- passes signal from one comp to another
SWITCH
SWITCH VS HUBUSED IN LANS
EXPENSIVE
MORE INTELLIGENT
SWITCHES CAN BE CONNECTED TO EACH OTHER - SO EASY TO ADD MORE DEVICES
REPEATER
electronic device - receives a low level signal - amplifies
– transmits used when the distance exceeds 70m
BRIDGE
- establishes an intelligent connection between 2 n/w of same stds but with
diff cabling
-- sends traffic from one side to the other ( switch sends data from either side )
-- uses physical address
Bridge – connects two LANS having the same protocol – (e.g. Ethernet or Token ring)
LAN A
Bridge
LAN B
Data not destined for other network is
prevented from
passing over the
bridge.
ROUTER
ROUTER
devices that join multiple wired or wireless networks (different protocols)
interfaces multiple networks to copy packets from one network to another.
uses logical (IP) address
Uses of Router
A router can be used to connect
a Local Area Network (LAN) to another LAN,
a Wide Area Network (WAN) to another
WAN,
a LAN to the Internet.
GATEWAY
Gateway
Gateway is a device that connects dissimilar networks.
Establishes intelligent connection between a local network and external networks with completely different structures.
Gateway is the ISP that connects the user to the internet.
small networks --> HUBS
when no of nodes grows ---> SWITCHES
if any protocol related problems arise --->
ROUTERS
COMMUNICATION PROTOCOLS
HTTP - Hyper Text Transfer Protocol (to read a web page)
FTP - File Transfer Protocol (to transfer files from one n/w to another)
TCP/IP - Transmission Control Protocol / Internet protocol
( provides end-to-end connectivity specifying how
data should be formatted, addressed, transmitted)
•SLIP/PPP - Serial Line Internet Protocol / Point to Point Protocol
•SMTP - Simple Mail Transfer Protocol
•POP - Post Office Protocol
•VoIP - Voice over IP
Wireless / Mobile computing Technologies
GSM - Global System for Mobile Communications
CDMA - Code Division Multiple Access
GPRS - General Packet Radio services
WLL - Wireless Local Loop
3G - Third Generation
SMS - Short Message Service
E-Mail - Electronic Mail
Chat
Video Conferencing
Wi Fi Bluetooth
WiMAX(Worldwide Interoperability for Microwave Access)
WiMAX is more similar to Wi-Fi than to 3G cellular technologies
Provides mobile broadband connectivity across cities and countries through a variety of devices.
World Wide Web Consortium
Purpose/focus-- Developing protocols and guidelines that ensure long-term growth for the Web.
Internet Engineering Task Force
Creating standards applying to the internet
Best of Luck!!!!