Download Networks

Networks
Ing. Ludmila Kunderová
[email protected]
Department of Informatics
Office Q 2.40
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Networks
Module „Networks“ includes
•
•
The theoretical part (lessons)
The practical part (exercises)
Topics of the module „Networks“
1. Network infrastructure
2. Network architecture
3. Internet services
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Networks
The aim of lessons
– To introduce to the basics and essential
principles of data communication, networks,
networking and network services
The aim of exercises
– To gain basic skill in usage of network utilities
and tools for network services
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Introduction and Basic Terms
• Network – series of points (nodes) interconnected by
communication path
• Communication path – physical and logical environment
enabling the data transmission. Communication path is
created with the transmitter and receiver that controls the
data transmission through the transmission medium
• Network nodes – devices interconnected within network in
order to be able to communicate with other network nodes.
Network nodes are or user-end computers or network
peripherals (printers, scanners …) or intermediate devices
(repeaters, network switches, network HUBs, network
routers, gateways ….)
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Components of the network infrastructure
• User-end devices
– Computers
• PC machines
• Servers
– Network peripheral devices
• Network devices
– HUBs
– Switches
– Routers
• Transmission media
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Networks - – Network infrastructure
• HUB is a device where data signal arrives from one or
more directions and is forwarded out in one or more other
directions (multiport repeater)
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• Switch is a device that selects the path for sending of the
data unit (data packet) to its next destination („intelligent
HUB“)
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• Router is a device that determines the next network point to
which a packet should be forwarded toward its destination. The
router is connected to at least two networks and decides which
way to send each packet
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Router for small LAN
Router for medium LAN
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Wireless Access Point
o
o
o
WAP allows mobile users to connect to a central network node
without using any wires .
It is useful for mobile workstations, since there is no wiring
involved.
Wireless access is specified by standards 802.11b/g/n.
WAP device
Back-panel of the WAP
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• Transmission medium is the physical environment that guide the
signal or enable the penetration of signal. The transmission
medium may be:
– Twisted pair
– Coaxial cable
– Optical fibre cable
– Air space (wireless transmission)
• Signal works as the data bearer. It is an electrical pulse or
electromagnetic wave that is used to convey data from one place to
another.
– Analog signal is the sine wave continually changing its value.
– Digital signal is the sequence of pulses changing value from
one to other level at once.
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• Twisted pair (UTP)
– Two insulated copper wires arranged
in regular spiral pattern
– 4 pairs are bundled together into a
cable by wrapping them in a tough
protective coat.
• Coaxial Cable
– One physical channel that carries the
signal surrounded (after a layer of
insulation) by another concentric
physical channel, both running along
the same axis.
– The outer channel serves as a ground
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Inner conductor
Insulation
Outer shielding conductor
Outer sheath
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• Optical Fiber Cable
– It transmits light pulses along a glass fiber.
– It carries much more information than
conventional copper wire.
– It is not subject to electromagnetic
interference and the need to retransmit
signals.
– There is one central core made up of best
glass material best possible refraction.
– The core is covered by another glass
material that has lower refraction rate to
keep light inside of core. This second layer
is covered by a plastic jacket.
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• Air space
– Electromagnetic spectrum is the range of all possible
frequencies of electromagnetic radiation – infinite and
continuous.
– Frequency ranges proper for wireless data transmission are:
• Radio frequencies in the range about 30 MHz to 1 GHz.
• Microwave frequencies in the range about 2 to 40 GHz.
• Infrared (IR) frequencies - higher than those of
microwaves, but lower than those of visible light.
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Radio and Microwave technologies
• Terrestrial transmission
• Satellite transmission
• Mobile networks
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Radio Transmission characteristics
• Radio waves – frequency to 300 GHz
can penetrate through the walls
• Lower frequency waves can travel on
the ground up to 1000 km over the
earth‘s surface
• Upper frequency waves reaches
ionosphere and are refracted back to
the earth
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Microwave Transmission
characteristics
• Frequency 300 MHz to 300GHz
• Waves can travel trough the
obstacles
• Usually performed in wireless
networks LAN (Wi-Fi
technology) and WAN
(WIMAX technology)
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Mobile Network
• Transmissions use the microwave
frequencies
• Hierarchical Structure of the
Mobile Network:
– BTS – Base Transceiver
Station
– BSC – Base Station Controller
– MSC – Mobile Switching
Center
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Infrared and Visible Light Transmission characteristics
• Wave lengths
– Infrared waves 300 GHZ – 430 THz
– Visible waves 430 THZ – 740 THz
• Waves cannot penetrate obstacles and
are distorted by wind, rain and fog
• Sender and receiver must be in the lineof-sight
• Utilization of the light/infrared
technologies is limited (point-to-point
connections)
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Network categories
• Local Area Network (LAN)
• Metropolitan Area Network (MAN)
• Wide Area Network (WAN)
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LAN
• LANs are typically owned, controlled, and managed by
a single person or organization. They also use certain
specific connectivity technologies, primarily Ethernet.
• LAN supplies networking capability to a group of
computers in relatively short distances to each other such
as in a building, in an organization or in an enterprise.
• LANs are useful for sharing resources like servers,
printers, or applications. A LAN consists of user-end
devices (PCs, workstations, servers) and intermediate
devices (switches, LAN routers, HUBs …)
• LAN is often connects to other LANs, and to the Internet
or to some other WAN
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WAN
• WAN spans a large geographic area, such as a state or
country. WANs often connect multiple smaller networks, such
as LANs or MANs.
• The most popular WAN in the world today is the Internet. Many
smaller portions of the Internet, such as extranets, are also
WANs.
• WANs generally utilize different and much more expensive
networking equipment than do LANs (WAN routers, WAN
switches)
• WAN technologies offer high-speed networking capabilities,
therefore they are called high-speed transmission technologies
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MAN
• MAN (Metropolitan Area Network) is a large computer
network that spans a metropolitan area or campus.
• Its geographic scope falls between a WAN and LAN.
• MANs provide Internet connectivity for LANs in a
metropolitan region, and connect them to wider area
networks like the Internet.
• The MAN technologies are similar to the WAN
technologies.
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Typical LAN topology
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LAN Equipment
Network Interface Card (NIC)
Network devices
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Typical WAN topology
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WAN Equipment
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Essential HW and SW elements of the user-end system
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• A network operating system (NOS) is a computer
operating system that is designed primarily to support
workstation, personal computer that are connected on a LAN
• NOS implements protocol stacks as well as device drivers for
network hardware (NIC).
• Network operating systems have existed for more than thirty
years.
– The UNIX® operating system was designed to support networking
from the early 80th´ years.
– Novell NetWare became the first popular network operating system for
the personal computer.
– Windows 95 and Windows for Workgroups were Microsoft's first
network operating system products.
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• Network nodes are equipped with one or more network
interface cards (NICs)
• The NIC creates the network interface for network
processes
• Network node identifiers:
– Physical (associated with the NIC) - MAC address
– Logical (associated with the SW configuration) - IP
address
– Symbolic - Domain name – for network applications
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MAC address
• A MAC address is a 12-digit hexadecimal number (total 48 bits – 6
octets). The first three octets define the manufacturer, while the
second three octets vary and identify the individual adapter.
• An example 00:40:96:E8:3A:77
IP address
• IP Addresses (IPv4) uses a 32-bit number and it defines both
network and host address.
• An IP address is written in "dotted decimal" notation, which is 4
sets of numbers separated by period each set representing 8-bit
number ranging from (0-255).
• An example of IPv4 address is 216.3.128.12
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Host Domain Name
MAC
IP
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• Domain name is the registered unique identifier of IP node
based on DNS (Domain Name System)
• The fully qualified domain name (FQDN)
www.juice.com
– www = Name of server (physical machine)
– juice.com = domain name
juice = sub domain of com (Second level domain name - SLD)
com= Top level domain name (TLD)
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DNS Hierarchy
com
juice
www
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Domain Name System (DNS)
Regional Internet Registry (RIR)
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Domain Name System (DNS)
Regional Internet Registry (RIR)
• African Network Information Centre (AfriNIC) for Africa
• American Registry for Internet Numbers (ARIN) for the
United States, Canada, several parts of the Caribbean region,
and Antarctica.
• Asia-Pacific Network Information Centre (APNIC) for Asia,
Australia, New Zealand, and neighboring countries
• Latin America and Caribbean Network Information Centre
(LACNIC) for Latin America and parts of the Caribbean
region
• Réseaux IP Européens Network Coordination Centre (RIPE
NCC) for Europe, Russia, the Middle East, and Central Asia
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