Transcript 1 - UTRGV Faculty Web

Introduction to Computer Networks
Dr. John P. Abraham
UT-RGV
Summary of material covered and
Protocol Suites
Data Communication
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Technologies used to send data across
communication lines
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Modulation
Digital to analog
Light
Multiplexing
Encryption
Packet Switching and networking
technologies
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Evolved from telegraph and telephone
technologies
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Mechanical connections are replaced with
electronic switches
Packet switching – eliminated the need for a
dedicated circuit
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Devices through out the network should have
information about how to reach the target destination
Takes into account speed, cost, distance and size of
packets
Network Protocols
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7 layer OSI model
5 layer TCP/IP suite
There exists three TCP/IP network environment today, Novell
Networking, Microsoft Windows Networking, and the UNIX/LINUX
networking.
Internetworking with TCP/IP
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Tolerance of heterogeneity of underlying
technologies.
The internet is formed by interconncecting
multiple packet-switching networks, as well
as public and private networks
Introduction to Computer Networks
Networking Protocol: TCP/IP
Network Interface has Physical and Datalink layers.
Introduction to Computer Networks
Computer Networks
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Computer
network
connects two or more
autonomous computers.
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The computers
geographically
anywhere.
can be
located
Introduction to Computer Networks
LAN, MAN & WAN
Network in small geographical Area (Room,
Building or a Campus) is called LAN (Local Area
Network)
Network in a City is call MAN (Metropolitan Area
Network)
Network spread geographically (Country or across
Globe) is called WAN (Wide Area Network)
Computer network architectures
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the client server
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all communication happens between the server and the client
only.
A client does not communicate directly with another client.
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If a client wishes to share a file with another client, it must place the
file in a commonly shared area at the server.
In case of an application, the client makes the request and the
server processes the request and returns the result to the client.
the peer-to-peer
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any node can act as a server as well as a client.
Only very limited security is available on a peer-to-peer
network.
Windows peer-to-peer networking
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may use the TCP/IP protocol suite or some other simpler protocols such
as the NetBIOS and the NetBEUI.
The NetBIOS, an application program interface (API) extends the BIOS
to include the support for I/O calls over a network.
The NetBIOS Extnded User Interface (NetBEUI), developed by IBM and
Microsoft, is the protocol used by Windows Workgroup networking.
Windows peer-to-peer networking
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NetBios is non-routable, therefore could not reach beyond the local
physical network.
It does not require an IP address, rather works with the name
registration within a workgroup.
In the newer Windows operating systems, the NetBEUI is encapsulated
inside the TCP/IP, referred to as NetBIOS over TCP/IP (NBT), and uses
the IP address.
Components used in a Computer
Network
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Computers
Communication ports
Cables
Hubs or switches
Routers
The network software.
Computers in a Client/Server
architecture
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Must be robust
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must be able to run for months or years without being shut down.
Must be fast enough to handle many requests from all the requests
from the clients.
Must have large fast hard drives to store information for all users.
Must have enough memory to cache all the directory information as
well as most used pages.
The computers must be reliable in case of power failures and
hardware failures:
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sufficient redundancy must exist.
Example of Types of Servers
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Fileserver
print server
database server
domain name server
communication server
DHCP server
Name Server
Communication ports
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Network may be done through any
communication ports such as serial,
parallel, network cards, etc.
Most common Network Cards used
today are Ethernet and Token Ring.
Network Interface Card
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Plug and play (PNP).
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Open the computer, install the card, and insert the driver
disk.
Legacy cards:
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the interrupt request line (IRQ), base memory address,
and the base I/O port must be manually set up on the card
by setting the jumpers or DIP switches, or through the use
of the manufacturer provided setup software.
Speed: 10 Megabits per second (Mbps), 100
Mbps (Fast Ethernet) or 1000 Mbps (Gigabit
Ethernet) depending on the card.
Connectors on NIC
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The connector on most Ethernet cards today is the RJ45 having 8 pins.
Older Ethernet cards may have a Bayonet Nut
Connector (BNC), an Attachment Unit Interface (AUI),
and/or a RJ-45 connector. A jumper or switch will
specify the type of connector used.
Network Addresses
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Every computer connected to a network should have two
unique identifying numbers, a physical address and an
Internet Protocol (IP) address.
 The physical address
 a 6 Byte number, is encoded on a ROM chip on the
Ethernet card at the time of manufacturing
 the IP address
 A 4 byte address
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is used to send messages to the outside world. The
physical address.
 configured on each machine.
Hub/Switch
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A Hub or switch connects cables from different nodes together. When
purchasing them the number of ports required and the speed of
transmission must be specified.
An active hub amplifies all signals received and sends the amplified
signals on all its ports.
Passive hubs are signal splitters and are used only in wiring panels.
Even though a little more expensive, a switch will provide faster
communication and great deal of diagnostic features.
Switches provide link management through physical address
identification.
Hubs/Switches
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As the network grows, multiple switches or hubs can be connected with
each other using an uplink port or a direct connect cable.
Most modern switches have the auto-sensing feature, which will allow
any port to work as an uplink.
The best location for a switch or hub is a centrally located closet to
which cables from all computers are brought.
Network Cabling
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Cabling is the most time consuming part of networking, particularly
when cables need to be hidden inside the walls.
For that reason it is advisable to have the cables installed or conduits
placed at the time of the building construction.
To hide wires inside existing buildings, a tape fish will be needed.
It may be well worth the time to investigate the wireless technology,
particularly when a small area is being networked.
Network cabling 2
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Three types of cables are used today: coaxial, twisted pair, and fiberoptic.
Twisted pair cables either can be unshielded or shielded with a foil.
Unshielded twisted pair (UTP) cable can transmit 10 Megabits per
second and the shielded can transmit more than 100 Mbps, perhaps all
the way up to 1000 Mbps.
Wires in each pair are twisted to reduce cross-talk and minimize the
effect of external electromagnetic interference.
Twisted pair cables are categorized into five categories, from Cat 1 to
Cat 5, based on the bandwidth capabilities.
The maximum length of a segment is 100 meters.
Network Cabling 3
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The UTP cable has 4 pairs of color-coded (orange, green, blue
and brown) wires.
The color of one of the wires in a pair will be solid and the other
will be striped with white.
Pins in the RJ-45 jack are numbered from 1 to 8.
When two computers are connected directly without the use of a
hub or a switch some wires need to be crossed (Transmit to
Receive). Such a cable is called a crossover cable. Crossover
cables need to be used when two hubs or switches that lack
uplink ports are connected together.
T-568A Straight-Through Ethernet
Cable
T-568B Straight-Through Ethernet
Cable
RJ-45 Crossover Ethernet Cable
Crossover cable
Configuring the windows network
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From the control panel’s, local area network, add a NIC if it does
not show up already. Insert the appropriate driver software.
Next Choose the protocols to be bound to the network card,
NetBios, TCP/IP, IPX/SPX, Appletalk, etc.
Set up the properties for the protocol you chose. For example, for
the TCP/IP, you will asked to either obtain the addresses
automatically or type in the IP Address, mask, default gateway, and
DNS. The default gateway is the address of the host through which
internetworks can be reached (a router or a computer that shares
Internet). DNS is the server that provides the IP address given a
domain name.
Install the client services and give your computer a name and a
group.
Finally, you may want to share your resources.
Introduction to Computer Networks
Applications of Networks
Resource Sharing
Hardware (computing resources, disks, printers)
Software (application software)
Information Sharing
Easy accessibility from anywhere (files, databases)
Search Capability (WWW)
Communication
Email
Message broadcast
Application of network 2
Remote computing
Virtualization
Supercomputing - used
for highly calculation-intensive
tasks in quantum physics, genetics, weather
modeling, etc.
Distributed processing – A program running on top of a
network that distributes the job.
GRID Computing – very similar to distributed. A middleware
is used to manage all the computers in the system
Cloud computing
Introduction to Computer Networks
Applications
E-mail
Searchable Data (Web Sites)
E-Commerce
News Groups
Internet Telephony (VoIP)
Video Conferencing
Chat Groups
Instant Messengers
Internet Radio
Grid computing
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Multiple independent computing clusters
which act like a “grid” because they are
composed of resource nodes not located
within a single administrative domain.
Offering online computation or storage
(like electricity sale).
The creation of a “virtual supercomputer”
by using spare computing resources
within an organization
Virtualization
the act of decoupling one computing resource
from others without impacting the usability
across these resources.
User state virtualization
Application virtualization.
Client-Hosted Desktop virtualization
Server-based Desktop virtualization
Application Virtualization
User state virtualization.
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separates the user data and settings from
any PC and enables IT to store them
centrally (i.e., in the datacenter) while also
making them accessible on any PC. It also
simplifies the central backup of user data
since data is already stored centrally on
servers.
http://technet.microsoft.com/enus/windows/ff629664
Application virtualization
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Only need to install once. Can run it from any
machine. Isolates applications from each other and
solves application to application compatibility issues
by allowing applications to run together even though
they may require the same resources from the OS
Application virtualization allows IT to store the
application centrally and stream the application to a
desktop based on user access.
http://www.youtube.com/watch?v=kSa9VBYyyk4
http://www.installfree.com/beta-signup
Client-Hosted Desktop Virtualization.
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technology (such as Microsoft® Virtual PC or
Sun xVM Virtual Box ) that separates
the operating system from the physical
hardware and allows a single PC to run
virtual machines side by side with the host
OS.
http://www.microsoft.com/virtualization/assets
/media/chv/local/index.htm
http://www.youtube.com/watch?v=0Y2eClEy7
jU
Server-Based Desktop Virtualization:
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Allows the execution of an environment at one place and
presentation of that environment or user interface at a different
location. These technologies usually use remote desktop
protocols, such as RDP, to decouple the user interface location
from the execution environment location. Remote execution
enables organizations to use older PCs as “thin clients,” giving
users the benefit of newer applications and versions of Windows
while helping save the environment by avoiding the dumping of
electronics into landfills.
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http://www.cio.com/article/504348/Desktop_Virtualizati
on_5_Most_Popular_Flavors_Explained
Cloud Computing
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is location independent computing
shared servers provide resources, software, and data to
computers.
computing is moved away from personal computers or an
individual application server to a “cloud” of computers.
Users of the cloud only need to be concerned with the computing
service being asked for, as the underlying details of how it is
achieved are hidden. This method of distributed computing is
done through pooling all computer resources together and being
managed by software rather than a human.
http://www.microsoft.com/en-us/server-cloud/new.aspx
Introduction to Computer Networks
Network Topology
The network topology
defines the way in which
computers, printers, and
other
devices
are
connected. A network
topology describes the
layout of the wire and
devices as well as the
paths used by data
transmissions.
Introduction to Computer Networks
Bus Topology
Commonly referred to as
a linear bus, all the
devices
on
a
bus
topology are connected
by one single cable.
Introduction to Computer Networks
Star & Tree Topology
The star topology is the most
commonly used architecture in
Ethernet LANs.
When installed, the star topology
resembles spokes in a bicycle
wheel.
Larger networks use the extended
star topology also called tree
topology. When used with network
devices that filter frames or
packets, like bridges, switches, and
routers, this topology significantly
reduces the traffic on the wires by
sending packets only to the wires of
the destination host.
Introduction to Computer Networks
Ring Topology
A frame travels around the ring,
stopping at each node. If a node wants
to transmit data, it adds the data as
well as the destination address to the
frame.
The frame then continues around the
ring until it finds the destination node,
which takes the data out of the frame.
Single ring – All the devices on the
network share a single cable
Dual ring – The dual ring topology
allows data to be sent in both
directions.
Introduction to Computer Networks
Mesh Topology
The
mesh
topology
connects
all
devices
(nodes) to each other for
redundancy and fault
tolerance.
It is used in WANs to
interconnect LANs and
for
mission
critical
networks like those used
by banks and financial
institutions.
Implementing the mesh
topology is expensive
and difficult.
Introduction to Computer Networks
Network Components
Physical Media
Interconnecting Devices
Computers
Networking Software
Applications
Introduction to Computer Networks
Networking Media
Networking media can be
defined simply as the
means by which signals
(data) are sent from one
computer
to
another
(either
by
cable
or
wireless means).
Introduction to Computer Networks
Networking Devices
HUB,
Switches,
Wireless
Access
Modems etc.
Routers,
Points,
Introduction to Computer Networks
Computers: Clients and Servers
In a client/server network
arrangement,
network
services are located in a
dedicated
computer
whose only function is to
respond to the requests
of clients.
The server contains the
file, print, application,
security,
and
other
services in a central
computer
that
is
continuously available to
respond
to
client
requests.