Computer Networks (EC-321)
Credits: 3(2,1)
Outline
•
•
•
•
•
Instructor/Material/Exam
Objectives/Goals
Course Contents
Course Outcome
Introduction
Instructor/Material/Exam (1)
• Who am I
Umar Shahzad
– Education: MS (Computer Science and Networking)
– Experience: Post graduate (1.5 years in
Telecommunication Industry)
– Email: engr.umarshahzad@yahoo.com
Availability after Class times:
– Contact after the class
– Email
Instructor/Material/Exam (2)
Text Book:
• Computer Networks – By Andrew S. Tanenbaum,
Latest Edition.
References:
• Computer Networks: a top down approach by Keith
Ross and J.Kurose, 3rd Ed
• Data and Computer Communication by W.Stalling, 7th
Ed
• Paper for review
Instructor/Material/Exam (3)
Exam Policy:
Written test
• Closed books
• Open questions, multiple-choice questions and problems
Note:
• There can be a slight change in the exam pattern (will be
informed)
Objectives/Goals
• Introduce to fundamental techniques/principles of CN.
• Ability to design different networks and analyze the
performance by using simulating or monitoring tool.
• Develop understanding of the communication protocols
used in internet.
• Ability to design and analyse MAC, Routing and Transport layer
protocols for different networks.
• Network programming skills : socket to implement various
applications based on client/server paradigm or peer-to-peer
communication.
• Introduce to emerging networking technologies 3G/4G
Course Contents
• Introduction
–
–
–
–
–
Uses of Computer Networks
Network Hardware and Software
Reference Models
Example Networks
Network Standardization
• The Physical Layer
–
Basis for Conventional Data Communication
–
–
–
–
–
Transmission Media
Wireless Transmission
Communication Satellites
Telephone System, Mobile Telephone System
Cable Television
Course Contents (cont.)
• Data Link Layer
–
–
–
–
–
–
Design Issues
Error Detection and Correction
Elementary Data Link Protocols
Sliding Window Protocols
Protocol Specification and Verification
Example Data Link Protocols
• MAC sub-layer
–
–
–
–
Channel Allocation Problem
Multiple Access Protocols
Bridges
High-Speed LANs
Course Contents (cont.)
• Wireless Systems, Technologies, Protocols
–
–
–
–
Evolution and Standards
Intro to radio propagation
Interference and PHY layer issue
Intro to MAC layer design and protocols
• Network layer
–
–
–
–
–
Design Issues
Routing Algos
Congestion Control Algos
Internetworking
Network Layer in Internet
Course Contents (cont.)
• Transport Layer
–
–
–
–
–
Transport Service
Elements of Transport Protocols
TCP and UDP
A simple Transport Protocol
Performance Issues
• The Application Layer
–
–
–
–
DNS
Electronic mail
WWW
Multimedia
Course Outcome
• Adequate knowledge of fundamental
techniques of computer networks particularly
internet.
• They will be able to design protocols and
implement.
Introduction
•
•
•
•
•
•
Basics and Background
Uses of Computer Networks
Network Hardware and Software
Reference Models
Example Networks
Network Standardization
Basics and Background
• What’s a network?
– Merriam-Webster Dictionary:
• “A fabric or structure of cords or wires that cross at
regular intervals…”
• “A system of computers, terminals and databases
connected by communication lines”
– “A computer network is defined as the
interconnection of 2 or more independent
computers.” [Ramteke,”Networks”, pg. 24].
Basics and Background (cont.)
• Why network?
– Before networks:
• One large, expensive computer (mainframe) in “computer
center” used for all processing in businesses, universities,
etc.
– Smaller, cheaper computers…
• Personal computers or workstations on desktops.
• Interconnecting many smaller computers is
advantageous! Why?
– Large number of separate but interconnected
computers do the job.
Basics and Background (cont.)
• Why network?
– Computers everywhere.
– Also means ubiquitous communication.
• Users connected anywhere/anytime.
• PC, laptop, cell phone.
– Networking computers together is critical!
– Provide access to local and remote resources.
– Collection of interconnected end systems:
• Computing devices (mainframes, workstations, PCs)
• Peripherals (printers, scanners, terminals).
Basics and Background (cont.)
• Why network?
– Resource sharing!
• Hardware: printers, disks, terminals, etc.
• Software: text processors, compilers, etc.
• Data.
– Robustness.
• Fault tolerance through redundancy.
– Load balancing.
• Processing and data can be distributed over the network.
– Location independence.
• Users can access their files, etc. from anywhere in the
network
Introduction
•
•
•
•
•
•
Basics and Background
Uses of Computer Networks
Network Hardware and Software
Reference Models
Example Networks
Network Standardization
Uses of Computer Networks
• Business Applications
• Home Applications
• Mobile Users
• Social Issues
Business Applications (1)
• Resource sharing
– All programs, equipment, and especially data available to
anyone on the network without regard to the physical
location of the resource or the user e.g printer, information
sharing (inventory, customer records, product information
etc.)
• Scattered offices and plants around the globe can be
connected e.g VPNs (individual scattered networks ----- one extended network)
Business Applications (2)
• Power-full
computer store
company’s data.
• A network with two clients and one server.
Business Applications (3)
• The client-server model involves requests and replies.
• IP telephony or Voice over IP (VoIP)
• A person at home accesses a page on the World Wide Web, the same model is
employed, with the remote Web server being the server and the user’s personal
computer being the client.
• Desktop sharing lets remote workers see and interact with a graphical computer
screen.
• e-commerce e.g Airlines
• Etc…..
Uses of Computer Networks
• Business Applications
• Home Applications
• Mobile Users
• Social Issues
Home Applications
• Access to remote information
– surfing the World Wide Web for information or just
for fun e.g online newspaper
– Online digital library e.g ACM, IEEE, ebooks
• Peer-to-Peer
– Every person can, in principle, communicate with
one or more other people; there is no fixed division
into clients and servers e.g BitTorrent.
– do not have any central database of content.
Home Applications
Home Applications
• Person-to-person communication
– above applications involve interactions between a
person and a remote database full of information
– Email, Instant messaging, Twitter
– Between person-to-person communications and
accessing information are social network
applications e.g Facebook
• Interactive entertainment
– MP3 songs, DVD-quality movies and IPTV etc
Home Applications
• Electronic commerce
– Home shopping
– Access to financial institutions e.g online bills
payment, manage their bank accounts, and handle
their investments electronically.
• Some forms of e-commerce.
Home Applications
• ubiquitous computing
– Homes equipped with sensors like security systems
that include door and window sensors, smoke
detectors call to fire department instead of making
noise
– electricity, gas and water meters could also report
usage over the network
– Etc…..
Uses of Computer Networks
• Business Applications
• Home Applications
• Mobile Users
• Social Issues
Mobile Users
• People on the go often want to use their mobile devices to read
and send email, tweet, watch movies, download music, play
games, or simply to surf the Web for information
• Wireless hotspots, cellular companies provide internet
• Smart phones, such as the popular iPhone, combine aspects
of mobile phones and mobile computers
• m-commerce (mobile-commerce) (Senn, 2000). Short text
messages from the mobile are used to authorize payments for
food in vending machines, movie tickets, and other small items
instead of cash and credit cards
• Wearable computers are another promising application. Smart
watches with radios.
Mobile Users
• distinction between fixed wireless and mobile wireless networks
Uses of Computer Networks
• Business Applications
• Home Applications
• Mobile Users
• Social Issues
Social Issues
• Along with the good comes the bad, this new-found
freedom brings with it many unsolved social,
political, and ethical issues.
• Social networks, message boards, content sharing
sites, and a host of other applications allow people to
share their views with like-minded individuals.
• As long as the subjects are restricted to technical
topics or hobbies like gardening, not too many
problems will arise.
• The trouble comes with topics that people actually
care about, like politics, religion etc.
Introduction
•
•
•
•
•
•
Basics and Background
Uses of Computer Networks
Network Hardware and Software
Reference Models
Example Networks
Network Standardization
Network Hardware (1)
• Two dimensions stand out as important in
computer networks
– transmission technology
– Scale
• Types of transmission technology
– Broadcast links
– Point-to-point links
Network Hardware (2)
• Point-to-point links
– connect individual pairs of machines.
– To go from the source to the destination on a network made
up of point-to-point links, short messages, called packets in
certain contexts, may have to first visit one or more
intermediate machines.
– Finding good route is important in point-to-point networks.
– One sender and exactly one receiver is sometimes called
Network Hardware (3)
• Broadcast links
– the communication channel is shared by all the
machines on the network; packets sent by any
machine are received by all the others.
• intended recipient
• all destinations ---broadcasting
Network Hardware (4)
• Scale
– Distance is important as a classification metric
because different technologies are used at different
scales.
Network Hardware (5)
•
•
•
•
•
Personal Area Networks
Local Area Networks
Metropolitan Area Networks
Wide Area Networks
Internetworks
PAN
• PANs (Personal Area Networks) let devices
communicate over the range of a person e.g computer
connect with its peripherals
• Cables
• Bluetooth (master, slave paradigm)
– master tells the slaves what addresses to use, when they
can broadcast, how long they can transmit, what frequencies
they can use, and so on
• PANs can also be built with other
technologies that communicate over
short ranges, such as RFID on
smartcards and library books
Network Hardware (5)
•
•
•
•
•
Personal Area Networks
Local Area Networks
Metropolitan Area Networks
Wide Area Networks
Internetworks
LAN (1)
• LAN (Local Area Network) is a privately owned
network that operates within and nearby a single
building like a home, office or factory.
• widely used to connect personal computers and
consumer electronics to let them share resources
(e.g., printers) and exchange information.
• When LANs are used by companies, they are called
enterprise networks.
LAN (2)
• topology of many wired LANs is built from point-topoint links
• Ethernet (802.3), is the most common type of wired
LAN
LAN (3)
• Divide one large physical LAN into two smaller logical
LANs is possible
– VLAN
• Two broadcast networks
• (a) Bus
• (b) Ring
LAN (4)
Token Ring (Ring
Topology)
LAN (5)
• Wireless and wired broadcast networks,
depending on channel allocation, can be
divided into
– static (time in discrete intervals, round robin)
– dynamic designs (centralized (e.g base station) and
decentralized (e.g choas like situation, CSMA/CD))
• Modern Home LAN
– Sensors e.g fire sensor
– Meter reading, clock (DLS)
– IP of Things etc…
Network Hardware (5)
•
•
•
•
•
Personal Area Networks
Local Area Networks
Metropolitan Area Networks
Wide Area Networks
Internetworks
MAN
• A MAN (Metropolitan Area Network) covers a
city
• (WiMAX(802.1
6))Wireless
MAN)
• A metropolitan area network based on cable TV.
Network Hardware (5)
•
•
•
•
•
Personal Area Networks
Local Area Networks
Metropolitan Area Networks
Wide Area Networks
Internetworks
WAN (1)
• A WAN (Long Haul) spans a large
geographical area, often a country or continent.
Hosts
WAN (2)
• A WAN (Long Haul) spans a large
geographical area, often a country or continent.
(Switching Element)
Transmission Lines
Hosts
WAN (3)
• Large (long wires) wired LAN.
– Differ to LAN
• the hosts and subnet are owned and operated by different
people (e.g employ and IT’s department)
• routers connect different kinds of networking technology
(ethernet to SONET)
• what is connected to the subnet (dual computers or
LANs)
WAN (4)
• VPN (use resources of internet)
• virtual links
• mileage vary with Internet
service
• Wireless
• Satellite
• Cellular Network
Network Software
• Protocol Hierarchies
• Design Issues for the Layers
• Connection-Oriented and Connectionless
Services
Protocol Hierarchies
• Layers to reduce design complexity of
network
•
•
•
Approach: “Divide and conquer”.
Lower layer offer certain service to
upper layer
Shielding how service is implemented
• Protocol is an agreement between the
communicating parties on how
communication is to proceed
• a set of rules governing the format
and meaning of the information that
is exchanged by the peer processes
within the same layer
• A set of layers and protocols is called a
network architecture
Analogy: Air Travel
• The problem: air travel.
• Decomposed into series of steps:
Arrival at airport
Departure from airport
Check-in
Baggage claim
Boarding
Deplane
Takeoff
Landing
Arrival
Departure
Check-in
Baggage claim
Boarding
Deplane
Takeoff
Landing
intermediate air traffic sites
Airplane routing
Traveling
Airplane routing
Arriving airport
Departing airport
Analogy: Air Travel
Design Issues for the Layers
•
Reliability
–
–
–
–
•
Making a network that operates correctly in the presence of unreliable components.
Error Detection (retransmission, CRC)
Error Correction (FEC)
Routing (finding a working path through a network)
Network Evolution
– Addressing and Naming
– Internetworking
• different network technologies often have different limitations (disassembling, transmitting,
and then reassembling messages)
– Scalable (designs that continue to work well when the network gets large)
•
Resource allocation (capacity of transmission medium)
–
–
–
–
•
divide resources so that one host does not interfere with another too much
flow control (e.g feedback from rx to tx)
Congestion (overloading of network)
QoS (Quality of Service (e.g in real time application))
Defend against different kinds of threats
Connection-Oriented and
Connectionless Services
• Layers can offer two different types of services to the layer
above: Connection-Oriented and Connectionless.
• Connection-Oriented, it is the service that the layer establish a
connection, uses the connection, and then releases the connection e.g
tube
– negotiation about the parameters to be used, such as maximum
message size, quality of service required, and other issues
– With and without virtual circuits
• Connectionless, each message (e.g letter in postal system) carries the
full destination address and each one is routed through the intermediate
nodes inside the system independent of all the subsequent messages.
Connection-Oriented and
Connectionless Services
• Some services are reliable in the sense that they never loss
data. By using Ack.
• Reliable connection-oriented service has two minor variations:
message sequence (SCTP) (message boundaries are
preserved e.g book sent as separate messages) and byte
stream (TCP) (e.g DVD movie download).
• Unreliable (meaning not acknowledged) connectionless service
is often called datagram service
• The acknowledged datagram service
– not having to establish a connection to send one message, but reliability
is essential
• Request-replay-service (client-server model)
Connection-Oriented and
Connectionless Services
• Why would anyone actually prefer unreliable communication to
reliable one?
• May not available in one layer e.g Ethernet
• Real Time application e.g multimedia
Introduction
•
•
•
•
•
•
Basics and Background
Uses of Computer Networks
Network Hardware and Software
Reference Models
Example Networks
Network Standardization
Reference Models
• OSI (Open System Interconnection) model
– Developed by the International Standards Organization
(ISO)
– 1st step toward international standardization of the protocols
used in the various layers
– Protocols are not used any more
– Model, quite general, still valid, and the features discussed
at each layer are still very important
• TCP/IP model
– Protocols widely used
– Model not of much use
OSI
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
OSI (cont…)
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
• OSI Model - The Lower Layers
The bottom four layers of the OSI model are often referred to as the
lower layers:




Layer-4 – Transport layer
Layer-3 – Network layer
Layer-2 – Data-Link layer
Layer-1 – Physical layer
Protocols that operate at these layers control the end-to-end
transport of data between devices, and are implemented in both
software and hardware.
OSI (cont…)
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
The Physical Layer
• Convert the logical 1’s and 0’s coming from layer 2 into electrical
signals.
• Controls the signalling and transferring of raw bits onto the
physical medium.
• Closely related to the Data-link layer, as many technologies
(such as Ethernet) contain both datalink and physical functions.
• The Physical layer provides specifications for a variety of
hardware:
• Cabling
• Connectors and transceivers
• Network interface cards (NICs)
• Wireless radios
• Hubs
OSI (cont…)
The Data-Link Layer
• Transporting data within a network.
• Packages the higher-layer data into frames, so that the data can
be put onto the physical wire
6 Presentation
• Frame contains the source and destination hardware (or
physical) address (uniquely identify host e.g MAC address),
5 Session
hardcoded on physical network interface
7 Application
4 Transport
3 Network
2 Data Link
1 Physical
The Data-Link layer consists of two sublayers:
Logical Link Control (LLC) sublayer
• Error control to compensate for the imperfections of the physical
layer.
• Flow control to keep a fast sender from swamping a slow
receiver.
• serves as the intermediary between the physical link and all higher
layer protocols
Media Access Control (MAC) sublayer
• Multiple Access (CSMA/CD)
OSI (cont…)
The Network Layer
• Controls internetwork communication
• Two key responsibilities:
• Logical addressing – provides a unique address that
6 Presentation
identifies both the host, and the network that host exists on.
7 Application
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
• Routing – determines the best path to a particular
destination network, and then routes data accordingly.
Two of the most common Network layer protocols are:
• Internet Protocol (IP) (IPv4 & IPv6)
• Novell’s Internetwork Packet Exchange (IPX).
OSI (cont…)
7 Application
The Transport Layer
• reliable transfer of data, by ensuring that data arrives at its
destination error-free and in order.
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Transport layer communication falls under two categories:
• Connection-oriented (TCP (Transmission Control Protocol))
• Connectionless (UDP (User Datagram Protocol ))
Connection-oriented protocols provide several important services:
• Segmentation and sequencing
• Data is segmented into smaller pieces for transport.
• Sequence number, to reassemble the data on arrival.
• Connection establishment – connections are established,
maintained, and ultimately terminated between devices.
• Acknowledgments – receipt of data is confirmed through the use
of acknowledgments. Otherwise, data is retransmitted,
guaranteeing delivery.
• Flow control (or windowing) – data transfer rate is negotiated to
prevent congestion.
OSI (cont…)
7 Application
6 Presentation
OSI Model - The Upper Layers
The top three layers of the OSI model are often referred to as the
upper layers:
5 Session
• Layer-7 - Application layer
• Layer-6 - Presentation layer
• Layer-5 - Session layer
4 Transport
Protocols that operate at these layers manage application-level
functions, and are generally implemented in software.
3 Network
2 Data Link
1 Physical
OSI (cont…)
The Session Layer
• Responsible for establishing, maintaining, and ultimately
terminating sessions between devices.
6 Presentation • Synchronization
• Dialog control (keeping track of whose turn it is to transmit),
• Token management (preventing two parties from attempting the
5 Session
same critical operation simultaneously)
7 Application
4 Transport
3 Network
2 Data Link
1 Physical
Sessions communication falls under one of three categories:
• Full-Duplex – simultaneous two-way communication
• Half-Duplex – two-way communication, but not simultaneous
• Simplex – one-way communication
OSI (cont…)
The Presentation Layer
• formatting and syntax of user data for the application layer.
• Ensures that data from the sending application can be understood
by the receiving application.
6 Presentation
7 Application
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Examples of Presentation layer formats include:
• Text - RTF, ASCII, EBCDIC
• Images - GIF, JPG, TIF
• Audio - MIDI, MP3, WAV
• Movies - MPEG, AVI, MOV
• conversion or translation services to facilitate communication.
• encryption and compression of data, as required
OSI (cont…)
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
The Application layer
• interface between the user application and the network. A web
browser and an email client are examples of user applications.
• The user application itself does not reside at the Application layer
– the protocol does. The user interacts with the application, which
in turn interacts with the application protocol.
Examples of Application layer protocols include:
• FTP, via an FTP client
• HTTP, via a web browser
• POP3 and SMTP, via an email client
• Telnet
The Application layer provides a variety of functions:
• Identifies communication partners
• Determines resource availability
• Synchronizes communication
OSI (Example)
A web browser serves as a good practical illustration of the OSI model and the
TCP/IP protocol suite:
• The web browser serves as the user interface for accessing a website. The
browser itself does not function at the Application layer. Instead, the web
browser invokes the Hyper Text Transfer Protocol (HTTP) to interface with
the remote web server, which is why http:// precedes every web address.
• The Internet can provide data in a wide variety of formats, a function of the
Presentation layer. Common formats on the Internet include HTML, XML,
PHP, GIF, and JPEG. Any encryption or compression mechanisms used on
a website are also considered a Presentation layer function.
• The Session layer is responsible for establishing, maintaining, and
terminating the session between devices, and determining whether the
communication is half-duplex or full-duplex. However, the TCP/IP stack
generally does not include session-layer protocols, and is reliant on lowerlayer protocols to perform these functions.
OSI (Example)
• HTTP utilizes the TCP Transport layer protocol to ensure the reliable
delivery of data. TCP establishes and maintains a connection from the client
to the web server, and packages the higher-layer data into segments. A
sequence number is assigned to each segment so that data can be
reassembled upon arrival.
• The best path to route the data between the client and the web server is
determined by IP, a Network layer protocol. IP is also responsible for the
assigned logical addresses on the client and server, and for encapsulating
segments into packets.
• Data cannot be sent directly to a logical address. As packets travel from
network to network, IP addresses are translated to hardware addresses,
which are a function of the Data-Link layer. The packets are encapsulated
into frames to be placed onto the physical medium.
• The data is finally transferred onto the network medium at the Physical
layer, in the form of raw bits. Signalling and encoding mechanisms are
defined at this layer, as is the hardware that forms the physical connection
between the client and the web server.
TCP/IP Reference Model
• Requirements (remain intact (DoD ), real-time) led to the choice of a packetswitching network based on a connectionless layer that runs across different
networks.
TCP (Transmission Control Protocol):
a reliable connection-oriented protocol.
UDP (User Datagram Protocol): an
unreliable connectionless protocol
Its job is to inject IP packets into any
network and have them travel independently
to the destination
• Describes what links, such as serial lines and
classic Ethernet, must do to meet the needs of
this connectionless internet layer.
• It is not really a layer at all, in the normal sense
of the term, but rather an interface between
hosts and transmission links
A Critique of the OSI Model
and Protocols
Why OSI did not take over the world
• Bad Timing:
The apocalypse of the two elephants.
• Timings
– Widespread adoption of the TCP/IP protocols preceded the formalization of the OSI
model.
– Vendors already begun offering TCP/IP based products.
– OSI emerged about 5 years after industry had adopted TCP/IP.
A Critique of the OSI Model
and Protocols
– Vendors were reticent to add support for a second protocol stack until momentum had
gathered behind OSI.
– The combination of these factors meant that OSI was never adopted in practice.
• Technology
– Some parts of the OSI model are fundamentally flawed.
• Although there are 7 layers, 2 of these (session, presentation) are almost empty and 2
others (data link, network) are cramped.
• Additionally some functions such as addressing, error control are recurring at each
layer.
• Implementations:
– Early implementations of OSI were inefficient, contrast with TCP/IP implementations
which are easy to use.
• Politics:
– OSI was widely perceived as the product of quasi-government standards processes rather
than driven by good design processes
A Critique of the TCP/IP
MODEL
• Lack of distinction between concepts.
• Doesn’t clearly distinguish between service, interface and protocol.
• Not adaptable – Not a general model and hence poorly adapted to other
protocol Stacks e.g Bluetooth.
• Link Layer is not really a layer, but an interface between network and data
link layers.
• Omitted layers – Physical and data link layers are not present.
• Early implementations were fragile.
Introduction
•
•
•
•
•
•
Basics and Background
Uses of Computer Networks
Network Hardware and Software
Reference Models
Example Networks
Network Standardization
Wireless LANs: 802.11
• Suitable Frequency Band
– operate in unlicensed bands such as the ISM (Industrial, Scientific,
and Medical) bands defined by ITU-R (e.g., 902-928 MHz, 2.4-2.5 GHz,
5.725-5.825 GHz)
• Architecture
Base
station
Wireless LANs: 802.11
• Multipath Fading
•
Echoes cancel or
reinforce each other
• Solution
•
Space Diversity
• 802.11 a/g (OFDM) – 54Mbps
• 802.11 n (wider frequency band and 4 antennas per computer)
– 450Mbps
Wireless LANs: 802.11
• CSMA
• Mobility
• network consist of multiple
cells
• change association with AP
• Security (encryption)
• WEP (Wired Equivalent
Privacy)
• WPA (WiFi Protected Access)
Architecture of the Internet
•
•
•
•
DSLAM (Digital
Subscriber Line
Access Multiplexer)
converts between
signals and packets
CMTS (Cable
Modem Termination
System) ( device at
cable head-end)
POP (Point of Presence) – location at which customer packets enter the ISP network for
service the ISP’s
IXPs (Internet eXchange Points) - ISPs connect their networks to exchange traffic at IXP.
The connected ISPs are said to peer with each other. Basically an IXP is a room full of
routers, at least one per ISP
Introduction
•
•
•
•
•
•
Basics and Background
Uses of Computer Networks
Network Hardware and Software
Reference Models
Example Networks
Network Standardization
Network Standardization
• Who’s Who in the Telecommunications World
– ITU (International Telecommunication Union)
– ITU-T sector
• Who’s Who in the International Standards
World
– ISO (International Standards Organization)
– IEEE (Institute of Electrical and Electronics Engineers)
• Who’s Who in the Internet Standards World
– IRTF (Internet Research Task Force)
– IETF (Internet Engineering Task Force)