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EEES404 / EEE 448
Computer Networkswith
(Network Programming)
Lecture #1
Dept of Electrical and Electronics Engineering
Çukurova University
• The aim of this course is to teach
– basic concepts in networking,
– the OSI model,
– error detection codes,
– flow control,
– routing,
– medium access control, and
– high-speed networks and
• to give basic level theoretical infrastructure students
about layered network architecture by using C#.
• Because, the course will be practiced in C#2
Course Descriptions
Course Objectives• Develop a fundamental understanding of the network
design principles and performance metrics
• Become familiar with the mechanisms and protocols
for reliable data communication via a computer
network
• Be able to evaluate the performance of various network
technologies and protocols
• Think as an engineer: What technologies should be
employed to build a network with particular
specifications?
• Develop interest in performing research in the area of
Computer Networks3
Topics to be covered
• Network architectures, performance metrics, layering
• Medium access control
• Internetworking, routing
• End-to-end protocols, flow control
• Congestion control and resource allocation
• Applications
• Network security4
• Introduction
• Layering, Hardware
• Network Programming
• Application Layer
• Session, Transport, Network, DataLink and
Physical Layers
• MultiMedia Networking
• Network Management
• Security 5
Weekly Schedule Course Logistics
• Textbook“Computer Networks: A Systems Approach”, L. Peterson, and B. Davie, 5th edition.
“Computer Networks: A top-down Approach”, Kurose and Ross, 6th Edition, Addison-Wesley.
• Additional References“Data Networks”D. Bertsekas, and R. Gallager, 2nd edition
“Computer Networks”, S. Tanenbaum and D. Wetherall, 5th edition,
• Course Website : eembdersler.wordpress.comLectures, Homework, Useful links,
Supplementary material, Announcements
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Where to find me
• My Office:
• EEE bldg: Room 305
• Office Hours by appointment
• My Email: [email protected]
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When the class
• Thursday
– EEE Bld Computer Lab: Room 223
– 9:30 – 12:00 AM
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Class Expectations
• Class participation – Your input is needed for good discussion
• Keep up with reading material
• Present your presentation clean and understandable
• Submit clean, organized, concise and on time your project (back
of a flyer is not ok!)
• Identify potential project partner early (in one week, if possible)
• Brush up prior knowledge (Probability theory, C# Programming)
• Follow academic integrity code (Remember EEE117)
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Class Presentation : Choose one topic to expalin to your classmates in 3 hours
Project Presentation: At least a 15 mins-presentation for the projects (How to use the time, to present the details, to answer the questions will be graded)
Final Exam: will be setup by the department- Closed books and materials
Grading Scheme
Assignment Points
Midterm(Presentation) 30% 40% of
Project 10%
30%
40% of
60% of
Final Exam 30% 60% of
Classes Bonus 10% +60%
Total 110% 100
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Computer Networks Topics• Social Webs / Networks Analysis
• Network Security (Cyber security)
• Understanding Internet protocols IPv4 and IPv6
• Wireless Technologies
• Cloud Systems and applications
• Mobile networks
• Smart Networks
• Software model checking of network applications
• Next Generation / New architecture for future networks
• Exploring Functionality and Quality of Web Services / APIs
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DATA COMMUNICATIONS
•The term telecommunication means communication
at a distance.
•The word data refers to information presented in
whatever form is agreed upon by the parties creating
and using the data.
•Data communications are the exchange of data
between two devices via some form of transmission
medium such as a wire cable.
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Characteristics that define
effectiveness of data communications
• Delivery
• Accuracy
• Timeliness
• Jitter
A data communications system must transmit data
to the correct destination in an accurate and timely
manner.
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Five components of data communication
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Components of Data Communication System
• Message is the information (data) to be
communicated (text, numbers, images, audio, and
video).
• Sender is the device that sends the data message
(computer, mobile phone, video camera and so on).
• Receiver is the device that receives the message.
• Transmission medium is the physical path by which
a message travels from sender to receiver (twisted-
pare, coaxial, fiber-optic cables and radio waves).
• Protocol is an agreement between the communicating
devices on how communication is to proceed. 18
Data flow modes
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Data flow modes
• Simplex as one-way street. Only one of the
two devices on a link can transmit; the other
can only receive.
• Half-duplex, each station can both transmit,
but not at the same time.
• Full-duplex (or duplex), both stations can
transmit and receive simultaneously.
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Networks
• Computer Network is a collection of
devices (nodes) interconnected by a single
technology (transmission medium link).
• Node can be a computer, printer, or any other
device capable of sending and/or receiving
data generated by other nodes on the network.
• Interconnected computers are two or
more computers that able to exchange
information.
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Computer network example
Networks
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• Internet is the network of networks (connection of
two or more networks)
• Intranet is a private business network.
• Most networks use distributed processing, in
which a task is divided among multiple computers.
• Distributed System is a software system built on
top of a network.
• World Wide Web is a distributed system that runs
on top of the Internet.
Networks
Internet
• An inter-net: a network of networks.– Networks are connected using
routers that support communication in a hierarchical fashion
– Often need other special devices at the boundaries for security, accounting, ..
• The Internet: the interconnected set of networks of the Internet Service Providers (ISPs)– About 17,000 different networks
make up the Internet
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Internet
Challenges of the Internet
• Heterogeneity
– Address formats
– Performance – bandwidth/latency
– Packet size
– Loss rate/pattern/handling
– Routing
– Diverse network technologies satellite
links, cellular links, carrier pigeons
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Challenges of the Internet
• Scale
– 21,220,000,000s of hosts( that is why IPv6)
– 72,400,000 (2010)
– 18,000+ administrative domains,
– Thousands of applications
• Adversarial environment
• Oh, and let’s make it easy to use…
• How to translate between various network technologies?
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Naming
What’s the IP address for www.cu.edu.tr?
It is 193.140.54.10
Translates human readable names to logical endpoints
Local DNS ServerComputer 1
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Routing
R
R
R
RRH
H
H
H
R
RH
R
Routers send
packet towards
destination
H: Hosts
R: Routers
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Networks criteria
• Performance can be measured in many ways, including:
1)Transit time (time required for a message to travel from one device to another);
2) Response time (elapsed time between inquiry and response).
Performance is often evaluated by two networking metrics:
• Throughput and delay : To enhance performance we need more throughput and less delay.
• Reliability is measured by :
1) accuracy of delivery;
2)frequency of failure;
3) time it takes a link recover from failure.
• Security include:
1) protecting data from unauthorized access;
2) protecting data from damage;
3) development recovery policies and procedures.
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Business Applications
- Resource Sharing (printers, scanners, storage
devices, and sharing information, client-server model)
-Communication Medium (E-mail)
- Being able to place orders in real time (Purchase)
- E-Commerce, M-Commerce
Benefits of Computer Networks I
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Business Applications of Networks
A network with two clients and one server.
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Home Network Applications
- Access to remote information (e.g. Google)
- Person to person communication (chat)
- Using social networks (e.g. Facebook)
- Interactive entertainment
- E- commerce, M-Commerce (web shopping)
Benefits of Computer Networks II
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Network attributes: 1 - Types of connection
• Point-to-point
• Multipoint (or multidrop, e.g. broadcasting networks)
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Network attributes: 2 –Topology
The topology of the network is the geometric
representation of the relationship of all the links
and nodes to each other.
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Categories of networks
The most common classification of networks is based on its
physical size (scale).
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LAN is a network within a single building or campus
of up to a few kilometres in size.
LANs share the following characteristics:
- their transmission media
- their size (restricted small size)
- their topology (Bus, Ring, Star)
- their setting up cost is low
- Data transfer rate is high (10Mbps, 100Mbps,
10Gbps)
Local Area Network (LAN)
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LAN example
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A fully connected mesh topology (five devices)
We need n(n-1)/2 duplex-mode point-to-point links to connect n devices
LAN topologies: Mesh (1)
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LAN topologies: Mesh (2)
Advantages of mesh topology:
•Eliminating traffic problem (each link is dedicated to pair of devices);
•Robustness (break in one line does not lead to break of all network);
•Privacy and security;
•Fault identification and isolation is easy.
Disadvantages of mesh topology:
•Large amount of cabling and I/O ports are required;
•Wiring can be greater than available space;
•It is expensive.
Mesh mainly is used to connect servers of a hybrid topology network
that can include several other topologies.
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LAN topologies: Star (1)
Star topology uses point-to-point connections (station-hub).
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LAN topologies: Star (2)
In a Star topology, each station is directly connected to
a central controller – hub.
The hub acts as exchange: device sends data to hub,
which then relays the data to other device.
Advantages of star topology:
•Less expensive than mesh;
•Less cabling;
•Easy maintenance.
Disadvantages of star topology:
•One single point of failure – hub.
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An isolated LAN connecting 12 computers to a hub in a closet
LAN topologies: Star (3)
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LAN topologies: Bus (1)
Bus topology is multipoint. One large cable acts as a
backbone to link all devices in a network.
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LAN topologies: Bus (2)
In a bus topology, all stations are attached to a liner
transmission medium (bus) through appropriate hardware
interface (tap).
Advantages of bus topology:
•Easy to install;
•Efficient use of wiring;
Disadvantages of bus topology:
•One single point of failure – backbone cable.
•Difficult maintenance.
IEEE 802.3 (Ethernet) is an example of bus topology.
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LAN topologies: Ring (1)
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In a Ring topology, each station on the network is connected to two
other stations, forming a loop or ring.
It uses token (signal circulating in a ring) to control transmission.
Advantages of ring topology:
•To add or delete a device requires changing only two
connections.
•Fault isolation is simplified
•No conflict in the transmission of data.
Disadvantages of ring topology:
- If one connection fails, the rest of the network will fail.
-To avoid this a dual ring could be used.
IEEE 802.5 ( IBM Token Ring) & FDDI (Fiber Distributed Data
Interface) are examples.
LAN topologies: Ring (2)
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LAN topologies: Hybrid
A hybrid topology: a star backbone with three bus networks
Network topology
• Advantages and Disadvantages of Network Topologies
Topology Advantages Disadvantages
Bus Cheap. Easy to install. Difficult to reconfigure.
Break in bus disables entire network.
Star Cheap. Easy to install.
Easy to reconfigure.
Fault tolerant.
More expensive than bus.
Ring Efficient. Easy to install. Reconfiguration difficult.
Very expensive.
Mesh Simplest. Most fault
tolerant.
Reconfiguration extremely difficult.
Extremely expensive.
Very complex.
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MAN is a network with a size between a LAN
and a WAN.
–A MAN spans the distance of a typical
metropolitan city.
–The cost of installation and operation is higher.
–MANs use high-speed connections such as fiber
optics to achieve higher speeds.
Examples of a MAN:
1) part of the telephone company network that can
provide a high-speed DSL line to the customer;
2) cable TV network.
Metropolitan Area Network (MAN) (1)
49MAN based on cable TV
Metropolitan Area Network (MAN) (2)
Metropolitan area network
Metropolitan Area Network (MAN) (3)
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Relation between hosts on LANs and the subnet.
Wide Area Network (WAN) (1)
The main differences between WAN and LAN are:
- LAN is fully controlled by the owner whilst the WAN needs
the involvement of another authority like Telephone Company.
- The transfer rate of LAN is higher than the transfer rate of
WAN.
– WAN network spans a large geographical area, it
contains a collection of hosts that are connected
by a communication subnet.
– The Internet is a good example of a WAN.
– Host is a machine that is used to run user (i.e.,
application) program and is owned by the
customers.
– Subnet consists of transmission lines and
switching elements, and its job is to carry
messages from host to host.
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Wide Area Network (WAN) (2)
Wide area network
Wide Area Network (WAN) (3)
• A stream of packets from sender to receiver.
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Wide Area Network (WAN) (4)
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Wide Area Network (WAN) (5)
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- Users have a dream to connect their
notebooks to the network without having to be
plugged into a telephone wall socket.
- To achieve a true mobility there is a need to
use a radio (or infrared) signals for communication.
Three main categories:
1- System interconnection
2- Wireless LANs
3- Wireless WANs
Wireless Networks (1)
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(a) Bluetooth configuration
(b) Wireless LAN
Wireless Networks (2)
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- System interconnection, it is about
interconnecting the components of a computer
using a short-range radio that uses the master-
slave paradigm.
Example:
- Bluetooth is a short-range wireless network
that allows digital components to connect to a
computer by merely being brought within range.
Wireless Networks (3)
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- Wireless LAN, it is a system where every
computer has a radio modem and antenna with
which it can communicate with other systems.
- Wireless LANs are used in small offices,
homes, older office building , conference rooms
and other places.
- IEEE 802.11 (WiFi) is a standard for wireless
LANs.
Wireless Networks (4)
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Wireless LAN
Wireless Networks (5)
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- Wireless WAN, it is similar to wireless LAN
system, but with lower bandwidth and is used in a
wide area systems.
- Three generations of Wireless WAN :
the first one was analog and for voice only
the second one was digital and for voice only
the third one is digital and for both voice and
data
- IEEE 802.16 (WiMAX) is a standard for
wireless WANs.
Wireless Networks (6)
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- Every device in the home will be capable of
communicating with every other device, and all of
them will be accessible over the Internet.
- Examples of devices that are capable of being
networked:
1. Computers (PC, Notebook, PDA)
2. Entertainment (TV, DVD, Camera...)
3. Telecommunications (telephone, intercom...)
4. Appliances (microwave, refrigerator, lights…)
5. Telemetry (smoke alarm, thermostat, babycam)
Home Networks
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TCP/ IP is a protocol suite in the Internet.
The main Internet applications are:
E-mail, News, Remote Login, File transfer, World Wide
Web (WWW)
The Internet (1)
The Internet has revolutionized many aspects of our
daily lives. It has affected the way we do business as well as
the way we spend our leisure time. The Internet is a
communication system that has brought a wealth of
information to our fingertips and organized it for our use.
History of Internet:
Beginning in 1969. It was called ARPANET.
64Hierarchical organization of the Internet
The Internet (2)
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- The Internet today is run by private companies, not the
government.
- The national Internet service providers are backbone
networks created and maintained by specialized companies.
- These backbone networks are connected by complex
switching stations (normally run by a third party) called
network access points (NAPs).
- Local ISPs can be connected to a regional or national
service provider.
- Most end users are connected to the local ISPs.
The Internet (3)
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The Internet (4)
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Networking Standards (1)
We define two widely used terms: protocols and standards.
First, we define protocol, which is synonymous with rule.
Then we discuss standards, which are agreed-upon rules.
A protocol is a set of rules that governs data communication;
the key elements of a protocol are syntax, semantics, and
timing.
- The term syntax refers to the structure or format of the data,
meaning the order in which they are presented.
- The word semantics refers to the meaning of each section
of bits. How is a particular pattern to be interpreted, and what
action is to be taken based on that interpretation?
- The term timing refers to two characteristics: when data
should be sent and how fast they can be sent. 68
Networking Standards (2)
Advantages of standards
• A standard assures that there will be a large market for
a particular piece of equipment or software.
• A standard allows products from multiple vendors to
communicate.
Disadvantages of standards
• A standard tends to freeze the technology.
• There are multiple standards for the same thing.
Standards are necessary to ensure that products from
different manufacturers can work together as expected.
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Networking Standards (3)
Standards are developed through the cooperation of standards
creation committees, forums, and government regulatory agencies.
The ISO, ITU-T, ANSI, IEEE, and IETF are some of the organizations
involved in standards creation.
ISO - International Organization for Standardization
ITU-T - International Telecommunication Union-Telecommunication
Standards Sector
ANSI - American National Standards Institute
IEEE - Institute of Electrical and Electronics Engineers
IETF - Internet Engineering Task Force
- Forums are special-interest groups that quickly evaluate and
standardize new technologies.
- A Request for Comment (RFC) is an idea or concept that is a
originator to an Internet standard.70
The 802 working groups. The important ones are marked with *.
The ones marked with are hibernating.
The one marked with † gave up.
Networking Standards (4)
https://5g.ieee.org/standards
Summary
• A network consists of two or more
entities sharing resources and
information.
• A computer network consists of two or
more computers that are connected and
are able to communicate.
Summary
• The basic purpose of networks is
– to enable effective communication,
– share resources, and
– facilitate centralized management of data.
• Networks can be classified according to
their geographical boundaries or their
component roles.
