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Chapter 1 (Set 1)
Dr. Ali Maqousi, Dr. Tatiana Balikhina
Department of Computer Networks
Faculty of Information Technology
A data communications system must transmit data to the correct destination in an accurate and timely manner.
Five components of data communication communications
Data flow modes communications
Computer network example
Networks criteria communications
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.
1) accuracy of delivery;
2)frequency of failure;
3) time it takes a link recover from failure.
1) protecting data from unauthorized access;
2) protecting data from damage;
3) development recovery policies and procedures.
Benefits of Computer Networks I communications
A network with two clients and one server.
Benefits of Computer Networks II communications
Network attributes: communications1 - Types of connection
Network attributes: communications2 –Topology
The topology of the network is the geometric representation of the relationship of all the links and nodes to each other.
Categories of networks communications
Local Area Network communications (LAN)
LAN topologies: Mesh (1) communications
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 (2) communications
Mesh mainly is used to connect servers of a hybrid topology network that can include several other topologies.
LAN topologies: Star (1) communications
Star topology uses point-to-point connections (station-hub).
LAN topologies: Star (2) communications
LAN topologies: Star (3) communications
An isolated LAN connecting 12 computers to a hub in a closet
LAN topologies: Bus (1) communications
Bus topology is multipoint. One large cable acts as a backbone to link all devices in a network.
LAN topologies: Bus (2) communications
LAN topologies: Ring (1) communications
LAN topologies: Ring (2) communications
LAN topologies: Hybrid communications
A hybrid topology: a star backbone with three bus networks
Metropolitan communicationsArea Network (MAN) (1)
Metropolitan communicationsArea Network (MAN) (2)
Wide Area Network (WAN) (1) communications
Relation between hosts on LANs and the subnet.
Wide Area Network (WAN) (2) communications
Wide Area Network (WAN) (3) communications
A stream of packets from sender to receiver.
Wide Area Network (WAN) (4) communications
Wide Area Network (WAN) (5) communications
Wireless Networks (1) communications
Wireless Networks (2) communications
(a) Bluetooth configuration
(b) Wireless LAN
Wireless Networks (3) communications
Wireless Networks (4) communications
Wireless Networks (5) communications
Wireless Networks (6) communications
Home Networks communications
A heterogeneous network made of four WANs and two LANs
The Internet (1) communications
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.
The Internet (2) communications
Hierarchical organization of the Internet
The Internet (3) communications
- 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
- Most end users are connected to the local ISPs.
The Internet (4) communications
Networking Standards (1) communications
In this section, 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 syntaxrefers to the structure or format of the data, meaning the order in which they are presented.
- The word semanticsrefers 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 timingrefers to two characteristics: when data should be sent and how fast they can be sent.
Networking Standards (2) communications
Standards are necessary to ensure that products from different manufacturers can work together as expected.
Networking Standards (3) communications
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.
Networking Standards (4) communications
The 802 working groups. The important ones are marked with *. The ones marked with are hibernating. The one marked with † gave up.