Presentation on theme: "Living in a Network Centric World"— Presentation transcript:
1Living in a Network Centric World IT305: Computer Networks – Chapter 1
2Course Info Dr. Walid Khedr, Ph.D. Web:Department of Information Technology
3Contents Living in a Network-Centric World Communicating over the NetworkApplication Layer Functionality and ProtocolsOSI Transport LayerOSI Network LayerAddressing the Network IPv4Data Link LayerOSI Physical LayerEthernetPlanning and Cabling NetworksConfiguring and Testing Your Network
4Living in a Network Centric World This chapter provides the introduction to the course by showing how networking pervades everyday life.
5Objectives Describe how networks impact our daily lives. Identify the key components of any data network.Identify converged networks.Describe the characteristics of network architectures: fault tolerance, scalability, quality of service and security.
6IntroductionAmong all of the essentials for human existence is the need to interact with others.Communication is almost as important to us as our reliance on air, water, food.The creation and interconnection of robust Data Networks is having a profound effect.
7How Networks Impact Daily Life Early communication relies on face-to-face conversations. Nowadays, telephone, fax, interconnection of data networks etc.Early data networks were limited to exchanging character-based information between connected computer systems.Current networks have evolved to carry voice, video streams, text, and graphics between many different types of devices
8Networks Supporting the Way We Learn Courses delivered using network or Internet resources are often called online learning experiences, or e-learning.Ex: Cisco NetacadOnline courseware and delivery offer many benefits to businesses. Among the benefits are:Current and accurate training materials.Availability of training to a wide audience.Cost reduction
9Networks Supporting the Way We Works Business networks evolved to enable the transmission of many different types of information services, including , video, messaging, and telephony
10Networks Supporting the Way We Play The widespread adoption of the Internet by the entertainment and travel industries enhances the ability to enjoy and share many forms of entertainment, regardless of location.
11IntroductionAmong all of the essentials for human existence is the need to interact with others.Communication is almost as important to us as our reliance on air, water, food.The creation and interconnection of robust Data Networks is having a profound effect.
12Data NetworksCurrent data networks have evolved to carry voice, video streams, text, and graphics between many different types of devices
13Communication It can be in many forms and occurs in many environments Before beginning to communicate with each other, we establish rules or agreements to govern the conversation. (Protocols)Among the protocols that govern successful human communication are:An identified sender and receiverAgreed upon method of communicating (face-to-face, telephone, letter, photograph)Common language and grammarSpeed and timing of deliveryConfirmation or acknowledgement requirements
14The Elements of Digital Communication Message sources devices that need to send a message to devices.A channel, consists of the media that provides the pathway over which the message can travel from source to destination.Messages can be sent across a network by first converting them into binary digits, or bits. These bits are then encoded into a signal that can be transmitted over the appropriate medium.
18Network CoreMesh of interconnected routers that connect the Internet’s end systems.The fundamental question: how is data transferred through net?Circuit Switching: dedicated circuit per call: telephone netPacket-Switching: data sent thru net in discrete “chunks”
19Network Core: Circuit Switching A circuit-switched network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate.
20Network Core: Circuit Switching The four circuit switches are interconnected by four links.Each of these links consists of n circuits, so that each link can support n simultaneous connections.
21Multiplexing Circuit Switching Frequency Spectrum: the difference between the highest and lowest frequencies available for network signals.Frequency Division Multiplexing (FDM): The frequency spectrum of a link is shared among the connections established across the link.The link dedicates a frequency band to each connection for the duration of the connection.Time Division Multiplexing (TDM): Time is divided into frames of fixed duration and each frame is divided into a fixed number of time slots.When the network establish a connection across a link, the network dedicates one time slot in every frame to the connection.
23Network Core: Packet Switching Packet switching splits traffic data into packets that are routed over a shared network.Packet-switching networks do not require a circuit to be established, and they allow many pairs of nodes to communicate over the same channel.
24Multiplexing Packet Switching STDM method analyzes statistics related to the typical workload of each input device (printer, fax, computer) and determines on-the-fly how much time each device should be allocated for data transmission on the cable or line.
25Four sources of packet delay transmissionApropagationBnodalprocessingqueueingdnodal = dproc + dqueue + dtrans + dpropdtrans: transmission delay:L: packet length (bits)R: link bandwidth (bps)dtrans = L/Rdprop: propagation delay:d: length of physical links: propagation speed in medium (~2x108 m/sec)dprop = d/sdtrans and dpropvery different* Check out the Java applet for an interactive animation on trans vs. prop delay25
26Communicating Over Networks All networks have four basic elements in common:Rules or agreements to govern how the messages are sent, directed, received and interpretedThe messages or units of information that travel from one device to anotherA means of interconnecting these devices - a medium that can transport the messages from one device to anotherDevices on the network that exchange messages with each other
27The Elements of a Network DevicesThese are used to communicate with one anotherMediumThis is how the devices are connected togetherMessagesInformation that travels over the mediumRulesGoverns how messages flow across network
29The Elements of a Network Network connections can be wired or wirelessCable: UTP, Coaxial, Optic Fibers etcWireless: Bluetooth, laser, microwave etc
30The Elements of a Network Protocols are the rules that the networked devices use to communicate with each other. The industry standard in networking today is a set of protocols called TCP/IP (Transmission Control Protocol/Internet Protocol).On the top of TCP/IP:
38Converged NetworksTraditional telephone, radio, television, and computer data networks each have their own individual versions of the four basic network elements.In the past, every one of these services required a different technology to carry its particular communication signal.
39Converged NetworksTechnology advances are enabling us to consolidate these disparate networks onto one platform - a platform defined as a converged network.
40Network Architecture Characteristics There are 4 basic characteristics for networks in general to meet user expectationsFault toleranceScalabilityQuality of service (QoS)Security
41A Fault Tolerant Network Architecture Fault tolerance is the ability for a network to recover from an error, such as the failure of a device or a link (a connection between two devices).Fault tolerance is often achieved by having redundant devices or links, so that if one fails, messages can be re-routed around the failure through other devices or links.
43A Fault Tolerant Network Architecture Packet switched networks, the data are broken up into many small packets that are sent independently through the network, each finding its own best route through the network.
44A Scalable Network Architecture Scalability means the ability to expand to meet new demands.Most networks are designed in a hierarchical, layered approach so new devices and links can be added without interfering with existing networks.
45Providing Quality of Service (QoS) Quality of Service is a control mechanism that can provide different priority to different users or data flow or guarantee a certain level of performance to a data flow in accordance with request from the application program.
48Providing Network Security Unauthorized use of communication data might have serious consequences2 types of network security concerns that must be addressed to prevent serious consequences:Network Infrastructure Security - physical securing of devices that provide network connectivity and preventing unauthorized access to the management software that resides on themContent Security - protecting the information contained within the packets being transmitted over the network and the information stored on network attached devices
49Providing Network Security Security measures taken in a network should:Prevent unauthorized disclosure or theft of informationPrevent unauthorized modification of informationPrevent Denial of ServiceMeans to achieve these goals include:Ensuring confidentialityMaintaining communication integrityEnsuring availability