REVIEW OF COMPUTER NETWORKS K. PALANIVEL Systems Analyst, Computer Centre Pondicherry University, Puducherry – COMS 525: TCPIP LECTURE 1 TOPIC.

REVIEW OF COMPUTER NETWORKS K. PALANIVEL Systems Analyst, Computer Centre Pondicherry University, Puducherry – 605014. COMS 525: TCPIP LECTURE 1 TOPIC COURSE

Internet in a Minute Department of Computer Science, Pondicherry University, Puducherry - 605014

Internet in a Minute Department of Computer Science, Pondicherry University, Puducherry - 605014 This is what happens in an internet minute in 2018 Internet connectivity: unique ICANN-overseen IP number for duration of connection; ability to exchange general Internet traffic (POP, http) with other ICANN-overseen IP addresses

Network in India (BSNL) Department of Computer Science, Pondicherry University, Puducherry - 605014 BSNL Core Router

Network in India (BSNL) Department of Computer Science, Pondicherry University, Puducherry - 605014 BSNL Core Network

Computer Networking

Computer Network - A collection of computing devices that are connected in various ways in order to communicate and share resources Usually, the connections between computers in a network are made using physical wires or cables However, some connections are wireless, using radio waves or infrared signals The generic term node or host refers to any device on a network Data transfer rate The speed with which data is moved from one place on a network to another Data transfer rate is a key issue in computer networks Department of Computer Science, Pondicherry University, Puducherry - 605014

Networking (Contd.) Computer networks have opened up an entire frontier in the world of computing called the client/server model Department of Computer Science, Pondicherry University, Puducherry - 605014

Networking (Contd.) File server A computer that stores and manages files for multiple users on a network Web server A computer dedicated to responding to requests (from the browser client) for web pages 15-12 Department of Computer Science, Pondicherry University, Puducherry - 605014

Types of Networks

Local-area network (LAN) A network that connects a relatively small number of machines in a relatively close geographical area A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organization. Department of Computer Science, Pondicherry University, Puducherry - 605014

Local Area Networks (LAN) LANs are confined to a relatively small area such as a school or a building LANs usually have one computer designated as the file server Other computers are connected to the network by cables connecting network interface cards in each computer Department of Computer Science, Pondicherry University, Puducherry - 605014

Wireless LANS Wireless networks use high frequency radio signals to communicate between the workstations and the fileserver or hubs. Disadvantages of wireless networks are: – they are expensive (relatively), – provide poor security, – are susceptible to interference and – are slower than cabled networks Department of Computer Science, Pondicherry University, Puducherry - 605014

Metropolitan-Area Network (MAN) MAN - The communication infrastructures that have been developed in and around large cities A MAN is a large computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks (or WAN) and the Internet. 15-17 Department of Computer Science, Pondicherry University, Puducherry - 605014

Wide-Area Network (WAN) Wide-area network (WAN) A network that connects two or more local-area networks over a potentially large geographic distance Often one particular node on a LAN is set up to serve as a gateway to handle all communication going between that LAN and other networks Communication between networks is called internetworking The Internet, as we know it today, is essentially the ultimate wide-area network, spanning the entire globe Department of Computer Science, Pondicherry University, Puducherry - 605014

Wide-Area Network (WAN) WANs connect larger areas, such as whole states, or even the world. Transoceanic cables and satellites are used to connect WANs Department of Computer Science, Pondicherry University, Puducherry - 605014

LAN vs. WAN Department of Computer Science, Pondicherry University, Puducherry - 605014 LANWAN 1.Diameter of not more than a few kilometers. 1.Span entire countries. 2.A total data rate of at least several mbps. 2.Data rate less than 1 mbps. 3.Complete ownership by a single organization. 3.Owned by multiple organization. 4.Very low error rates.4.Comparitively higher error rates.

Protocol A protocol is a set of rules that governs the communications between computers on a network These rules include guidelines that regulate the method of access, types of cabling and speed of data transfer PROTOCOL = SET OF RULES ABOUT COMMUNICATIO NS BETWEEN NETWORKS! Department of Computer Science, Pondicherry University, Puducherry - 605014

The most common protocols are: Ethernet Local Talk Token Ring FDDI ATM Protocol = a formal description of a set of rules and conventions that govern how devices on a network exchange information Department of Computer Science, Pondicherry University, Puducherry - 605014

Sample LAN Implementation Department of Computer Science, Pondicherry University, Puducherry - 605014

Topology

The physical topology of a network refers to the configuration of cables, computers and other peripherals. The main types of network topologies are: – Linear Bus – Star – Ring – Tree or Hybrid Department of Computer Science, Pondicherry University, Puducherry - 605014

Types of Networks Topology Various configurations, called topologies, have been used to administer LANs – Ring topology A configuration that connects all nodes in a closed loop on which messages travel in one direction – Star topology A configuration that centers around one node to which all others are connected and through which all messages are sent – Bus topology All nodes are connected to a single communication line that carries messages in both directions Department of Computer Science, Pondicherry University, Puducherry - 605014

Types of Topology A bus technology called Ethernet has become the industry standard for local-area networks Department of Computer Science, Pondicherry University, Puducherry - 605014

Linear Bus A linear bus topology consists of a main run of cable with a terminator at each end. All servers workstations and peripherals are connected to the linear cable Department of Computer Science, Pondicherry University, Puducherry - 605014

Star A star network is designed with each node (file server, workstation, peripheral) connected directly to a central network hub or server Department of Computer Science, Pondicherry University, Puducherry - 605014

Ring A ring network is one where all workstations and other devices are connected in a continuous loop. There is no central server Department of Computer Science, Pondicherry University, Puducherry - 605014

Tree or hybrid A tree or hybrid topology combines characteristics of linear bus and star and/or ring topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable Department of Computer Science, Pondicherry University, Puducherry - 605014

Mesh Topology In a mesh network topology, each of the network node, computer and other devices are interconnected with one another. Every node not only sends its own signals but also relays data from other nodes. in fact a true mesh topology is the one where every node is connected to every other node in the network. This type of topology is very expensive as there are many redundant connections, thus it is not mostly used in computer networks. Department of Computer Science, Pondicherry University, Puducherry - 605014

Sending a packet from One Location to Another

Sending a packet from Argon to Neon 34 Department of Computer Science, Pondicherry University, Puducherry - 605014

Explanation 35 DNS: The IP address of “neon.tcpip-lab.edu ” is 128.143.71.21 ARP: What is the MAC address of 128.143.137.1? DNS: What is the IP address of “neon.tcpip-lab.edu ” ? ARP: The MAC address of 128.143.137.1 is 00:e0:f9:23:a8:20 128.143.71.21 is not on my local network. Therefore, I need to send the packet to my default gateway with address 128.143.137.1 frame 128.143.71.21 is on my local network. Therefore, I can send the packet directly. ARP: The MAC address of 128.143.137.1 is 00:20:af:03:98:28 ARP: What is the MAC address of 128.143.71.21? frame Department of Computer Science, Pondicherry University, Puducherry - 605014

Communications Architecture

The complexity of the communication task is reduced by using multiple protocol layers: Each protocol is implemented independently Each protocol is responsible for a specific subtask Protocols are grouped in a hierarchy A structured set of protocols is called a communications architecture or protocol suite 37 Department of Computer Science, Pondicherry University, Puducherry - 605014

OSI Reference Model The OSI model is now considered the primary Architectural model for inter-computer communications. The OSI model describes how information or data makes its way from application programmes (such as spreadsheets) through a network medium (such as wire) to another application programme located on another network. The OSI reference model divides the problem of moving information between computers over a network medium into SEVEN smaller and more manageable problems. This separation into smaller more manageable functions is known as layering. Department of Computer Science, Pondicherry University, Puducherry - 605014

OSI Reference Model: 7 Layers Department of Computer Science, Pondicherry University, Puducherry - 605014

OSI Reference Model: Packet Movement Department of Computer Science, Pondicherry University, Puducherry - 605014

OSI Reference Model: Protocols Department of Computer Science, Pondicherry University, Puducherry - 605014

OSI Reference Model: LAN to WAN Department of Computer Science, Pondicherry University, Puducherry - 605014

OSI: A Layered Network Model The process of breaking up the functions or tasks of networking into layers reduces complexity. Each layer provides a service to the layer above it in the protocol specification. Each layer communicates with the same layer’s software or hardware on other computers. The lower 4 layers (transport, network, data link and physical —Layers 4, 3, 2, and 1) are concerned with the flow of data from end to end through the network. The upper four layers of the OSI model (application, presentation and session—Layers 7, 6 and 5) are orientated more toward services to the applications. Data is Encapsulated with the necessary protocol information as it moves down the layers before network transit. Department of Computer Science, Pondicherry University, Puducherry - 605014

Physical Layer Provides physical interface for transmission of information. Defines rules by which bits are passed from one system to another on a physical communication medium. Covers all - mechanical, electrical, functional and procedural - aspects for physical communication. Such characteristics as voltage levels, timing of voltage changes, physical data rates, maximum transmission distances, physical connectors, and other similar attributes are defined by physical layer specifications. Department of Computer Science, Pondicherry University, Puducherry - 605014

Data Link Layer Data link layer attempts to provide reliable communication over the physical layer interface. Breaks the outgoing data into frames and reassemble the received frames. Create and detect frame boundaries. Handle errors by implementing an acknowledgement and retransmission scheme. Implement flow control. Supports points-to-point as well as broadcast communication. Supports simplex, half-duplex or full-duplex communication. Department of Computer Science, Pondicherry University, Puducherry - 605014

Network Layer Implements routing of frames (packets) through the network. Defines the most optimum path the packet should take from the source to the destination Defines logical addressing so that any endpoint can be identified. Handles congestion in the network. Facilitates interconnection between heterogeneous networks (Internetworking). The network layer also defines how to fragment a packet into smaller packets to accommodate different media. Department of Computer Science, Pondicherry University, Puducherry - 605014

Transport Layer Purpose of this layer is to provide a reliable mechanism for the exchange of data between two processes in different computers. Ensures that the data units are delivered error free. Ensures that data units are delivered in sequence. Ensures that there is no loss or duplication of data units. Provides connectionless or connection oriented service. Provides for the connection management. Multiplex multiple connection over a single channel. Department of Computer Science, Pondicherry University, Puducherry - 605014

Session Layer Session layer provides mechanism for controlling the dialogue between the two end systems. It defines how to start, control and end conversations (called sessions) between applications. This layer requests for a logical connection to be established on an end-user’s request. Any necessary log-on or password validation is also handled by this layer. Session layer is also responsible for terminating the connection. This layer provides services like dialogue discipline which can be full duplex or half duplex. Session layer can also provide check-pointing mechanism such that if a failure of some sort occurs between checkpoints, all data can be retransmitted from the last checkpoint. Department of Computer Science, Pondicherry University, Puducherry - 605014

Presentation Layer Presentation layer defines the format in which the data is to be exchanged between the two communicating entities. Also handles data compression and data encryption (cryptography). Department of Computer Science, Pondicherry University, Puducherry - 605014

Application Layer 1.Application layer interacts with application programs and is the highest level of OSI model. 2.Application layer contains management functions to support distributed applications. 3.Examples of application layer are applications such as file transfer, electronic mail, remote login etc. Department of Computer Science, Pondicherry University, Puducherry - 605014

OSI in Action A message begins at the top application layer and moves down the OSI layers to the bottom physical layer. As the message descends, each successive OSI model layer adds a header to it. A header is layer-specific information that basically explains what functions the layer carried out. Conversely, at the receiving end, headers are striped from the message as it travels up the corresponding layers. Department of Computer Science, Pondicherry University, Puducherry - 605014

Data Encapsulation Department of Computer Science, Pondicherry University, Puducherry - 605014

OSI Vs TCP/IP Department of Computer Science, Pondicherry University, Puducherry - 605014

Network Devices

Data Transmission Via UTP Department of Computer Science, Pondicherry University, Puducherry - 605014

Data Transmission Via Devices Department of Computer Science, Pondicherry University, Puducherry - 605014

Data Transmission Via UTP Cables Department of Computer Science, Pondicherry University, Puducherry - 605014

Data Transmission Via Wirless Devices Department of Computer Science, Pondicherry University, Puducherry - 605014

Data Transmission Via Wireless Devices Department of Computer Science, Pondicherry University, Puducherry - 605014

Network Devices: Hub Department of Computer Science, Pondicherry University, Puducherry - 605014

Network Devices: Switch Department of Computer Science, Pondicherry University, Puducherry - 605014

Network Devices: Router Department of Computer Science, Pondicherry University, Puducherry - 605014

Communication : Satellite Department of Computer Science, Pondicherry University, Puducherry - 605014

Communication : Mobile Department of Computer Science, Pondicherry University, Puducherry - 605014

Communication : Satellite Department of Computer Science, Pondicherry University, Puducherry - 605014

Questions? 77 Department of Computer Science, Pondicherry University, Puducherry - 605014

Review Department of Computer Science, Pondicherry University, Puducherry - 605014

REVIEW OF COMPUTER NETWORKS K. PALANIVEL Systems Analyst, Computer Centre Pondicherry University, Puducherry – COMS 525: TCPIP LECTURE 1 TOPIC.

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REVIEW OF COMPUTER NETWORKS K. PALANIVEL Systems Analyst, Computer Centre Pondicherry University, Puducherry – COMS 525: TCPIP LECTURE 1 TOPIC.

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Presentation on theme: "REVIEW OF COMPUTER NETWORKS K. PALANIVEL Systems Analyst, Computer Centre Pondicherry University, Puducherry – COMS 525: TCPIP LECTURE 1 TOPIC."— Presentation transcript:

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