11/30/2018 Subject Name: COMPUTER NETWORKS I Subject Code: 10CS55 Prepared By: KRISHNA SOWJANYA.K SANTHIYA, SHRUTHI N Department: CSE Date: 30/8/2014 11/30/2018

Data Communication: Definition Engineered for Tomorrow Data Communication: Definition Data Communication: Transfer of data from one device to another via some form of transmission medium.

Data Communication Hi, how are you? Hi, how are you? 01010001 01010001 Engineered for Tomorrow Data Communication Hi, Hi, how how are are you? you? Hi, how are you? Hi, how are you? Computer 01010001 01010001

Data Communication Characteristics Engineered for Tomorrow Data Communication Characteristics Delivery Deliver data to correct destination Accuracy Data not alterer or left uncorrected Timeliness Data delivery at correct time Jitter No variation in packet arrival time

Components in Communication Engineered for Tomorrow Components in Communication 1 Message Hi, how are you? 5 Protocol 2 Sender 3 Receiver 4 Medium

Data Representation Numbers Text Images Engineered for Tomorrow Data Representation Numbers 8/16/32 bit integers floating point Text ASCII, Unicode Images Bit patterns, Graphics formats JPG/GIF/etc Audio  Samples of continuous signal Video  Sequence of bitmap images 150 2 255

Data Flow Simplex: One direction only data flow Server Monitor Engineered for Tomorrow Data Flow Simplex: One direction only Server Monitor data flow data flow Keyboard

Direction of Data Flow Half Duplex: Both directions, one at a time Engineered for Tomorrow Direction of Data Flow Half Duplex: Both directions, one at a time E.g., walkie-talkies data flow at time 1 data flow at time 2

Direction of Data Flow Full Duplex: Both directions simultaneously Engineered for Tomorrow Direction of Data Flow Full Duplex: Both directions simultaneously E.g., telephone Can be emulated on a single communication link using various methods data flow data flow

Networks Network: a set of devices connected by media links Laptop Engineered for Tomorrow Networks Network: a set of devices connected by media links Media Links Printer Workstation Laptop Scanner Server

Network Criteria Performance Throughput Delay Reliablility Engineered for Tomorrow Network Criteria Performance Throughput Delay Reliablility Accuracy of delivery Frequency of failure Robustness Security Protection from unauthorized access Protecting data from damage and development

Types of Connections Point-to-point Multipoint (multidrop) Engineered for Tomorrow Types of Connections Point-to-point Multipoint (multidrop)

Point-To-Point Connection Engineered for Tomorrow Point-To-Point Connection

Multipoint Connection Engineered for Tomorrow Multipoint Connection Wireless

Topology Topology: physical or logical arrangement of devices Mesh Engineered for Tomorrow Topology Topology: physical or logical arrangement of devices Mesh Star Bus Ring Hybrid

Fully Connected Mesh Topology Engineered for Tomorrow Fully Connected Mesh Topology Pros: Dedicated links Robustness Privacy Easy to identify fault Cons: A lot of cabling I/O ports Difficult to move

Star Topology Pros: Cons: One I/O port per device Little cabling Engineered for Tomorrow Star Topology Pros: One I/O port per device Little cabling Easy to install Robustness Easy to identify fault Cons: Single point of failure More cabling still required Hub

Bus Topology Pros: Cons: Little cabling Easy to install Engineered for Tomorrow Bus Topology Pros: Little cabling Easy to install Cons: Difficult to modify Difficult to isolate fault Break in the bus cable stops all transmission

Ring Topology Pros: Cons: Easy to install Easy to identify fault Engineered for Tomorrow Ring Topology Pros: Easy to install Easy to identify fault Cons: Delay in large ring Break in the ring stops all transmission

Engineered for Tomorrow Hybrid Topologies

Network Categories Local Area Network (LAN) Wide Area Network (WAN) Engineered for Tomorrow Network Categories Local Area Network (LAN) Wide Area Network (WAN) Metropolitan Area Network (MAN)

Local Area Networks Network in a single office, building, or campus Engineered for Tomorrow Local Area Networks Network in a single office, building, or campus

Engineered for Tomorrow Wide Area Networks Network providing long-distance communication over a country, a continent, or the whole world

Metropolitan Area Networks Engineered for Tomorrow Metropolitan Area Networks Network extended over an entire city Bangkhen Kampangsaen

Engineered for Tomorrow Internetworking How to allow devices from different standards to communicate Gateways/routers – devices capable of communicating in several standards These become "network of networks"

Engineered for Tomorrow Internetworks Two or more networks connected become an internetwork, or internet Example: The Internet Network1 Network2 Gateway Network3

Protocols and Standards Engineered for Tomorrow Protocols and Standards Protocol A set of rules governing data communications Syntax: format of data block Semantics: meaning of each section Timing: speed and sequencing Standards De facto (in practice) standards  not approved but widely adopted De jure (in law) standards  approved by an organization

Standards Organizations Engineered for Tomorrow Standards Organizations Creation Committees International Organization for Standardization(ISO) International Telecommunication Union- Telecommunication Standards Sector(ITU-T) AmericanNational Standards Institue(ANSI) Institute of Electrical and Electronics Engineers(IEEE) Electonics Industries Association(EIA) Forums Regulatory Agencies

Engineered for Tomorrow NETWORK MODELS

Engineered for Tomorrow Layered Tasks We use the concept of layers in our daily life. As an example, let us consider two friends who communicate through postal mail. The process of sending a letter to a friend would be complex if there were no services available from the post office.

Tasks involved in sending a letter Engineered for Tomorrow Tasks involved in sending a letter

Logical communication path Engineered for Tomorrow Layer Model Layer N uses services provided by Layer N-1 HOST A HOST B Logical communication path Layer N Layer N Layer N protocol Using services Providing services Layer N-1 Layer N-1 Layer N-2 Layer N-2 Virtual Communication System

Why Layers? Guidelines for protocol developments Modularity Engineered for Tomorrow Why Layers? Guidelines for protocol developments Reference model Modularity Eases maintenance and updating of systems A change in one layer is transparent to the rest Is layering always the best thing to do? Maybe not  cross-layer optimization

THE OSI Model Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s. Engineered for Tomorrow

Seven layers of the OSI model Engineered for Tomorrow Seven layers of the OSI model

Responsible for transmitting individual bits from one node to the next Engineered for Tomorrow Physical Layer Responsible for transmitting individual bits from one node to the next Duties/services Physical characteristics of interfaces and media Representation of bits Data rate (transmission rate) Synchronization of bits

Engineered for Tomorrow Physical Layer

Responsible for transmitting frames from one node to the next Engineered for Tomorrow Data Link Layer Responsible for transmitting frames from one node to the next Duties/services Framing Physical addressing Flow control (hop-to-hop) Error control (hop-to-hop) Access control

Data Link Layer from Network to Network Data Data Data Link Layer T2 Engineered for Tomorrow Data Link Layer from Network to Network Data Data Data Link Layer T2 Data H2 T2 Data H2 (frame) to Physical from Physical

Network Layer Duties/services Engineered for Tomorrow Network Layer Responsible for the delivery of packets from the original source to the destination Duties/services Logical addressing Routing

Network Layer from Transport to Transport Data Data Network Layer Data Engineered for Tomorrow Network Layer from Transport to Transport Data Data Network Layer Data H3 Data H3 (packet) to Data Link from Data Link

Responsible for delivery of a message from one process to another Engineered for Tomorrow Transport Layer Responsible for delivery of a message from one process to another Duties/services Port addressing Segmentation and reassembly Connection control Flow control (end-to-end) Error control (end-to-end)

Transport Layer from Application to Application Data Data Engineered for Tomorrow Transport Layer from Application to Application Data Data Transport Layer Data1 H4 Data2 H4 Data3 H4 Data1 H4 Data2 H4 Data3 H4 (segments) to Network from Network

Session Layer Duties/services Engineered for Tomorrow Session Layer Responsible for establishing, managing and terminating connections between applications Duties/services Interaction management  Simplex, half-duplex, full-duplex Session recovery

Presentation Layer Duties/services Engineered for Tomorrow Presentation Layer Responsible for handling differences in data representation to applications Duties/services Data translation Encryption Decryption Compression

Responsible for providing services to the user Engineered for Tomorrow Engineered for Tomorrow Application Layer Responsible for providing services to the user Duties/services Network Virtual Terminal File transfer, access and management Mail services Directory service

Engineered for Tomorrow TCP/IP Protocol Suite TCP/IP model is also called as the TCP/IP protocol suite. It is a collection of protocols. The TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application. The first four layers provide physical standards, network interfaces, internetworking, and transport functions that correspond to the first four layers of the OSI model. The Network layer of TCP/IP model corresponds to the Network Layer of OSI model The Host to network layer of TCP/IP model corresponds to the Physical and Datalink Layer of OSI model.

TCP/IP Model User Application Layer Transport Layer Network Layer Engineered for Tomorrow TCP/IP Model User Application Layer Transport Layer Network Layer Data Link Layer Physical Layer Software Hardware Transmission Medium

Engineered for Tomorrow TCP/IP and OSI model

Engineered for Tomorrow Addressing Four levels of addresses are used in an internet employing the TCP/IP protocols: Physical Logical Port Specific

Engineered for Tomorrow Physical Address Physical Address is the lowest level of addressing, also known as link address. It is local to the network to which the device is connected and unique inside it. The physical address is usually included in the frame and is used at the data link layer. MAC is a type of physical address that is 6 byte (48 bit) in size and is imprinted on the Network Interface Card (NIC) of the device.

Logical Addresses are used for universal communication. Engineered for Tomorrow Logical Address Logical Addresses are used for universal communication. Logical Address is also called as IP Address (Internet Protocol address). At the network layer, device i.e. computers and routers are identified universally by their IP Address. IP addresses are universally unique. Currently there are two versions of IP addresses being used: IPV4 and IPV^

For example TELNET uses port address 23, HTTP uses port address 80 Engineered for Tomorrow Port Address A logical address facilitates the transmission of data from source to destination device. But the source and the destination both may be having multiple processes communicating with each other. A Port Address is the name or label given to a process. It is a 16 bit address. For example TELNET uses port address 23, HTTP uses port address 80

Specific Address Port addresses address facilitates the transmission of data from process to process but still there may be a problem with data delivery. Again the responsibility of the port address is over here and there is a need of addressing that helps identify the different instances of the same process. Such address are user friendly addresses and are called specific addresses. Examples: Multiple Tabs or windows of a web browser work under the same process that is HTTP but are identified using Uniform Resource Locators (URL), Email addresses.   Engineered for Tomorrow

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