Subject Name COMPUTER NETWORKS I Subject Code 10

Subject Name: COMPUTER NETWORKS I Subject Code: 10 CS 55 Prepared By: KRISHNA SOWJANYA. K SANTHIYA, SHRUTHI N Department: CSE Date: 30/8/2014 3/15/2018

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

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

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

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

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

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

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

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

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

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

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

Engineered for Tomorrow Point-To-Point Connection

Engineered for Tomorrow Multipoint Connection Wireless

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

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

Engineered for Tomorrow Star Topology Pros: Hub 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 17

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

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

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

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

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 Network 2 Network 1 Gateway Network 3 Example: The Internet

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 27

Engineered for Tomorrow Standards Organizations • Creation Committees • International Organization for Standardization(ISO) • International Telecommunication Union. Telecommunication Standards Sector(ITU-T) • American. National Standards Institue(ANSI) • Institute of Electrical and Electronics Engineers(IEEE) • Electonics Industries Association(EIA) • Forums • Regulatory Agencies 28

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.

Engineered for Tomorrow Tasks involved in sending a letter

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

Engineered for Tomorrow Why Layers? § Guidelines for protocol developments § § Modularity § § § Reference model 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

Engineered for Tomorrow 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 1970 s.

Engineered for Tomorrow Seven layers of the OSI model

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

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

Engineered for Tomorrow Data Link Layer from Network to Network Data Link Layer T 2 Data (frame) Data H 2 to Physical T 2 Data H 2 from Physical

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

Engineered for Tomorrow Network Layer from Transport Data Network Layer Data to Transport Data H 3 (packet) to Data Link Data H 3 from Data Link

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)

Engineered for Tomorrow Transport Layer from Application Data Transport Layer Data 1 H 4 Data 2 H 4 Data 3 H 4 to Application Data 1 H 4 Data 2 H 4 Data 3 H 4 (segments) to Network from Network 43

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 44

Engineered for Tomorrow Presentation Layer Responsible for handling differences in data representation to applications Duties/services Data translation Encryption Decryption Compression 45

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 46

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.

Engineered for Tomorrow TCP/IP Model User Application Layer Software Transport Layer Network Layer Data Link Layer Physical Layer Hardware Transmission Medium 48

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.

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: IPV 4 and IPV^

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 Engineered for Tomorrow § 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