Lecture 1: Data Networks’ Infrastructures PDF

Lecture 1: Data Networks’ Infrastructures Dr. Reza Djavanshir, Professor, Johns Hopkins University  FYI: Mobile Internet The Web applications will evolve as telecom networks expand and mobile computing devices dominate internet connectivity. By...

Lecture 1: Data Networks’ Infrastructures Dr. Reza Djavanshir, Professor, Johns Hopkins University  FYI: Mobile Internet The Web applications will evolve as telecom networks expand and mobile computing devices dominate internet connectivity. By 2025, mobile connectivity could be accessed by an additional 4.3 billion people  FYI: Cloud technology One of the biggest used words of the last decade will continue to impact the next. Nearly all IT services and web apps could be delivered through the cloud with more enterprises using the public cloud as cyber security improves.  FYI: Internet of Things (IoT) Past 3 decades were dominated by the Internet Services. But, started in the mid 2010s, the Intent has been evolved into New Products called the IoT that will dominate the next 50 years in the future. So far, More than 10 billion IoT devices are connected to the internet – that number is estimated to grow between 50 billion to nearly 1 trillion in the next decade. DATA NETWORKS & INFRASTURES  What is Data Communications ◼ “The encoded transmission of data arranged in Sequences of Bits (0 or 1) via electrical, optical, or wireless means between computers or network processors.” Example of Data transmitted in a Sequence of Bits: – “0100 0001” It represents 'A' – “0100 0010” It represents 'B’, – etc.  Major Factors in Telecom Networks There are 3 Major Factors that you should consider in Acquiring, Architecting, and Operating any Telecom Networks: 1. Transmission Mode (Wired or Wireless) 2. Access Methodology (Protocols) 3. Network’s Topology (Star, Hierarchy, Mesh, Direct Connections)  What are Communications Protocols (Standards) Protocols are The Rules of the Game for Connection and Communications in a meaningful way. Network Topology: Direct Connection Network Topology: Star Network Topology: Hierarchical Network Topology: Mesh  Terminology Verizon,…: – Local Central office (CO) = Local Exchange Carrier (LEC) = Telco – Local Transmission Line = Local Loops (for Houses, or Businesses) – Long Distance Transmission Line= Interoffice Carrier (IOC) AT&T, Sprint: – Long Distance Provider =Interoffice Exchange Carrier (IXC), POP – Transmission Line= Interoffice Carrier (IOC) Local Access Transport Area(LATA) v. Area Codes  Local Calls (Same LATA) LEC, LEC, Tel CO, LEC Interface Tel CO, CO CO or IOC Local Loop Local Loop 703-610-YYYY 301-294-XXXX Long Distance Calls (Source & Destination are in Different LATAs) AT&T IXC Sprint IXC IXC’s IOC AT&T IXC Sprint IXC IOC IOC LATA 1 Verizon Verizon LEC, LEC, Tel CO, Tel CO, CO CO Local Loop Local Loop LATA 2 301-294-XXXX 213-921-YYYY  Network Access Architecture: LATA’s and Basic infrastructure Local access transport areas (LATA) were established as a result of the breakup of AT&T to segment long-distance traffic  Protocols In general, a protocol is the rule of a game. In Telecommunications, a protocol is a set of Rules that govern communication between hardware and/or software components. These Rules make computer to understand their communications  Protocols: The OSI Model The International Standards Organization (ISO) has developed a framework of Rules for organizing networking technology and protocol solutions known as the Open Systems Interconnection (OSI) network reference model. The OSI Model consists of a hierarchy of 7 layers that loosely group the functional requirements for communication between two computing devices.  Open System Interconnect (OSI) The OSI model Network analysts literally talk in terms of the OSI model. When troubleshooting network problems, the network analyst starts with the physical layer and ensures that protocols and interfaces are operational at each layer. Another benefit of the OSI model is that it allows discussion about the interconnection of two networks or computers in common terms without dealing in proprietary vendor jargon International Stand Organization’s (ISO)/ Open Systems Interconnect (OSI) Model Peer to Peer Communication  Application Layer include utilities and network based services that support end-user application programs. the best examples of application layer protocols are the OSI protocols X.400 (e-mail) and or X.500 (Directory Services), Word, Excel, PowerPoint, DNS, Domain Name Service, which is an Internet protocol that resolves a computer's common or domain name to a specific IP address, is also considered an application layer protocol  Presentation Layer Presentation layer protocol Formats the message content and provides an interface between user applications and various presentation-related services required by those applications. For example, your e-mails have Standard Formats, – Data Encryption/decryption protocols are considered presentation layer protocols as are protocols that translate between encoding schemes such as ASCII to EBCDIC  Presentation Layer: Responsible for Formatting (That is the Receiver(s) Receives the Message in the Same Format that it Was Sent).  EDI Electronic Data Interchange; – Developed over presentation layer – For Formal Formatted Documents such as: Lawyers use, Accountants use, Tax Form Insurance Forms,….mmn  Session Layer Session layer protocols are responsible for Establishing, Maintaining, and Terminating Sessions between user application programs. Sessions are interactive dialogues between networked End Users (Terminals/PCs, Laptops,..).  Why Do we need Sessions Layer We Made it comparing (mimicking) Humans’ Telephone Communications and Mapping it to the Internet: 1. Pickup the Phone 2. Dial the Destination Address 3. Listen to Tone (If busy, Hang up and dial back again). 4. Keep Calling Until the other side Pickups the phone 5. The Caller and other side Say Hello 6. Start Communicating, …. 7. Sometimes you Hear Silence from the other side, To make sure that the Communication is On, You Say are Listing... 8. To End the Communcatio , Onside Says Goodby 9. Handup  Transport Layer Transport Layer protocols are responsible for providing Reliable, end-to-end Terminal-to- Terminal connections. Transport layer protocols provide Reliable, End-to- end (Terminal-to-Terminal) Error Recovery and Flow control between End users. It also provide mechanisms for Sequentially organizing multiple network layer packets into a coherent message. Fire-wall and and Gate-way Functions are mainly Implemented from Transports and Network’s Layers.  Packet or Network Layer Network Layer protocols are responsible for the Establishment, Maintenance, and Termination of Network links (it is a Network layer protocol between Network’s Switching Systems – Routers,..). Network layer protocols are responsible for providing network layer Packetizing. Addressing, Routing, Priority Setting and Time Tagging schemes.  Network Layer (Packets v. Frames) The term Packets is usually associated with Network Layer Protocols While the term Frames is usually associated with Data Link layer protocols. “ It represents 'B’ Space X Space Y  Data Link or Frame Layer Responsible for providing protocols that deliver reliable point-to-point connections organizing the Bit stream into structured Frames which add Frame Addresses and Error checking Information. Additional information added to the front of data is called a header, information added to the back of data is called a trailer. Data link layer protocols provide Error Detection, Notification, and Recovery  Physical Layer Physical Level can be Wires or Wireless Transmits and receives a stream of bits Responsible for the establishment, maintenance and termination of physical connections between communicating devices. No data recognition at the physical layer. Where to Apply Networking Technologies (Systems) to ISO 7-Layer Architectures SOURCE DEVICE (SYSTEM NEEDED) DESTINATION 7. Application Layer 7. Application Layer 6. Presentation 6. Presentation Layer 5. Session Layer Gateway 5. Session Layer 4. Transport Layer 4. Transport Layer 3. Network Layer Router/ Switch 3. Network Layer 2. Data Link Layer Bridge 2. Data Link Layer 1. Physical Layer Repeater 1. Physical Layer Note: Firewall = Router/Switch + Gateway TCP/IP Model Physical Layer  TCP/IP Five-Layer Protocol FROM TOP TO BOTTOM LAYERS: Layer 5 - Application layer: It includes all the higher-level protocols Software Applications, like, email, Words, Dbase, Window…. Applications (Word, PPT, Excel, e-Mail…), Directory, Text Messages….. HTTP, Telnet, FTP, SMTP (Simple Mail Transfer),. Plus Functions of Presentation (Formatting And Encryptions,…), and Sessions Layers Layer 4- Transport Layer: The purpose is to allow the source destination computers to reliable and error free communications. It breaks down the information into small segments. The main protocols included at Transport layer is TCP  TCP/IP Communication Protocol 3. Layer 3 - Internet Layer (IP): Performs all the functions of Packet layer*. 2. Layer 2 - Network Access Layer: Performs the combined functions of Data link and physical layers. 1. Layer 1- Physical Layer (Wired or Wireless connections) *Note: later we will learn that IP is a Connectionless protocol. But together with TCP, TCP/IP becomes Connection oriented protocol.  Function of A Typical Multiplexer Speed = A + B + C +… kbps A kbps B kbps C kbps, …. Concentrator (Telecom Switches) (PAD or FRAD Switches) Speed = < A + B + C +… kbps Concentrator PAD Buffers A kbps B kbps C kbps, ….