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  1. 1. 1 Chapter 1 Introduction TCP/IP Assignment -by Harshwardhan Pusadkar Bhavesh Bhandarkar
  2. 2. TCP/IP Protocol 2 OBJECTIVES:  To give a brief history of the Internet.  To give the definition of the two often-used terms in the discussion of the Internet: protocol and standard.  To categorize standard organizations involved in the Internet and give a brief discussion of each.  To define Internet Standards and explain the mechanism through which these standards are developed.  To discuss the Internet administration and give a brief description of each branch.
  3. 3. TCP/IP Protocol 3 Chapter Outline 1.1 A Brief History 1.2 Protocols and Standards 1.3 Standards Organizations 1.4 Internet Standards 1.5 Internet Administration
  4. 4. TCP/IP Protocol 4 1-1 A BRIEF HISTORY A network is a group of connected, communicating devices such as computers and printers. An internet is two or more networks that can communicate with each other. The most notable internet is called the internet, composed of hundreds of thousands of interconnected networks. Private individuals as well as various organizations such as government agencies, schools, research facilities, corporations, and libraries in more than 100 countries use the Internet.
  5. 5. TCP/IP Protocol 5 Topics Discussed in the Section ARPANET Birth of the Internet TCP/IP MILNET CSNET NSFNET ANSNET The Internet Today World Wide Web Growth of the Internet
  6. 6. TCP/IP Protocol 6 Figure 1.1 Internet today
  7. 7. TCP/IP Protocol 7 1-2 PROTOCOLS AND STANDARDS In this section, we define two widely used terms: protocols and standards. First, we define protocol, which is synonymous with “rule.” Then we discuss standards, which are agreed-upon rules.
  8. 8. TCP/IP Protocol 8 Topics Discussed in the Section Protocols Standards
  9. 9. TCP/IP Protocol Suite 9 1-3 STANDARDS ORGANIZATION Standards are developed through the cooperation of standards creation committees, forums, and government regulatory agencies.
  10. 10. TCP/IP Protocol Suite 10 Topics Discussed in the Section Standards Creation Committees Forums Regulatory Agencies
  11. 11. TCP/IP Protocol Suite 11 1-4 INTERNET STANDARDS An Internet standard is a thoroughly tested specification that is useful to and adhered to by those who work with the Internet. It is a formalized regulation that must be followed. There is a strict procedure by which a specification attains Internet standard status. A specification begins as an Internet draft. An Internet draft is a working document with no official status and a six-month lifetime.
  12. 12. TCP/IP Protocol Suite 12 Topics Discussed in the Section Maturity Levels Requirement Levels
  13. 13. TCP/IP Protocol Suite 13 Figure 1.2 Maturity levels of an RFC
  14. 14. TCP/IP Protocol Suite 14 Figure 1.3 Requirement levels of an RFC
  15. 15. TCP/IP Protocol Suite 15 1-5 INTERNET ADMINISTRATION The Internet, with its roots primarily in the research domain, has evolved and gained a broader user base with significant commercial activity. Various groups that coordinate Internet issues have guided this growth and development. Appendix G gives the addresses, e-mail addresses, and telephone numbers for some of these groups. Figure 1.4 shows the general organization of Internet administration.
  16. 16. INTERNET ARCHITECTURE • Sometimes called TCP/IP • Evolved from an earlier packet-switched network called ARPANET • Internet and ARPANET were funded by ARPA (Advanced Research Projects Agency) • Both existed before the OSI architecture • Both affected the OSI model
  17. 17. INTERNET ARCHITECTURE Internet Protocol Graph Alternative view of the Internet architecture. The “Network” layer shown here is sometimes referred to as the “sub- network” or “link” layer.
  18. 18. INTERNET ARCHITECTURE • Defined by IETF • Three main features • Does not imply strict layering. The application is free to bypass the defined transport layers and to directly use IP or other underlying networks • An hour-glass shape – wide at the top, narrow in the middle and wide at the bottom. IP serves as the focal point for the architecture (host-to-host connectivity is separate from all channel types) • In order for a new protocol to be officially included in the architecture, there needs to be both a protocol specification and at least one (and preferably two) representative implementations of the specification
  19. 19. INTERNET ARCHITECTURE • NET1, NET2, … • Could be Ethernet, Wireless, etc. • Encapsulate both hardware and data link layers from OSI model • IP (Internet Protocol) • Supports the interconnection of multiple networking technologies into a single logical internetwork • Analogy to the network layer in the OSI • The routing protocol
  20. 20. INTERNET ARCHITECTURE • TCP provides reliable, byte-stream channel (connection oriented protocol) • UDP provides unreliable, datagram (message) delivery channel. • TCP and UDP are called (besides Transport) end-to-end protocols
  21. 21. INTERNET ARCHITECTURE • Application Protocols • HTTP, FTP, Telnet (remote login), Simple Mail Transfer Protocol (SMTP), and much more • Enables the interoperation of popular applications • Many different web browsers interoperate with web servers because they all conform/use the HTTP protocol
  22. 22. NETWORK ARCHITECTURE Example of a layered network system
  23. 23. NETWORK ARCHITECTURE Layered system with alternative abstractions available at a given layer
  24. 24. TCP/IP Protocol Suite 24 Figure 1.4 Internet administration
  25. 25. CONNECTIVITY • Need to understand the following terminologies • Scale: A system that is designed to support growth to an arbitrarily large size • Link: Physical medium that connects nodes • Node: a device (could be a computer, switch, etc) on the network • Point-to-point: direct link between two nodes • Multiple access: multiple nodes share the same link (a) Point-to-point (b) Multiple access
  26. 26. CONNECTIVITY • Switched Network: a network that uses switches for forwarding • Circuit Switched • Telephone companies • Dedicated/reserved when connection is established • Less utilization of the resources • Packet Switched • Overwhelming majority of computer networks • Messages are divided into pieces (discrete blocks) called packets • No dedication is required • More sharing, thus more utilization • Store-and-forward: a switch stores the incoming traffic (packets) in its own buffers then forwards them.
  27. 27. CONNECTIVITY • Cloud: used to represent any kind of network technology • Point-to-point, multiple-access, or switched network • Hosts: nodes outside the cloud (usually computer or end users devices and use the network) • Switches: nodes inside the cloud and implement the network (store and forward packets) • Internetwork (or internet with small “i”): a set of independent interconnected networks (clouds) • Internet (with big “I”): is the globally known network
  28. 28. CONNECTIVITY • Router/gateway: connects two or more networks (plays much the same role as a switch—stores and forwards) • Host-to-host connectivity: hosts can talk to hosts • Address: the way to find nodes. It is a byte string that identifies a node. • Routing: the process of determining systematically how to forward messages toward the destination node based on its address • Unicast: send to single destination • Broadcast: send to all nodes on the network • Multicast: send to subset of nodes
  29. 29. CONNECTIVITY (a) A switched network (b) Interconnection of networks (a) (b)
  30. 30. LAN, MAN, WAN, AND SAN • Characterize networks according to their size (they usually use diff. technologies): • LAN: Local Area Network, typically less than 1km • WAN: Wide Area Network, worldwide • MAN: Metropolitan Area Network, tens of kilometers • SAN: Systems/Storage Area Network, single room that has high-performance components (like leading-edge storage devices) connected together
  31. 31. ABSTRACTION AND LAYERING • Abstraction • The hiding of details behind a well-defined interface • Define a model • Capture important aspects of the system • Abstractions naturally leads to layering • The general idea • Start from services offered by the underlying hardware • Add a sequence of layers, each providing a higher (i.e., more abstract) level of service. • Manageability and Mudularity
  32. 32. PROTOCOALS • The abstract objects the make up the layers of a network system are called protocols • Building blocks of a network architecture • Each protocol object has two differentinterfaces • service interface: operations on this protocol • peer-to-peer interface: messages exchanged with peer (indirect communication, except for the hardware)
  33. 33. INTERFACES Service and Peer Interfaces
  34. 34. PROTOCOLS • Protocol Specification: • Written description (prose) • pseudo-code • state transition diagram • Packet format • RFCs: Request For Comments • IETF: Internet Engineering Task Force • Standardization body • Ex. RFC 2616 for HTTP protocol • Interoperable: when two or more protocols that implement the specification accurately
  35. 35. PROTOCOL GRAPH Example of a protocol graph nodes are the protocols and links the “depends-on” relation
  36. 36. ENCAPSULATION High-level messages are encapsulated inside of low-level messages
  37. 37. ABSTRACTION AND LAYERING • Abstraction • The hiding of details behind a well-defined interface • Define a model • Capture important aspects of the system • Abstractions naturally leads to layering • The general idea • Start from services offered by the underlying hardware • Add a sequence of layers, each providing a higher (i.e., more abstract) level of service. • Manageability and Mudularity
  38. 38. APPLICATION PROGRAMMING INTERFACE • Interface exported by the network • Since most network protocols are implemented (those in the high protocol stack) in software and nearly all computer systems implement their network protocols as part of the operating system, when we refer to the interface “exported by the network”, we are generally referring to the interface that the OS provides to its networking subsystem • The interface is called the network Application Programming Interface (API)
  39. 39. APPLICATION PROGRAMMING INTERFACE (SOCKETS) • Socket Interface was originally provided by the Berkeley distribution of Unix - Now supported in virtually all operating systems • Each protocol provides a certain set of services, and the API provides a syntax by which those services can be invoked in this particular OS
  40. 40. SOCKET • What is a socket? • The point where a local application process attaches to the network • An interface between an application and the network • An application creates the socket • The interface defines operations for • Creating a socket • Attaching a socket to the network • Sending and receiving messages through the socket • Closing the socket
  41. 41. BANDWIDTH • Frequency band (measured in Hertz): we don’t mean that • Number of bits per second that can be transmitted over a communication link • Throughput vs. bandwidth (from the most confusing terms in computer networks. • Bandwidth: the maximum data rate (bits per second) • Throughput: number of bits per second that we actually transmit over the link in practice • 1 Mbps: 1 x 106 bits/second = 1x220 bits/sec • 1 x 10-6 seconds to transmit each bit or imagine that a timeline, now each bit occupies 1 micro second space. • On a 2 Mbps link the width is 0.5 micro second. • Smaller the width more will be transmission per unit time.
  42. 42. BANDWIDTH Bits transmitted at a particular bandwidth can be regarded as having some width: (a) bits transmitted at 1Mbps (each bit 1 μs wide); (b) bits transmitted at 2Mbps (each bit 0.5 μs wide).
  43. 43. LATENCY • How long it takes a message to travel from one end of a network to the other. • Measured in time
  44. 44. LATENCY • Three components • Speed-of-light propagation delay • Different media at different speeds • 3.0 × 108 m/s in a vacuum • 2.3 × 108 m/s in copper cable • 2.0 × 108 m/s in optical fiber • Amount of time to transmit a unit of data • Queuing delays (switches store packets)
  45. 45. THANK YOU!