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komdat1

  1. 1. Komunikasi Data TKE 107 – 3 sks Bab 1 - 2 Protokol and Arsitektur
  2. 2. A Communications Model <ul><li>Source </li></ul><ul><ul><li>generates data to be transmitted </li></ul></ul><ul><li>Transmitter </li></ul><ul><ul><li>Converts data into transmittable signals </li></ul></ul><ul><li>Transmission System </li></ul><ul><ul><li>Carries data </li></ul></ul><ul><li>Receiver </li></ul><ul><ul><li>Converts received signal into data </li></ul></ul><ul><li>Destination </li></ul><ul><ul><li>Takes incoming data </li></ul></ul>
  3. 3. Communications Tasks Flow control Network management Error detection and correction Security Exchange management Message formatting Synchronization Recovery Signal generation Routing Interfacing Addressing Transmission system utilization
  4. 4. Simplified Communications Model - Diagram
  5. 5. Simplified Data Communications Model
  6. 6. Frame Relay <ul><li>Packet switching systems have large overheads to compensate for errors </li></ul><ul><li>Modern systems are more reliable </li></ul><ul><li>Errors can be caught in end system </li></ul><ul><li>Most overhead for error control is stripped out </li></ul>
  7. 7. Asynchronous Transfer Mode <ul><li>ATM </li></ul><ul><li>Evolution of frame relay </li></ul><ul><li>Little overhead for error control </li></ul><ul><li>Fixed packet (called cell) length </li></ul><ul><li>Anything from 10Mbps to Gbps </li></ul><ul><li>Constant data rate using packet switching technique </li></ul>
  8. 8. Local Area Networks <ul><li>Smaller scope </li></ul><ul><ul><li>Building or small campus </li></ul></ul><ul><li>Usually owned by same organization as attached devices </li></ul><ul><li>Data rates much higher </li></ul><ul><li>Usually broadcast systems </li></ul><ul><li>Now some switched systems and ATM are being introduced </li></ul>
  9. 9. LAN Configurations <ul><li>Switched </li></ul><ul><ul><li>Switched Ethernet </li></ul></ul><ul><ul><ul><li>May be single or multiple switches </li></ul></ul></ul><ul><ul><li>ATM LAN </li></ul></ul><ul><ul><li>Fibre Channel </li></ul></ul><ul><li>Wireless </li></ul><ul><ul><li>Mobility </li></ul></ul><ul><ul><li>Ease of installation </li></ul></ul>
  10. 10. Metropolitan Area Networks <ul><li>MAN </li></ul><ul><li>Middle ground between LAN and WAN </li></ul><ul><li>Private or public network </li></ul><ul><li>High speed </li></ul><ul><li>Large area </li></ul>
  11. 11. Networking Configuration
  12. 12. Karakteristik <ul><li>Langsung – Tak Langsung </li></ul><ul><li>Monolitik – Terstruktur </li></ul><ul><li>Simetris – Asimetris </li></ul><ul><li>Standard - Nonstandard </li></ul>
  13. 13. Kebutuhan thd Protokol Arsitektur <ul><li>Perpindahan data memerlukan prosedur yang komplek </li></ul><ul><li>Lebih baik bila dipecah dlm sub-sub task </li></ul><ul><li>Diimplementasikan dlm tumpukan layer </li></ul><ul><ul><li>Tiap-tiap layer menyediakan fungsi-fungsi yang diperlukan untuk berkomunikasi dengan layer di atasnya </li></ul></ul><ul><ul><li>Memanfaatkan fungsi-fungsi yang disediakan layer di bawahnya </li></ul></ul><ul><li>Peer layer berkomunikasi dengan layer </li></ul>
  14. 14. Elemen kunci sebuah Protokol <ul><li>Sintaks : format </li></ul><ul><li>Semantiks : info kontrol dan penanganan kesalahan </li></ul><ul><li>Timing : Kesesuaian kecepatan dan urutan </li></ul>
  15. 15. Langsung – Tak Langsung <ul><li>Langsung </li></ul><ul><ul><li>Sistem membagi saluran point to point </li></ul></ul><ul><ul><li>Sistem membagi saluran multi-point </li></ul></ul><ul><ul><li>Data dapat lewat tanpa intervensi agen aktif </li></ul></ul><ul><li>Tak Langsung </li></ul><ul><ul><li>Switched networks </li></ul></ul><ul><ul><li>Internetworks atau internets </li></ul></ul><ul><ul><li>Transfer data bergantung pada entitas lain </li></ul></ul>
  16. 16. Monolitik - Terstruktur <ul><li>Komunikasi adalah sebuah task yang kompleks </li></ul><ul><li>To complex for single unit </li></ul><ul><li>Terstruktur : melakukan ‘break down’ masalah ke dalam unit-unit yang lebih kecil </li></ul><ul><li>Struktur berlayer </li></ul>
  17. 17. Simetrik - Asimetrik <ul><li>Simetrik </li></ul><ul><ul><li>Komunikasi antara peer entities </li></ul></ul><ul><li>Asimetrik </li></ul><ul><ul><li>Client/server </li></ul></ul>
  18. 18. Standard – Nonstandard <ul><li>Protokol yang tidak standar dibuat untuk komputer-komputer dan task khusus </li></ul><ul><li>K sources dan L receivers menjadikan K*L protocols dan ada 2*K*L implementasi </li></ul><ul><li>Jika protokol bersama yang digunakan, ada K + L implementasi diperlukan </li></ul>
  19. 19. Penggunaan Protokol Standard
  20. 20. Fungsi <ul><li>Enkapsulasi </li></ul><ul><li>Segmentasi(Fragmentasi) dan Reassembly </li></ul><ul><li>Connection control </li></ul><ul><li>Ordered delivery </li></ul><ul><li>Flow control </li></ul><ul><li>Error control </li></ul><ul><li>Addressing </li></ul><ul><li>Multiplexing </li></ul><ul><li>Transmission services </li></ul>
  21. 21. Enkapsulasi <ul><li>Penambahan informasi kontrol ke data </li></ul><ul><ul><li>Informasi alamat </li></ul></ul><ul><ul><li>Kode Error-detecting </li></ul></ul><ul><ul><li>Kontrol Protocol </li></ul></ul>
  22. 22. Segmentasi (Fragmentasi) <ul><li>Data blocks are of bounded size </li></ul><ul><li>Application layer messages may be large </li></ul><ul><li>Network packets may be smaller </li></ul><ul><li>Splitting larger blocks into smaller ones is segmentation (or fragmentation in TCP/IP) </li></ul><ul><ul><li>ATM blocks (cells) are 53 octets long </li></ul></ul><ul><ul><li>Ethernet blocks (frames) are up to 1526 octets long </li></ul></ul><ul><li>Checkpoints and restart/recovery </li></ul>
  23. 23. Mengapa Fragmentasi? <ul><li>Advantages </li></ul><ul><ul><li>More efficient error control </li></ul></ul><ul><ul><li>More equitable access to network facilities </li></ul></ul><ul><ul><li>Shorter delays </li></ul></ul><ul><ul><li>Smaller buffers needed </li></ul></ul><ul><li>Disadvantages </li></ul><ul><ul><li>Overheads </li></ul></ul><ul><ul><li>Increased interrupts at receiver </li></ul></ul><ul><ul><li>More processing time </li></ul></ul>
  24. 24. Connection Control <ul><li>Connection Establishment </li></ul><ul><li>Data transfer </li></ul><ul><li>Connection termination </li></ul><ul><li>May be connection interruption and recovery </li></ul><ul><li>Sequence numbers used for </li></ul><ul><ul><li>Ordered delivery </li></ul></ul><ul><ul><li>Flow control </li></ul></ul><ul><ul><li>Error control </li></ul></ul>
  25. 25. Connection Oriented Data Transfer
  26. 26. Ordered Delivery <ul><li>PDUs may traverse different paths through network </li></ul><ul><li>PDUs may arrive out of order </li></ul><ul><li>Sequentially number PDUs to allow for ordering </li></ul>
  27. 27. Flow Control <ul><li>Done by receiving entity </li></ul><ul><li>Limit amount or rate of data </li></ul><ul><li>Stop and wait </li></ul><ul><li>Credit systems </li></ul><ul><ul><li>Sliding window </li></ul></ul><ul><li>Needed at application as well as network layers </li></ul>
  28. 28. Error Control <ul><li>Guard against loss or damage </li></ul><ul><li>Error detection </li></ul><ul><ul><li>Sender inserts error detecting bits </li></ul></ul><ul><ul><li>Receiver checks these bits </li></ul></ul><ul><ul><li>If OK, acknowledge </li></ul></ul><ul><ul><li>If error, discard packet </li></ul></ul><ul><li>Retransmission </li></ul><ul><ul><li>If no acknowledge in given time, re-transmit </li></ul></ul><ul><li>Performed at various levels </li></ul>
  29. 29. Addressing <ul><li>Addressing level </li></ul><ul><li>Addressing scope </li></ul><ul><li>Connection identifiers </li></ul><ul><li>Addressing mode </li></ul>
  30. 30. Addressing level <ul><li>Level in architecture at which entity is named </li></ul><ul><li>Unique address for each end system (computer) and router </li></ul><ul><li>Network level address </li></ul><ul><ul><li>IP or internet address (TCP/IP) </li></ul></ul><ul><ul><li>Network service access point or NSAP (OSI) </li></ul></ul><ul><li>Process within the system </li></ul><ul><ul><li>Port number (TCP/IP) </li></ul></ul><ul><ul><li>Service access point or SAP (OSI) </li></ul></ul>
  31. 31. Address Concepts
  32. 32. Addressing Scope <ul><li>Global nonambiguity </li></ul><ul><ul><li>Global address identifies unique system </li></ul></ul><ul><ul><li>There is only one system with address X </li></ul></ul><ul><li>Global applicability </li></ul><ul><ul><li>It is possible at any system (any address) to identify any other system (address) by the global address of the other system </li></ul></ul><ul><ul><li>Address X identifies that system from anywhere on the network </li></ul></ul><ul><li>e.g. MAC address on IEEE 802 networks </li></ul>
  33. 33. Connection Identifiers <ul><li>Connection oriented data transfer (virtual circuits) </li></ul><ul><li>Allocate a connection name during the transfer phase </li></ul><ul><ul><li>Reduced overhead as connection identifiers are shorter than global addresses </li></ul></ul><ul><ul><li>Routing may be fixed and identified by connection name </li></ul></ul><ul><ul><li>Entities may want multiple connections - multiplexing </li></ul></ul><ul><ul><li>State information </li></ul></ul>
  34. 34. Addressing Mode <ul><li>Usually an address refers to a single system </li></ul><ul><ul><li>Unicast address </li></ul></ul><ul><ul><li>Sent to one machine or person </li></ul></ul><ul><li>May address all entities within a domain </li></ul><ul><ul><li>Broadcast </li></ul></ul><ul><ul><li>Sent to all machines or users </li></ul></ul><ul><li>May address a subset of the entities in a domain </li></ul><ul><ul><li>Multicast </li></ul></ul><ul><ul><li>Sent to some machines or a group of users </li></ul></ul>
  35. 35. Multiplexing <ul><li>Supporting multiple connections on one machine </li></ul><ul><li>Mapping of multiple connections at one level to a single connection at another </li></ul><ul><ul><li>Carrying a number of connections on one fiber optic cable </li></ul></ul><ul><ul><li>Aggregating or bonding ISDN lines to gain bandwidth </li></ul></ul>
  36. 36. Transmission Services <ul><li>Priority </li></ul><ul><ul><li>e.g. control messages </li></ul></ul><ul><li>Quality of service </li></ul><ul><ul><li>Minimum acceptable throughput </li></ul></ul><ul><ul><li>Maximum acceptable delay </li></ul></ul><ul><li>Security </li></ul><ul><ul><li>Access restrictions </li></ul></ul>
  37. 37. OSI - The Model <ul><li>A layer model </li></ul><ul><li>Each layer performs a subset of the required communication functions </li></ul><ul><li>Each layer relies on the next lower layer to perform more primitive functions </li></ul><ul><li>Each layer provides services to the next higher layer </li></ul><ul><li>Changes in one layer should not require changes in other layers </li></ul>
  38. 38. The OSI Environment
  39. 39. OSI as Framework for Standardization
  40. 40. Layer Specific Standards
  41. 41. Elements of Standardization <ul><li>Protocol specification </li></ul><ul><ul><li>Operates between the same layer on two systems </li></ul></ul><ul><ul><li>May involve different operating system </li></ul></ul><ul><ul><li>Protocol specification must be precise </li></ul></ul><ul><ul><ul><li>Format of data units </li></ul></ul></ul><ul><ul><ul><li>Semantics of all fields </li></ul></ul></ul><ul><ul><ul><li>allowable sequence of PCUs </li></ul></ul></ul><ul><li>Service definition </li></ul><ul><ul><li>Functional description of what is provided </li></ul></ul><ul><li>Addressing </li></ul><ul><ul><li>Referenced by SAPs </li></ul></ul>
  42. 42. OSI Layers (1) <ul><li>Physical </li></ul><ul><ul><li>Physical interface between devices </li></ul></ul><ul><ul><ul><li>Mechanical </li></ul></ul></ul><ul><ul><ul><li>Electrical </li></ul></ul></ul><ul><ul><ul><li>Functional </li></ul></ul></ul><ul><ul><ul><li>Procedural </li></ul></ul></ul><ul><li>Data Link </li></ul><ul><ul><li>Means of activating, maintaining and deactivating a reliable link </li></ul></ul><ul><ul><li>Error detection and control </li></ul></ul><ul><ul><li>Higher layers may assume error free transmission </li></ul></ul>
  43. 43. OSI Layers (2) <ul><li>Network </li></ul><ul><ul><li>Transport of information </li></ul></ul><ul><ul><li>Higher layers do not need to know about underlying technology </li></ul></ul><ul><ul><li>Not needed on direct links </li></ul></ul><ul><li>Transport </li></ul><ul><ul><li>Exchange of data between end systems </li></ul></ul><ul><ul><li>Error free </li></ul></ul><ul><ul><li>In sequence </li></ul></ul><ul><ul><li>No losses </li></ul></ul><ul><ul><li>No duplicates </li></ul></ul><ul><ul><li>Quality of service </li></ul></ul>
  44. 44. OSI Layers (3) <ul><li>Session </li></ul><ul><ul><li>Control of dialogues between applications </li></ul></ul><ul><ul><li>Dialogue discipline </li></ul></ul><ul><ul><li>Grouping </li></ul></ul><ul><ul><li>Recovery </li></ul></ul><ul><li>Presentation </li></ul><ul><ul><li>Data formats and coding </li></ul></ul><ul><ul><li>Data compression </li></ul></ul><ul><ul><li>Encryption </li></ul></ul><ul><li>Application </li></ul><ul><ul><li>Means for applications to access OSI environment </li></ul></ul>
  45. 45. Use of a Relay
  46. 46. TCP/IP Protocol Suite <ul><li>Dominant commercial protocol architecture </li></ul><ul><li>Specified and extensively used before OSI </li></ul><ul><li>Developed by research funded US Department of Defense (DARPA=Defense Advanced Research Project Agency) for ARPANET packet switchet network </li></ul><ul><li>Used by the Internet </li></ul>
  47. 47. Physical Layer <ul><li>Concerned with physical interface between computer and network </li></ul><ul><li>Concerned with issues like : </li></ul><ul><ul><li>Karakteristik dari media transmisi </li></ul></ul><ul><ul><li>Level sinyal </li></ul></ul><ul><ul><li>Data rate </li></ul></ul>
  48. 48. Network Access Layer <ul><li>Pertukaran data antara sebuah ‘end system’ dan ‘attached network’ </li></ul><ul><li>Berkonsentrasi pada hal-hal “ </li></ul><ul><ul><li>Penyediaan alamat tujuan </li></ul></ul><ul><ul><li>Menyediakan layanan khusus seperti prioritas </li></ul></ul><ul><ul><li>Akses dan routing data melalui sebuah jaringan antaran ‘attached systems’ </li></ul></ul><ul><li>Membolehkan layer di atas untuk mengabaikan </li></ul><ul><li>Logical interface between end system and network </li></ul>
  49. 49. Internet Layer (IP) <ul><li>Fungsi routing melewati berbagai jaringan </li></ul><ul><li>Menggunakan protokol IP </li></ul><ul><li>Terimplementasikan di ‘end system’ dan router </li></ul><ul><li>Router menghubungkan dua network dan merelay data antar keduanya </li></ul>
  50. 50. Transport Layer (TCP) <ul><li>End to end transfer of data </li></ul><ul><li>May include reliability mechanism (TCP) </li></ul><ul><li>Hides detail of underlying network </li></ul>
  51. 51. Application Layer <ul><li>Menyediakan dukungan terhadap aplikasi user </li></ul><ul><li>Memerlukan modul-modul terpisah untuk tiap-tiap aplikasi </li></ul><ul><li>Communication between processes or applications </li></ul>
  52. 52. PDUs in TCP/IP
  53. 53. Some Protocols in TCP/IP Suite
  54. 54. Transmission Control Protocol (TCP) <ul><li>Menyediakan koneksi yang handal untuk transfer data antara aplikasi-aplikasi </li></ul><ul><li>Sebuah segmen TCP adalah unit protokol dasar </li></ul><ul><li>TCP melacak segmen-segmen antara entitas-entitas untuk penentuan durasi dari tiap koneksi </li></ul>
  55. 55. TCP Header
  56. 56. User Datagram Protocol (UDP) <ul><li>Alternatif dari TCP </li></ul><ul><li>Tidak ada garansi </li></ul><ul><li>Tidak ada preservation of sequence </li></ul><ul><li>Tidak ada perlindungan terhadap duplikasi </li></ul><ul><li>Overhead minimal </li></ul><ul><li>Menambah alamat port ke IP </li></ul>
  57. 57. UDP Header

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