Pertemuan 1 Network System Overview I Made Astawa

Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa dapat : menjelaskan berbagai macam komponen / element pada sistem jaringan menjelaskan fungsi protokol pada jaringan komoputer

3 Outline Materi Network System Elements Network software Communications Protocol Protocol layer OSI Model TCP/IP Reference Model Network Programming Tools Aplikasi Client Server

4 Network System Overview Network System Elements – Computing Terminals (e.g. PC, Workstation, PDA, etc.) – Communication Links (e.g. LAN, WAN, Modem, ISDN, etc.) – Communication Protocols (e.g. TCP, UDP, and IP) – System Software (e.g. OS, Protocol Stack and NIC Drivers) – Application Software (e.g. Web, FTP, etc.)

5 Network System Overview

6 Network software? – Software untuk mentransfer data dari satu proses ke proses yang lainnya. – System-level Network Software Software untuk mengoperasikan dan mengelola jaringan – Network Interface Card drivers – Routing Software – Name Servers, etc. Software for communications services – Transport protocol – Application-level Network Software Integrate other functions (e.g. HTML ) to provide a particular service Contoh: web servers and browsers, dll

7 Network System Overview Communications Protocol A specification for two or more parties to convey information across a communications link. – Defines the interaction model (e.g. using a finite-state machine model) – Defines data encoding and structure Examples: TCP, HTTP, FTP, etc. Packet / Frame / Segment / Message A unit (finite number of bytes) for communications in a certain protocol Unit has predefined structure such as header and trailer Analogy – A bus is a unit for transportation. Every bus has a driver, an engine, etc.

8 Network System Overview Communications Protocol – Software yang menerapkan protocol komunikasi tertentu. – Contoh: TCP Layer, IP Layer, dll.

9 Network System Overview Protocol Stack – A collection of related Protocols or Protocol Layers – Example: a TCP/IP protocol stack

10 OSI Reference Model The OSI Reference Model Developed by the International Standards Organization (ISO). The model is called Open Systems Interconnection (OSI). Consists of seven layers. A paper design without practical implementation. Provides a standard way to divide networking functions into seven layers.

11 OSI Reference Model

12 OSI Reference Model Physical Layer – Physical layer merubah bit ke signal dan sebaliknya. – Media yg dipergunakan untuk mentransmisikan signal : Radio, Twisted pair, Coaxial cable, Optical fiber, dll. Data Link Layer – Menyediakan suatu layanan yang bebas dari kesalahan transmisi, dengan kata lain Data link layer menjaga agar paket tiba dengan baik sampai di ujung media yg digunakan – Menyediakan error control (error detection) and flow control /acknowledgment

13 OSI Reference Model The Network Layer – Network layer berkaitan dengan pengambilan paket dari source node ke destination node, routing, addressing physical device. The Transport Layer – Transport layer mengontrol pengiriman pesan antara dua node di dalam network. – Divide message into packets – If required reorder packet that arrive out of order – If required resend lost or damaged packets

14 OSI Reference Model The Session Layer – Provides session management Pengendalian dialog (satu arah atau dua arah) Token management (untuk memastikan bahwa kedua belah pihak yg berhubungan tdk melakukan operasi yang sama) synchronization or crash recovery The Presentation Layer – Concerns the syntax and semantics of the information transmitted – Performs information encoding and decoding to facilitate the exchange of information Text: ASCII versus Unicode Numbers: byte ordering and byte size differences

15 OSI Reference Model The Application Layer – Defines the protocols and services for a specific application. – Examples: File Transfer (FTP) (SMTP, POP3) WWW (HTTP) Network News (NNTP)

16 TCP/IP Reference Model – A reference model created from the Internet protocols – Model assumptions: Network is inherently unreliable Network is connection-less – Consists primary of three layers Internet Layer (IP) Transport Layer (TCP, UDP) Application Layer (HTTP, FTP, etc.)

17 TCP/IP Reference Model

18 TCP/IP Reference Model

19 TCP/IP Reference Model The TCP/IP stack is shorter than the OSI one: TCP is a connection-oriented protocol, UDP (User Datagram Protocol) is a connectionless protocol

20 TCP/IP Reference Model The Internet Layer – Protocol used: Internet Protocol (IP) – Assumes a packet-switching network – Connectionless – Handles routing of IP packets – Similar to OSI’s network layer – IP (internet protocol) breaks communication into packets. Packets routed and delivered separately No delivery guarantee Max packet size: (less a 20 byte header) Sockets enable two machines to communicate via IP.

21 TCP/IP Reference Model The Transport Layer – Protocol one: Transmission Control Protocol (TCP) Provides a reliable, connection-oriented, stream service. Handles data packetization and reassembly. Handles flow control, sequencing, and error recovery. Handles designation among processes in the same host by means of service port numbers. – Protocol two: User Datagram Protocol (UDP) Provides an unreliable, connectionless, datagram service. Handles designation among processes in the same host by means of service port numbers. No flow control, sequencing, and error recovery.

22 TCP/IP Reference Model The Application Layer Services Protocols Virtual Terminal TELNET File Transfer FTP Electronic Mail SMTP/POP3 Name Resolution DNS Network News NNTP World Wide Web HTTP Streaming Video RTSP Network File System NFS Network Management SNMP

23 Network Programming Tools Essential Components – A Programming Environment Editor, Debugger, Compiler, etc. Examples: gcc in UNIX, Visual C++ in Windows, etc. – A Network Programming Library Application Programming Interface Must be compatible with the Programming Environment Examples: BSD Sockets, Winsocks, etc. – A Networked Operating System Providing the required protocols Controlling the network hardware Examples: UNIX, Windows, etc.

24 Useful Network Tools ping – Sends a packet (ICMP Echo, RFC792) to a remote machine, which then sends back a reply. – Useful for checking whether remote machine is online telnet – As a quick debugging tool for text-based application protocols running over TCP netstat – Finding out active connections and their status Ipconfig (windows), ifconfig (linux)

25 Aplikasi Client Server Pendahuluan Sebagian besar aplikasi-aplikasi pada jaringan komputer dibagi dua bagian yaitu : Client dan Server

26 Aplikasi Client Server

27 Aplikasi Client Server Contoh : – Web Browser (Clinet) vs Web Server – FTP Client vs FTP Server – Telnet Client vs Telnet Server Client berkomunikasi dengan satu Server, sedangkan Server dapat berkunikasi dengan beberapa Client pada saat yg sama

28 Aplikasi Client Server Client Server Server handling multiple clients at the same time

29 Aplikasi Client Server

30 Aplikasi Client Server Komunikasi antara Client dan Server pada jaringan komputer umumnya menggunakan Protokol jaringan al: TCP/IP, UDP dll. TCP (pada Transport layer) menggunakan Internet Protokol / IP (pada Network layer). IP berkomunikasi dengan Lapisan Data Link

31 Aplikasi Client Server Istilah IP yg telah dikenal mulai awal th. 80-an disebut juga dengan IP versi 4.0 (IPv4), dan pada pertengahan tahun 1990-an telah dikembanagkan IP Versi 6 (IPv6). Aplikasi Client – Sever tidak hanya pada LAN yang sama tetapi juga pada LAN yg berbeda

32 Aplikasi Client Server

33 Aplikasi Client Server Network Programming – Mempelajari bagian apa nya ??

34 Simplified Network Model Process Transport Network Data Link Process Transport Network Data Link Interface Protocols Peer-to-peer Protocols

35 Network API

36 Letter FedX Layers Letter Addressed Envelope Addressed Envelope