Matakuliah
Tahun
Versi
: H0483 – Network Programming
: 2008
: 2.0
Pertemuan 1
Network System Overview
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Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
dapat :
• menjelaskan berbagai macam komponen /
element pada sistem jaringan
• menjelaskan fungsi protokol pada jaringan
komoputer
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Outline Materi
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Network System Elements
Network software
Communications Protocol
Protocol layer
OSI Model
TCP/IP Reference Model
Network Programming Tools
Aplikasi Client Server
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Network System Overview
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.)
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Network System Overview
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Network System Overview
• 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
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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.
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Network System Overview
• Communications Protocol
– Software yang menerapkan protocol
komunikasi tertentu.
– Contoh: TCP Layer, IP Layer, dll.
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Network System Overview
• Protocol Stack
– A collection of related Protocols or Protocol
Layers
– Example: a TCP/IP protocol stack
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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.
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OSI Reference Model
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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
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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
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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
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OSI Reference Model
• The Application Layer
– Defines the protocols and services for a
specific application.
– Examples:
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File Transfer (FTP)
Email (SMTP, POP3)
WWW (HTTP)
Network News (NNTP)
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TCP/IP Reference Model
• 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.)
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TCP/IP Reference Model
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TCP/IP Reference Model
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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
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TCP/IP Reference Model
• The Internet Layer
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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.
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Packets routed and delivered separately
No delivery guarantee
Max packet size: 65535 (less a 20 byte header)
Sockets enable two machines to communicate via IP.
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TCP/IP Reference Model
• The Transport Layer
– Protocol one: Transmission Control Protocol
(TCP)
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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.
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TCP/IP Reference Model
• The Application Layer
Services
Protocols
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TELNET
FTP
SMTP/POP3
DNS
NNTP
HTTP
RTSP
NFS
SNMP
Virtual Terminal
File Transfer
Electronic Mail
Name Resolution
Network News
World Wide Web
Streaming Video
Network File System
Network Management
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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.
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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)
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Aplikasi Client Server
Pendahuluan
• Sebagian besar aplikasi-aplikasi pada
jaringan komputer dibagi dua bagian yaitu
: Client dan Server
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Aplikasi Client Server
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Aplikasi Client Server
• Contoh :
– Web Brouser (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
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Aplikasi Client Server
Client
Server
Client
Client
Server handling multiple clients at the
same time
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Aplikasi Client Server
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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
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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 1990an telah dikembanagkan IP Versi 6 (IPv6).
• Aplikasi Client – Sever tidak hanya pada
LAN yang sama tetapi juga pada LAN yg
berbeda
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Aplikasi Client Server
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Aplikasi Client Server
• Network Programming
– Mempelajari bagian apa nya ??
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Simplified Network Model
Process
Process
Interface Protocols
Transport
Transport
Peer-to-peer
Protocols
Network
Network
Data Link
Data Link
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Network API
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FedX Layers
Letter
Addressed
Envelope
Letter
Addressed
Envelope
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