Transcript Computer Networks - Gadjah Mada University

Layered Protocol
Types of Networks by Logical
Connectivity
Peer to Peer and Client-Server
 Peer-to-peer Networks
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 Every
computer can communicate directly with
every other computer
 By default, no computer has more authority than
another
 Every computer is capable of sending and
receiving information to and from every other
computer
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Peer-to-peer Networks
Figure 1-1: Resource sharing on a simple peer-to-peer network
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Type of Networks
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Client/Server
 Server:
central computer used to facilitate communication
and resource sharing between other computers on the
network (called clients)
 Client/server network: uses a server to enable clients to
share data, data storage space, and devices
 To function as a server, a computer must be running a
network operating system (NOS)
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Client/Server Networks (continued)
Figure 1-2: Resource sharing on a client/server network
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Client/Server Networks
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Advantages of using client/server networks
over peer-to-peer networks:
 User
logon accounts and passwords can be
assigned in one place
 Access to multiple shared resources can be
centrally granted to a single user or groups of
users
 Problems can be tracked, diagnosed, and often
fixed from one location
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Client/Server Networks
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Advantages of using client/server networks
over peer-to-peer networks (continued):
 Servers
are optimized to handle heavy processing
loads and dedicated to handling requests from
clients, enabling faster response time
 Because of their efficient processing and larger
disk storage, servers can connect more than a
handful of computers on a network
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Network Classification by Area
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PAN (Personal Area Network)
Local area network (LAN): confined to a relatively
small space, such as a building or an office
Metropolitan area network (MAN): larger than a LAN;
connects clients and servers from multiple buildings
Wide area network (WAN): connects two or more
geographically distinct LANs or MANs
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LANs, MANs, and WANs
Figure 1-4: A simple WAN
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Network Topology
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What is Communication
Communication is successful when the message
May
have
to agree
on the
Agree on the
method
used
already
received
andlanguage
confirmedused
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Protocols
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Driving Force: need for different proprietary
networking system to communicate
Protocol: set of rules for acceptable behaviour to
enable communication
Specifically:
 the
set of rules used by communicating parties for that
communication to be successful
 Suite of protocols cover all required behaviour
 Mostly implemented in software
 Complexity demands that protocols are ‘layered’
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ISO/OSI Reference Model

ISO in 1984
 Open
Systems Interconnect (OSI)
 A design guideline for network layering
 Abstract layers provide different services
 Defines 7 layers of service
 Each layer provides service to adjacent layers
 Each layer communicates with same layer in
remote machine.
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OSI Reference Model
Application Layer
Application Layer
Presentation Layer
Presentation Layer
Session Layer
Session Layer
Transport Layer
Transport Layer
Network Layer
Network Layer
Link Layer
Link Layer
Physical Layer
Physical Layer
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OSI Model
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OSI Layers
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OSI Layers
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OSI Layers
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OSI Layers
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OSI Layers
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OSI Layers
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OSI Layers
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TCP/IP Model
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Data Encapsulation
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Data Encapsulation
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OSI Layer vs. TCP/IP Layer
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5-7
4
3
1-2
FTP – File Transfer Protocol
HTTP – Hypertext Transfer Protocol
WAP – Wireless Application Protocol
SMTP – Simple Mail Transfer Protocol
TCP
UDP
IP
e.g. IEEE 802.x
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Packet Tracer
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Example of packet data unit (PDU) in layered
network
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Movie
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GoodWarriors
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Quiz
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What are the differences between
 Circuit
switching and packet switching
 Connection oriented and connectionless oriented
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Protocols
 What
are they?
 Why do we layer protocols?
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ISO/OSI – 7 layer reference model
 How
does the OSI abstract services?
 How does TCP/IP stack relate to OSI?
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Topik
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IM & SIP protocol
Dhcp & e-mail protocol
p2p protocol
ipv6 & packettracer
Vlan
rip & ospf
Ns2, contoh aplikasi
omnet++, contoh aplikasi
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