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Computer Network

Computer Network

Purposes Increase efficiency (Resource sharing) Information sharing or distribution of information

Categories LAN (Local Area Network) WAN (Wide Area Network)

Computer Communications type Peer-to-peer Client-Server (Ex: Web, Database, File, Mail)

LAN Topologies

Some Network Devices

Guided Media Network Interface Card (NIC) or LAN Card

Ethernet card Hub Switch (Smarter than Hub) Router

Unguided Media Wireless Adapter Wireless Access Point (Radio) Antenna Wireless Router

Twisted Pair Wiring Standard

Straight Cable

Twisted Pair Wiring Standard

Cross Cable (PC-to-PC)

Wiring Tool Set

Crimping ToolRJ-45 connectorUTP cable testerMultimeter

Network Setup

TCP/IP (Internet Concept) IP address Subnet Mask Default Gateway DNS (Domain name server) Alternate DNS DHCP (Automatic)

Microsoft Network Computer name Workgroup name Domain name

9

Set up Identitas Komputer

IP address : Alamat IP yang menunjukkan

identitas dari komputer agar dapat dikenal oleh jaringan

Default Gateway : Alamat IP dari Router yang

terkoneksi dimana permintaan akses internet akan diteruskan

DNS Server (Domain Name System) Alamat IP dari server yang

berfungsi melayani permintaan penterjemahan nama domain menjadi alamat IP

Static IP dan Dynamic IP

Dua metode pemberian alamat IPStatic IP

Diset secara manual. Semua jenis komputer bisa Untuk perangkat mobile umumnya tidak bisa

Dynamic IP Diset “obtain IP address automatically” Pemberian IP address dll dilakukan oleh yang disebut

DHCP server yang umumnya juga ada dalam router Perangkat mobile (HP, Smartphone, X-pad, dll)

umumnya menggunakan metode ini10

Some Network Utilities

ipconfigpingtraceroute / tracert (Microsoft)netstatNote : protocol used is icmp

TCP/IP Protocol Architecture

developed by US Defense Advanced Research Project Agency (DARPA)

for ARPANET packet switched networkused by the global Internetprotocol suite comprises a large collection of

standardized protocols

Simplified Network Architecture

TCP/IP Layers

no official model but a working one Application layer Host-to-host, or transport layer Internet layer Network access layer Physical layer

Physical Layer

concerned with physical interface between computer and network

concerned with issues like: characteristics of transmission medium signal levels data rates other related matters

Network Access Layer

exchange of data between an end system and attached network

concerned with issues like : destination address provision invoking specific services like priority access to & routing data across a network link

between two attached systemsallows layers above to ignore link specifics

Internet Layer (IP)

routing functions across multiple networksfor systems attached to different networksusing IP protocolimplemented in end systems and routersrouters connect two networks and relays data

between them

Transport Layer (TCP)

common layer shared by all applicationsprovides reliable delivery of datain same order as sentcommonly uses TCP

Application Layer

provide support for user applicationsneed a separate module for each type of

application

Operation of TCP and IP

Addressing Requirements

two levels of addressing requiredeach host on a subnet needs a unique global

network address its IP address

each application on a (multi-tasking) host needs a unique address within the host known as a port

Overview of Wireless LANs

use wireless transmission mediumissues of high prices, low data rates,

occupational safety concerns, & licensing requirements now addressed

key application areas: LAN extension cross-building interconnect nomadic access ad hoc networking

Single Cell LAN Extension

Multi Cell LAN Extension

Cross-Building Interconnect

connect LANs in nearby buildingspoint-to-point wireless link

Not a LAN per seconnect bridges or routers

Nomadic Access

link LAN hub & mobile data terminal laptop or notepad computer enable employee to transfer data from portable

computer to serveralso useful in extended environment such as

campus or cluster of buildings users move around with portable computers may wish access to servers on wired LAN

Infrastructure Wireless LAN

Ad Hoc Networkingtemporary peer-to-peer network

Wireless LAN Requirements

throughput - efficient use wireless mediumno of nodes - hundreds of nodes across multiple

cellsconnection to backbone LAN - using control

modulesservice area - 100 to 300 mlow power consumption - for long battery life on

mobilestransmission robustness and securitycollocated network operationlicense-free operationhandoff/roamingdynamic configuration - addition, deletion, and

relocation of end systems without disruption to users

Technology

infrared (IR) LANs individual cell of IR LAN limited to single room IR light does not penetrate opaque walls

spread spectrum LANs mostly operate in ISM (industrial, scientific, and

medical) bands no Federal Communications Commission (FCC)

licensing is required in USAnarrowband microwave

microwave frequencies but not use spread spectrum

some require FCC licensing

Infrared LANsTransmission Techniques

directed-beam IR point-to-point links range depends on power and focusing for indoor use can set up token ring LAN IR transceivers positioned so data circulates in

ringomnidirectional

single base station with line of sight to other stations

acts as a multiport repeater other stations use directional beam to it

diffused configuration stations focused / aimed at diffusely reflecting

ceiling