Aplikasi Jaringan 2

Pertemuan 1 / Sesi 1Motivation dan Introduction

to Telecommunication & Computer Networks

Email: [email protected]

Deff Arnaldy, M.Si

Courtesy:Bagian Net-Centric ComputingFaskultas Sains dan TeknologiUniversitas Islam Negeri Jakarta (UIN)

mailto:[email protected]

Agenda

Overview dan Klasifikasi JaringanOverview OSI dan TCP/IPManajemen, Desain, dan Kinerja Tradisional

(“How not to manage a network”)Kinerja, Disain, dan ManajemenMetode-metode Analisis KinerjaContoh-contoh

Diharapkan Anda dapat…1)

menjelaskan klasifikasi jaringan komputer/telekomunikasi skema mode komunikasi cara kerja ethernet (CSMA/CD) cara kerja perangkat intermediate system arsitektur lapisan OSI dan TCP/IP


menyebutkan landasan teori dan motivasiEvaluasi Kinerja (Performance evaluation)Teknik Disain Sistematis (Systematic design techniques)Manajemen Jaringan (Network management)

menggambarkan dan menyebutkan contoh 3 model sistem jaringanResource sharing networksProcess networksSwitching networks


mendaftarkan dan menggambarkan 3 tipe metode studi kinerja jaringan dan karakteristiknyaAnalyticalSimulationMeasurementsMendaftarkan langkah-langkah dasar dalam studi kinerja jaringanMenerapkan langkah-langkah tersebut untuk merumuskan sebuah studi kinerja jaringan pada sistem dan tujuan yang telah diberikanMendefinisikan perbedaan antara Validasi dan Verifikasi

Ganjil - November 2007/2008 6Perkembangan TIK (Bagian I)

Klasifikasi Jaringan

Communication Network

SwitchedCommunication

Network

BroadcastCommunication

Network

Circuit-SwitchedCommunication

Network

Packet-SwitchedCommunication

Network

Datagram Network

Virtual Circuit Network

PSTN, ISDN

Ethernet, Token Ring, FDDI, etc.

ATM, Frame Relay, X.25, etc.IP


Jaringan telekomunikasi dapat diklasifikasikan berdasarkan bagaimana sinyal ditransmisikan dan diterimabroadcastswitched

•Jaringan broadcastsinyal yg ditransmisikan oleh satu peralatan end-user secara otomatis didengar oleh semua peralatan end-user lainnya

•Switched networkssinyal harus dirutekan melalui node jaringan atau di-switch ke rute yg diinginkan


Node jaringan mempunyai berbagai nama yg berbeda:Data Circuit Terminating equipment (DTE) - ITU-TInterface Message Processor (IMP) - ARPANETSwitch - jaringan teleponRouter - LANdsb

Peralatan user biasa disebut Data Terminal Equipment (DTE) - ITU-T :terminaltelepon sethostPCworkstation, dll


•HybridTipe jaringan telekomunikasi ini merupakan gabungan dari broadcast dan switched networkmisalnya: segment Ethernet (broadcast) dihubungkan dengan Router

Broadcast vs Switched Networks

Broadcast

Hybrid

Switch


Jaringan juga dapat diklasifikasikan berdasarkan cakupan geografisnya:

Local Area Network (LAN) :

dibatasi beberapa Km, kantor atau kampusMetropolitan Area Network (MAN)

puluhan Km, kotaWide Area Network (WAN)

ratusan - ribuan KmTerrestrial radio networks

Wireless communications

Satellite networks - internasional

Klasifikasi Jaringan Lainnya

Cara Pengontrolan: Centralized vs. Distributed

Kepemilikan: Publik, Private

Tipe Transmisi: Voice, data, video

Teknik Transmisi: Analog, digital, radio, satelit

Topologi: Mesh (mata jala), bus, ring, star, tree

Laju Data/Kecepatan Respon: Broadband / Narrowband

Media: Single media (seperti: Telepon) , Multi media (seperti: Broadband ISDN)


Skema Pengiriman Data

Routing merupakan proses pemilihan jalur (path) dalam sebuah jaringan selama pengiriman data atau lalu-lintas (trafik) fisik.Jaringan (network) di sini meliputi jenis jaringan apa saja termasuk telephone network, Internet, dan transport networks.Routing | Rute | Skema Pengiriman Data:UnicastBroadcastMulticastAnycast

Ganjil - November 2007/2008Perkembangan TIK (Bagian I) 15

http://en.wikipedia.org/wiki/Network

http://en.wikipedia.org/wiki/Network

http://en.wikipedia.org/wiki/PSTN

http://en.wikipedia.org/wiki/Internet

http://en.wikipedia.org/wiki/Transport_network

Unicast

unicast adalah proses pengiriman paket informasi ke sebuah tujuan tunggaldisebut juga komunikasi point-to-point.


Broadcast

broadcasting adalah proses pengiriman paket informasi ke segala tujuan (node, peralatan) dalam sebuah jaringan


Multicast (atau Multiplexed Broadcast)

Multicast merupakan sebuah mekanisme pengiriman informasi ke sebuah grup dalam sebuah jaringan,Biasanya pesan hanya dikirim sekali pada setiap link jaringan dan dicopy (gandakan) ketika link tujuan terbagi (split)


Anycast

Anycast merupakan sebuah skema pengalamatan dan perutean is a network addressing and routing scheme di mana data dirutekan ke tujuan terdekat (terbaik)


http://en.wikipedia.org/wiki/Addressing

http://en.wikipedia.org/wiki/Routing

Tambahan: Komunikasi Broadcast

Broadcast address, an IP address allowing information to be sent to all machines on a given subnetBroadcasting (computing), transmitting a packet that will be received by every device on the networkBroadcast domain, a logical area where any computer connected to the network can directly transmit to any other


EthernetHistory

"The diagram ... was drawn by Dr. Robert M. Metcalfe in 1976 to present Ethernet ... to the National Computer Conference in June of that year. On the drawing are the original terms for describing Ethernet. Since then other terms have come into usage among Ethernet enthusiasts."Just as a reminder: in 1976, INTEL had just developed the 8080, which was running at an unbelievable speed of 4.77 MHz !!!


Sabtu, 7 April 2007Computer Network Analysis - Review ICT 22

Broadcast Networks


Protokol IEEE 802.3: Ethernet

CSMA/CDCarrier Sense Multiple Access / Collision DetectionCarrier SenseSebelum sistem memulai pengiriman data ke networkCek kabel (media transmisi), apakah ada sinyal carrier (ada pengiriman data lain)? *)

YES: tunggu sampai pengiriman selesaiNO: sistem langsung mulai mengirimkan data*) mirip seperti kita saat mengangkat telepon dan mendengarkan suara dial-tone


Protokol IEEE 802.3: Ethernet

CSMA/CDCarrier Sense Multiple Access / Collision Detection

Multiple AccessSelama tidak ada ‘sinyal sibuk (carrier)’ pada kabel, semua node yang terkoneksi ke network dapat segera memulai mengirimkan data

Collision DetectionJika ada ≥ 2 node mengirimkan data bersamaan Signal CollisionProtokol mendeteksi collision sinyal saling mengganggu satu sama lainstop pengiriman memaksa semua node untuk back-offTunggu beberapa saat (secara random) back-off algorithmLakukan mekanisme CSMA lagi

Mekanisme CSMA

Mekanisme CSMA/CD


Signal Collision

≥ 2 signal carrier bertemu dan saling menginterferensi


Repeater, Hub, Bridge, Switch

Hub, RepeaterLAN basedWorks based on Ethernet (IEEE 802.3) protocolCSMA/CD mechanismNon-intelligent (Stupid) Device ;)InexpensiveEasy to installUnconfigurable, unmanageable1 domain collisionworks on Layer 1


BridgeLAN basedWorks based on Ethernet (IEEE 802.3) protocolCSMA/CD mechanismIntelligent (Smart) Device ;)More expensiveEasy to installconfigurable, unmanageable> 1 domain collisionworks on Layer 2




SwitchLAN based, Internet BasedWorks based on Ethernet (IEEE 802.3) protocolCSMA/CD mechanismIntelligent (Smarter) Device than Bridge ;)More expensive than BridgeEasy to installconfigurable, manageable> 1 domain collision (each port has domain collision)works on Layer 2


Switched Networks



Service - menyatakan apa yang dilakukan suatu layerInterface – menyatakan bagaimana mengakses serviceProtokol - menyatakan bagaimana service diimplementasikanProtokol - satu set aturan yang mengatur komunikasi di antara peers yang berkomunikasiSyntax: menentukan format informasi yang dikomunikasikanSemantic: arti dari sinyal yang dipertukarkanTiming: kapan data ditransmisikan/dilihat, ururtan informasi, matching kecepatan, dll.Protocol diperlukan untuk interaksi diantara peers

Protocol stack: satu set protocol layersTiap layer menggunakan layer di bawahnya dan menyediakan service ke layer di atasnya

Konsep Model OSI


Fungsi Setiap Layer OSI

Presents the interface to the user to access the provided functionality.

Higher layers

Presentation

Lower layers

Application

Session

Transport

Network

Data link

Physical

Formats the data

Controls a communications link between two hosts (open, manipulate, and close)

Provides data transfer services (either reliable or unreliable)

Provides an addressing mechanism between hosts and also routes packetsControls the physical communication link between two hosts. Also responsible for shaping the data for transmittal on the physical medium.The physical medium responsible for sending data as a series of electrical transmissions.


Skenario komunikasi dan fungsi utama masing-masing layer

Application

Presentation

Session

Transport

Network

Datalink

Physical

Application

Presentation

Session

Transport

Network

Datalink

Physical

Network

Datalink

Physical

Physical medium

User service

Transformation of encoding

Dialog control

End-to-end reliability

Route set-up

Error control, access control

Interface to medium

Hig

he

r la

yers

Lo

we

r la

yers

Open System Interconnection (OSI)


Proses pembentukan dan pembuangan protocol headers Encapsulation, Fragmentation, Reassembly

data

data

data

data

data

data

data

data

data

data

data

data

data

data

Encapsulation, MTU, Fragmentation, Reassembly, Datagram Size


Concatenation of Networks

Protocol Stack

R2

R1

H4

H5

H3H2H1

Network 2 (Ethernet)

Network 1 (Ethernet)

H6

Network 3 (FDDI)

Network 4(point-to-point)

H7 R3 H8

R1

ETH FDDI

IPIP

ETH

TCP R2

FDDI PPP

IP

R3

PPP ETH

IP

H1

IP

ETH

TCP

H8

IP Internet


MTU ~ Maximum Transmission Unit

Maksimum jumlah data yang dapat di’bawa’ oleh teknologi hardware networkKarakteristik Network HardwareTidak dirancang untuk menerima/mengirim frame ‘melebihi’ MTUUkuran Data ≤ MTUJika Ukuran Data > MTUDatagram tidak dapat dienkapsulasiDatagram tidak akan dikirim

Header overhead for Various Protocol Information Frames


Protocol Overhead Max Frame Size Description(bytes) (bytes)

Ethernet 18 1518 6 source, 6 destination 2 type, 4 CRC

IEEE 802.3 21 1521 6 source, 6 destination 2 length, 3 LLC, 4 CRC

IEEE 802.5 Token Ring

28 4472 & 79006 source, 6 destination 4 misc., 3 LLC, 5 802.2 SAP, 4 CRC Up to 16 source-routing octets may be added

FDDI (RFC 1390) 28 45003 802.2 LLC, 5 802.2 SNAP, 4 source, 4 dest, 4 misc., 8 FCS. The source and dest addr may be 12 bytes

ATM (RFC 1483) 8 534 CRC, 2 length, 1 CPI, 1 CPCS-UU. For AAL-5 multiprotocol encapsulation. The ATM cell header is only 5 bytes

FR (RFC 1490) 8 NA 2 flags, 2 Q.922 addr, 1 control, 1 NLPID, 2 FCS. For multi protocol encapsulation.

PPP (RFC 1662) 10 NA 8 HDLC framing, 2 PPP protocol itself

HDLC 8 NA 1 flag, 1 addr, 1 control, 4 CRC, 1 flag

TCP (RFC 793) 20 65535 8 seq number, 4 ports, 2 win, 6 other. RFC 1106 extends the win size to over 1 GB

IP (RFC 791) 20 65535 8 IP addr, 12 other


Ilustrasi MTU

H1 terhubung ke jaringan yang memiliki MTU=1500 octets (bytes)H2 terhubung ke jaringan yang memiliki MTU=1000 octets (bytes)H1 R X H2

H2 R H1

H1 H1RNet 1 (MTU=1500)

Net 2 (MTU=1000)

1500


Solusi: Fragmentation & ReassemblySetiap network punya harga MTUStrategifragment jika diperlukan (MTU < Datagram)Usahakan mencegah fragmentation pada source hostre-fragmentation dimungkinkanfragments adalah self-contained datagramstunda reassembly sampai destination hostTidak melakukan recover dari fragments hilang

Bagaimana Jika Data > MTU


Ilustrasi MTU

H1 terhubung ke jaringan yang memiliki MTU=1500 octets (bytes)H2 terhubung ke jaringan yang memiliki MTU=1000 octets (bytes)H1 R mem-fragment data ke H2

H2 R H1

H1 H1RNet 1 (MTU=1500)

Net 2 (MTU=1000)

1500 1000500

Observasi

Dengan kemajuan dlm kecepatan transmisi, total delay didominasi oleh delay propagasi dg batas atas kecepatan cahaya

Circuit switching menambahkan ekstra roundtrip delay dibandingkan datagram packet switching, tetapi menghilangkan delay store-and-forward

Ada dua kasus:jika link lambat bottleneck ada pada kecepatan transmisi link. Delay store-and-forward cukup berarti. Penambahan ekstra roundtrip delay tidak berarti circuit switching (total delay )Jika link cepat bottleneck ada pada delay propagasi. Penambahan roundtrip cukup berarti. Delay store-and-forward delay tidak cukup berarti packet switching (total delay )

Pertemuan 1 / Sesi 2Motivation dan Introduction

to Telecommunication & Computer Networks

Email: [email protected]

Deff Arnaldy, M.Si

Courtesy:Bagian Net-Centric ComputingFakultas Sains dan TeknologiUniversitas Islam Negeri Jakarta (UIN)

Algorithm untuk Kerja Jaringan1)

Contoh kerja sebuah LAN untuk Aplikasi Intranet Klien/Server

1. deploy LAN based on current technology and constrained by budget;

2. do {3. while (no complaints) { surf the web }4. surf to a trade magazine site;5. buy latest technology constrained by

budget;6. deploy latest technology;7. if (key users not happy) { increase

budget and go to 5 }8. } while (still employed)


Kendati pendekatan tadi sangat jauh dari optimalisasi kerja sebuah jaringan, namun terdapat relasi antara evaluasi, disain, dan manajemen:Management: Note the lack of user complaintsEvaluation: Ascertain the reason for the whiningDesign: Buy some stuff and make it work

Masalah-masalah:Likely to spend too muchExcessive periods of poor performanceProblem may not be fixedResponding to perception, not reality


Contoh kerja sebuah LAN untuk Aplikasi Intranet Klien/Server

1. deploy LAN based on current technology and constrained by budget;

2. do {3. while (no complaints) { surf the web }4. surf to a trade magazine site;5. buy latest technology constrained by

budget;6. deploy latest technology;7. if (key users not happy) { increase

budget and go to 5 }8. } while (still employed)

Evaluation

Relasi antara Kinerja, Disain, dan Manajemen Jaringan

DisainJaringan

ManajemenJaringan

Evaluasi/AnalisisKinerja

Evaluasi/Analisis Kinerja

We can predict the behavior of networks “using pencil, paper, the poetry of mathematics and the number-crunching ability of computers.”(T. Robertazzi)Peralatan Evaluasi/Analisis KinerjaTeori Peluang dan Teori AntrianModel-model TrafikSimulasi

Disain

“A network design is a blueprint for building a network. The designer has to create the structure of the network [and] decide how to allocate resources and spend money.”

(R. Cahn)

Peralatan Disain:Teknik-teknik Pekerjaan berkaitan dg KapasitasTeori GraphComputer-aided design tools (e.g.: AutoCAD, Visio, etc.)

Manajemen

“… our only real option is to use the network to manage the network. This means we need a protocol that allows us to read, and possibly write, various pieces of state information on different nodes.” (L. Peterson & B. Davie)

Peralatan ManajemenProtokol-protokol Manajemen, e.g.: SNMPManagement tools, e.g.: netstatEksperimen (Percobaan)

Model-model Jaringan

Apa yang sedang kita modelkan?

Secara umum, kita memodelkan jaringan untuk 3 kategori berikut:Resource sharing networksProcess networksSwitching networks

Resource sharing networks1)

Time-shared computer (Programs : CPU/Disk/IO)

Statistical multiplexer/concentrator

Packet-based (Packets : Links)

Channel-based (Calls : Channels)

Multiple-Access and random access networks (Packets: Shared Medium)

USER 1

USER N

SharedResources

Resource sharing networks2)

Kinerja Jaringan yang diukur (metrics):Waktu tunggu (Waiting time)Peluang Blocking (Blocking probability)

Pertanyaan kita sekarang adalah:Bagaimana hubungan antara User, Pola Penggunaan, Jumlah Kebutuhan Resources dan Kinerja Jaringan?Apakah setiap User menggunakan Resources secara “ADIL”?

Process Networks1)

Multi-stage switch

Distributed simulation system

Manufacturing process

Input 1Input 1

Input 2Input 2

Input 3Input 3

Input 4Input 4 Process 5Process 5

Process 2Process 2

Process 1Process 1

OutputOutput

Process Networks2)

Kinerja Jaringan yang diukur (metrics):Waktu Penyelesaian (Time to complete ~ delay)Throughput (completions per unit time)

Pertanyaan kita sekarang adalah:Bagaimana kinerja dapat dipengaruhi oleh Pola-pola Penggunaan yang berbeda?Proses-proses mana yang merupakan “bottlenecks” yang merupakan Batasan Kinerja Jaringan?Apakah input yang berbeda diperlakukan secara ADIL berkenaan dengan Kinerja Jaringan?

Switching Networks1)

Telephone network (Phones : Circuit Switches)Telephone signaling network (Switches : STPs)X.25 packet network (Computers : Packet Switches)Internet (Computers : Routers)

EndpointEndpoint

EndpointEndpoint

SwitchSwitch

SwitchSwitch

Process 5Process 5

SwitchSwitch

EndpointEndpoint

EndpointEndpoint

Switching Networks2)

Kinerja Jaringan yang diukur (metrics):Delay (endpoint to endpoint)ThroughputUtilizationBlocking probabilityLosses

Pertanyaan kita sekarang adalah:Bagaimana Topologi yang terbaik?Bagaimana kita melakukan perutean?Bagaimana kita menjamin QoS?

Analisis Kinerja1)

Why?Bottleneck atau analisis kapasitasSensitivitas (Kepekaan) dari kinerja parameter-parameterMendeteksi lingkup masalah untuk memandu system tuningPerencanaan konfigurasi dan trade-offsBenchmarking

When?Arsitektur atau Desain SistemDesain dan Implementasi DetailOperasional

Analisis Kinerja2)

How?Analytical models, e.g., queuing models with closed form or numerical solutionsSimulation experiments, e.g., discrete-event simulation with statistical resultsEmpirical measurements, e.g., instrumented code and network monitoring

Pendekatan Sistematis1)

Sebutkan ‘goals’ dari studi dan definisikan sistem yang akan dianalisisSket batasan-batasan sistem‘Goals’ akan menentukan batasan-batasan yang sesuai

Daftarkan layanan/fungsi dan hasil dari layanan tersebutPilih ukuran/satuan (metrics) yang akan dianalisisContoh: throughput, latency, availability, etc.

Buat daftar parameter-parameter yang mempengaruhi kinerja (performance)Parameter-parameter SistemParameter-parameter Beban Kerja (Workload)


Pilih faktor-faktor yang menjadi studi (akan diteliti)Faktor-faktor merupakan parameter-parameter yang mungkin akan bervariasiParameter-parameter lainnya akan ditetapkan

Pilih teknik evaluasiAnalitik (Analytical) -> Formula Erlang’s BlockingSimulasi (Simulation) -> Simulasi dengan NS2Pengukuran (Measurement) -> Worst-case Analysis

Pilih beban kerja (workload) atau daftar permintaan layananProbability distributions for analytical studyTrace or distribution for simulation studyScripts for measurements

Next

Contoh Teknik Evaluasi Analitik:: Traffic intensity ::

In telephone networks:

Traffic ↔ Calls

The amount of traffic is described by the traffic intensity aDefinition: the traffic intensity a is the product of the arrival rate and the mean holding time h:

a = h

Note that the traffic intensity is a dimensionless quantity. However, to emphasize the context, the “unit” of the traffic intensity a is called erlang (erl)

By Little’s formula: the traffic intensity tells the number of ongoing calls in the corresponding (hypothetical) infinite system.

Back

Example

Consider a local exchange. Assume that,on the average, there are 1800 new calls in an hour, andthe mean holding time is 3 minutes

It follows that the traffic intensity isa = 1800 3/60 = 90 erlang∗

If the mean holding time increases from 3 minutes to 10 minutes, then

a = 1800 10/60 = 300 erlang∗

Back

Traffic characteristic

Here are typical characteristic traffics for some subscriber categories (of ordinary telephone users):private subscriber: 0.01 - 0.04 erlangbusiness subscriber: 0.03 - 0.06 erlangprivate branch exchange (PBX): 0.10 - 0.60 erlangpay phone: 0.07 erlang

This means that, for example,a typical private subscriber uses from 1% to 4% of her time in the telephone (during a “busy hour”)

Referring to the previous example, note thatit takes between 2250 - 9000 private subscribers to generate 90 erlang traffic

Back

Contoh Teknik Evaluasi Analitik :: Erlang’s formula ::

Then the quantitive relation between the three factors (system capacity, traffic load and quality of service) is given by the Erlang’s formula

Note: n! = n (n-1) (n-2) … (2) (1), 0! = 1

Other names:Erlang’s blocking formulaErlang’s B-formulaErlang’s loss formulaErlang’s first formula

Back

Example

Assume that there are n = 4 channels on a link and the offered traffic is a = 2.0 erlang. Then the call blocking probability Bc is

If the link capacity is raised to n = 6 channels, then Bc reduces to

Back

Contoh Teknik Evaluasi Simulasi :: Network Simulator 2 ::

Parameter: kapasitas = 2 Mbps, delay = 10 ms

Protokol: TCP; Layanan: FTP

Performance Metric: Throughput, Connection-oriented Protocol

Komputer A(Sender)

Komputer B(Receiver)

C = 2 Mbps, Delay = 10 ms

Layer 4: TCP Reno

Aplikasi FTP

Script Program

Back

Network Properties and Time BudgetDocument size = 800 KbyteTo be copied from a file server at the hub site to a workstation at a spoke siteDocument transfer over Frame Relay NetworkWe have initial speed:1,544 Kbps port speed at the Hub site56 Kbps port speed at the Spoke site

Lets vary the hub port speed!

Contoh Teknik Evaluasi Measurement:: Document Retrieval over FR Network ::

Worst-case Analysis example

Back


Desain percobaan/eksperimenPhase 1: Large number of factors, few valuesPhase 2: Small number of factors, many values

Analisa dan interpretasikan hasilnyaResults are randomStatistical techniques needed to compare results

Presentasi HasilGraphical techniquesRefinement and iteration may be needed

Teknik-teknik Evaluasi

HighMediumLow“Sale ability”

HighMediumLowCost

DifficultModerateEasyTrade-off Evaluation

VariesModerateLowAccuracy

VariesMediumSmallTime required

Post-prototypeAnyAnyStage

MeasurementSimulationAnalyticalCriterion

Contoh: ISP1)

Sebuah ISP menyediakan akses circuit-switched (saluran telepon PSTN) ke InternetBerapa banyak saluran (koneksi aktif simultan maksimum) yang harus kita sediakan?Kepuasan Pelanggan Large number of lines to reduce probability of blocking (busy)Biaya Operasi Small number of lines to reduce equipment, line, maintenance, and power costs

Kapan saluran baru harus disediakan?Apa toleransi terhadap Kepuasan Pelanggan dan biaya operasi?

Contoh: ISP2)

Kebijakan apa yang harus dibuat untuk memaksimumkan keuntungan/profit?Charge a flat fee or charge for connect time?Limit sessions to X hours?Automatically disconnect inactive users after Y minutes?Differentiate service based on price?

Pertanyaan-pertanyaan berikut mendefinisikan TUJUAN dan SISTEM untuk studi kinerja jaringan:Management information needed for the studyResults of study can be applied to optimize design of modem pool (and policies)

Contoh: ISP3)

DisainJaringan

ManajemenJaringan


Effect ofnumber of linesand polices onperformance

Workloadcharacteristicsand currentperformance

Optimized modempool and polices

Contoh: ISP4)

Ingat bahwa model ini merupakan sebuah “resource sharing network”Users must share a limited number of linesNumber of users exceeds the number of linesIf number of active users equals the number of lines, further use attempts by other users will be blocked

USER 1

USER N

SharedResources

Contoh: ISP5)

MetricsBlocking probabilityWait time (until a line is free)

System parametersNumber of lines

Workload parametersNumber of calls (arrival or attempt rate)Length of call (holding or service time)Time until retry attempt if blocked

Factors to vary for the studyNumber of linesNumber of users (attempt rate)

Contoh: ISP6)

Evaluation techniquesAnalytical (Erlang model)Measurement of specific configuration(s) to validate analytical results

Select workloadsAssumptionsHolding timeProbability of an attempt from a userRetry characteristicsAssumptions can be developed by monitoring use patternsRequires network management (monitoring)

Contoh: ISP7)

Design and conduct experimentsEasy for analytical studyMore difficult for measurements

Analyze and interpret resultsAgain, easy for analytical study and more difficult for measurements

Present resultsValidation of analytical results using measurements increases confidence in results

Validasi vs. Verifikasi

Verification (usually easy to do)Is the model properly constructed?Analytical model: “Is the math right?”Simulation model: “Is the model properly coded?”

Validation (often hard to do)Does the model accurately represent the behavior of the system of interest?Analytical model: “Is the model ‘correct’?”Simulation model: “Is this an accurate simulation for the questions of interest?”

Contoh: Layanan Backbone1)

A carrier provides backbone services to companies and lower-tier ISPsInternet access to companies and ISPsVirtual private network (VPN) service for corporate networks


This is a “switching network”Customer networks are endpointsIP routers in the backbone are switches

Backbone network defines system boundary


Throughput objectives – relatively simpleMaximize network throughput given a maximum cost constraintMinimize cost given a minimum throughput constraint

Throughput factorsNetwork topologyLink capacityRouter capacityRouting algorithm (efficiency)Workload (characteristics of traffic leaving customer networks)


Network managementIdentify problemsBottlenecksRouting problemsMisbehaved customer networksLink and router failuresMonitor traffic to model workload

Performance evaluationStudy affects of network design changesStudy affects of workload changesIdentify bottlenecksProactive planning for network grown


Network designAdjust link capacity, router capacity, and topologyOptimize routing

DisainJaringan

ManajemenJaringan


? ?

?


Quality of service (QoS) or service level agreement (SLA) objectives – relatively complexGuaranteed throughput over some period of timeMaximum delayMaximum delay variationAvailability

Customer network issues imply need for network managementMonitoring service level agreementsPolicing traffic


Backbone network issuesTo what set of SLAs can a carrier commit with a given set of network resources?How to optimize the network for a given set of SLAs?How much to charge for a given SLA?How to optimize revenue?

Management, performance evaluation, and design must be considered to optimize the network operation (and revenues)

Contoh: Packet Switch Design1)

An equipment vendor is designing a high-performance Layer 3 IP switch


This system is a “process network” if implemented as a multi-stage switch


This system is a “resource sharing network” if implemented as a TDMA bus


There are many performance issuesAggregate and per port throughputInput-to-output delayIntroduced delay variation (jitter)Blocking probabilityPacket loss due to queue overflowReliability


There is not an operational system to manage (monitor), so the process involves just …DesignPerformance (and cost) evaluation

DisainSistem

EvaluasiKinerja

Contoh: MAC Protocol Design1)

A researcher is developing a new multiaccess control protocol for a wireless ad hoc network

This is a “resource sharing network”Stations (e.g., A, B, and C) are the usersRadio spectrum is the shared resource (medium)


There are many performance issuesSystem throughputPacket delayAllocation of system throughput (fairness)Channel utilizationProbability of collision

There are a number of factors affecting performanceOffered trafficNumber of stations (and placement)Channel characteristicsProtocol operation


And, there are many design issues …How to share the spectrum?Circuit-switched schemesFrequency division multiple access (FDMA)Time division multiple access (TDMA)Code division multiple access (CDMA)Packet-switched time division multiplexed (TDM) schemesReservation-based TDM schemes, e.g., packet reservation multiple access (PRMA)Contention-based TDM schemes, e.g., carrier sense multiple access (CSMA)


Optimizing or “tuning” a basic schemeHow many channels to allocate in a circuit-switched system?Effectiveness of collision avoidance schemes in a contention-based system?Efficiency of scheduling schemes in a reservation-based system?

Specifying system performanceHow many users?How much capacity per user?Physical layer requirements?

::: Referensi :::

•Stallings, W. 1998. High Speed Networks: TCP/IP and ATM Design Principles, Prentice-Hall.•McDysan, D. 2000. QoS and Traffic Management in IP and ATM Networks. McGraw-Hill, Corp. New Jersey.•Bloomers, J. 1996. Practical Planning for Network Growth. Prentice Hall, Inc. New Jersey.•R. Jain, The Art of Computer Systems Performance Analysis: Techniques for Experimental Design, Measurement, Simulation, and Modeling, John Wiley and Sons, 1991.•M. H. MacDougall, Simulating Computer Systems: Techniques and Tools, MIT Press, 1987.•D. W. Petr, Course Notes, The University of Kansas, 1999.

Referensi

(1)Leon, A. and Indra W. 2000. Communication Networks: Fundamental Concepts and Key Architectures. Int'l Ed. McGraw Hill Inc. Singapore. ISBN 0-07-022839-6.(2)Internet Software Consortium. Internet at http://www.isc.org(3)NGN. Seminar NGN di ITB & Jakarta(4)ZTE telecom, Next Generation Network, Huawei Technologies, ANJA 2003(5) _______, ‘Next Generation Network’, paper, Nusantara 2001, TELKOM(6)NEC Corp. , NGN Scenario for broadband services, presentation, 2003(7)_______, ‘Next Generation Network’, Web Forum Tutorial, International Engineering Consortium (IEC), www.iec.org.(8)_______, ‘Next Generation Network’, Web Forum Tutorial, International Engineering Consortium (IEC), www.iec.org.(9)_______, ‘Next Generation Network’, paper, iSwitch, www.UTstar.com.(10) KPSI. 2007. Laporan Program INHERENT dan IMHERE.(11) KPSI. 2006. Laporan Kegiatan Tahunan KPSI IPB.(12) KPSI. 2004 – 2006. Laporan Proyek Pengembangan Infrastruktur dan Layanan TIK IPB.(13) KPSI. 2004. Panduan Prosedur Standar (SOP) KPSI. IPB.(14) IPB. 2004. Press Release Pembangunan Jaringan Backbone Kampus Berbasiskan Serat Optik IPB.(15) KPSI. 2000. Panduan Singkat IPBNet.

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