Struktura e Internetit : Rrjeti i rrjetave

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnetaccess

net

accessnet

…

………

…

…

Opcion: lidh cdo ISP aksesi ne nje ISP global tranziti? KLientat dhe providerat ISP kane marreveshje biznesi

globalISP

Struktura e Internetit : Rrjeti i rrjetave

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnetaccess

net

accessnet

…

………

…

…

Por duhet te jene disa ISP globale qe te kete konkurence ….

ISP B

ISP A

ISP C

Struktura e Internetit : Rrjeti i rrjetave

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnetaccess

net

accessnet

…

………

…

…

Por duhet te jene disa ISP globale qe te kete konkurence …. Dhe keto ISP duhet te nderlidhen

ISP B

ISP A

ISP C

IXP

IXP

peering link

Internet exchange point

Struktura e Internetit : Rrjeti i rrjetave

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnetaccess

net

accessnet

…

………

…

…

… dhe rrjeta rajonale mund te duhen per te lidhur rrjetat e aksesit

ISP B

ISP A

ISP C

IXP

IXP

regional net

Struktura e Internetit : Rrjeti i rrjetave

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnet

accessnetaccess

net

accessnet

…

………

…

…

… dhe providerat e pembajtjes (psh., Google, Microsoft, Akamai ) mund te kene rrjetat e veta qe te sjellin sherbimet, permbajtjen prane perdoruesve

ISP B

ISP A

ISP B

IXP

IXP

regional net

Content provider network

Introduction

Struktura e Internetit : Rrjeti i rrjetave

Ne qender: numer i vogel rrjetash te medha mire te lidhura “tier-1 (rreshti i pare)” ISP komerciale (psh., Level 3,

Sprint, AT&T, NTT), mbulim kombetar e nderkombetar Rrjetat providerave te permbajtjes (psh, Google): rrjet

privat qe lidh qendrat e te dhenave te saj me Internet, shpesh duke tejkaluar tier-1, providerat rajonale

1-6

accessISP

accessISP

accessISP

accessISP

accessISP

accessISP

accessISP

accessISP

Regional ISP Regional ISP

IXP

IXP

Tier 1 ISP Tier 1 ISP Google

IXP

Introduction

Tier-1 ISP: psh., Sprint

…

to/from customers

peering

to/from backbone

…

………

POP: point-of-presence

1-7

Introduction

Chapter 1: roadmap1.1 Cfare eshte Interneti?1.2 rrjeti skajor

sistemet fundore, rrjetat e aksesit, linjat1.3 rrjeti qendror

transmetimi (kycja) me pakete, kycja me qark, struktura e rrjetave

1.4 vonesa, humbje, sjellja ne rrjeta1.5 shtresat e protokolleve, modelet e

sherbimeve1.6 rrjetat nen sulm: siguria1.7 histori

1-8

Introduction

Si ndodhin humbjet dhe vonesat?

Paketat vihen ne rradhe ne buferat e routerave

Ritmi i paketave ne arrdhje tejkalon (perkohesisht) kapacitetin e linkut te daljes

Paketat presin tu vije rradha

A

B

Pakete qe po transmetohet (vonesa)

pakete ne rradhe (vonesa)

Bufer i lire: paketat ne ardhje humben nese nuk ka bufera te lire

1-9

Introduction

Kater burimet e vonesave te paketave

dproc: perpunimi ne nyje

Kontroll i gabimeve te biteve

Percakton linkun e daljes

zakonisht < msec

A

B

perhapja

transmetimi

Perpunimi ne nyjerradha

dqueue: vonesa prej rradhes

Koha e pritjes ne linkun e daljes per transmetim

Varet nga niveli i bllokimit te ruterit

dnodal = dproc + dqueue + dtrans + dprop

1-10

Introduction

dtrans: vonesa e transmetimit:

L: gjatesia e paketes (bits)

R: bandwidth i linkut (bps)

dtrans = L/R

dprop: vonesa e perhapjes: d: gjatesia e linkut fizik s: shpejtesia e perhapjes ne

mjedis (~2x108 m/sec) dprop = d/sdtrans and dprop

very different

Kater burimet e vonesave te paketave

Perhapje

propagation

Perpunim ne nyje

(Processing)Rradha(queueing)

dnodal = dproc + dqueue + dtrans + dprop

1-11

A

B

tranmetim

* Check out the Java applet for an interactive animation on trans vs. prop delay

Introduction

Analogjia me karvanin

Makinat “perhapen” me shpejtesi100 km/hr

kontrolli do 12 sec per te sherbyer nje makine (koha e transmetimit te nje biti)

makina~bit; karvani ~ paketa

Pyetje: Sa kohe do qe karvani te rreshtohet perpara kontrollit te dyte?

Koha per te “shtyre” te gjithe karvanin nga kontroli ne autostrade = 12*10 = 120 sec

Koha e “perhapjes” se makines se fundit nga kontrolli i pare ne ate te dytin: 100km/(100km/hr)= 1 hr

Pergjigje: 62 minutes

Kontrolli/pagesa

Kontrolli/pagesa

Karvan me 10 makina

100 km 100 km

1-12

Introduction

Analogjia me karvanin(me shume)

Supozo tani makinat “perhapen” me 1000 km/hr Dhe supozo kontrolli do nje min t’i sherbeje nje

makine Pyetje: A do te arrijne makinat ne kontrollin e dyte

perpara se te gjithe makinat te jene sherbyer ne kontrollin e pare? A: Po! Mbas 7 min, makina e pare arrin ne

kontrollin e dyte; tre makina jane akoma ne kontrollin e pare.

kontroll i takses

kontroll i takses

Karvani me 10 makina

100 km 100 km

1-13

Introduction

R: bandwidth i linkut (bps)

L: gjatesia e paketes (bits)

a: ritmi mesatar i arritjes se paketave traffic intensity

= La/R

La/R ~ 0: vonesa mesatare ne rradhe e vogel

La/R -> 1: vonesa mesatare ne rradhe e madhe

La/R > 1: me shume “pune” po arrin qe duhet sherbyer, vonesa mesatare

infinit!

ave

rage

qu

eue

ing

d

ela

y

La/R ~ 0

Vonesa ne rradhes (e ripare)

La/R -> 11-14

* Check out the Java applet for an interactive animation on queuing and loss

Introduction

Vonesat dhe rruget “reale” te Internetit

Si duken vonesat dhe humbjet “reale” te Internetit?

Programi Traceroute: jep matjen e voneses nga burimi ne router gjate rruges ne Internet fillim-fund deri ne arritje. Per te gjitha i: Dergon tre paketa qe do te arrijne cdo router i ne

rrugen drejt arritjes router i do te ktheje paketa tek derguesi Derguesi mat intervalin e kohes midis

transmetimit dhe pergjigjes.3 probes

3 probes

3 probes

1-15

Introduction

Vonesat dhe rruget “reale” te Internetit

1 cs-gw (128.119.240.254) 1 ms 1 ms 2 ms2 border1-rt-fa5-1-0.gw.umass.edu (128.119.3.145) 1 ms 1 ms 2 ms3 cht-vbns.gw.umass.edu (128.119.3.130) 6 ms 5 ms 5 ms4 jn1-at1-0-0-19.wor.vbns.net (204.147.132.129) 16 ms 11 ms 13 ms 5 jn1-so7-0-0-0.wae.vbns.net (204.147.136.136) 21 ms 18 ms 18 ms 6 abilene-vbns.abilene.ucaid.edu (198.32.11.9) 22 ms 18 ms 22 ms7 nycm-wash.abilene.ucaid.edu (198.32.8.46) 22 ms 22 ms 22 ms8 62.40.103.253 (62.40.103.253) 104 ms 109 ms 106 ms9 de2-1.de1.de.geant.net (62.40.96.129) 109 ms 102 ms 104 ms10 de.fr1.fr.geant.net (62.40.96.50) 113 ms 121 ms 114 ms11 renater-gw.fr1.fr.geant.net (62.40.103.54) 112 ms 114 ms 112 ms12 nio-n2.cssi.renater.fr (193.51.206.13) 111 ms 114 ms 116 ms13 nice.cssi.renater.fr (195.220.98.102) 123 ms 125 ms 124 ms14 r3t2-nice.cssi.renater.fr (195.220.98.110) 126 ms 126 ms 124 ms15 eurecom-valbonne.r3t2.ft.net (193.48.50.54) 135 ms 128 ms 133 ms16 194.214.211.25 (194.214.211.25) 126 ms 128 ms 126 ms17 * * *18 * * *19 fantasia.eurecom.fr (193.55.113.142) 132 ms 128 ms 136 ms

traceroute: gaia.cs.umass.edu to www.eurecom.fr

3 matje te voneses ngagaia.cs.umass.edu ne cs-gw.cs.umass.edu

* Do te thote nuk ka pergjigje (probe e humbur, router nuk pergjigjet)

trans-oceaniclink

1-16* Do some traceroutes from exotic countries at www.traceroute.org

Introduction

Humbja e paketave rradha(ose buffer) e linkut paraardhes ne

buffer ka kapacitet te fundem Paketat qe arrijne kur rradha eshte plot

hidhen (ose humben) Paketat e humbura mund te

ritransmetohennga nyja paraardhese, nga burimi ne sistem, ose te mos ritransmetohet

A

B

Paketa qe po transmetohet

paketa qe po arrin ne nje buffer plot eshte humbur

buffer (zona e pritjes)

1-17* Check out the Java applet for an interactive animation on queuing and loss

Introduction

Throughput - sjellja throughput: ritmi (bite/ne njesine e

kohes) me te cilen bitet transferohen midis derguesit /marresit E castit: ritmi ne nje cast te kohes mesatare: ritmi ne nje periudhe te gjate

server, withfile of F bits

to send to client

link capacity

Rs bits/sec

link capacity

Rc bits/secserveri dergon

bite(ngjashmeri me

leng) ne tub

tub qe mban leng

me ritem Rs

bits/sec)

tub qe mban leng

me ritem Rc bits/sec)

1-18

Introduction

Throughput (vazhdim)

Rs < Rc Sa eshte throughputi mesatar fillim-mbarim?

Rs bits/sec Rc bits/sec

Rs > Rc Sa eshte throughputi mesatar fillim-mbarim?

Linku ne rrugen fillim-fund qe kufizon throughputin fillim-fund

bottleneck link (linku me i ngushte)

Rs bits/sec Rc bits/sec

1-19

Introduction

Throughput: Skenari ne Internet

10 lidhje (ne menyre te drejte) ndajnelinkun bottleneck R bits/sec

Rs

Rs

Rs

Rc

Rc

Rc

R

throughput: min per lidhjen fillim-fund (Rc,Rs,R/10)

Ne praktike: Rc ose Rs eshte zakonisht bottleneck

1-20

Introduction

Chapter 1: roadmap1.1 what is the Internet?1.2 network edge

end systems, access networks, links1.3 network core

packet switching, circuit switching, network structure

1.4 delay, loss, throughput in networks1.5 Shtresat e protokollit, Modelet e

sherbimit1.6 networks under attack: security1.7 history

1-21

Introduction

“Shtresat” e ProtokollitRrjetat jane

komplekse,Me shume “pjese”:

hoste routera linke me

mjedise te ndryshme

zbatime protokolle hardware,

software

Pyetje: A ka ndonje shprese

per strukture te organizuar te

rrjetave?

…. Ose se paku diskutimi yne mbi

rrjetat?

1-22

Introduction

Organizimi i udhetimit ajror

Nje seri hapash

bileta (blerje)

bagzhe (kontrol)

porta (hyrje)

ngritja e aeroplanit

airplane routing

bileta (complain)

bagazhe (claim)

porta (dalje)

Ulje e aeroplanit

airplane routing

airplane routing

1-23

Introduction

ticket (purchase)

baggage (check)

gates (load)

runway (takeoff)

airplane routing

Airporti I nisjesAirport i arritjesQendrat e ndermjetme te konrollit te trafikut ajror

airplane routing airplane routing

ticket (complain)

baggage (claim

gates (unload)

runway (land)

airplane routing

ticket

baggage

gate

takeoff/landing

airplane routing

Shtresezimi i funksioneve te fluturimit

lshtresa: cdo shtrese implementon nje sherbim Nepermjet veprimeve te tij brenda

shtreses Mbeshtetet ne sherbimet e dhena

nga shtresa e meposhteme 1-24

Introduction

Pse shtresezim?Duke u marre me sisteme

komplekse: Strukture eksplicite lejon identifikimin,

marrdheniet ndermjet pjeseve te sistemit kompleks reference model reference i shtesezuar per

diskutim Modularizimi lehteson mirembajtjen,

updating e sistemeve Ndryshimi i implementimit te sherbimit te

eshte transparent per pjesen tjeter te sistemit

P.sh, ndryshimi i procedurave ne porta nuk ndikon ne pjesen tjeter te sistemit

Shtresezimi i konsideruar i demshem?1-25

Introduction

Internet protocol stack zbatim: zbatime me

mbeshtetje nga rrjeti FTP, SMTP, HTTP

transport: trnsmetim te dhenash proces-proces TCP, UDP

rrjet: routing i datagrameve nga burimi ne destinacion IP, routing protocols

link: transferim te dhenash midis elemente komshinj ne rrjet Ethernet, 802.111 (WiFi), PPP

fizik: bits “ne tel”

zbatim

transport

rrjet

link

fizik

1-26

Introduction

ISO/OSI modeli i referimit prezantim: lejon zbatimet

te interpretojne kuptimin e te dhenave, p.sh., enkriptimi, kompresimi, konvencione specifike te makines

sesion: sinkronizim, kontroll, recovery of data exchange

Internet stack “nuk I ka” keto shtresa! Keto sherbime, nese

kerkohen, duhet te implementohenne zbatime

Jane te nevojshme?

zbatim

prezantim

sesion

transport

rrjet

link

fizik

1-27

Introduction

source

applicationtransportnetwork

linkphysical

HtHn M

segment Ht

datagram

destination

applicationtransportnetwork

linkphysical

HtHnHl M

HtHn M

Ht M

M

networklink

physical

linkphysical

HtHnHl M

HtHn M

HtHn M

HtHnHl M

router

switch

Enkapsulimimessage M

Ht M

Hn

frame

1-28

Introduction

Chapter 1: roadmap1.1 what is the Internet?1.2 network edge

end systems, access networks, links1.3 network core

packet switching, circuit switching, network structure

1.4 delay, loss, throughput in networks1.5 protocol layers, service models1.6 networks under attack: security1.7 history

1-29

Introduction

Siguria e Rrjetave Fusha e sigurise se rrjetave:

Si munden te keqinjte te sulmojne rrjetat e kompjuterave

Si mund t’i mbrojme rrjetat nga sulmet Si te projektohen arkitektura qe jane imune

ndaj sulmeve Interneti nuk eshte projektuar fillimisht

me (shume) siguri ne mendje Vizioni origjinal: “nje grup perdoruesish qe

besojne njeri-tjetrin te lidhur me nje rrjet transparent”

Projektuesit e protokolleve te Internet duke u pershtatur kushteve

Konsiderata sigurie ne te gjitha shtresat!1-30

Introduction

Te keqinjte: fut malware ne hoste nepermjet Internetit

malware mund te futet ne host nga: virus: infektim qe vete replikohet duke

marre/ekzekutuar objekte (psh., e-mail attachment)

krimb: infektim qe vete replikohet duke marre ne menyre pasive objekte qe vete ekzekutohen

spyware malware mund te regjistroje keystrokes, web site te vizituara, upload info tek faqja e mbledhjes

Hostet e infektuara mund te futen ne botnet, te perdorura per spam. Sulmet DDoS

1-31

Introduction

target

Denial of Service (DoS) (Mohim sherbimi): sulmuesit bejne resurset (server, bandwidth) te pamunduara per trafikun ligjitim duke mbingarkuar me trafik te rreme1. zgjidh target

2. Thyerje ne hostet ne rrjet

3. Dergo paketa ne target nga hostet e komprementuara

Te keqinjte: sulm servareve, infrastruktures se rrjetit

1-32

Introduction

Te keqinjte mund pergjojne paketatpaket “sniffing”:

broadcast media (shared ethernet, wireless) promiscuous network interface reads/records

all packets (e.g., including passwords!) passing by

A

B

C

src:B dest:A payload

wireshark software used for end-of-chapter labs is a (free) packet-sniffer

1-33

Introduction

Te keqinjte mund perdorin adresa te rremeIP spoofing: dergo paketa me adrese

burimi te rremeA

B

C

src:B dest:A payload

1-34

… lots more on security (throughout, Chapter 8)

Introduction

Introduction: summary

covered a “ton” of material!

Internet overview what’s a protocol? network edge, core,

access network packet-switching

versus circuit-switching

Internet structure performance: loss,

delay, throughput layering, service models security history

you now have: context, overview,

“feel” of networking more depth, detail

to follow!

1-35