Networks Lecture Notes

7/24/2019 Networks Lecture Notes

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Introduction 1-1

EECS 325/425

Michael Rabinovich

[email protected]

Introduction


2/28

Introduction 1-2

Logistics Lecture time: Wed/Fri 9:00-10:15am !!ice hours: Wednesda"s 1:00-#:00$m or b"

a$$ointment %lin 50&' (rading:

)ome*or+s: #5,

.o be turned in on the due date FR class verdue home*or+ loses 10, o! value once $ast due and !urther 10,

ever" # hours %including *ee+ends etc2' )ome*or+ not acce$tedonce it3s over hours $assed due

4roects: #0, Midterm: #0,

Final: 65, .e7t: 8urose and Ross om$uter ;et*or+s: a to$-do*n

a$$roach2


3/28

8e" =dvice: e Resource!ul>

?I learned ever"thing !rom the boo+2@ Atud" grou$s !!ice hours .=s

Whatever *or+s>

Introduction 1-3

Atud" grou$s:

8 to discuss home*or+/$roect 8 to e7$lain a home*or+ solution to each other as long as no one takes notes with them from

discussion!


4/28

Introduction 1-4

Bnderstanding om$uter;et*or+s What ha$$ens *hen I clic+ on this lin+C

htt$://cnn2com

= number o! com$uters across the countr" are involved

)undreds o! +ilob"tes travel thousands o! miles )andled b" doDens o! rela" devices

= number o! $rotocols *or+ together: )..4 E;A BE4

.4 I4 (4 A4F =R4 thernet WiFi

= number o! com$anies get involved The course oecti"e# a $eak ehind the scene%
http://cnn.com/http://cnn.com/


5/28

Introduction 1-5

ourse bectives

4rovide basic overvie* o! the net*or+ing area Internet $rotocol stac+ 4rotocol e7am$les at a$$lication trans$ort net*or+ and

lin+ la"ers Internet hierarch" addressing routing algorithms

4re$are !or in-de$th stud" in selected areas (ain initial e7$erience in creating net*or+

a$$lications (et e7$osure to lo*-level net*or+ $rogramming ;ot a vocational course>


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Introduction 1-6

.hese lecture notes are based heavil" on the slides $rovided b" theauthors o! the boo+2 =ll material $rovided b" the authors should beconsidered as belonging to their co$"right: G 199


7/28

Introduction 1-7

What3s the Internet: an architecture vie*

millions o! connectedcom$uting devices: hosts 0nd hosts end s"stems

4s servers la$to$s smart$hones

running net*or+ a$$s

mail Web (ames 4#4 communication lin+s

!iber co$$er radio satellite

routers:!or*ard $ac+ets%chun+s o! data'

Internet:net*or+ o! net*or+s 4rotocols:)..4 it.orrent

A+"$e

mobile network

global ISP

regional ISPhomenetwork

institutional network


8/28

Introduction 1-8

What3s a $rotocolC

human $rotocols: =t restaurant =t a doctor3s o!!ice Introductions

s$eci!ic msgs sent

s$eci!ic actions ta+en

*hen msgs receivedor other events

Ee!ine con"entions

What time is itC

7cuse me

JesC

#:00

time

?(ot .imeC@ 4rotocol

.han+s


9/28

Introduction 1-9

What3s a net*or+$rotocolC

machines rather thanhumans

4rotocols:

Fde!ine !ormat K order o! msgs sentamong net*or+ entities9

Factions ta+en on msg recei$t9 otherevents

.4 connectionreuest

.4 connectionres$onse

!ileN

time

Web $age do*nload

(et headlines2html

=ll communication activit" in Internet governed b" $rotocols


10/28

Whats the Internet: a service view

Infrastructure that providesservices to applications: Web, VoIP, email, games, e-

commerce, social nets,

provides programminginterface to apps hooks that allow apps to

connect to Internet

sen messages

receive messages

provies service options,analogo!s to postal service

mobile network

global ISP



Intro!ction

"-"#


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Introduction 1-11

= closer loo+ at net*or+ structure:

net*or+ edge:a$$lications andhosts

access net*or+s:*ired *irelesscommunication lin+s

net*or+ core: interconnected

routers net*or+ o!

net*or+s

mobile network

global ISP




12/28

Intro!ction

$ccess networks

Q: How to connect endsystems to edgerouter?

resiential access nets

instit!tional accessnetworks %school,compan&'

Wireless access networks

keep in mind: banwith %bits persecon' o( accessnetwork)

share or eicate)

"-"*


13/28

Intro!ction

$ccess net: igital s!bscriberline %+'

central office

ISP

telephone

network

DSLAM

.se existingtelephone line to central o/ce +$0 %+ $ccess0!ltiple1er' ata over + phone line goes to Internet voice over + phone line goes to telephone net 2re3!enc& ivision m!ltiple1ing:

16O +)D - 1 M)D !or do*nstream

#5 +)D - 16O +)D !or u$stream

0 +)D - +)D !or ordinar" tele$hone

4 *56 0bps !pstream transmission rate %t&picall& 4 " 0bps' 4 *7 0bps ownstream transmission rate %t&picall& 4 "# 0bps'

DSLmodem

splitter

"-"8

Eedicated Lin+s>


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Intro!ction

$ccess net: cablenetwork

cablemodem

splitter

cable headend

Channels

V

I

D

E

V

I

D

E

V

I

D

E

V

I

D

E

V

I

D

E

V

I

D

E

D

A

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A

D

A

!

A

C

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#

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$ % & ' ( ) * + ,

"-"7

ISP

cable modemtermination system

Shared access

frequency divisionmultiplexing: data,TV transmitted atdifferentfrequencies overshared cable network

92: h&bri ;ber coa1 as&mmetric: !p to 8#0bps ownstream

transmission rate, * 0bps !pstream


15/28

Intro!ction

$ccess 1amples

$?@? .-Verse

VeriAon 2i=

"-"6


16/28

Intro!ction

$ccess net: homenetwork

to-from headend orcentral office

cable or DSL modem

router. firewall. "A!

wired Ethernet /$00 Mbps1

wireless accesspoint /(' Mbps1

wirelessde2ices

often combinedin single bo3

"-"B


17/28

Intro!ction

>nterprise access networks%>thernet'

t&picall& !se in companies, !niversities, etc

"# 0bps, "##0bps, "Cbps, "#Cbps transmission rates

toa&, en s&stems t&picall& connect into >thernet switch

Ethernetswitch

institutional mail.web ser2ers

institutional router

institutional link toISP /Internet1

"-"D


18/28

Intro!ction

Wireless access networks

share wirelessaccess network connects en s&stem to ro!ter via base station aka access point

wireless LAs: within b!iling %"## (t'

E#*5""bFg %Wi2i': "", 670bps transmission rate

wie-area wireless access provie b& telco %cell!lar'

operator, "#s km between " an "# 0bps 8C, 7C: ?>

to Internet

to Internet

"-"E


19/28

Introduction 1-19

.he ;et*or+ ore

mesh o! interconnectedrouters

the!undamentaluestion:ho* is datatrans!erred through netC circuit s*itching:

dedicated circuit $ercall: tele$hone net

$ac+et-s*itching:datasent thru net indiscrete ?chun+s@


20/28

Introduction 1-20

;et*or+ ore: ircuit A*itching

nd-end resourcesreserved !or ?call@

lin+ band*idth s*itch

ca$acit" dedicated resources:

no sharing circuit-li+e

%guaranteed'$er!ormance call setu$ reuired


21/28

Introduction 1-21

;et*or+ ore: ircuit A*itching

net*or+ resources%e2g2 band*idth'divided into ?slices@

slices allocated to calls resource slice idlei! not

used b" o*ning call %nosharing'

dividing lin+ band*idthinto ?slices@ !reuenc" division time division


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Introduction 1-22

ircuit A*itching: FEM and .EM

!DM

fre4uenc5

time

6DM

fre4uenc5

time

' usersE3ample7


23/28

Introduction 1-23

;et*or+ ore: 4ac+et A*itching

each end-end data streamdivided into $ac+ets

$ac+ets !rom di!!erentusers sharenet*or+

resources each $ac+et uses !ull lin+

band*idth resources used as needed

resource contention: aggregate resource

demand can e7ceedavailable ca$acit"

congestion: $ac+etsueue *ait !or lin+ use

store and !or*ard:$ac+ets move one ho$

at a time ;ode receives com$lete

$ac+et be!ore !or*arding

and*idth division into ?slices@

Eedicated allocation

Resource reservation


24/28

Introduction 1-24

4ac+et A*itching: Atatistical Multi$le7ing

Aeuence o! = K $ac+ets does not have !i7ed $atternshared on demand statistical multi$le&ing2

.EM: each host gets same slot in revolving .EM !rame2

=

10 Mb/sthernet

125 Mb/s

E

statistical multi$le&ing

ueue o! $ac+ets*aiting !or out$utlin+


25/28

Introduction 1-25

4ac+et s*itching versus circuit s*itching

1 Mb/s lin+ each user:

100 8b/s *hen ?active@ active 10, o! time

circuit-s*itching: 10 users

$ac+et s*itching: *ith 65 users

$robabilit" N 10 activeless than 2000

4ac+et s*itching allo*s more users to use net*or+>

; users

1 Mb$s lin+


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Introduction 1-26

4ac+et s*itching versus circuit s*itching

(reat !or burst" data resource sharing

sim$ler no call setu$ 7cessive congestion:$ac+et dela" and loss

$rotocols needed !or reliable data trans!ercongestion control

;o guaranteed $er!ormance P: )o* to $rovide circuit-li+e behaviorC

band*idth guarantees needed !or audio/video a$$s

Is $ac+et s*itching a ?slam dun+ *innerC@


27/28

Introduction 1-27

4ac+et-s*itching: datagram and virtualcircuit net*or+s

(oal:move $ac+ets through routers !rom source todestination

datagram net*or+: destination address in $ac+et determines ne7t ho$

4ath ma" change !rom one datagram to another Routers !orget about a datagram a!ter !or*arding to ne7t

ho$

virtual circuit net*or+: each $ac+et carries tag %virtual circuit IE' tag

determines ne7t ho$ !i7ed $ath determined at call setu$ time remains the same

thru call routers maintain$er-call state


28/28

Introduction 1-28

;et*or+ .a7onom"

.elecommunicationnet*or+s

ircuit-s*itchednet*or+s

FEM .EM

4ac+et-s*itchednet*or+s

;et*or+s

*ith Qs

Eatagram

;et*or+sEM

Networks Lecture Notes

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