CS

E 1

23b

CS

E 1

23b

Com

mun

icat

ions

Sof

twar

eC

omm

unic

atio

ns S

oftw

are

Spr

ing

2003

Spr

ing

2003

Lect

ure

1: In

trodu

ctio

n &

Rev

iew

Lect

ure

1: In

trodu

ctio

n &

Rev

iew

Ste

fan

Sav

age

Ste

fan

Sav

age

sava

ge@

cs.u

csd.

edu

sava

ge@

cs.u

csd.

edu

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

2

Cla

ss O

verv

iew

Cla

ss O

verv

iew

Cou

rse

Mat

eria

l◆

Cla

ss le

ctur

es, t

extb

ook

read

ings

, and

han

dout

s

Cou

rse

Ass

ignm

ents

◆H

omew

ork

ques

tions

from

boo

k an

d ha

ndou

ts»

Han

ded

out o

n Tu

esda

ys d

ue th

e fo

llow

ing

Tues

day

»R

ough

ly e

very

2-3

wee

ks◆

Net

wor

k pr

otoc

ol p

rogr

amm

ing

proj

ects

(3-5

)»

We

will

impl

emen

t rou

ting

prot

ocol

s, tr

ansp

ort p

roto

cols

, etc

.

Exa

ms

◆M

idte

rm a

nd F

inal

◆I w

ill b

e ex

plic

it ab

out w

hat i

s co

vere

d in

eac

h

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

3

Gra

ding

Gra

ding

Hom

ewor

k25

%P

roje

cts

25%

Mid

term

20%

Fina

l30

%

Ext

ra c

redi

t for

cla

ss p

artic

ipat

ion

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

4

Som

e hi

nts

Som

e hi

nts

Com

e to

lect

ure

◆Y

es, I

will

dis

tribu

te th

e sl

ides

onl

ine,

and

yes

the

mat

eria

l is

in th

e bo

ok◆

How

ever

, lec

ture

mat

eria

ls a

re th

e ba

sis

for e

xam

sD

o th

e ho

mew

ork

◆Y

ou w

ill h

ave

a ha

rd ti

me

with

the

exam

s w

ithou

t do

ing

the

hom

ewor

k◆

Its 2

5% o

f you

r gra

de (e

asily

the

diffe

renc

e be

twee

n an

A a

nd C

)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

5

Som

e hi

nts

(2)

Som

e hi

nts

(2)

Ask

que

stio

ns◆

In c

lass

, via

e-m

ail a

nd a

t offi

ce h

ours

◆

Inev

itabl

y yo

u w

on’t

unde

rsta

nd s

omet

hing

… th

at’s

m

y fa

ult,

but y

ou n

eed

to h

elp

Sta

rt as

sign

men

ts e

arly

◆Th

ere

is a

sta

tistic

al re

latio

nshi

p be

twee

n w

hen

you

star

t and

wha

t gra

de y

ou g

etS

leep

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

6

Adm

inis

trat

iva

Adm

inis

trat

iva

Web

pag

eht

tp://

ww

w-c

se.u

csd.

edu/

clas

ses/

sp03

/cse

123B

/(w

ill b

e up

sho

rtly

) Te

xtbo

ok (r

equi

red)

Com

pute

r Net

wor

ks: A

Sys

tem

s A

ppro

ach

(2nd

ed) b

y P

eter

son

and

Dav

ieTA

’s◆

Yuc

hung

Che

ng, C

ristia

n E

stan

and

Alv

in A

uyou

ngM

ailin

g lis

t, of

fice

hour

s, d

iscu

ssio

n se

ctio

n (T

BA

)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

7

Com

mon

que

stio

nsC

omm

on q

uest

ions

Can

I ta

ke th

is c

lass

con

curr

ently

with

X?

(whe

re X

is

typi

cally

120

)◆

Yes

, but

this

may

be

chal

leng

ing.

We

assu

min

g ba

sic

know

ledg

e ab

out O

S s

truct

ure

and

som

e of

the

issu

es th

at

are

disc

usse

d in

120

that

rela

ted

to n

etw

orki

ng.

Fair

war

ning

.

How

muc

h pr

ogra

mm

ing

is th

ere?

◆Th

e pr

ojec

ts w

ill re

quire

that

you

can

und

erst

and

and

writ

e co

de in

C.

If yo

u’re

a p

rofic

ient

pro

gram

mer

and

don

’t kn

ow

C, y

ou s

houl

d be

abl

e to

pic

k it

up q

uick

ly.

If yo

u’ve

don

e al

mos

t no

prog

ram

min

g, th

en th

is c

lass

may

be

pain

ful.

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

8

Cou

rse

mat

eria

lC

ours

e m

ater

ial

The

key

aspe

cts

of m

oder

n co

mpu

ter

netw

orks

and

net

wor

k se

rvic

es◆

Rel

iabl

e co

mm

unic

atio

n◆

Con

gest

ion

cont

rol

◆R

outin

g (in

trado

mai

nan

d in

terd

omai

n)◆

Nam

ing

◆M

obili

ty◆

Web

ser

vice

, cac

hing

, loa

d ba

lanc

ing,

CD

Ns

◆E

-mai

l◆

Pee

r-to

-pee

r net

wor

ks◆

Sec

urity

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

9

We

will

not

cov

erW

e w

ill n

ot c

over

Que

uing

theo

ryS

igna

lsH

ardw

are

desi

gnS

witc

hing

des

ign

Phy

sica

l/dat

a lin

k la

yers

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

10

Ove

rall

goal

sO

vera

ll go

als

Und

erst

and

how

to la

rge

scal

e,

hete

roge

neou

sdi

strib

uted

netw

orks

are

bu

ilt◆

Fund

amen

tal p

robl

ems

◆E

stab

lishe

d de

sign

prin

cipl

es◆

Sta

ndar

d In

tern

et p

roto

cols

and

impl

emen

tatio

ns

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

11

Larg

e sc

ale?

Larg

e sc

ale?

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

12

Larg

e sc

ale?

(2)

Larg

e sc

ale?

(2)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

13

Het

erog

eneo

us?

Het

erog

eneo

us?

Hom

ogen

ous

netw

ork:

the

tele

phon

e sy

stem

◆D

esig

ned

for m

akin

g ph

one

calls

◆K

now

n ca

ll du

ratio

n di

strib

utio

n, b

andw

idth

, ser

vice

co

nstra

ints

, ser

vice

mod

elH

eter

ogen

ous:

the

Inte

rnet

◆S

uppo

rts E

-mai

l, w

eb, e

-com

mer

ce, a

udio

, vid

eo,

mul

ti-pl

ayer

gam

es…

◆Fe

w u

nder

lyin

g as

sum

ptio

ns –

a st

reng

th a

nd a

w

eakn

ess

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

14

Dis

trib

uted

?D

istr

ibut

ed?

Dec

entra

lized

com

pone

nts

◆M

ust u

pdat

e/m

anag

e ch

ange

s in

sta

teLo

ng c

omm

unic

atio

n la

tenc

y◆

Act

ions

take

tim

eP

artia

l fai

lure

s ◆

Mus

t tol

erat

e fa

ilure

s

“A d

istr

ibut

ed s

yste

m is

a s

yste

m in

whi

ch I

can’

t do

my

wor

k be

caus

e so

me

com

pute

r has

file

d th

at I’

ve n

ever

eve

n he

ard

of”

–

Lesl

ie L

ampo

rt

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

15

Som

e re

view

Som

e re

view

Ele

men

tary

com

pone

nts

Circ

uit s

witc

hing

vs

pack

et s

witc

hing

Bas

ic n

etw

ork

mod

el/m

etric

sLa

yerin

g/pr

otoc

ols

◆La

yerin

g by

exa

mpl

e: fe

tchi

ng a

Web

pag

e

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

16

Net

wor

k co

mpo

nent

sN

etw

ork

com

pone

nts

Hos

ts: e

ndpo

ints

that

com

mun

icat

e◆

e.g.

wor

ksta

tion,

ser

ver,

PD

ALi

nks:

tran

smis

sion

med

ium

◆e.

g. E

ther

net,

802.

11b,

FD

DI

Rou

ters

/Sw

itche

s: m

oves

bits

bet

wee

n lin

ks◆

Circ

uit s

witc

hing

: gua

rant

eed

chan

nel f

or a

ses

sion

(T

elep

hone

sys

tem

)◆

Pac

ket s

witc

hing

: sta

tistic

al m

ultip

lexi

ng o

f in

depe

nden

t pie

ces

of d

ata

(Inte

rnet

)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

17

Cir

cuit

Sw

itch

ing

Cir

cuit

Sw

itch

ing

Thre

e ph

ases

1.ci

rcui

t est

ablis

hmen

t (d

ial)

2.da

ta tr

ansf

er (

talk

) 3.

circ

uit t

erm

inat

ion

(han

g up

)If

circ

uit n

ot a

vaila

ble:

“Bus

y si

gnal

”E

xam

ples

◆Te

leph

one

netw

orks

◆IS

DN

(Int

egra

ted

Ser

vice

s D

igita

l Net

wor

ks)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

18

Cir

cuit

Sw

itch

ing

Cir

cuit

Sw

itch

ing

A n

ode

(sw

itch)

in a

circ

uit s

witc

hing

net

wor

k

inco

min

g lin

ksou

tgoi

ng li

nks

Nod

e

Slid

e co

urte

sy Io

n St

oica

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

19

Cir

cuit

sw

itch

ing:

C

ircu

it s

wit

chin

g:

tim

e di

visi

on m

ulti

plex

ing

tim

e di

visi

on m

ulti

plex

ing

Tim

e di

vide

d in

fram

es a

nd fr

ames

div

ided

in s

lots

◆R

elat

ive

slot

pos

ition

insi

de a

fram

e de

term

ines

whi

ch

conv

ersa

tion

the

data

bel

ongs

to◆

Nee

ds s

ynch

roni

zatio

n be

twee

n se

nder

and

rece

iver

In c

ase

of n

on-p

erm

anen

t con

vers

atio

ns◆

Nee

d to

dyn

amic

ally

bin

d a

slot

to a

con

serv

atio

n

◆S

igna

ling

prot

ocol

Slid

e co

urte

sy Io

n St

oica

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

20

Pac

ket

Sw

itch

ing

Pac

ket

Sw

itch

ing

Dat

a is

sen

t in

a bu

ndle

of b

it-se

quen

ces,

cal

led

a pa

cket

.P

acke

ts h

ave

the

follo

win

g st

ruct

ure:

»H

eade

r and

Tra

iler c

arry

con

trol i

nfor

mat

ion

(e.g

., de

stin

atio

n ad

dres

s, c

heck

sum

)E

ach

pack

et is

pas

sed

thro

ugh

the

netw

ork

from

nod

e to

nod

e al

ong

som

e pa

th (R

outin

g)A

t eac

h no

de th

e en

tire

pack

et is

rece

ived

, sto

red

brie

fly, a

nd th

en fo

rwar

ded

to th

e ne

xt n

ode

(Sto

re-

and-

Forw

ard

Net

wor

ks)

Typi

cally

no

capa

city

is p

re-a

lloca

ted

for p

acke

ts

Hea

der

Dat

aTr

aile

r

Slid

e co

urte

sy Io

n St

oica

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

21

Pac

ket

Sw

itch

ing

Pac

ket

Sw

itch

ing

A n

ode

in a

pac

ket s

witc

hing

net

wor

k

inco

min

g lin

ksou

tgoi

ng li

nks

Nod

e

Mem

ory

Slid

e co

urte

sy Io

n St

oica

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

22

Pac

ket

Sw

itch

ing:

P

acke

t S

wit

chin

g:

Sta

tist

ical

mul

tipl

exin

gS

tati

stic

al m

ulti

plex

ing

Dat

a fro

m a

ny c

onve

rsat

ion

can

be tr

ansm

itted

at

any

giv

en ti

me

How

to te

ll th

em a

part?

◆us

e he

ader

)to

desc

ribe

data

Slid

e co

urte

sy Io

n St

oica

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

23

Pro

/con

s of

pac

ket

swit

chin

gP

ro/c

ons

of p

acke

t sw

itch

ing

Effi

cien

cy◆

Can

sha

re n

etw

ork

up to

its

capa

city

–no

ove

rhea

d fo

r re

serv

ing

band

wid

th th

at is

unu

sed

◆C

an s

uppo

rt m

any

diffe

rent

ser

vice

type

s

Low

com

plex

ity◆

Don

’t ne

ed to

mai

ntai

n st

ate

abou

t eac

h “c

all”

Har

der t

o gu

aran

tee

band

wid

th/d

elay

We

will

focu

s on

pac

ket s

witc

hing

in th

is c

lass

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

24

Sim

ple

netw

ork

mod

elS

impl

e ne

twor

k m

odel

Net

wor

k is

a p

ipe

conn

ectio

n tw

o co

mpu

ters

Bas

ic M

etric

s◆

Ban

dwid

th, d

elay

, ove

rhea

d, e

rror r

ate

and

mes

sage

siz

e

Packet

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

25

Net

wor

k m

etri

csN

etw

ork

met

rics

Ban

dwid

th◆

Dat

a tra

nsm

itted

at a

rate

of R

bits

/sec

Del

ay o

r Lat

ency

◆Ta

kes

D s

econ

ds fo

r bit

to p

ropa

gate

dow

n w

ire

Ove

rhea

d◆

take

s O

sec

sfo

r CP

U to

put

mes

sage

on

wire

Err

or ra

te◆

Pro

babi

lity

P th

at m

essa

ge w

ill n

ot a

rriv

e in

tact

Mes

sage

siz

e◆

Siz

e M

of d

ata

bein

g tra

nsm

itted

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

26

How

long

to

send

a m

essa

ge?

How

long

to

send

a m

essa

ge?

Tran

smit

time

T =

M/R

+ D

◆10

Mbp

s E

ther

net L

AN

(M=1

KB

byte

, or 8

000b

its)

»M

/R=0

.8m

s, D

~=5

us

◆15

5Mbp

s cr

oss

coun

try A

TM (M

=1K

B)

»M

/R =

~51

us, D

~=

40-1

00m

s

R*D

is th

e “s

tora

ge” o

f pip

e

(a

lso

calle

d ba

ndw

idth

del

ay p

rodu

ct)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

27

Laye

ring

Laye

ring

Wha

t is

laye

ring?

◆D

ecom

posi

tion

of a

com

plex

sys

tem

into

an

orde

red

serie

s of

dis

tinct

abs

tract

ions

◆Th

e se

rvic

es p

rovi

ded

by a

laye

r dep

end

only

on th

e se

rvic

es p

rovi

ded

by th

e pr

evio

us, l

ess

abst

ract

, lay

erLa

yerin

g in

net

wor

king

◆Se

rvic

e: w

hat a

laye

r doe

s(e

.g. m

essa

ge d

eliv

ery)

◆In

terf

ace:

how

to u

seth

e se

rvic

e (e

.g. p

acke

t for

mat

)◆

Prot

ocol

: how

the

serv

ice

is im

plem

ente

d(e

.g. T

CP

)◆

Prot

ocol

sta

ck: c

olle

ctio

n of

pro

toco

ls im

plem

entin

g a

serie

s of

laye

rs (e

.g. E

ther

net/I

P/T

CP

/Web

)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

28

The

OS

I la

yeri

ng M

odel

The

OS

I la

yeri

ng M

odel

App

licat

ion

Pres

enta

tion

Sess

ion

Tran

spor

t

Net

wor

k

Dat

alin

k

Phys

ical

End

host

App

licat

ion

Pres

enta

tion

Sess

ion

Tran

spor

t

Net

wor

k

Dat

alin

k

Phys

ical

End

host

Net

wor

k

Dat

alin

k

Phys

ical

Net

wor

k no

deN

etw

ork

Dat

alin

k

Phys

ical

Net

wor

k no

de

•Top

four

laye

rs a

re e

nd-to

-end

•Low

er 3

laye

rs a

re p

eer-

to-p

eer

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

29

Wha

t th

e la

yers

are

for

?W

hat

the

laye

rs a

re f

or?

App

licat

ion:

any

ser

vice

(e.g

. WW

W, S

MTP

)Pr

esen

tatio

n: d

ata

form

at c

onve

rsio

n (e

.g. X

DR

)Se

ssio

n: c

onne

ctio

n m

anag

emen

t, sy

nchr

oniz

atio

n (e

.g. S

MIL

)Tr

ansp

ort:

erro

r-co

ntro

l, flo

w-c

ontro

l, ch

anne

l m

ultip

lexi

ng (e

.g. T

CP

, UD

P)

Net

wor

k: R

outin

g (e

.g. I

P)

Dat

alin

k: F

ram

ing,

med

ia a

cces

s (e

.g. E

ther

net,

FDD

I, S

ON

ET)

Phys

ical

: Tra

nsm

issi

on/m

odul

atio

n (e

.g. 1

00B

aseT

)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

30

Ben

efit

s of

laye

ring

Ben

efit

s of

laye

ring

Enca

psul

atio

n◆

Func

tiona

lity

insi

de a

laye

r is

self-

cont

aine

d; o

ne

laye

r doe

sn’t

need

to re

ason

abo

ut o

ther

laye

rsM

odul

arity

◆C

an re

plac

e a

laye

r with

out i

mpa

ctin

g ot

her l

ayer

s◆

Low

er la

yers

can

be

reus

ed b

y hi

gher

laye

rs

(e

.g. T

CP

and

UD

P b

oth

are

laye

red

upon

IP)

One

obv

ious

dra

wba

ck◆

Info

rmat

ion

hidi

ng c

an p

rodu

ce in

effic

ient

im

plem

enta

tions

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

31

Laye

r en

caps

ulat

ion

Laye

r en

caps

ulat

ion

App

licat

ion

Pres

enta

tion

Sess

ion

Tran

spor

t

Net

wor

k

Dat

alin

k

Phys

ical

End

host

App

licat

ion

Pres

enta

tion

Sess

ion

Tran

spor

t

Net

wor

k

Dat

alin

k

Phys

ical

End

host

Dat

a

Dat

aP

Dat

aS

Dat

aT

Dat

aN

Dat

aD

Dat

aPh

Dat

a Dat

aP

Dat

aS

Dat

aT

Dat

aN

Dat

aD

Dat

aPh

Laye

r N+1

pac

ket

beco

mes

Laye

r N d

ata

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

32

Laye

r E

ncap

sula

tion

(2)

Laye

r E

ncap

sula

tion

(2)

Typi

cal W

eb p

acke

t

Not

ice

that

laye

rs a

dd o

verh

ead

◆S

pace

(hea

ders

), ef

fect

ive

band

wid

th◆

Tim

e (p

roce

ssin

g he

ader

s, p

eelin

g th

e on

ion)

, la

tenc

y

IP H

drP

aylo

ad (W

eb o

bjec

t)TC

P H

drH

TTP

Hdr

Eth

erne

t Hdr

Sta

rt of

pac

ket

End

of p

acke

t

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

33

The

Int

erne

t la

yeri

ng m

odel

The

Int

erne

t la

yeri

ng m

odel

App

licat

ion

(Web

,FTP

,SM

TP)

Net

wor

k (IP

)

Tran

spor

t (TC

P,U

DP)

Dat

alin

k(E

ther

net,8

02.1

1)

Phys

ical

(100

Bas

eTX,

1000

Bas

eSX)

•So-

calle

d “h

ourg

lass

” m

odel

• One

net

wor

k la

yer p

roto

col

•Sig

nific

ant d

iver

sity

at o

ther

la

yers

•No

pres

enta

tion

or s

essi

on

laye

rs

•Im

plem

enta

tions

mor

e im

port

ant t

han

inte

rfac

es

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

34

Laye

ring

by

exam

ple…

Laye

ring

by

exam

ple…

RO

UG

HLY

, wha

t hap

pens

whe

n I c

lick

on a

W

eb p

age

from

UC

SD

?

Inte

rnet

ww

w.y

ahoo

.com

?M

y co

mpu

ter

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

35

App

licat

ion

laye

r (H

TT

P)

App

licat

ion

laye

r (H

TT

P)

Turn

clic

k in

to H

TTP

requ

est

GET

http

://w

ww

.yah

oo.c

om/r/

mp

HTT

P/1.

1H

ost:

ww

w.y

ahoo

.com

Con

nect

ion:

keep

-aliv

e…

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

36

App

licat

ion

laye

r?

App

licat

ion

laye

r?

Nam

e re

solu

tion

(D

NS

)N

ame

reso

luti

on (

DN

S)

Whe

re is

ww

w.y

ahoo

.com

?

Wha

t’s th

e ad

dres

s for

www

.yah

oo.c

omM

y co

mpu

ter

(132

.239

.9.6

4)

Oh,

you

can

find

it a

t 64.

58.7

6.17

7

Loc

al D

NS

serv

er(1

32.2

39.5

1.18

)

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

37

Tra

nspo

rt la

yer

(TC

P)

Tra

nspo

rt la

yer

(TC

P)

Bre

ak m

essa

ge in

to p

acke

ts (T

CP

seg

men

ts)

Sho

uld

be d

eliv

ered

relia

bly

& in

-ord

er

GET

http

://w

ww

.yah

oo.c

om/r/

mp

HTT

P/1.

1H

ost:

ww

w.y

ahoo

.com

Con

nect

ion:

keep

-aliv

e…

GET

htt

1

“and

let m

e kn

ow w

hen

they

got

ther

e”

p://w

ww

.2

yaho

o.c

3

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

38

Net

wor

k la

yer:

IP

Add

ress

ing

Net

wor

k la

yer:

IP

Add

ress

ing

Add

ress

eac

h pa

cket

so

it ca

n tra

vers

e ne

twor

k an

d ar

rive

at h

ost

My

com

pute

r(1

32.2

39.9

.64)

ww

w.y

ahoo

.com

(64.

58.7

6.17

7)

GET

htt

164

.58.

76.1

7713

2.23

9.9.

64

Des

tinat

ion

Sour

ceD

ata

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

39

Qw

est

Net

wor

k la

yer:

IP

Rou

ting

Net

wor

k la

yer:

IP

Rou

ting

Spr

int

UU

Net

AT&T

UC

SD

ww

w.y

ahoo

.com

(64.

58.7

6.17

7)

Eac

h ro

uter

forw

ards

pac

ket t

owar

ds d

estin

atio

n

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

40

Dat

alin

kD

atal

ink

laye

r (E

ther

net)

laye

r (E

ther

net)

Too

borin

g fo

r a p

ictu

re (s

orry

)

Bre

ak m

essa

ge in

to fr

ames

Med

ia A

cces

s C

ontro

l (M

AC

)S

end

fram

e

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

41

Phy

sica

l lay

erP

hysi

cal l

ayer

802.

11b

Wire

less

A

cces

s Po

int

Ethe

rnet

sw

itch/

rout

er

To c

ampu

s ba

ckbo

ne

2.4G

hz R

adio

DS/

FH R

adio

(1-1

1Mbp

s)

Cat

5 C

able

(4 w

ires)

100B

ase

TX E

ther

net

100M

bps 62

.5/1

25um

850

nm M

MF

1000

Bas

eSX

Ethe

rnet

1000

Mbp

s

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

42

Sum

mar

yS

umm

ary

Pac

kets

sw

itchi

ng is

an

effic

ient

and

sim

ple

arch

itect

ure

for d

ata

com

mun

icat

ions

◆G

ives

up

guar

ante

es o

n se

rvic

e

Laye

ring

is a

tech

niqu

e fo

r man

agin

g co

mpl

exity

in

syst

ems

◆E

ncap

sula

te re

late

d fu

nctio

nalit

y in

a la

yer a

nd p

rovi

de a

n in

terfa

ce to

upp

er a

nd lo

wer

laye

rs◆

A m

odel

: im

plem

enta

tions

do

not n

eces

saril

y re

spec

t lay

ers

April

9, 2

003

CSE

123

b --

Lect

ure

1 –

Intr

oduc

tion

and

Rev

iew

43

For

Nex

t T

ime…

For

Nex

t T

ime…

ATT

EN

TIO

N –

Wak

e up

!◆

Thur

sday

’s c

lass

is c

ance

lled

◆Th

e ne

xt c

lass

will

be

Tues

day

Apr

il 8t

h

For t

hen:

◆G

et th

e te

xtbo

ok◆

Rev

iew

Pat

ters

on&

Dav

ieC

hap1

◆R

ead

Cha

p 4.

1 -4

.1.4