tdts06: course information tdts06 lecture 1: introduction
TRANSCRIPT
1
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-1
TDTS
06 C
ompu
ter
netw
orks
Le
ctur
e 1:
Cou
rse
info
rmat
ion;
Com
pute
r ne
twor
king
con
cept
s an
d th
e In
tern
etJu
ha T
akkine
n, juh
ta@
ida.
liu.s
eID
A/A
DIT
, Link
öpings
unive
rsitet
2010
-08-
30
Slid
es a
re m
odifi
ed fr
om J
.F K
uros
e an
d K
.W. R
oss
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-2
TDTS
06: C
ours
e in
form
atio
nA
cou
rse
for
whom
?Pr
ereq
uisi
tes?
Web
site
: ht
tp:/
/www
.ida.
liu.s
e/~T
DTS
06/
sche
dule
, lect
ure
cont
ents
, re
adin
g in
stru
ctio
ns, s
lides
, le
arni
ng g
oals
lab
inst
ruct
ions
, ass
ignm
ents
, ro
utin
es &
pol
icy
FAQ
, old
exa
ms
Upd
ates
and
cha
nges
mes
sage
s on
cour
se w
ebco
urse
mai
ling
list
Text
book
: Kur
ose,
Jam
es F
. &
Ross
, Kei
th W
. (20
09),
Com
pute
r ne
twor
king
: A to
p-do
wn a
ppro
ach.
Fi
fth
editi
on. A
ddis
on-W
esle
y.A
lso,
che
ck o
ut t
he e
rrat
a sh
eet
(link
fr
om c
ours
e we
b, u
nder
Cou
rse
liter
atur
e)
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-3
TDTS
06: C
ours
e st
aff
Juha
Tak
kine
n (m
e)Ex
amin
er, l
ectu
rer
and
lab
assi
stan
tju
hta@
ida.
liu.s
e
Jose
M. P
eña
lect
urer
josp
e@id
a.liu
.se
Rahu
l Hir
anla
b as
sist
ant
rahu
l.hira
n@liu
.se
Chri
stia
n Ve
stlu
ndla
b as
sist
ant
chrv
e@id
a.liu
.se
Lena
Str
ömbä
ckD
irect
or o
f st
udie
s (h
andl
es la
te c
ours
e re
gist
ratio
ns)
lest
r@id
a.liu
.se
Cour
se a
dmin
istr
ator
: M
adel
eine
Häg
er
Dah
lqvi
st,
mad
ha@
ida.
liu.s
e
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-4
TDTS
06: G
roun
d ru
les
for
clas
sBe
her
e on
tim
eM
inim
ize
disr
upti
ons
Pick
up
your
tra
shM
emor
ize
the
inst
ruct
or’s
offi
ce h
ours
Tues
day
and
Frid
ays
13.15
-15.
00Fo
r co
ntac
t at
oth
er t
imes
: Boo
k ap
poin
tmen
t vi
a e-
mai
lD
eadl
ines
mus
t be
res
pect
edRe
ad th
e Co
urse
info
rmat
ion
http
://w
ww.id
a.liu
.se/
~TD
TS06
/
2
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-5
TDTS
06: G
roun
d ru
les
for
labs
If y
ou n
eed
to c
hang
e la
b gr
oup
afte
r th
e la
b re
gist
rati
on d
eadl
ine,
e-m
ail t
he la
b as
sist
ant
(LA
)If
you
are
alo
ne a
nd a
re lo
okin
g fo
r a
lab
part
ner,
e-
mai
l the
LA
If y
ou a
re d
oing
the
labs
on
your
own
, reg
iste
r in
th
e SI
NG
grou
pGr
oups
of
pairs
hav
e pr
eced
ence
over
sin
gle-
pers
on la
b gr
oups
and
hav
e fi
rst-
acce
ss t
o la
b te
rmin
als
on s
ched
uled
lab
hour
s
Read
the
Lab
info
rmat
ion
http
://w
ww.id
a.liu
.se/
~TD
TS06
/lab
s/
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-6
LiU
: Dis
cipl
inar
y ac
tion
s
Any
kin
d of
aca
dem
ic d
isho
nest
y, s
uch
as
chea
ting
, pla
giar
ism
, use
of
unau
thor
ized
as
sist
ance
, fra
ud a
nd f
ailu
re t
o co
mpl
y wi
th U
nive
rsit
y ex
amin
atio
n ru
les,
may
re
sult
in t
he f
iling
of
a co
mpl
aint
to
the
Uni
vers
ity
Dis
cipl
inar
y Co
mm
itte
e. T
he
pote
ntia
l pen
alti
es in
clud
e ex
puls
ion,
su
spen
sion
, and
rev
ocat
ion
of p
revi
ousl
y ea
rned
gra
de o
r de
gree
. Li
U R
ules
and
reg
ulat
ions
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-7
TDTS
06: I
DA
’s la
b po
licy
You
are
expe
cted
to
do la
b as
sign
men
ts in
gro
up o
r in
divi
dual
ly, a
s in
stru
cted
for
a c
ours
e. H
owev
er,
exam
inat
ion
is a
lway
s ba
sed
on in
divi
dual
per
form
ance
. It
is n
ot a
llowe
d to
han
d in
sol
utio
ns c
opie
d fr
om o
ther
st
uden
ts, o
r fr
om e
lsew
here
, eve
n if
you
mak
e ch
ange
s to
th
e so
lutio
ns. I
f th
ere
is s
uspi
cion
of
such
, or
any
othe
r fo
rm o
f ch
eatin
g, t
each
ers
are
oblig
ed t
o re
port
it t
o th
e U
nive
rsity
Dis
cipl
inar
y Bo
ard.
Be
pre
pare
d to
ans
wer
ques
tions
abo
ut d
etai
ls in
spe
cifi
c co
de a
nd it
s co
nnec
tion
to t
heor
y. Y
ou m
ay a
lso
be a
sked
to
exp
lain
why
you
hav
e ch
osen
a s
peci
fic
solu
tion.
Thi
s ap
plie
s to
all
grou
p m
embe
rs.
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-8
If y
ou f
ores
ee p
robl
ems
mee
ting
a de
adlin
e, c
onta
ct
your
tea
cher
. You
can
the
n ge
t so
me
help
and
may
be
the
dead
line
can
be s
et t
o a
late
r da
te. I
t is
alw
ays
bett
er t
o di
scus
s pr
oble
ms,
inst
ead
of, e
.g.,
to c
heat
. A
ny k
ind
of a
cade
mic
dis
hone
sty,
suc
h as
che
atin
g, e
.g.
plag
iaris
m o
r us
e of
una
utho
rized
ass
ista
nce,
and
fa
ilure
to
com
ply
with
uni
vers
ity e
xam
inat
ion
rule
s, m
ay
resu
lt in
the
fili
ng o
f a
com
plai
nt t
o th
e U
nive
rsity
D
isci
plin
ary
Boar
d. T
he p
oten
tial p
enal
ties
incl
ude
susp
ensi
on, w
arni
ng.
3
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-9
Man
agin
g la
b re
port
sYo
u m
ust
use
IDA
’s la
b wr
appe
r an
dfi
ll in
all
fiel
dsW
here
and
how
to
hand
in la
bs?
durin
g la
b ho
urs
(or
offi
ce h
ours
) to
your
lab
assi
stan
tm
ail r
oom
opp
osite
Caf
é Ja
va•
put
lab
repo
rt in
to b
rown
wra
pper
wit
h th
e la
b as
sist
ant’s
nam
e on
itRe
trie
ving
labs
durin
g la
b ho
urs
(or
offi
ce h
ours
) fro
m y
our
lab
assi
stan
tW
hen
resu
bmit
ting
Impo
rtan
t: Y
ou m
ust
reus
eol
d wr
appe
r co
ntai
ning
ass
ista
nt’s
com
men
ts a
ndfi
ll in
res
ubm
issio
nda
te w
hen
resu
bmitt
ing
the
upda
ted
lab
repo
rtwe
breg
’s “in
term
edia
te”
mea
ns t
hat
som
ethi
ng is
mis
sing
fro
m t
he
lab.
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-10
Wha
t’s n
ext?
Regi
ster
for
the
cou
rse
ASA
PSi
gn u
p fo
r th
e la
bs a
t la
test
on
Sept
embe
r 3Re
ad u
p on
the
lab
docu
men
tati
on:
lab
assi
gnm
ent
1x-
kern
el T
utor
ial
•Ti
p: p
rint
out
one
A4-
size
d m
anua
l per
gro
up,
incl
udin
g th
e x-
kern
el P
rogr
amm
er’s
man
ual
the
ASP
pro
toco
l wal
k-th
roug
hRe
ad u
p on
the
C-p
rogr
amm
ing
lang
uage
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-11
Chap
ter
1: I
ntro
duct
ion
Our
goa
l:ge
t “f
eel”
and
term
inol
ogy
mor
e de
pth,
det
ail
late
rin
cou
rse
appr
oach
:us
e In
tern
et a
s ex
ampl
e
Ove
rvie
w:w
hat’s
the
Int
erne
t?w
hat’s
a p
roto
col?
netw
ork
edge
; hos
ts, a
cces
s ne
t, p
hysi
cal m
edia
netw
ork
core
: pac
ket/
circ
uit
swit
chin
g, I
nter
net
stru
ctur
epe
rfor
man
ce: l
oss,
del
ayhi
stor
y
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-12
Care
ful!
A c
ours
e fu
ll of
acr
onym
sTh
e lo
nges
t ac
rony
m, a
ccor
ding
to
the
1965
edi
tion
of A
cron
yms,
In
itial
ism
s an
d A
bbre
viat
ions
Dic
tiona
ry, i
s A
DCO
MSU
BORD
COM
PHIB
SPA
C, a
Uni
ted
Stat
es N
avy
term
tha
t st
ands
for
"A
dmin
istr
ativ
e Co
mm
and,
Am
phib
ious
For
ces,
Pac
ific
Fl
eet
Subo
rdin
ate
Com
man
d."
The
worl
d's
long
est
initi
alis
m, a
ccor
ding
to
the
Guin
ness
Boo
k of
W
orld
Rec
ords
is
NII
OM
TPLA
BOPA
RMBE
TZH
ELBE
TRA
BSBO
MO
NIM
ON
KON
OTD
TEK
HST
ROM
ON
T. T
he 5
6-le
tter
initi
alis
m (
54 in
Cyr
illic
) is
fro
m
the
Conc
ise
Dic
tiona
ry o
f So
viet
Ter
min
olog
y an
d m
eans
"Th
e la
bora
tory
for
shu
tter
ing,
rei
nfor
cem
ent,
con
cret
e an
d fe
rroc
oncr
ete
oper
atio
ns f
or c
ompo
site
-mon
olith
ic a
nd m
onol
ithic
co
nstr
uctio
ns o
f th
e D
epar
tmen
t of
the
Tec
hnol
ogy
of B
uild
ing-
asse
mbl
y op
erat
ions
of
the
Scie
ntif
ic R
esea
rch
Inst
itute
of
the
Org
aniz
atio
n fo
r bu
ildin
g m
echa
niza
tion
and
tech
nica
l aid
of
the
Aca
dem
y of
Bui
ldin
g an
d A
rchi
tect
ure
of t
he U
SSR.
"
4
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-13
“Coo
l” in
tern
et a
pplia
nces
Wor
ld’s
sm
alle
st w
eb s
erve
rht
tp:/
/ww
w-c
cs.c
s.um
ass.
edu/
~sh
ri/iP
ic.h
tml
IP p
ictu
re fr
ame
http
://w
ww
.cei
va.c
om/
Web
-ena
bled
toas
ter +
wea
ther
fore
cast
er
Inte
rnet
pho
nes
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-14
Wha
t’s t
he I
nter
net:
“nu
ts a
nd b
olts
” vie
w
prot
ocol
sco
ntro
l se
ndin
g, r
ecei
ving
of
msg
s e.g.
, TCP
, IP,
HTT
P,
Skyp
e, E
ther
net
Inte
rnet
: “ne
twor
k of
net
wor
ks”
loos
ely
hier
arch
ical
publ
ic I
nter
net
vers
us
priv
ate
intr
anet
Inte
rnet
sta
ndar
dsRF
C: R
eque
st f
or
com
men
tsIE
TF: I
nter
net
Engi
neer
ing
Task
Fo
rce
Hom
e ne
twor
k
Inst
itutio
nal n
etwo
rk
Mob
ile n
etwo
rk
Glob
al I
SP
Regi
onal
ISP
rout
er
PC serv
er
wire
less
lapt
opce
llula
r ha
ndhe
ld
wire
dlin
ks
acce
ss
poin
ts
netw
ork
edge
netw
ork
core
acce
ss n
etwo
rks
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-15
Wha
t’s a
pro
toco
l?a
hum
an p
roto
col a
nd a
com
pute
r ne
twor
k pr
otoc
ol:
Q:O
ther
hum
an p
roto
cols
?
Hi
Hi
Got
the
tim
e?2:
00
TCP
conn
ecti
onre
ques
tTC
P co
nnec
tion
resp
onse
Get h
ttp:
//ww
w.aw
l.com
/kur
ose-
ross
<file
>ti
me
synt
ax, s
eman
tics,
tim
ing
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-16
The
netw
ork
edge
end
syst
ems
(hos
ts):
run
appl
icat
ion
prog
ram
se.
g. W
eb, e
-mai
lat
“edg
e of
net
work
”cl
ient
-ser
ver
mod
elcl
ient
hos
t re
ques
ts,
rece
ives
serv
ice
from
al
ways
-on
serv
ere.
g. W
eb b
rows
er-
serv
er; e
-mai
l clie
nt-
serv
erpe
er-p
eer
mod
el:
min
imal
(or
no) u
se o
f de
dica
ted
serv
ers
e.g.
Sky
pe,
BitT
orre
nt
clie
nt-s
erve
r
peer
-pee
r
5
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-17
Net
work
edg
e: r
elia
ble
data
tra
nsfe
r se
rvic
e
Goal
:dat
a tr
ansf
er
betw
een
end
syst
ems
hand
shak
ing:
setu
p (p
repa
re f
or) d
ata
tran
sfer
ahe
ad o
f ti
me
Hel
lo, h
ello
bac
k hu
man
pr
otoc
olse
t up
“sta
te”i
n tw
o co
mm
unic
atin
g ho
sts
TCP
-Tr
ansm
issi
on
Cont
rol P
roto
col
Inte
rnet
’s re
liabl
e da
ta
tran
sfer
ser
vice
TCP
serv
ice
[RFC
793
]re
liabl
e, in
-ord
erby
te-
stre
am d
ata
tran
sfer
loss
: ack
nowl
edge
men
ts
and
retr
ansm
issi
ons
flow
con
trol
:se
nder
won
’t ov
erwh
elm
re
ceiv
erco
nges
tion
con
trol
:se
nder
s “s
low
down
sen
ding
ra
te” w
hen
netw
ork
cong
este
d
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-18
Net
work
edg
e: b
est
effo
rt (u
nrel
iabl
e)
data
tra
nsfe
r se
rvic
e
Goal
:dat
a tr
ansf
er b
etw
een
end
syst
ems
sam
e as
bef
ore!
UD
P-
Use
r D
atag
ram
Pro
toco
l [RF
C 76
8]:
conn
ecti
onle
ss
unre
liabl
e da
ta t
rans
fer
no f
low
con
trol
no c
onge
stio
n co
ntro
l
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-19
Acc
ess
netw
orks
and
phy
sica
l med
ia
Q: H
ow to
con
nect
end
sy
stem
s to
edg
e ro
uter
?re
side
ntia
l acc
ess
nets
inst
itut
iona
l acc
ess
netw
orks
(sch
ool,
com
pany
)w
irel
ess
acce
ss
netw
orks
Keep
in m
ind:
ba
ndw
idth
(bit
s pe
r se
cond
) of
acce
ss
netw
ork?
shar
ed o
r de
dica
ted?
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-20
Com
pany
(and
res
iden
tial
) acc
ess:
loca
l are
a ne
twor
ks (L
AN
s)co
mpa
ny/u
nive
rsit
y/re
side
ntia
l loc
al a
rea
netw
ork
(LA
N) c
onne
cts
end
syst
em t
o ed
ge r
oute
rEt
hern
et:
10 M
bs, 1
00 M
bps,
1
Gbps
, 10
Gbps
mod
ern
conf
igur
atio
n:
end
syst
ems
conn
ect
into
Eth
erne
tsw
itch
LAN
s: c
hapt
er 5
6
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-21
Wir
eles
s ac
cess
net
work
ssh
ared
wir
eles
sac
cess
ne
twor
k co
nnec
ts e
nd s
yste
m
to r
oute
rvi
a ba
se s
tati
on a
ka “a
cces
s po
int”
wir
eles
s LA
Ns:
802.
11b/
g (W
iFi):
11
or 5
4 M
bps
802.
11n:
248
Mbp
sw
ider
-are
a w
irel
ess
acce
sspr
ovid
ed b
y te
leco
m o
pera
tor
~1 M
bps
over
cel
lula
r sy
stem
(E
VDO
, HSD
PA)
next
up
(?):
WiM
AX
(10
s of
M
bps)
ove
r wi
de a
rea
base
stat
ion
mob
ileho
sts
rout
er
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-22
Hom
e ne
twor
ksTy
pica
l hom
e ne
twor
k co
mpo
nent
s:
DSL
or
cabl
e m
odem
rout
er/f
irew
all/
NA
TEt
hern
etw
irel
ess
acce
sspo
int
wire
less
acce
ss
poin
t
wire
less
lapt
ops
rout
er/
fire
wall
cabl
em
odem
to/f
rom
cabl
ehe
aden
d
Ethe
rnet
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-23
Phys
ical
Med
ia: c
oppe
r, c
oax,
fib
er
Coax
ial c
able
Fibe
r op
tic
cabl
e
Twis
ted
pair
(TP)
guid
ed m
edia
:si
gnal
s pr
opag
ate
in s
olid
med
ia:
copp
er, f
iber
, coa
x
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-24
Phys
ical
med
ia: r
adio
sign
al c
arri
ed in
el
ectr
omag
neti
c sp
ectr
umno
phy
sica
l “w
ire”
bidi
rect
iona
lpr
opag
atio
n en
viro
nmen
t ef
fect
s:re
flec
tion
ob
stru
ctio
n by
obj
ects
inte
rfer
ence
Radi
o lin
k ty
pes:
terr
estr
ial
mic
row
ave
e.g.
up
to 4
5 M
bps
chan
nels
LAN
(e.g
., W
ifi)
11 M
bps,
54
Mbp
sw
ide-
area
(e.g
., ce
llula
r)3G
cel
lula
r: ~
1 M
bps
sate
llite
kbps
to
45-M
bps
chan
nel (
or
mul
tipl
e sm
alle
r ch
anne
ls)
270
mse
c en
d-to
-end
del
ayge
osta
tion
ary
(GEO
) ve
rsus
lo
w al
titu
de (M
EO, L
EO)
ungu
ided
med
ia:
sign
als
prop
agat
e fr
eely
, e.g
., ra
dio
7
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-25
The
Net
work
Cor
e
mes
h of
inte
rcon
nect
ed
rout
ers
the
fund
amen
tal
ques
tion
:how
is d
ata
tran
sfer
red
thro
ugh
net?
circ
uit
swit
chin
g:de
dica
ted
circ
uit
per
call:
tel
epho
ne n
etpa
cket
-sw
itch
ing:
data
se
nt t
hru
net
in
disc
rete
“chu
nks”
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-26
Net
work
Cor
e: C
ircu
it S
witc
hing
End-
end
reso
urce
s re
serv
ed f
or “c
all”
link
band
wid
th,
swit
ch
capa
city
dedi
cate
d re
sour
ces:
no
sha
ring
circ
uit-
like
(gua
rant
eed)
pe
rfor
man
ceca
ll se
tup
requ
ired
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-27
Circ
uit
Swit
chin
g: F
DM
and
TD
M
FD
M
freq
uenc
y
time
TD
M
freq
uenc
y
time
4 us
ers
Exa
mpl
e:
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-28
Net
work
Cor
e: P
acke
t Sw
itch
ing
each
end
-end
dat
a st
ream
di
vide
d in
to p
acke
tsus
er A
, B p
acke
ts s
hare
netw
ork
reso
urce
sea
ch p
acke
t us
es f
ull l
ink
band
wid
th
reso
urce
s us
ed a
s ne
eded
reso
urce
con
tent
ion:
aggr
egat
e re
sour
ce
dem
and
can
exce
ed
amou
nt a
vaila
ble
cong
esti
on: p
acke
ts
queu
e, w
ait
for
link
use
stor
e an
d fo
rwar
d:
pack
ets
mov
e on
e ho
p at
a t
ime
Nod
e re
ceiv
es c
ompl
ete
pack
et b
efor
e fo
rwar
ding
Band
widt
h di
visi
on in
to “
piec
es”
Ded
icat
ed a
lloca
tion
Reso
urce
res
erva
tion
8
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-29
Pack
et S
witc
hing
: Sta
tist
ical
Mul
tipl
exin
g
Sequ
ence
of
A &
B p
acke
ts d
oes
not
have
fix
ed p
atte
rn,
band
wid
th sh
ared
on
dem
and
stat
istica
l multiplex
ing.
TDM
: eac
h ho
st g
ets
sam
e sl
ot in
rev
olvi
ng T
DM
fra
me.
A
B
C10
0 M
b/s
Ethe
rnet
1.5 M
b/s
DE
stat
istica
l multiplex
ing
queu
e of
pac
kets
waiti
ng f
or o
utpu
tlin
k
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-30
Pack
et-s
witc
hing
: sto
re-a
nd-f
orwa
rd
take
s L/
R se
cond
s to
tr
ansm
it (p
ush
out)
pa
cket
of
L bi
ts o
n to
lin
k at
R b
psst
ore
and
forw
ard:
en
tire
pac
ket
mus
t
arri
ve a
t ro
uter
bef
ore
it c
an b
e tr
ansm
itte
d on
nex
t lin
kde
lay
= 3L
/R (a
ssum
ing
zero
pro
paga
tion
del
ay)
Exam
ple:
L =
7.5
Mbi
tsR
= 1.5
Mbp
str
ansm
issi
on d
elay
= 1
5 se
c
RR
RL
mor
e on
del
ay s
hort
ly …
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-31
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-32
Stat
isti
cal m
ulti
plex
ing
9
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-33
Pack
et s
witc
hing
ver
sus
circ
uit
swit
chin
g
1 M
bps
link
each
use
r:
100
kbps
whe
n “a
ctiv
e”ac
tive
10%
of
tim
e
circ
uit-
swit
chin
g:10
use
rspa
cket
swi
tchi
ng:
with
35
user
s,
prob
abili
ty >
10 a
ctiv
e at
sam
e ti
me
is le
ss
than
.000
4
Pack
et s
witc
hing
allo
ws m
ore
user
s to
use
net
work
!
N u
sers
1 M
bps
link
Q: H
ow d
id w
e ge
t va
lue
0.00
04?
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-34
Pack
et s
witc
hing
ver
sus
circ
uit
swit
chin
g
grea
t fo
r bu
rsty
dat
are
sour
ce s
hari
ngsi
mpl
er, n
o ca
ll se
tup
exce
ssiv
e co
nges
tion
:pac
ket
dela
y an
d lo
sspr
otoc
ols
need
ed f
or r
elia
ble
data
tra
nsfe
r,
cong
esti
on c
ontr
olQ
: How
to
prov
ide
circ
uit-
like
beha
vior
?ba
ndw
idth
gua
rant
ees
need
ed f
or a
udio
/vid
eo a
pps
still
an
unso
lved
pro
blem
(cha
pter
7)
Is p
acke
t sw
itch
ing
a “s
lam
dun
k w
inne
r?”
Q: h
uman
ana
logi
es o
f re
serv
ed r
esou
rces
(circ
uit
switc
hing
) ve
rsus
on-
dem
and
allo
catio
n (p
acke
t-sw
itch
ing)
?
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-35
Four
sou
rces
of
pack
et d
elay
1. N
odal
pro
cess
ing
chec
k bi
t er
rors
dete
rmin
e ou
tput
link
A
B
prop
agat
ion
tran
smis
sion
noda
lpr
oces
sing
queu
eing
2. Q
ueue
ing
tim
e wa
itin
g at
out
put
link
for
tran
smis
sion
de
pend
s on
cong
esti
on le
vel o
f ro
uter
3. T
rans
mis
sion
del
ay:
R=lin
k ba
ndwi
dth
(bps
)L=
pack
et le
ngth
(bit
s)ti
me
to s
end
bits
into
link
=
L/R
4. P
ropa
gati
on d
elay
:R=
link
band
widt
h (b
ps)
d =
leng
th o
f ph
ysic
al li
nks
= pr
opag
atio
n sp
eed
in m
ediu
m
(~2x
108
m/s
ec)
prop
agat
ion
dela
y =
d /
s
Not
e: s
and
R a
re v
ery
diff
eren
t qu
anti
ties
!20
10-0
8-30
TD
TS
06 L
ectu
re 1
: In
trod
uctio
n1-
36
Que
uein
g de
lay
(rev
isit
ed)
R=lin
k ba
ndw
idth
(bps
)L=
pack
et le
ngth
(bit
s)a=
aver
age
pack
et
arri
val r
ate
traf
fic
inte
nsit
y =
La/R
La/R
~ 0
: ave
rage
que
uein
g de
lay
smal
lLa
/R ->
1: d
elay
s be
com
e la
rge
La/R
> 1:
mor
e “w
ork”
arr
ivin
g th
an c
an b
e se
rvic
ed, a
vera
ge d
elay
infi
nite
!
10
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-37
Pack
et lo
ssW
hy?
Que
ue (a
ka b
uffe
r) p
rece
ding
link
in
outp
ut b
uffe
r ha
s fi
nite
cap
acit
ypa
cket
arr
ivin
g to
ful
l que
ue o
r wi
th w
rong
ch
ecks
um is
dro
pped
(aka
lost
)lo
st p
acke
t m
ay b
e re
tran
smit
ted
by p
revi
ous
node
, by
sour
ce e
nd s
yste
m, o
r no
t at
all
A
B
pack
et b
eing
tra
nsm
itted
pack
et a
rriv
ing
tofu
ll bu
ffer
is lo
st
buff
er
(wai
ting
area
)
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-38
Inte
rnet
His
tory
1961
:Kle
inro
ck -
queu
eing
th
eory
sho
ws
effe
ctiv
enes
s of
pac
ket-
swit
chin
g19
64:B
aran
-pa
cket
-sw
itch
ing
in m
ilita
ry n
ets
1967
:ARP
Ane
t co
ncei
ved
by A
dvan
ced
Rese
arch
Pr
ojec
ts A
genc
y19
69:f
irst
ARP
Ane
t no
de
oper
atio
nal
1972
: ARP
Ane
t pu
blic
dem
onst
rati
onN
CP (N
etwo
rk C
ontr
ol P
roto
col)
firs
t ho
st-h
ost
prot
ocol
fi
rst
e-m
ail p
rogr
amA
RPA
net
has
15 n
odes
1961
-197
2: E
arly
pac
ket-
swit
chin
g pr
inci
ples
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-39
Inte
rnet
His
tory
1970
:ALO
HA
net
sate
llite
ne
twor
k in
Haw
aii
1974
:Cer
f an
d Ka
hn -
arch
itec
ture
for
in
terc
onne
ctin
g ne
twor
ks19
76:E
ther
net
at X
erox
PA
RCla
te 7
0s:p
ropr
ieta
ry
arch
itec
ture
s: D
ECne
t, S
NA
, X
NA
late
70s
:swi
tchi
ng f
ixed
le
ngth
pac
kets
(ATM
pr
ecur
sor)
1979
:ARP
Ane
t ha
s 20
0 no
des
Cerf
and
Kah
n’s in
tern
etwo
rkin
g pr
inci
ples
:m
inim
alis
m, a
uton
omy
-no
in
tern
al c
hang
es r
equi
red
to in
terc
onne
ct n
etwo
rks
best
eff
ort
serv
ice
mod
elst
atel
ess
rout
ers
dece
ntra
lized
con
trol
defi
ne t
oday
’s In
tern
et
arch
itect
ure
1972
-198
0: I
nter
netw
orki
ng, n
ew a
nd p
ropr
ieta
ry n
ets
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-40
Inte
rnet
His
tory
1983
:dep
loym
ent
of
TCP/
IP19
82:s
mtp
e-m
ail
prot
ocol
def
ined
19
83:D
NS
defi
ned
for
nam
e-to
-IP-
addr
ess
tran
slat
ion
1985
:ftp
pro
toco
l de
fine
d19
88:T
CP c
onge
stio
n co
ntro
l
new
nat
iona
l net
wor
ks:
Csne
t, B
ITne
t,
NSF
net;
Min
itel
in
Fran
ce10
0,00
0 ho
sts
conn
ecte
d to
co
nfed
erat
ion
of
netw
orks
1980
-199
0: n
ew p
roto
cols
, a p
rolif
erat
ion
of n
etwo
rks
11
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-41
Inte
rnet
His
tory
Earl
y 19
90s:
ARP
Ane
t de
com
mis
sion
ed19
91: N
SF li
fts
rest
rict
ions
on
com
mer
cial
use
of
NSF
net
(dec
omm
issi
oned
, 199
5)ea
rly
1990
s:W
ebhy
pert
ext
[Bus
h 19
45, N
elso
n 19
60s]
HTM
L, H
TTP:
Ber
ners
-Lee
1994
: Mos
aic,
late
r N
etsc
ape
late
199
0s: c
omm
erci
aliz
atio
nof
the
Web
Late
199
0s –
2000
s:m
ore
kille
r ap
ps: i
nsta
nt
mes
sagi
ng, P
2P f
ile s
hari
ngne
twor
k se
curi
ty t
o fo
refr
ont
est.
50
mill
ion
host
, 100
m
illio
n+ u
sers
back
bone
link
s ru
nnin
g at
Gb
ps
1990
, 200
0s: c
omm
erci
aliz
atio
n, t
he W
eb, n
ew a
pps
2010
-08-
30T
DT
S06
Lec
ture
1:
Intr
oduc
tion
1-42
Intr
oduc
tion
: Sum
mar
yCo
vere
d a
“ton
” of
mat
eria
l!In
tern
et o
verv
iew
wha
t’s a
pro
toco
l?ne
twor
k ed
ge, c
ore,
acc
ess
netw
ork
pack
et-s
wit
chin
g ve
rsus
ci
rcui
t-sw
itch
ing
Inte
rnet
str
uctu
repe
rfor
man
ce: l
oss,
del
ayhi
stor
y
You
now
hav
e:co
ntex
t, o
verv
iew
, “f
eel”
of n
etw
orki
ngm
ore
dept
h, d
etai
l to
follo
w!