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1Ji
m B
inkl
ey
An
Ove
rvie
w o
f Rou
ting
Theo
ry
IP R
outin
gJi
m B
inkl
eyPo
rtlan
d St
ate
Uni
vers
ity
2Ji
m B
inkl
ey
Rou
ting
Theo
ry
topo
logi
es a
nd sc
alab
ility
basi
c to
ols &
idea
s & a
ttrib
utes
»st
atic
vs d
ynam
ic, f
lood
ing,
tunn
els,
cont
rol t
heor
y
som
e is
sues
; e.g
., co
nges
tion
algo
rithm
s: v
ecto
r-di
stan
ce v
s lin
k-st
ate
3Ji
m B
inkl
ey
fund
amen
tal i
deas
rout
ing
-fin
ding
a p
ath
from
one
end
to th
e ot
her f
or a
pac
ket
we
need
one
or m
ore
algo
rith
mst
hat a
re
mos
t lik
ely
dist
ribu
ted
amon
gst a
set o
f ho
sts a
nd ro
uter
wha
t are
the
prop
ertie
s of s
aid
algo
rithm
?w
hat i
ssue
s aff
ect i
t?
4Ji
m B
inkl
ey
elem
ents
of a
rout
ing
sche
me
rout
ing
prot
ocol
s tha
t allo
w in
fo to
be
gath
ered
and
dis
tribu
ted
-ro
utin
g ag
ents
co
mm
unic
ate
with
thes
e pr
otoc
ols
rout
ing
algo
rith
ms -
may
be
dist
ribut
ed,
use
prot
ocol
s and
dat
a to
det
erm
ine
and
diss
emin
ate
path
sro
utin
g da
taba
ses (
tabl
es in
rout
ers)
(to b
oard
wal
k, v
ia n
ew je
rsey
, $1
00)
5Ji
m B
inkl
ey
a ro
utin
g do
mai
na
rout
ing
dom
ain
== se
t of r
oute
rs u
nder
sam
e ad
min
runn
ing
sam
e ro
utin
g pr
otoc
ol
e.g.
, all
thes
e ro
uter
s are
con
trolle
d by
Joe
Bob
Inc,
run
OSP
F
6Ji
m B
inkl
ey
idea
l rou
ting
algo
rithm
corr
ect -
wha
t if a
lgor
ithm
s too
com
plex
?ro
bust
-ca
n de
al w
ith ro
uter
rebo
ot?
–tw
o pr
oble
ms:
loss
of r
oute
r and
loss
of l
ink
(i/f f
ailu
re ..
.)
stab
le -
do ro
utin
g ch
ange
s sta
biliz
e in
dis
tribu
ted
syst
em?
–co
nver
genc
e-a
stat
e, a
ll ro
uter
s hav
e “s
ame”
rout
ing
tabl
e
effic
ient
-al
l rou
ting
and
no d
ata
not g
ood
topo
logi
cally
flex
ible
, can
allo
w a
ggre
gatio
nm
aint
aina
ble
-adm
in n
ot to
o co
mpl
icat
edsc
alab
leto
man
y ro
uter
s, m
any
host
s? (d
istri
bute
d)de
adlo
ck?
-ro
utin
g lo
op-f
ree?
secu
re -
can
intru
ders
inje
ct ro
utes
?
7Ji
m B
inkl
ey
clas
sic
prob
lem
rout
ing
loop
path
to Z
?“h
ey, I
’m Z
...”
crea
ted
stat
ical
ly o
r dyn
amic
ally
AB
C
(To
Z, V
ia C
)
(To
Z, V
ia A
)
(To
Z, V
ia B
)
8Ji
m B
inkl
ey
topo
logy
Tane
nbau
mm
entio
ns lo
gica
l abs
urdi
ties
no r
oute
r -e
very
hos
t wire
d to
eve
ry o
ther
ho
st (
mes
h )
N *
N w
ires,
go
ahea
d ad
d a
host
...1
rout
er -
for a
ll ho
sts (
star
)–
1 he
ck o
f a ro
utin
g ta
ble
–th
is is
why
cor
e ca
n ha
ve p
robl
ems
–si
ngle
poi
nt o
f fai
lure
?!–
ever
ythi
ng sh
ould
be
fully
con
nect
ed?!
9Ji
m B
inkl
ey
one
solu
tion
typi
cally
a fl
atte
ned
tree
to g
ive
hier
arch
yat
the
top
a sm
all c
ircle
of c
ore
rout
ers t
hat
know
all
the
rout
esid
ea:
defa
ult r
oute
–if
you
are
not i
n th
e ce
nter
AN
D y
ou d
on’t
know
wha
t to
do w
ith it
, se
nd it
“U
P”to
sm
arte
r ent
ity
10Ji
m B
inkl
ey
rout
ing
hier
arch
y
R
RR
R
net
Leve
l 1
Leve
l 2
defa
ult r
oute
H
core
rout
ers
R
rout
er
this
cou
ld b
e th
e m
odel
for a
n in
trane
t OR
the
Inte
rnet
as a
who
le (m
ultip
le c
ore
rings
)
11Ji
m B
inkl
ey
leve
ls
the
top
leve
l has
to k
now
eve
ryth
ing
–in
a ro
utin
g do
mai
n, ro
uter
s kno
w a
ll th
e ro
uter
s at l
evel
1–
in B
GP,
top
of In
et, r
oute
rs m
ay h
ave
full
rout
ing
tabl
e ro
uter
s may
als
o ch
oose
to h
ide
inte
rior
stru
ctur
e (s
ubne
t/CID
R) i
n or
der t
o ag
greg
ate
rout
ing
info
–re
duce
rout
ing
tabl
e si
ze e
lsew
here
12Ji
m B
inkl
ey
divi
de ro
utin
g w
orld
into
3 p
arts
topo
logy
IETF
ISO
/OSI
sam
e “l
ink”
or
wire
none
, int
ra-li
nk?
none
, int
ra-li
nk?
ente
rpris
e or
cam
pus
Inte
rior G
atew
ayPr
otoc
ol -
IGP
intra
-dom
ain
rout
ing
prot
ocol
betw
een
ente
rpris
esEx
terio
r Gat
eway
Prot
ocol
- EG
Pin
ter-
dom
ain
13Ji
m B
inkl
ey
prot
ocol
s acc
. to
topo
logy
topo
logy
IETF
ISO
/OSI
intra
-link
AR
PES
-IS
intra
-dom
ain
RIP
, RIP
(2),
OSP
FIS
-IS
inte
r-do
mai
nEG
P, B
GP(
4)ID
PR
14Ji
m B
inkl
ey
the
Inte
rior -
RIP
or O
SPF
out
Joe
Bob
Inc’
sN
etw
ork
Map
link
neig
hbor
sor
pee
rs
the
“wor
ld”
(fro
m ro
uter
PO
V)
15Ji
m B
inkl
ey
scal
abili
ty is
a L
AR
GE
conc
ern
10’s
of h
osts
and
a fe
w ro
uter
s -st
atic
ro
utin
gw
hat a
bout
put
ting
all o
f tho
se to
aste
rs o
n th
e In
tern
et?
(wha
t if t
he n
et/h
osts
big
ger?
)on
e ho
me/
offic
e, to
bus
ines
s/en
terp
rise,
to
stat
e, n
atio
n, p
lane
t, so
lar s
yste
m, g
alax
y...
com
pone
nts a
ffec
ted
incl
ude
the
netw
ork
addr
ess a
nd th
e ro
uter
hie
rarc
hy
16Ji
m B
inkl
ey
scal
abili
ty...
ip’s
curr
ent p
robl
ems
–ne
t/hos
ts v
ia c
lass
or e
ven
subn
et d
on’t
mat
ch n
umbe
r of
hos
ts re
ally
util
ized
–to
o m
any
rout
es in
cor
e ta
bles
(aga
in tr
ue p
ost C
IDR
)–
ip a
ddre
ss a
lloca
tion
from
cla
ss C
slic
e of
pie
mea
ns in
ef
fect
maj
ority
of n
umbe
rs a
re w
aste
d
scal
abili
ty a
ffec
ts a
ddre
sses
and
how
they
are
sl
iced
up;
als
o ro
uter
hie
rarc
hyho
w m
uch
low
-leve
l inf
o (e
.g.,
link-
leve
l det
ails
) ca
n w
e af
ford
to d
isse
min
ate
upw
ards
?
17Ji
m B
inkl
ey
Som
e cu
rren
t BG
P is
sues
# en
tries
> 1
0000
0, g
row
ing
fast
er th
an a
lin
ear r
ate?
–
CID
R h
elp
in m
id-9
0s h
as w
orn
out?
# en
tries
that
are
/24
or b
igge
r?–
I.e.,
not e
noug
h ag
greg
atio
n –
entri
es m
ay n
eed
dam
peni
ngag
grav
ated
by
mes
h re
dund
ancy
–if
mul
ti-ho
med
mor
e pa
ths a
nnou
nced
to w
orld
18Ji
m B
inkl
ey
N**
2 is
not
our
frie
ndH
as a
tend
ency
to sh
ow u
p in
rout
ing
prot
ocol
s/th
eory
bec
ause
nat
ural
ly:
rout
ers (
node
s) ti
mes
link
s (co
nnec
tions
)re
mem
ber A
ndre
w T
. and
wha
t hap
pens
if a
ll no
des d
irect
ly c
onne
ct!
The
prob
lem
her
e is
mem
ory
stor
age
in in
divi
dual
co
re ro
uter
s–
how
muc
h m
emor
y if
a co
re ro
uter
mus
t rem
embe
r: 1.
A
ll lin
k m
etric
s, 2.
All
host
attr
ibut
es,
3. H
ost X
hos
t at
tribu
tes
19Ji
m B
inkl
ey
to in
crea
se sc
alab
ility
, add
a
pref
ix dom
ain
rout
ers a
s 1st
ass
umpt
ion
-ass
ume
they
kn
ow a
ll th
e ro
utes
. if
that
isn’
t sca
labl
e, th
en a
dd n
ew h
iera
rchy
and
in
trodu
ce n
ew la
yer o
f stru
ctur
e, fi
nd p
oint
s of
aggr
egat
ion
IP is
mov
ing
tow
ards
this
(CID
R)
phon
e co
mpa
nies
hav
e pr
efix
es (n
ot e
noug
h...
nobo
dy is
per
fect
)N
AT,
MIP
(tunn
els)
, IPv
4+A
S, a
ll w
ays o
f doi
ng
this
(to
say
noth
ing
of 1
28bi
t add
ress
es)
20Ji
m B
inkl
ey
hier
arch
y pi
ctur
e
boun
dary
rout
er1 2
3
core
(4)
[ net
regi
on =
1..4
,su
bnet
in re
gion
,ho
st ]
Add
ress
To 3
.x.y
, via
4.1
.1
21Ji
m B
inkl
ey
gene
ral s
olut
ion
to p
robl
em e
xist
s
whe
n in
dou
bt, a
dd a
new
pre
fix to
ad
dres
s and
a n
ew S
MA
LLER
cen
ter t
o th
e w
orld
pref
ix m
usts
umm
ariz
e in
tern
al st
ruct
ure
divi
de w
orld
into
ce
nter
: (la
yer 1
) bou
ndar
y ro
uter
sdo
mai
ns: (
laye
r 2) i
nsid
e ro
uter
sbo
unda
ry ro
uter
s hav
e su
mm
ary
rout
es in
them
, no
t all.
22Ji
m B
inkl
ey
btw
, thi
s is r
elat
ed to
a m
agic
al
arch
itect
ural
des
ign
prin
cipl
ead
d a
laye
r of
indi
rect
ion
== P
OW
ERco
nsid
er IP
v6 a
ddre
ss (i
p pa
rt, IE
EE m
acpa
rt)M
obile
-IP
2-pa
rt A
WA
Y a
ddre
ss (F
A C
are-
Of-
Add
ress
, M
obile
-IP
Hom
e A
ddre
ss)
–iro
ny h
ere
is th
e po
wer
of t
his i
s not
wel
l und
erst
ood
BG
P IP
v4 “
addr
ess”
is (
set o
f AS
#s, I
P ds
t)ah
em: N
AT
sinc
e th
is m
ay a
dd to
the
IP a
ddre
ss
spac
e po
ol (
a fe
w re
al ip
add
r, m
appe
d to
man
y pr
ivat
e ip
add
ress
), un
der s
ever
e co
nstra
ints
23Ji
m B
inkl
eytrans
it A
Stra
nsit
trans
it
a st
ub A
S
to a
noth
er st
ub exch
ange
anot
her s
tub
Inet
has
mul
tiple
cen
ters tra
nsit
-pac
kets
mos
tlycr
oss
stub
-pa
cket
s mos
tly si
nkor
sour
ce (E
S)
24Ji
m B
inkl
ey
3 w
ays r
oute
s get
into
rout
ing
tabl
es stat
ic -
load
ed b
y ne
twor
k ad
min
s–
put i
nto
conf
igto
aut
o-lo
ad a
t boo
t–
rout
e ad
d 10
.0.0
.0 -g
wga
tew
ay-ip
dyna
mic
rout
ing
–do
ne b
y ro
utin
g da
emon
s run
ning
a ro
utin
g pr
otoc
olkn
eeje
rkm
odifi
catio
n to
hos
t rou
tes b
y IC
MP
redi
rect
s–
typi
cally
way
to p
opul
ate
rout
ing
tabl
e w
ith
defa
ult r
oute
25Ji
m B
inkl
ey
stat
ic ro
utin
gst
atic
pro
s:–
sim
ple,
may
be
easi
est t
hing
to d
o in
sim
ple
topo
logy
, es
peci
ally
for l
eaf h
ost w
ith 1
rout
er o
nly
–yo
u m
ay b
e sm
arte
r tha
n th
e ro
uter
s (w
ant a
pat
h th
ey
won
’t gi
ve y
ou) -
polic
y ro
utin
g po
ssib
le
stat
ic c
ons:
–ca
n’t r
eact
dyn
amic
ally
to c
rash
ed ro
uter
(stil
l nee
d tw
o ro
uter
s to
reac
t tho
ugh.
..), a
nti-r
edun
danc
y–
not s
cala
ble,
not
goo
d if
you
have
100
rout
ers t
o co
nfig
ure
right
now
(or 1
000
host
s)
26Ji
m B
inkl
ey
dyna
mic
rout
ing
we
need
a d
istri
bute
d ro
utin
g pr
otoc
olgo
als:
–in
telli
gent
(sic
?) c
hoic
e of
rout
e ba
sed
on
met
ric (s
ingl
e m
ore
likel
y th
an m
ultip
le)
–au
tom
atic
pop
ulat
ion
of ro
utin
g ta
ble
to a
void
m
anua
l set
up–
redu
ndan
cy o
f rou
ting
path
; i.e
., co
nver
genc
e po
st p
ath
failu
re d
ue to
loss
of r
oute
r, in
terf
ace,
or
sudd
en o
nset
of b
ackh
oe
27Ji
m B
inkl
ey
theo
ry: r
outin
g pr
otoc
ol ty
pes
cent
raliz
edve
rsus
dis
trib
uted
vers
us e
nd-
node
–ce
nter
is n
eces
sary
, can
’t ha
ve d
efau
lts
ever
ywhe
re»
why
not
just
com
pute
and
put
in c
ente
r?
–if
end
node
s hav
e ro
ute
info
, and
big
net
, »
not s
cala
ble,
then
rout
e ta
bles
hug
e -n
eed
to li
mit
size
som
e so
rt of
dis
tribu
ted
syst
em is
co
nven
tiona
l ans
wer
28Ji
m B
inkl
ey
type
s/to
ols -
sour
ce ro
utin
g
sour
ce-r
outin
g vs
hop-
by-h
op–
end
node
has
exa
ct P
ATH
and
dat
agra
m fo
llow
s tha
t pa
th:
( firs
t to
Joe,
the
n to
Bob
, the
n to
Gra
ndm
a’s )
–IP
opt
ion,
but
rare
ly u
sed
(stri
ct/lo
ose)
–ch
alle
nge
to se
curit
y: w
hat i
f hos
tile
entit
y co
nvin
ces
you
to ro
ute
all p
acke
ts th
roug
h it?
»m
aybe
it c
an m
asqu
erad
e as
you
afte
r tha
t?–
still
a p
ossi
ble
tool
-use
d in
BG
P, c
an c
omm
unic
ate
POLI
CIE
S, f
rom
Nov
ell t
o In
tel,
plea
se S
kip
Bel
levu
e–
as sc
alab
le a
s hop
by
hop
?
29Ji
m B
inkl
ey
rout
ing
tunn
els a
re b
asic
tool
tunn
els a
re e
xam
ple
of so
urce
rout
ing
(doh
!)–
stric
t or l
oose
?
IP d
atag
ram
with
IP h
eade
r (IP
IP)
–M
BO
NE
DV
MR
P, M
obile
-IP
(uni
cast
)
IPX
, APP
LETA
LK d
atag
ram
insi
de IP
hea
der
–C
isco
GR
E tu
nnel
s des
igne
d as
gen
eral
way
to d
o tu
nnel
s (G
ENER
IC R
OU
TIN
G E
NC
APS
ULA
TIO
N)
–IP
v6,
IPv4
IPv6
, or
IPv6
IPv4
secu
rity
tunn
els,
IP IP
SEC
IP, b
asis
of V
PNs
30Ji
m B
inkl
ey
enca
psul
atio
n sc
hem
e
IP sr
c =
rout
er tu
nnel
src
IP d
st =
rout
er tu
nnel
sink
enca
psul
ated
IPda
tagr
am (o
r IPX
or ?
??)
IPIP
(btw
: IP
next
pro
to =
= 4
for I
PIP)
IP
T
CP
data
31Ji
m B
inkl
ey
IP tu
nnel
ing
mes
h
IPv6
net
wor
k A
IPv6
net
wor
k B
IPv4
net
/tunn
el
rout
e to
net
B, f
orw
ard
to A
bor
der r
oute
r, w
hich
will
enc
apsu
late
and
send
to B
bor
der r
oute
r
rout
ers h
ere
do n
ot sp
eak
IPv6
IPv4
| IP
v6 d
atag
ram
virt
ual n
etw
ork
32Ji
m B
inkl
ey
cont
rol-t
heor
yro
utin
g is
con
trol
, with
out i
t, da
ta c
anno
t flo
wch
icke
n&eg
g pr
oble
m: r
outin
g in
term
s of
addr
essa
bilit
ym
ust e
xist
a p
riori
befo
re ro
utin
g ca
n oc
cur
–I c
an’t
send
you
pac
kets
if I
can’
t fin
d yo
u ...
–th
ink
abou
t thi
s in
term
s of e
very
rout
ing
prot
ocol
–ad
dres
sabi
lity
is fu
ndam
enta
lly li
nk d
epen
dent
–so
met
imes
we
rely
on
man
ual c
onfig
urat
ion
(ser
ial)
–so
met
imes
info
rmat
ion
auto
mat
ical
ly g
athe
red
(arp
or
mul
ticas
t on
ethe
rnet
)
33Ji
m B
inkl
ey
addr
essa
bilit
y pr
oble
m
broa
dcas
t lin
k
rout
er A
B
rout
er C
how
can
A k
now
of B
/C?
seria
l lin
kAB
and
send
its p
eers
rout
ing
data
?
34Ji
m B
inkl
ey
type
s/to
ols -
flood
ing
flood
ing
-ass
ume
N in
terf
aces
–pa
cket
com
es in
N(1
)–
pack
et g
oes o
ut N
(2)..
N(N
)
35Ji
m B
inkl
ey
be c
aref
ul w
ith fl
oodi
ng...
36Ji
m B
inkl
ey
flood
ing,
con
t.im
porta
nt ro
utin
g al
gorit
hm “
tool
”-u
sed
in
man
y ro
utin
g al
gorit
hms i
n so
me
sens
est
rong
pro
and
con
/spr
o -p
erfe
ct r
outin
g, y
ou fo
llow
the
best
pa
th (r
edun
danc
y he
re is
a fe
atur
e!)
con
-“pe
rfec
t con
gest
ion”
-you
use
up
too
muc
h ba
ndw
idth
con
–yo
u m
ay lo
op p
acke
ts
37Ji
m B
inkl
ey
flood
ing
may
be
cons
train
ed o
f co
urse yo
u m
ight
sim
ply
use
broa
dcas
t to
send
info
you
may
pas
s jud
gem
ent o
n th
e in
fo b
efor
e yo
u se
nd it
out
the
“oth
er”
inte
rfac
es–
not f
orw
ard
it if
it is
not
new
–or
inte
rest
ing
man
y ro
utin
g pr
otoc
ols r
ely
on so
me
sort
of
flood
ing
(eve
n B
GP,
alth
ough
not
link
-la
yer)
38Ji
m B
inkl
ey
rout
ing
is 2
1-w
ay p
robl
ems
path
bet
wee
n A
and
Z m
ay n
ot b
e th
e sa
me
asym
met
ric ro
utin
g N
OT
unus
ual
cons
ider
Mob
ile-I
P–
solv
es p
robl
em o
f pac
kets
TO
rem
ote
host
»pa
cket
s tun
nele
d fr
om H
OM
E to
AW
AY
–no
t pac
kets
FR
OM
rem
ote
host
»or
dina
ry “
defa
ult”
rout
ing
cons
ider
mul
ti-ho
med
stub
with
def
ault
rout
e
39Ji
m B
inkl
ey
Mob
ile-I
P as
one
-way
IPIP
tu
nnel
You
r hom
esu
bnet
pk
ts to
you
com
e to
your
hom
e su
bnet
you
mov
ed ..
.
IPIP
tunn
el“F
orei
gn A
gent
”
pkts
FR
OM
node
are
del
iver
edno
rmal
ly
40Ji
m B
inkl
ey
asym
met
ric p
aths
my
rout
ing
dom
ain
the
wild
s of t
he In
et ..
..
mul
ti-ho
med
stub
with
def
ault
rout
e
defa
ult
rout
e
pkts
in
41Ji
m B
inkl
ey
you
may
hav
e to
deb
ug tw
ice
this
pat
h w
orks
...
rout
ing
failu
re o
n pa
th b
ack
...
42Ji
m B
inkl
ey
cont
rol i
dea:
rout
es v
s dat
a
on a
giv
en li
nk, y
ou m
ight
SEN
D ro
utin
g in
fo, w
hich
will
cau
seda
ta to
CO
ME
BA
CK
on
that
pat
hro
utin
g in
fo O
UT
driv
es d
ata
com
ing
IN
here
I am
, ta
lk to
me!
!!da
ta fl
ows o
ppos
ite o
f con
trol
43Ji
m B
inkl
ey
exam
ple:
mul
ti-ho
med
stub
, 2
defa
ult r
oute
s
assu
me
full
rout
ing
tabl
eB
GP
peer
BG
P pe
er
inte
rior I
GP/
rout
ing
dom
ain,
lots
of i
nter
ior r
oute
rs (o
r 1)
defa
ult r
oute
+
defa
ult
rout
etra
ffic
...
44Ji
m B
inkl
ey
issu
es -
cong
estio
ndo
es n
ot re
fer t
o br
onch
ial c
ondi
tion
conn
ectio
nles
s rou
ters
hav
e on
ly so
man
y bu
ffer
s, to
o m
any
pack
ets,
they
dro
p th
emth
ings
get
wor
se a
t the
“fr
eew
ay e
xcha
nges
”do
es ro
utin
g pr
otoc
ol a
dd c
onge
stio
n bu
rden
?ho
w d
o w
e pr
even
t/det
ect c
onge
stio
n?ob
viou
sly
circ
uit-s
witc
hes d
on’t
have
this
pr
oble
m o
nce
circ
uit i
s set
, but
they
was
te
band
wid
th
45Ji
m B
inkl
ey
cong
estio
n?w
ays t
o pr
even
t con
gest
ion:
–ad
d ca
rryi
ng c
apac
ity -
big
pipe
theo
ry–
shut
up, e
spec
ially
if h
igh-
volu
me
src
how
do
we
notif
y ne
twor
k ab
out i
t?–
TCP
dete
cts c
onge
stio
n w
hen
send
er n
otes
that
AC
KS
are
mis
sing
, slo
w, o
r dup
licat
ed,
send
er sl
ows r
ate
of
send
ing,
this
is E
ND
to E
ND
met
hod,
rout
ers n
ot
invo
lved
(Dav
id C
lark
/MIT
, end
to e
nd p
aper
)–
som
e sc
hem
es h
ave
rout
ers f
orw
ard
or p
ass b
ack
cong
estio
n bi
ts
46Ji
m B
inkl
ey
cong
estio
n sc
hem
es -
rout
ers
invo
lved
IP se
nds b
ack
ICM
P so
urce
que
nch
mes
sage
to se
nder
(dep
reca
ted)
–pr
o: y
ou se
nt it
the
right
way
–co
n: y
ou p
oure
d ga
s on
the
fire
ISO
CN
LP se
ts fl
ag in
net
wor
k he
ader
–pr
o: d
oesn
’t ad
d da
ta to
net
–co
n: c
onge
stio
n no
tific
atio
n is
sent
to th
e D
ESTI
NA
TIO
N (o
h, g
oody
)»
dest
inat
ion
calls
send
er w
ith P
OTS
? “s
hutu
p”
47Ji
m B
inkl
ey
cong
estio
n co
nt.
TCP
solu
tion
is n
ot b
ad B
UT
–w
hat a
bout
pro
toco
ls th
at u
se In
tern
et th
at
don’
t im
plem
ent o
r can
’t se
nsib
ly im
plem
ent
it? »N
FS o
r Nov
ell c
ould
but
don
’t, d
rive
TCP
out
»au
dio/
vide
o tra
nsm
issi
on is
stea
dy-s
tate
dat
a flo
w
cong
estio
n de
tect
ion
is a
n op
en q
uest
ion
larg
e is
sue
in Q
OS
term
s
48Ji
m B
inkl
ey
issu
es -
link
cost
s
we
need
a m
etri
c, w
hich
one
?–
cost
? n
ot a
ppro
pria
te w
ithin
dom
ain
but
betw
een;
e.g
., w
hich
long
-dis
tanc
e co
mpa
ny?
–ho
p co
unt-
how
man
y ro
uter
s do
we
trave
rse
–av
aila
ble
band
wid
th -
go le
ast c
onge
sted
rout
e–
spee
d of
und
erly
ing
netw
ork,
use
ATM
as
oppo
sed
to 1
200
baud
mod
em?
–tim
e: sh
orte
st p
ath
in te
rms o
f tim
e»
time
is ty
pica
lly a
n ap
p ...
49Ji
m B
inkl
ey
issu
es -
link
cost
s (m
etric
s)if
link
cost
s cha
nge,
that
info
rmat
ion
mus
t con
verg
e of
co
urse
we
typi
cally
onl
y us
e on
e m
etri
c w
ithin
a d
omai
nw
e ty
pica
lly o
nly
use
stat
ic m
etri
cs, n
ot d
ynam
ic
met
rics
(e.
g., n
ot c
onge
stio
n, b
ut h
op c
ount
)w
e co
uld
have
mul
tiple
met
rics i
n us
e?!
–sa
y ho
p co
unt,
pow
er u
se, r
adio
stre
ngth
for m
obile
wire
less
no
des?
ques
tion:
wou
ld m
ore
com
plex
alg
orith
ms (
if po
ssib
le)
that
dyn
amic
ally
acc
ount
for l
ink
cost
s do
qual
itativ
e be
tter j
ob th
an c
urre
nt si
mpl
e al
gorit
hms o
r jus
t use
ba
ndw
idth
?
50Ji
m B
inkl
ey
type
of s
ervi
cem
y pa
cket
s bef
ore
your
pac
kets
!m
ight
wan
t to
prio
ritiz
e ce
rtain
traf
fic c
lass
es;
.e.g
., 1
cont
rol.,
2. i
soch
rono
us.,
3 bu
rsty
polic
y-ba
sed
rout
ing
(pb
cons
train
ts) -
decr
ee a
ce
rtain
pat
h, o
r out
law
a c
erta
in p
ath
–so
urce
and
stat
ic ro
utin
g ca
n be
use
ful h
ere
–B
GP
clai
ms t
o do
“po
licy”
-rec
ogni
ze th
at m
any
rout
ing
theo
ry ty
pes t
hink
NO
T EN
UF!
!!
51Ji
m B
inkl
ey
pack
et c
olor
ove
rvie
w1.
3 m
echa
nism
s nee
ded
for p
acke
t cl
assi
ficat
ion
2.so
me
way
to se
tup
a lo
gica
l circ
uit
1.en
d to
end
pro
toco
l or r
oute
r-ro
uter
pro
toco
l1.
pack
ets w
ith c
lass
ifier
X sh
ould
be
treat
ed li
ke
first
-cla
ss p
asse
nger
s2.
per p
acke
t cla
ssifi
er (f
low
ID, m
acad
dres
s)3.
rout
er/s
witc
h sc
hedu
ling
algo
rithm
1.if
pack
et c
lass
ifier
, the
n gi
ve it
a b
uffe
r
52Ji
m B
inkl
ey
issu
es -
som
e m
isc.
one
slo
ad-b
alan
cing
-if w
e ha
ve tw
o eq
ual r
oute
s to
X, c
an w
e sp
lit th
e lo
ad b
etw
een
them
?–
equa
l cos
t mul
ti pa
thm
igra
ting
rout
ing
algo
rithm
s -yo
u ha
ve R
IP a
nd n
ow y
ou
wan
t to
switc
h to
OSP
F (a
nd n
o re
boot
ing
mul
tiple
tim
es)
–ca
n yo
u ru
n bo
th?,
sw
itchi
ng o
ne b
y on
e is
dis
rupt
ive
rout
e re
dist
ribu
tion
-at r
outin
g do
mai
n bo
unda
ry, h
ow
exac
tly d
o yo
u ta
ke in
fo fr
om o
ne ro
utin
g pr
otoc
ol a
nd
inje
ct in
to a
noth
er?
(Cis
co ro
ute
map
s)ro
utin
g pa
rtiti
onre
pair
-if t
wo
path
s to
one
net,
and
one
goes
dow
n, c
an ro
uter
s fix
it in
face
of h
iera
rchy
?
53Ji
m B
inkl
ey
a bi
t mor
e on
that
part
ition
–ba
sica
lly m
eans
2 n
ets,
1 lin
k, th
e lin
k bl
ew u
p (o
r ca
me
back
), n
ow w
hat?
»is
ther
e a
way
to g
lue
the
two
nets
toge
ther
thru
som
e ot
her
path
?»
is th
ere
a w
ay to
opt
imiz
e tra
ffic
whe
n th
e ne
ts re
conn
ect i
n or
der t
o m
inim
ize
cont
rol t
raff
ic
aggr
egat
ion
-in
gene
ral,
if ro
utin
g is
con
trol,
can
we
min
imiz
e it
–by
lum
ping
add
ress
es to
geth
er ..
. –
dow
nsid
e./s
: too
muc
h ro
utin
g, to
o m
any
rout
es
54Ji
m B
inkl
ey
type
s: v
ecto
r-di
stan
ce
vect
or-d
ista
nce
algo
rithm
s:“t
ell t
he n
eigh
bors
abo
ut th
e w
orld
”ve
ctor
is d
estin
atio
n (n
et/h
ost)
dist
ance
is m
etric
(hop
coun
t)if
we
calle
d it
dest
inat
ion-
met
ric, o
ther
peo
ple
wou
ld u
nder
stan
d (g
ood
poin
t, D
r. Pe
rlman
)yo
u flo
od y
our d
estin
atio
n, h
opco
unti
nfo
to y
our
dire
ctly
con
nect
ed n
eigh
bor r
oute
rsR
IP is
an
exam
ple,
but
so is
BG
P, I
GR
P, E
IGR
P,
and
rem
embe
r the
fuzz
balls
... (t
ime
as m
etric
)
55Ji
m B
inkl
ey
type
s: li
nk-s
tate
link-
stat
e or
shor
test
pat
h fir
st (S
PF)
“tel
l the
wor
ld a
bout
you
r ne
ighb
ors”
find
out w
ho is
up
loca
lly, a
nd fl
ood
that
in
form
atio
n to
the
entir
e se
t of r
oute
rsth
ey c
an u
se th
e “l
ink-
stat
e”to
bui
ld a
sh
orte
st p
ath
map
to e
very
body
LS is
com
pute
-inte
nsiv
e. V
D is
ban
dwid
th
inte
nsiv
e.
56Ji
m B
inkl
ey
vect
or-d
ista
nce
algo
rithm
exam
ples
: R
IP,
BG
P, IG
RP,
EIG
RP
algo
rithm
ic e
lem
ents
:–
send
: eve
ry N
seco
nds o
ut a
ll co
nnec
ted
inte
rfac
es
broa
dcas
t 2-tu
ples
:(to
net
wor
k X
, ho
p co
unt Y
) ...
–re
cv: i
f new
tupl
e, a
dd to
rout
ing
tabl
eif
bette
r tup
le, c
hang
e ex
istin
gif
“de
ad”
tupl
e, re
mov
e–
timeo
ut: i
f no
refr
esh,
tim
eout
ent
ry in
N *
Y se
cond
s»
broa
dcas
t may
be
lost
, the
refo
re ti
meo
ut is
slow
er
57Ji
m B
inkl
ey
vect
or-d
ista
nce
assu
me
3 ro
uter
s, an
d th
at d
irect
ly
conn
ecte
d ne
ts a
re in
rout
ing
tabl
es to
star
t w
ith.
How
doe
s fol
low
ing
conv
erge
?
r1
r
2
r3
n1
n2
n
3
n4
r1 ta
ble:
(n1
, 1)
(n2,
1)
58Ji
m B
inkl
ey
slow
con
verg
ence
/cou
nt to
infin
ity
vect
or-d
ista
nce
like
this
(RIP
) has
def
ects
chan
ges c
an b
e se
nt w
hen
they
occ
ur, b
ut
mus
t rec
ompu
tea
bit s
o co
nver
genc
e ta
kes
time
(mad
e w
orse
by
poss
ible
loop
s)
coun
t to
infin
ity p
robl
em c
an o
ccur
too
-ro
utin
g lo
op u
ntil
hopc
ount
reac
hes
impo
ssib
le v
alue
59Ji
m B
inkl
ey
coun
t to
infin
ityA
BC
C c
rash
es,
B k
now
s C c
rash
ed b
ut h
asn’
t tol
d A
,bu
t unf
ortu
nate
ly A
talk
s to
B fi
rst
B is
told
by
A:
I can
get
to C
in tw
o ho
ps (a
nd n
ote
it do
esn’
t men
tion
to B
that
the
path
isth
ruB
)B
says
AH
A!,
that
mea
ns I
can
get t
o C
in th
ree
hops
and
repo
rts th
at to
AA
says
AH
A!,
it’s n
ow fo
ur h
ops t
o B
and
tells
Bet
c...
RIP
max
hop
cou
nt (i
nfin
ity) i
s 16
60Ji
m B
inkl
ey
split
-hor
izon
fixu
p(v
ecto
r-di
stan
ce)
A te
lls B
that
its d
ista
nce
to C
is in
finity
–(b
ecau
se B
is th
e di
rect
ion
A g
ets t
he in
fo
from
)w
hen
link
goes
aw
ay, B
will
kno
w th
at
ther
e is
no
path
to C
, and
tell
Ado
esn’
t wor
k in
all
case
s
61Ji
m B
inkl
ey
link-
stat
e al
gorit
hm“t
ell t
he w
orld
abo
ut y
our n
eigh
bors
”ex
ampl
es: O
SPF,
IS-
IS,
NLS
P, I
DPR
link-
stat
e re
quire
s eac
h pa
rtici
patin
g ro
uter
to
keep
map
of c
ompl
ete
topo
logy
in 3
par
ts–
1. d
eter
min
e ne
ighb
or c
onne
ctiv
ity–
2. se
nd (“
flood
”) li
nk-s
tate
pac
ket t
hat s
tate
s whi
ch li
nk
neig
hbor
s are
up
–3.
use
Dijk
stra
shor
test
-pat
h fir
st to
com
pute
bes
t pat
h to
that
net
wor
k
62Ji
m B
inkl
ey
link-
stat
e#de
term
ine
link-
stat
e
“pin
g”ne
ighb
ors t
o de
term
ine
if th
ey a
re u
p or
they
may
bro
adca
st (m
ultic
ast)
thei
r ex
ista
nce
“i m
ultic
ast,
ther
efor
e i a
m...
”C
AB
63Ji
m B
inkl
ey
link-
stat
e#se
nd L
SP
each
par
ticip
atin
g ro
uter
“flo
ods”
(ver
y ca
refu
lly) r
outin
g do
mai
n w
ith L
SPls
p
64Ji
m B
inkl
ey
link-
stat
e#co
mpu
te sh
orte
st p
ath
each
par
ticip
atin
g ro
uter
take
s LSP
s, st
ores
th
em, a
nd c
ompu
tes s
horte
st p
ath
to se
nder
src
dest
65Ji
m B
inkl
ey
link-
stat
e: p
ros/
cons
pros –co
nver
ges f
aste
r, no
cou
nt to
infin
ity p
robl
em +
rout
er
can
forw
ard
LSP
imm
edia
tely
, mus
t rec
ompu
teD
V–
mor
e fu
nctio
nalit
y; e
.g.,
each
rou
ter
has m
ap o
f net
, ca
n m
ake
netw
ork
debu
ggin
g ea
sier
cons
–m
ore
com
pute
than
vd
(doe
s thi
s mat
ter?
)
toss
ups
–ba
ndw
idth
? v
dbr
oadc
asts
sum
mar
y ve
rsio
n of
rout
e ta
ble,
lsr
oute
rs se
nd L
SP a
roun
d ne
t
66Ji
m B
inkl
ey
basi
c to
ols f
or a
dmin
s:pi
ng, b
asic
reac
habi
lity,
pkt
loss
, lat
ency
trac
erou
te, l
aten
cy a
nd h
op c
ount
–re
mem
ber p
aths
may
be
asym
met
ric–
trace
rout
e “-
g”m
ay/m
ay n
ot w
ork
ttcp
, mem
ory
to m
emor
y xf
ersp
eed
–C
isco
is b
uild
ing
it in
to IO
S no
w–
can
mea
sure
tcp-
base
d th
rupu
t, al
so U
DP
pack
et fl
ing
(o
ne w
ay)..
sniff
ers,
free
tcpd
ump
(ww
w.tc
pdum
p.or
g).
67Ji
m B
inkl
ey
high
er-le
vel w
onde
rsve
ry w
ell m
ay in
volv
e SN
MP
–M
RT
Gan
d its
des
cend
ants
»C
ricke
t, a
nd o
ther
fron
t-end
s
–gr
aphs
SN
MP
inte
gers
on
strip
-cha
rts»
port
byte
cou
nts i
n/ou
t
Com
mer
cial
tool
s–
com
mer
cial
mon
itors
, sni
ffer
s, in
trusi
on d
etec
tion
–sn
mp
RM
ON
pro
bes o
r rou
gh/fr
ee e
quiv
alen
ts (n
top)
–ne
twor
k m
gmt.
GU
I won
ders
(HP
open
view
/Cis
co/IB
M, N
etw
ork
Ass
ocia
tes,
etc.
, etc
.)
