TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

1

The

Inte

rnet

Pro

toco

l (IP

)

John

Kris

toff

jtk@

depa

ul.e

du+

1 31

2 36

2-58

78D

ePau

l Uni

vers

ityC

hica

go, I

L 60

604

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

2

Will

laye

r 2

net

wo

rkin

g s

uff

ice?

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

3

Lay

er 3

usu

ally

pro

vid

es

�

Inte

rnet

wor

king

for

data

link

tech

nolo

gies

�

Glo

bally

uni

que

addr

esse

s

�

Sca

labl

e ro

utin

g

�

A c

omm

on c

omm

unic

atio

ns fo

rmat

�

Pac

ket f

ragm

enta

tion

capa

bilit

y

�

A h

ardw

are

inde

pend

ent i

nter

face

�

Pac

ket i

ndep

ende

nce

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

4

An

IP R

ou

ter

(or

gat

eway

)

�

Usu

ally

a s

peci

al p

urpo

se, d

edic

ated

dev

ice

�

Con

nect

s he

tero

geno

us n

etw

orks

�

Dire

cts

pack

ets

tow

ard

ultim

ate

dest

inat

ion

�

Dyn

amic

rou

ting

algo

rithm

s of

ten

used

�

The

y m

ake

auto

mat

ic fo

rwar

ding

dec

isio

ns

�

The

y ca

n fo

rwar

d ba

sed

on v

ario

us m

etric

s

�

Offi

cial

pro

noun

ciat

ion

is r

eally

root

er

�

Laye

r 3

switc

h =

rou

ter

= la

yer

3 sw

itch

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

5

IP R

ou

tin

g

�

Sco

pe

�

Aut

onom

ous

syst

em, i

nter

ior,

ext

erio

r

�

Dyn

amic

rou

ting

�

Pro

toco

l for

rou

te e

xcha

nge

and

com

puta

tion

�

Sta

tic r

outin

g

�

Man

ually

con

figur

ed r

oute

s

�

Des

tinat

ion

addr

ess

driv

en

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

6

Inte

rnet

pro

toco

l (IP

)

�

Sta

ndar

dize

d in

RF

C 7

91

�

Con

nect

ionl

ess

�

Unr

elia

ble

�

Fai

rly s

impl

e

�

The

Inte

rnet

Glu

e

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

7

IP a

dd

ress

es

�

Virt

ual –

not

bou

nd to

har

dwar

e

�

32-b

it fix

ed s

ize

�

Uni

que

addr

ess

for

each

IP in

terf

ace

�

Glo

bal a

utho

ries

assi

gn a

pre

fix (

netw

ork)

�

Loca

l adm

inis

trat

ors

assi

gn th

e su

ffix

(hos

t)

�

Usu

ally

writ

ten

as d

otte

d de

cim

al n

otat

ion

�

e.g.

140

.192

.1.6

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

8

IP a

dd

ress

typ

es

�

Uni

cast

(on

e-to

-one

)

�

Sou

rce

addr

ess

shou

ld a

lway

s be

uni

cast

�

Mul

ticas

t (on

e-to

-man

y)

�

Rec

eive

rs jo

in/li

sten

to m

ultic

ast g

roup

add

ress

�

Bro

adca

st (

one-

to-a

ll)

�

Spe

cial

cas

e of

a m

ultic

ast,

usua

lly b

est a

void

ed

�

Any

cast

(on

e-to

-one

-of-

man

y)

�

Pre

fera

bly

one-

to-n

eare

st, d

efin

ed fo

r IP

v6

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

9

IP a

dd

ress

no

tati

on

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

10

Sp

ecia

l IP

ad

dre

sses

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

11

Cla

ssfu

l IP

ad

dre

ssin

g

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

12

Cla

ssfu

l ad

dre

ss s

izes

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

13

Exa

mp

le IP

net

wo

rk

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

14

Exa

mp

le IP

ro

ute

r ad

dre

ssin

g

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

15

Lim

itat

ion

s o

f cl

assf

ul a

dd

ress

ing

�

Inte

rnet

gro

wth

�

Rou

te ta

ble

size

�

Add

ress

dep

letio

n

�

Mis

appr

opria

tion

of a

ddre

sses

�

Lack

of s

uppo

rt fo

r di

ffere

nt s

ized

net

wor

ks

�

Cla

ss B

too

big,

cla

ss C

too

smal

l

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

16

IP a

dd

ress

ing

so

luti

on

s

�

Sub

netti

ng

�

Sup

erne

tting

�

Cla

ssle

ss in

terd

omai

n ro

utin

g (C

IDR

)

�

Var

iabl

e le

ngth

sub

net m

asks

(V

LSM

)

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

17

Su

bn

etti

ng

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

18

Su

bn

et m

ask

�

The

bit

leng

th o

f the

pre

fix (

netw

ork)

�

Pre

fix (

netw

ork)

is n

o lo

nger

cla

ssfu

l

�

Dot

ted

deci

mal

or

'/' n

otat

ion

�

140.

192.

1.6'

s su

bnet

mas

k is

255

.255

.255

.128

�

...or

140

.192

.1.6

/25

�

You

may

wan

t to

conv

ert t

o bi

nary

for

clar

ity

�

A /2

5 or

255

.255

.255

.128

sub

net m

ask

is:

�

1111

1111

.111

1111

1.11

1111

11.1

0000

000

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

19

Exa

mp

le:

Usi

ng

su

bn

et m

asks

�

Giv

en 1

40.1

92.5

0.8/

20, w

hat i

s th

e:

�

subn

et m

ask

in d

otte

d de

cim

al n

otat

ion?

�

dire

cted

bro

adca

st a

ddre

ss in

dot

ted

deci

mal

�

tota

l num

ber

of h

osts

that

can

be

addr

esse

d?

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

20

Su

per

net

tin

g

�

Com

bine

sm

alle

r bl

ocks

into

larg

er a

ggre

gate

�

If cl

ass

B to

o bi

g, c

lass

C to

o sm

all..

.

�

May

be d

o th

is:

�

Com

bine

199

.63.

0.0/

24 to

199

.63.

15.0

/24

�

Equ

als

199.

63.0

.0/2

0

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

21

Exa

mp

le:

Usi

ng

Su

per

net

s

�

Giv

en th

at IS

P h

as 1

28.1

5.0.

0/16

:

�

If a

cust

omer

nee

ds to

add

ress

300

hos

ts, h

ow

mig

ht th

e IS

P a

ssig

n th

em a

ddre

ss s

pace

?

�

Wha

t is

the

addr

ess

spac

e as

sign

ed in

the

exam

ple

abov

e in

'sla

sh' n

otat

ion?

�

How

man

y, if

any

, max

imum

free

IP a

ddre

sses

w

ill th

e cu

stom

er h

ave

at th

eir

disp

osal

?

�

Can

you

thin

k of

any

rea

son

why

the

cust

omer

m

ight

hav

e le

ss th

an th

at m

axim

um?

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

22

CID

R

�

Use

sup

erne

tting

for

rout

ing

tabl

es

�

Rou

tes

adve

rtis

ed a

s sm

alle

r C

IDR

blo

cks

�

So

inst

ead

of a

dver

tisin

g:

�

199.

5.6.

0/24

, 199

.5.6

.1/2

4, 1

99.5

.6.2

/24

and

199.

5.6.

1/24

sep

arat

ely

�

Adv

ertis

e:

�

199.

5.6.

0/22

one

tim

e

�

Inte

rnet

CID

R r

epor

t

�

http

://w

ww

.em

ploy

ees.

org/

~tb

ates

/cid

r-re

port

.htm

l

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

23

Exa

mp

le:

Usi

ng

CID

R

�

Giv

en th

at a

n IS

P a

nnou

nces

net

bloc

ks

64.5

.0.0

/20,

64.

5.16

.0/2

0, 1

92.0

.2.0

/25

and

192.

0.2.

192/

26 a

nd 1

92.0

.2.1

28/2

6:

�

Wha

t is

the

smal

lest

num

ber

of C

IDR

an

noun

cem

ents

that

this

ISP

can

mak

e?

�

If th

ese

rout

es a

re r

ecei

ved

from

ano

ther

pr

ovid

er, c

an y

ou th

ink

of a

ny r

easo

n w

hy th

ey

mig

ht n

ot b

e ab

le to

be

CID

R-iz

ed?

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

24

VL

SM

�

Mul

tiple

sub

net s

izes

in a

sin

gle

AS

�

Allo

ws

effic

ient

use

of a

ddre

ss s

pace

�

Can

be

used

to b

uild

inte

rnal

hie

rarc

hy

�

Ext

erna

l vie

w o

f AS

doe

s no

t cha

nge

�

An

orga

niza

tion

may

hav

e 14

0.19

2.0.

0/16

�

But

inte

rnal

ly m

ay u

se 1

40.1

92.0

.0/1

7,

140.

192.

128.

0/24

, 140

.192

.129

.0/2

4 an

d so

on.

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

25

Exa

mp

le:

Usi

ng

VL

SM

�

Giv

en a

n ad

dres

s sp

ace

of 1

40.1

92.0

.0/1

6 to

w

ork

with

, ass

ign

netb

lock

s an

d ad

dres

ses

base

d on

the

follo

win

g ne

twor

k:

�

6 sa

telli

te s

ites

and

1 m

ain

offic

e ce

nter

�

Abo

ut 7

000

host

s ex

ist o

n en

tire

netw

ork

toda

y

�

Mai

n si

te u

ses

appr

oxim

atel

y 50

% o

f add

ress

es

�

Sat

ellit

es v

ary

from

200

to 7

00 to

tal a

ddre

sses

�

Ove

rall

grow

th fo

r or

gani

zatio

n is

500

hos

ts/y

ear

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

26

Ob

tain

ing

IP a

dd

ress

es

�

IAN

A h

as g

loba

l aut

horit

y fo

r as

sign

men

t

�

Reg

iona

l reg

istr

ies

dele

gate

(A

RIN

/RIP

E/A

PN

IC)

�

ISP

s as

sign

add

ress

es to

end

end

use

rs

�

RF

C 1

918

defin

es p

rivat

e ad

dres

s ne

tblo

cks

�

NO

T g

loba

lly u

niqu

e

�

Mus

t not

app

ear

on th

e pu

blic

Inte

rnet

�

10.0

.0.0

/8, 1

72.1

6.0.

0/12

, 192

.168

.0.0

/16

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

27

IP d

atag

ram

layo

ut

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

28

Insi

de

an IP

v4 d

atag

ram

�

Ver

sion

fiel

d

�

Bin

ary

0100

(eq

uals

wha

t in

deci

mal

?)

�

Hea

der

leng

th

�

Leng

th o

f the

IP h

eade

r in

32

bit w

ords

�

Will

usu

ally

be

equa

l 5 (

in d

ecim

al)

�

Typ

e of

Ser

vice

(no

w D

iffS

erv

field

)

�

An

indi

catio

n of

qua

lity/

clas

s of

ser

vice

�

Rar

ely

used

, but

if s

o us

ually

with

in s

ingl

e A

S

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

29

Insi

de

an IP

v4 d

atag

ram

[co

nt.

]

�

Tot

al le

ngth

�

Tot

al IP

dat

agra

m le

ngth

in o

ctet

s

�

Max

imum

val

ue is

655

35, b

ut r

arel

y >

150

0

�

Iden

tific

atio

n

�

Use

d fo

r to

iden

tify

frag

men

ted

pack

ets

�

Exp

erim

enta

l use

for

trac

ing

(D)D

oS a

ttack

s

�

Fla

gs

�

Bit

0 re

serv

ed, o

ther

s co

ntro

l fra

gmen

tatio

n

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

30

Insi

de

an IP

v4 d

atag

ram

[co

nt.

]

�

Fra

gmen

t offs

et

�

Hel

ps p

iece

toge

ther

frag

men

t dat

agra

ms

�

Tim

e to

live

(T

TL)

�

Bou

nds

time/

hops

of I

P d

atag

ram

in n

etw

ork

�

Cou

nts

dow

n to

zer

o an

d st

ops

bein

g fo

rwar

ded

�

Pro

toco

l typ

e

�

Indi

cate

s ne

xt le

vel p

roto

col i

n da

ta p

ortio

n

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

31

Insi

de

an IP

v4 d

atag

ram

[co

nt.

]

�

Hea

der

chec

ksum

�

Use

d to

ver

ify h

eade

r va

lidity

at e

ach

hop

�

Sou

rce

addr

ess

�

32-b

it IP

add

ress

�

Des

tinat

ion

addr

ess

�

32-b

it IP

add

ress

�

Opt

ions

�

Var

iabl

e, n

ot o

ftenl

y us

ed

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

32

Dem

o:

Un

der

stan

din

g P

ING

�

Set

up p

acke

t cap

ture

ses

sion

usi

ng tc

pdum

p

�

tcpd

ump

-n -

s 15

00 -

w p

ing.

cap

icm

p an

d \(

dst

hos

t <m

y-ip

> o

r sr

c ho

st <

my-

ip>

\)

�

Pin

g re

mot

e ho

st

�

ping

<re

mot

e-ip

>

�

Vie

w c

aptu

re u

sing

Eth

erea

l

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

33

Dem

o:

Un

der

stan

din

g t

race

rou

te

�

Set

up p

acke

t cap

ture

ses

sion

usi

ng tc

pdum

p

�

tcpd

ump

-n -

s 15

00 -

w tr

acer

oute

.cap

\( u

dp o

r ic

mp

\) a

nd \(

dst

<m

y-ip

> o

r sr

c <

my-

ip>

\)

�

Tra

ce r

emot

e ho

st

�

trac

erou

te -

n <

rem

ote-

ip>

�

Vie

w c

aptu

re u

sing

Eth

erea

l

TD

C 3

75 W

inte

r 20

02Jo

hn K

risto

ff -

DeP

aul U

nive

rsity

34

Oth

er t

oo

ls a

nd

ref

eren

ces

�

Fin

d co

ntac

ts fo

r IP

add

ress

or

netb

lock

s

�

who

is <

ip-a

ddre

ss-o

r-ne

twor

k>

�

Vei

w n

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