1Ji

m B

inkl

ey

Rou

ting

Con

cept

s

TCP/

IP c

lass

2Ji

m B

inkl

ey

Rou

ting

-Con

cept

s

intro

con

cept

s–

topo

logi

es–

type

s/pr

oper

ties

–is

sues

vect

or-d

ista

nce

link-

stat

ese

eR

adia

Per

lman

’sIn

terc

onne

ctio

ns, f

or

mor

e in

form

atio

n

3Ji

m B

inkl

ey

issu

es/p

rope

rties

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

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

6Ji

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

7Ji

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

8Ji

m B

inkl

ey

conn

ectio

nles

s/co

nnec

ted

netw

ork-

laye

r in

TCP/

IP c

onne

ctio

nles

sO

SI st

ack

has c

onne

cted

+ c

onne

ctio

nles

sco

nnec

tionl

ess -

each

pac

ket r

oute

d vi

a ro

ute

tabl

e, p

aths

may

cha

nge

dyna

mic

ally

conn

ecte

d -r

oute

setu

p at

“co

nnec

t”tim

e in

ci

rcui

t sw

itch,

torn

dow

n at

dis

conn

ect

rout

ing

prob

lem

s stil

l sim

ilar

9Ji

m B

inkl

ey

idea

l rou

ting

algo

rithm

fair

or u

nfai

r (w

hat i

f we

wan

tiso

chro

nous

data

?)

corr

ect -

wha

t if a

lgor

ithm

s too

com

plex

?ro

bust

-ca

n de

al w

ith ro

uter

rebo

ot?

stab

le -

do ro

utin

g ch

ange

s sta

biliz

e in

dis

tribu

ted

syst

em?

effic

ient

-al

l rou

ting

and

no d

ata

not g

ood

topo

logi

cally

flex

ible

mai

ntai

nabl

e -a

dmin

not

too

com

plic

ated

scal

able

to m

any

rout

ers,

man

y ho

sts?

(dis

tribu

ted)

dead

lock

? -l

oops

?se

cure

(+ c

lean

, che

erfu

l, ta

kes o

ut th

e tra

sh, e

tc.)

10Ji

m B

inkl

ey

clas

sic

prob

lem

rout

ing

loop

path

to Z

?

11Ji

m B

inkl

ey

type

s of r

outin

g al

gorit

hms

stat

ic v

ersu

s dyn

amic

stat

ic p

ros:

–si

mpl

e, m

ay b

e ea

sies

t thi

ng to

do

in si

mpl

e to

polo

gy,

espe

cial

ly fo

r lea

f hos

t with

1 ro

uter

onl

y–

you

may

be

smar

ter t

han

the

rout

ers (

wan

t a p

ath

they

w

on’t

give

you

)

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.

..)–

not s

cala

ble

12Ji

m B

inkl

ey

rout

ing

algo

rithm

type

s

cent

raliz

ed v

ersu

s dis

tribu

ted

vers

us e

nd-

node

–ce

nter

is n

eces

sary

, can

’t ha

ve d

efau

lts

ever

ywhe

re–

if en

d no

des h

ave

rout

e in

fo, a

nd b

ig n

et, t

hen

rout

e ta

bles

hug

e -n

eed

to li

mit

size

13Ji

m B

inkl

ey

type

s/to

ols -

sour

ce ro

utin

g

sour

ce-r

outin

gvs

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

–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

-us

ed 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?

14Ji

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

)

15Ji

m B

inkl

ey

be c

aref

ul w

ith fl

oodi

ng...

16Ji

m B

inkl

ey

type

s -flo

odin

g

impo

rtant

rout

ing

algo

rithm

“to

ol”

-use

d in

m

any

rout

ing

algo

rithm

s in

som

e se

nse

stro

ng p

ro a

nd c

onpr

o -p

erfe

ct r

outin

g, y

ou fo

llow

the

best

pa

thco

n -“

perf

ect c

onge

stio

n”-y

ou u

se u

p to

o m

uch

band

wid

th

17Ji

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

dyo

u flo

od y

our d

estin

atio

n,ho

pcou

ntin

fo to

you

r di

rect

ly c

onne

cted

nei

ghbo

r rou

ters

RIP

is a

n ex

ampl

e

18Ji

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 nei

ghbo

rs”

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.

19Ji

m B

inkl

ey

issu

es -

scal

abili

ty?

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?

one

hom

e/of

fice,

to b

usin

ess/

ente

rpris

e, to

st

ate,

nat

ion,

pla

net,

sola

r sys

tem

, gal

axy.

..co

mpo

nent

s aff

ecte

d in

clud

e th

e ne

twor

k ad

dres

s and

the

rout

er h

iera

rchy

20Ji

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

–ip

add

ress

allo

catio

n fr

om c

lass

Csl

ize

of p

ie m

eans

in

effe

ct m

ajor

ity o

f num

bers

are

was

ted

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

?

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

ust s

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

add

a pr

efix

...

dom

ain

rout

ers a

s 1st

ass

umpt

ion

-ass

ume

they

kno

w a

ll th

e ro

utes

. if

that

isn’

t sca

labl

e, th

en a

dd n

ew

hier

arch

y an

d in

trodu

ce n

ew la

yer o

f st

ruct

ure

IP is

mov

ing

tow

ards

this

(CID

R)

phon

e co

mpa

nies

hav

e pr

efix

es (n

ot

enou

gh...

nob

ody

is p

erfe

ct)

23Ji

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

24Ji

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

sally

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

25Ji

m B

inkl

ey

cong

estio

n?pr

even

t con

gest

ion:

–ad

d ca

rryi

ng c

apac

ity–

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

–so

me

sche

mes

hav

e ro

uter

s for

war

d or

pas

s bac

k co

nges

tion

bits

26Ji

m B

inkl

ey

cong

estio

n

IP se

nds b

ack

ICM

P so

urce

que

nch

mes

sage

to se

nder

–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

)

27Ji

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

28Ji

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

ent

erpr

ise

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

29Ji

m B

inkl

ey

issu

es -

link

cost

sif

link

cost

s cha

nge,

that

info

rmat

ion

mus

t co

nver

ge o

f cou

rse

answ

er n

ow is

that

link

cos

t is u

sual

ly h

op c

ount

on

ly (1

met

ric)

ques

tion:

wou

ld m

ore

com

plex

alg

orith

ms (

if po

ssib

le) t

hat d

ynam

ical

ly a

ccou

nt fo

r lin

k co

sts

do q

ualit

ativ

e be

tter j

ob th

an c

urre

nt si

mpl

e al

gorit

hms o

r jus

t use

ban

dwid

th?

30Ji

m B

inkl

ey

type

of s

ervi

ce

my

pack

ets b

efor

e yo

ur p

acke

ts!

mig

ht w

ant t

o pr

iorit

ize

certa

in tr

affic

cl

asse

sm

ight

wan

t to

optim

ize

on m

ultip

le m

etric

spo

licy-

base

d ro

utin

g (p

bco

nstra

ins)

-ou

tlaw

cer

tain

link

s or r

oute

rs–

sour

ce a

nd st

atic

rout

ing

can

be u

sefu

l her

e

31Ji

m B

inkl

ey

issu

es -

som

em

isc.

one

slo

ad-s

plitt

ing

-if w

e ha

ve tw

o sa

me-

leve

l rou

ters

, ca

n w

e sp

lit th

e lo

ad b

etw

een

them

addr

ess m

atch

ing

-rou

ter n

eeds

to d

o th

is fa

st o

r m

ay ru

n ou

t of b

uffe

r spa

cem

igra

ting

rout

ing

algo

rithm

s -yo

u ha

ve R

IP a

nd

now

you

wan

t to

switc

h to

OSP

F–

can

you

run

both

?, s

witc

hing

one

by

one

is d

isru

ptiv

e

parti

tion

repa

ir -i

f tw

o pa

ths t

o on

e ne

t, an

d on

e go

es d

own,

can

rout

ers f

ix it

?

32Ji

m B

inkl

ey

vect

or-d

ista

nce

algo

rithm

exam

ples

: R

IP,

BG

Pal

gorit

hmic

ele

men

ts:

–se

nd: e

very

N se

cond

s out

all

conn

ecte

d in

terf

aces

br

oadc

ast 2

-tupl

es:

(to n

etw

ork

X,

hop

coun

t Y) .

..–

recv

: if n

ewtu

ple,

add

to ro

utin

g ta

ble

if be

ttert

uple

, cha

nge

exis

ting

if “

dead

”tu

ple,

rem

ove

–tim

eout

: if n

o re

fres

h, ti

meo

ut e

ntry

in N

* Y

seco

nds

»br

oadc

ast m

ay b

e lo

st, t

here

fore

tim

eout

is sl

ower

33Ji

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)

34Ji

m B

inkl

ey

slow

con

verg

ence

/cou

nt to

infin

ity

vect

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