Routes Redistribution

7/24/2019 Routes Redistribution

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1

Understanding Route

Redistribution

ICNP 2007

October 17th, 2007

Franck Le, Geore! G" #ie, $ui %hang


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2

Internet&ork and Routing

' Co((on )ie&*

+ Intrado(ain routing using O-PF, RIP

+ Interdo(ain routing using .GP

' In rea/it!, internet&orking is (uch (ore co(/e+ I-P net&orks*

' O-PF routes to be redistributed into .GP and )ice )ersa3

+ 4nterrise net&orks*

' 5hen .GP is not used, needs (echanis( to distribute routes

a(ong O-PF, RIP, 4IGRP do(ains

' 6/so, needs to distribute routes a(ong (u/ti/e O-PF

do(ains


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5hat is Route Re8istribution RR39

router ospf 27

redistribute rip metric

200 subnets route-map

rip2ospf

distance ospf external

200!

route-map rip2ospf permit

100

match ip address 100

set tag 22

set metric-type-1

6

. 8

4

Oice branch 1 Oice branch 2

RIP O-PF

RIP O-PF Loca/

FI.

C

.! deau/t, O-PF routers ha)e no )isibi/it! o RIP routers


4/31

:

$o& 8oes RR Co(are to .GP9

' In (an! scenarios, RR, not .GP, is used to interconnect

net&ork do(ains,

' 4)en &hen .GP is used, RR is re;uired to connect .GP

and IGP

' RR can i(/e(ent o/ic!, /ike .GP

' Un/ike .GP, RR is NO< a rotoco/

+ RR is =ust a coniguration (echanis(, usedsearate/! at each router

RR is more commonly used than BGP, but much

less understood, and much more error-prone


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>

Prob/e( -tate(ents

' Gi)en an internet&ork &ith RR

conigurations, &hat are the /ooree and

con)ergence roerties9

' 5hat are the guide/ines o using RR i one

&ants to ha)e /ooree and con)ergent

internet&ork9


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?

-!nthesis o the Paer

' @ode/ that reasons about the /ooree and

con)ergence roerties

'-uicient condition to guarantee /ooreeand con)ergence roerties


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7

Out/ine

1" Introduction to Route Redistribution RR3

2" I//ustration o routing ano(a/ies

" 6 @ode/ or RR:" -uicient condition or /ooree and

con)ergent RR


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A

Route -e/ection Process

6

.

C

8

4


RIP O-PF

RIP

FI.

O-PF Loca/

P

P

P -igna/ing

8ata ath


9/31

B

Route -e/ection Process

6

.

C

8

4


RIP O-PF

RIP

FI.

O-PF Loca/

-e/ected routing rocess

P P

PP

P -igna/ing

8ata ath

O-PF

110120 01


10/31

10

FI.

Route Redistribution Process

6

.

C

8

4


RIP O-PF

RIP O-PF Loca/

110120 01

O-PF

RIP Udate

P

P -igna/ing

8ata ath


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11

Out/ine




con)ergent RR


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12

Instabi/ities

' 5ide range o ossib/e routing instabi/ities

' No genera/ guide/ine to conigure RR


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1

RIP

O-PF

RIP

For(ation o Routing Loos

6

.

C

8

4

RIP1203 O-PF1103

O-PF Loca/

FI.

RIP O-PF Loca/

FI.

P

Netho* .

Netho* C

Netho* 4

Netho* 8

P

P

P -igna/ing

8ata ath


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1:

Out/ine




con)ergent RR


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1>

Cha//enges

'


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1?

-o/utions

'


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17

6 @ode/ or RR

' 6bstracts the d!na(ic echange o routing

inor(ation or a rei P

' 6//o&s to redict aths


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1A

Route Proagation Grah

' Routing instance

' Originating routing instance

' Conigured redistribution

' 6ctua/ redistribution

' Route )s" no route

' Eariab/es* CL, S

21103

1

1203

1

1203

2

1103

A0, 6, B0

1

1203

2

1103

A0, 6, B0

1

1203

2

1103

A0, 6, B0 2

1103


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1B

I//ustration o @ode/

2O-PF1

1103

RIP

1203

:

O-PF21103

F

F

L

L

$

$

4

4

0Loca/

03

1RIP

1203

6

6

. C 8 4

F G $ I

L @N

D

RIP RIPO-PF1 O-PF2

P


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20

I//ustration o @ode/

-e;uence 1

-igna/ing

8ata ath

1

RIP

1203

2

O-PF1

1103

RIP

1203

:

O-PF2

1103

F

F

L

L

$

$

4

4

0

Loca/

03

61

RIP

1203

2

O-PF1

1103

RIP

1203

CLt03 H6 CLt13 H4, F CLt23 H4, L CLt3 H4, $

CLt:3 H4CLt>3 H6, FCLt?3 H

-t13 H6 -t23 HF -t3 HL

-t:3 H$-t>3 H4-t?3 H6, F

:

O-PF2

1103


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21

Route Redistribution Coniguration

C!c/e 8etection RRCC83 Prob/e(

' Gi)en a RR coniguration, deter(ining

&hether there is an acti)ation se;uence

such that the redistributions con)erge to

state inc/uding a c!c/e o acti)eredistributions is NPhard


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22

Out/ine




con)ergent RR


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2

-uicient condition or saet!

' Pruning o Route Proagation Grah

+ For each redistributing router, on/! conser)e

redistributions ro( the routing rocesses

&ith /o&est ad(inistrati)e distances

' Rationa/e

+ Focus on reerred redistributions

1

1003

2

703

1203

:

B03

6 6 6


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2:

-uicient condition

I resu/ting grah satisies

1" 4)er! redistributing router redistributes ro( a

sing/e routing instance (predictable outcome)

2" For a// )ertice, there is a redistribution athro( aoriginating )erte (active redistributio)

"


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2>

6/ication o -uicient

Condition

1

RIP

1203

2

O-PF1

1103

RIP

1203

:

O-PF2

1103

F

F

L

L

$

$

4

4

0

Loca/

03

6


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2?


Condition

@odiications

1

RIP

1203

2

O-PF1

1103

RIP

1203

:

O-PF2

1103

A0, F

F, A0

L

L

$

$

A0, 4

4, A0

0

Loca/

03

6


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27


Condition

Pruning

1

RIP

1203

2

O-PF1

1103

RIP

1203

:

O-PF2

1103

A0, F

F, A0

L

L

$

$

A0, 4

4, A0

0

Loca/

03

6


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2A


Condition

Pruning

1

RIP

1203

2

O-PF1

1103

RIP

1203

:

O-PF2

1103

A0, F L

$

0

Loca/

03

6

A0, 4


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2B


Condition

1" 4)er! redistributing router is redistributing

ro( a sing/e routing instance"

2" For a// )ertice, there is a redistribution ath

ro( a originating )erte"

"


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0

-u((ar!

' Internet&ork is ar (ore co(/e &ith RRthan the concetua/ (ode/ o .GPO-PF

' RR ser)es a unda(enta/ need, but is not

&e//understood or e)en &e//designed' First or(a/ stud! routeree and

con)ergence roerties o RR

internet&ork+ @ode/

+ -uicient condition


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1

Future 5ork

' I one &ere to redesign the RR, &hat

shou/d be the so/ution that suorts a// the

RR a/ications but a)oid the ita//s9

Routes Redistribution

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