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USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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(RPS) Routing Policy System Working Group

Chairs:

Cengiz Alaettinoglu Daniel Karrenberg

<cengiz@isi.edu> <Daniel.Karrenberg@ripe.net>

Mailing List: rps@isi.edu

To subscribe: rps-request@isi.edu

Ftp archive: ftp://ftp.isi.edu/rps

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Autonomous System Path Expression Extension to Ripe-181

Cengiz Alaettinoglu

Jessica Yu

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Autonomous System Objects and Import Policies

aut-num: AS1

as-name: foo

as-in: from AS2 1 accept {128.8.0.0/16}

as-in: from AS3 2 accept {128.8.0.0/16}

128.8/16
AS1

AS2

AS3

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Autonomous System Objects and Export Policies

aut-num: AS2

as-name: bar

as-out: to AS1 announce {128.8.0.0/16}

as-out: to AS3 announce {128.8.0.0/16}

128.8/16
AS1
AS2

AS3

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Route Objects Originating AS, Communities in Policy

route: 128.8.0.0/16 descr: University of Maryland origin: AS86 comm-list: COMM_NSFNET

route: 192.101.80.0/24 descr: WVWC origin: AS86

as-in: from AS2 1 accept AS86 as-out: to AS3 announce COMM_NSFNET

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AS-Macro Objects

as-macro: AS-ANSLA

descr: List of ANS LA ASes

as-list: AS1322 AS1671 AS2930

as-in: from AS2 1 accept AS-ANSLA

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Logical Combination

as-in: from AS2 1 accept

AS-ANSLA AND NOT AS1322 OR {128.8.0.0/16}

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Multiple Interconnections

aut-num: AS1 as-in: from AS2 1 accept {128.8.0.0/16} interas-in: from AS2 l1 r1 (pref=1) accept {128.8.0.0/16} interas-in: from AS2 l2 r2 (pref=2) accept {128.8.0.0/16} interas-out: to AS2 ...

AS2AS1 128.8/16 l1 r1

l2 r2

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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AS Path Expressions in Policy

Many providers have AS path based policies:

as-in: ... accept AS1 is not in the AS path

as-out: ... announce AS1 is the first AS in the AS path

Need AS Path Expressions!

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AS Path Regular Expressions

ASn ?ASn? . any AS number [AS1 AS2 AS4-AS6] AS1, AS2, AS4, AS5, AS6 [^AS1 AS2 AS4-AS6] AS3, AS7, AS8, ... ^ beginning of an AS path $ end of an AS path exp* exp+ exp? 0 or more, 1 or more, 0 or 1 exp1 exp2 catenation exp1 | exp2 alternative ()

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AS Path Expression

< AS-Path-Regular-Expression >

matches routes whose AS paths are matched

by the AS-Path-Regular-Expression

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AS Path Expressions in Policy

aut-num: AS1

as-in: from AS2 1 accept NOT <AS1>

as-in: from AS2 1 accept <^AS1$>

as-out: to AS2 announce <^[AS1 AS3 AS4 AS5]>

Existing tools will break!

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Extended Attributes

Original attributes:

as-in

as-out

interas-in

interas-out

Extended attributes:

extended-as-in

extended-as-out

extended-interas-in

extended-interas-out

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Valid Policies: Original Attributes Only

as-in: from AS2 1 accept AS86 as-out: to AS3 announce COMM_NSFNET

old tools: will work

new tools: will work

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Valid Policies: Extended Attributes Only

extended-as-in: from AS2 1 accept <AS8$> extended-as-out: to AS3 announce <^[AS1-AS9]>

old tools: will assume default policy ?NOT ANY?

new tools: will work

USC / Information Sciences Institute Cengiz Alaettinoglu, IETF July ?95

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Valid Policies: Mixing Rule

on a per peer basis

if policies are mixed

for *-in policies

for each extended-as-in specify as-in

for each extended-interas-in specify interas-in

for *-out policies

for each extended-as-out specify as-out

for each extended-interas-out specify interas-out

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Tools and Mixed Policies

Old tools: use original attributes only

New tools: on import

use extended attributes if exist

use original attributes otherwise

on export

use extended attributes if exist

use original attributes otherwise

Eventually all tools will be upgraded!

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Valid Examples

aut-num: AS1 as-in: from AS2 1 accept ANY as-out: to AS2 announce NOT AS10 extended-as-in: from AS2 1 accept NOT <AS5> extended-as-out: to AS2 announce NOT <AS1.* AS5.* AS10>

aut-num: AS1 as-in: from AS2 1 accept AS2 as-out: to AS2 announce AS1 extended-as-out: to AS2 announce <^[AS3 AS4 AS5]> OR AS1

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Invalid Example

aut-num: AS1 as-in: from AS2 1 accept ANY extended-as-in: from AS2 1 accept ANY extended-as-out: to AS2 announce NOT <AS1 . * AS5.* AS10>

There should be an as-out attribute.

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Conclusions

AS path expressions can now be specified

To avoid breaking tools:

extended-as-in

improved-extended-as-in

super-improved-extended-as-in

yet-another-super-improved-extended-as-in

Extensibility should be part of RPSL!