Avoidance for ROA Containing Multiple IP Prefixes
draft-ietf-sidrops-roa-considerations-06

SIDR Operations                                                   Z. Yan
Internet-Draft                                                     CNNIC
Intended status: Informational                                   R. Bush
Expires: 31 July 2023                    IIJ Research Lab & Arrcus, Inc.
                                                               G.G. Geng
                                                        Jinan University
                                                              T. de Kock
                                                                RIPE NCC
                                                                  J. Yao
                                                                   CNNIC
                                                            January 2023

           Avoidance for ROA Containing Multiple IP Prefixes
                draft-ietf-sidrops-roa-considerations-06

Abstract

   When using the RPKI, address space holders need to issue a ROA
   object(s) to authorize one or more ASes to originate routes to IP
   prefix(es).  This memo discusses operational problems which may arise
   from ROAs containing multiple IP prefixes, and recommends that each
   ROA only contain a single IP prefix.

Status of This Memo

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   This Internet-Draft will expire on 5 July 2023.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Recommendations . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   In the Resource Public Key Infrastructure (RPKI), a Route Origin
   Authorization (ROA) is a digitally signed object which identifies
   that a single Autonomous System (AS) has been authorized by the
   address space holder to originate routes to one or more prefixes
   within the address space [RFC6482].

   Each ROA contains an "asID" field and an "ipAddrBlocks" field.  The
   "asID" field contains one single AS number which is authorized to
   originate routes to the given IP address prefix(es).  The
   "ipAddrBlocks" field contains one or more IP address prefixes to
   which the AS is authorized to originate the routes.

   If the address space holder needs to authorize more than one AS to
   advertise the same set of IP prefixes, multiple ROAs must be issued
   (one for each AS number [RFC6480]).  Prior to this document, there
   was no guidance for choosing to issue a separate ROA for each IP
   prefix or a single ROA containing multiple IP prefixes.

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2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Problem Statement

   An address space holder can issue a separate ROA for each of its
   routing announcements.  Alternatively, for a given asID, it can issue
   a single ROA for multiple routing announcements, or even for all of
   its routing announcements.  Since a given ROA is either valid or
   invalid, the routing announcements for which that ROA was issued will
   "share fate" when it comes to RPKI validation.  Currently, no
   guidance is offered in existing RFCs to recommend what kinds of ROA
   are issued: one per prefix, or one ROA for multiple routing
   announcements.  The problem of fate-sharing is not discussed or
   addressed.

   In the RPKI trust chain, the Certification Authority (CA) certificate
   issued by a parent CA to a delegate of some resources may be replaced
   by the parent at any time resulting in changes to resources specified
   in the [RFC3779] certificate extension.  Any ROA object that includes
   resources which are a) no longer contained in the new CA certificate,
   or b) contained in a new CA certificate that is not yet discovered by
   Relying Party (RP) software, will be rejected as invalid.  Since ROA
   invalidity affects all routes specified in that ROA, unchanged
   resources with associated routes via that asID cannot be separated
   from those affected by the change in the CA certificate validity.
   They will fall under this invalid ROA even though there was no
   intention to change their validity.  Had these resources been in a
   separate ROA, there would have been no neccessary change to the
   issuing CA certificate, and therefore no necessary invalidity.

   CAs should carefully coordinate ROA updates with resource certificate
   updates.  This process may be automated if a single entity manages
   both the parent CA and the CA issuing the ROAs (scenario D in
   [[RFC8211] Section 3]).  However, in other deployment scenarios, this
   coordination becomes more complex.  For the ROA containing multiple
   IP prefixes, these IP prefixes share the same expiry configuration.
   If the ROA is not reissued in a timely manner, the whole set of IP
   prefixes will be affected after expiry as the ROA becomes invalid.
   Had these prefixes been in separately issued ROA, their validity
   interval would be unique to each ROA, and invalidity only affected by
   re-issuance of the specific parent CA which issued them.

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   A prefix could be allowed to be originated from an AS only for a
   specific period of time, for example if the IP prefix was leased out
   temporarily.  This would be more difficult to manage, and potentially
   be more error-prone if a ROA with multiple IP prefixes was used.
   Similarly more complex routing may demand changes in asID or routes
   for a subset of prefixes.  Re-issuance of the ROA may cause change to
   validity for all routes in the affected ROA.  If the time limited
   resources are in a separate ROA, or for more complex routing if each
   change in asID or routes for a given prefix reflects changes to
   discrete ROA, then no change to validity of unaffected routes will be
   caused.

   The use of ROA with a single IP prefix can minimize these side-
   effects.  It avoids fate-sharing irrespective of the causes, where
   the parent CA issuing each ROA remains valid and where each ROA
   itself remains valid.

4.  Recommendations

   For normal ROA issuance, it is recommended to include a single IP
   prefix in each ROA, and to issue one ROA for each advertised prefix.

   In some special scenarios, for example where the resource ownership
   and route origin state is stable (e.g., the IP addresses of a DNS
   root server and the related AS number), or a CA has operational
   problems producing increased number of individual ROAs, or if the
   goal is to implement fate-sharing for a set of prefixes as a
   deliberate policy then multiple IP prefixes may be grouped into one
   ROA.

   Where announced prefixes align and would permit aggregation, but the
   aggregated one is not announced in Border Gateway Protoco (BGP), it
   is not recommended to aggregate multiple announced prefixes into one
   ROA by adjusting prefix length ([RFC9319] Section 5: Recommendations
   about Minimal ROAs and maxLength).  Instead, the specific announced
   prefixes should have their own ROA.

5.  Security Considerations

   Issuing separate ROAs for independent IP prefixes may increase the
   file fetch burden on RP during validation.  Then some compression
   algorithm as in [GSG17] MAY be adopted to reduce the potential impact
   on the performance of the RPKI ecosystem.

6.  IANA Considerations

   This document does not request any IANA action.

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7.  Acknowledgements

   The authors wish to thank the following people for their review and
   contributions to this document: George Michaelson, Tim Bruijnzeels,
   Job Snijders, Di Ma, Geoff Huston, Tom Harrison, Rob Austein, Stephen
   Kent, Christopher Morrow, Russ Housley, Ching-Heng Ku, Keyur Patel,
   Cuiling Zhang and Kejun Dong.  Thanks are also due to Warren Kumari
   for the Security Area Directorate review.

   This work was supported by the Beijing Nova Program of Science and
   Technology under grant Z191100001119113.

   This document was produced using the xml2rfc tool [RFC2629].

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3779]  Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
              Addresses and AS Identifiers", RFC 3779,
              DOI 10.17487/RFC3779, June 2004,
              <https://www.rfc-editor.org/info/rfc3779>.

   [RFC6480]  Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
              February 2012, <https://www.rfc-editor.org/info/rfc6480>.

   [RFC6482]  Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
              Origin Authorizations (ROAs)", RFC 6482,
              DOI 10.17487/RFC6482, February 2012,
              <https://www.rfc-editor.org/info/rfc6482>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8211]  Kent, S. and D. Ma, "Adverse Actions by a Certification
              Authority (CA) or Repository Manager in the Resource
              Public Key Infrastructure (RPKI)", RFC 8211,
              DOI 10.17487/RFC8211, September 2017,
              <https://www.rfc-editor.org/info/rfc8211>.

8.2.  Informative References

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   [GSG17]    Gilad, Y., Sagga, O., and S. Goldberg, "MaxLength
              Considered Harmful to the RPKI", CoNEXT '17,
              DOI 10.1145/3143361.3143363, December 2017,
              <https://eprint.iacr.org/2016/1015.pdf>.

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              DOI 10.17487/RFC2629, June 1999,
              <https://www.rfc-editor.org/info/rfc2629>.

   [RFC9319]  Gilad, Y., Goldberg, S., Sriram, K., Snijders, J., and B.
              Maddison, "The Use of maxLength in the Resource Public Key
              Infrastructure (RPKI)", BCP 185, RFC 9319,
              DOI 10.17487/RFC9319, October 2022,
              <https://www.rfc-editor.org/info/rfc9319>.

Authors' Addresses

   Zhiwei Yan
   CNNIC
   No.4 South 4th Street, Zhongguancun
   Beijing, 100190
   P.R. China
   Email: yanzhiwei@cnnic.cn

   Randy Bush
   IIJ Research Lab & Arrcus, Inc.
   Email: randy@psg.com

   Guanggang Geng
   Jinan University
   No.601, West Huangpu Avenue
   Guangzhou
   510632
   P.R. China
   Email: gggeng@jnu.edu.cn

   Ties de Kock
   RIPE NCC
   Stationsplein 11
   Amsterdam
   Netherlands
   Email: tdekock@ripe.net

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   Jiankang Yao
   CNNIC
   No.4 South 4th Street, Zhongguancun
   Beijing, 100190
   P.R. China
   Email: yaojk@cnnic.cn

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