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Versions: 00 01 02 03                                    Standards Track
Network Working Group                                            R. Bush
Internet-Draft                           IIJ Research Lab & Arrcus, Inc.
Updates: 8481 (if approved)                                     K. Patel
Intended status: Standards Track                            Arrcus, Inc.
Expires: 7 January 2023                                         P. Smith
                                        PFS Internet Development Pty Ltd
                                                                M. Tinka
                                                             6 July 2022

                RPKI-Based Policy Without Route Refresh


   A BGP Speaker performing RPKI-based policy should not issue Route
   Refresh to its neighbors because it has received new RPKI data.  This
   document updates RFC8481 by describing how to avoid doing so by
   either keeping a full Adj-RIB-In or saving paths dropped due to ROV
   so they may be reevaluated with respect to new RPKI data.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "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.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 7 January 2023.

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Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Related Work  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  ROV Experience  . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Keeping Partial Adj-RIB-In Data . . . . . . . . . . . . . . .   3
   5.  Operational Recommendations . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Memory constraints in early BGP speakers caused classic [RFC4271] BGP
   implementations to not keep a full Adj-RIB-In (Sec. 1.1).  When doing
   RPKI-based Route Origin Validation ([RFC6811] and [RFC8481]), and
   similar RPKI-based policy, if such a BGP speaker receives new RPKI
   data, it might not have kept paths previously marked as Invalid etc.
   Such an implementation must then request a Route Refresh [RFC7313]
   from its neighbors to recover the paths which might be covered by
   these new RPKI data.  This will be perceived as rude by those
   neighbors as it passes a serious resource burden on to them.  This
   document recommends implementations keep and mark paths affected by
   RPKI-based policy so Route Refresh is no longer needed.

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2.  Related Work

   It is assumed that the reader understands BGP, [RFC4271] and Route
   Refresh [RFC7313], the RPKI [RFC6480], Route Origin Authorizations
   (ROAs), [RFC6482], The Resource Public Key Infrastructure (RPKI) to
   Router Protocol [I-D.ietf-sidrops-8210bis], RPKI-based Prefix
   Validation, [RFC6811], and Origin Validation Clarifications,

3.  ROV Experience

   As Route Origin Validation dropping Invalids has deployed, some BGP
   speaker implementations have been found which, when receiving new
   RPKI data (VRPs, see [I-D.ietf-sidrops-8210bis]) issue a BGP Route
   Refresh [RFC7313] to all sending BGP peers so that it can reevaluate
   the received paths aginst the new data.

   In actual deployment this has been found to be very destructive,
   transferring a serious resource burden to the unsuspecting peers.  In
   reaction, RPKI based Route Origin Validation (ROV) has been turned
   off.  There have been actual de-peerings.

   As RPKI registration and ROA creation have steadily increased, this
   problem has increased, not just proportionally, but on the order of
   the in-degree of ROV implementing BGP speakers.  As ASPA
   ([I-D.ietf-sidrops-aspa-verification]) becomes used, the problem will

4.  Keeping Partial Adj-RIB-In Data

   Ameliorating this problem by keeping a full Adj-RIB-In can be a
   problem for resource constrained BGP speakers.  In reality, only some
   data need be retained.

   When RPKI data cause one or more paths to be dropped due to ROV,
   those paths MUST NOT be evaluated for best path, but MUST be saved
   (either separately or marked) so they may be reevaluated with respect
   to new RPKI data.

   If new RPKI data arrive which invalidate the best path, and the BGP
   speaker did not keep all alternatives, then it MUST issue a route
   refresh so those alternatives may be evaluated for best path.

   Policy which may drop paths due to RPKI-based checks such as ROV,
   ASPA, BGPsec [RFC8205], etc.  MUST be run, and the dropped paths
   saved per the above paragraph, before non-RPKI policies are run, as
   the latter may change path attributes.

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   As storing these paths could cause problems in resource constrained
   devices, there MUST be a knob allowing operator control of this
   feature.  Such a knob MUST NOT be per peer, as this could cause
   inconsistent behavior.

   If Route Refresh has been issued toward more than one peer, the order
   of receipt of the refresh data can cause churn in both best path
   selection and in outbound signaling.

5.  Operational Recommendations

   Operators deploying ROV and/or other RPKI based policies SHOULD
   ensure that the BGP speaker implementation is not causing unnecessary
   Route Refresh requests to neighbors.

   BGP Speakers MUST either keep the full Adj-RIB-In or implement the
   specification in Section 4.

   If the BGP speaker does not implement these recommendations, the
   operator SHOULD enable the vendor's knob to keep the full Adj-RIB-In,
   sometimes referred to as "soft reconfiguration inbound".  The
   operator should then measure to ensure that there are no unnecessary
   Route Refresh requests sent to neighbors.

   If the BGP speaker has insufficient resources to support either of
   the two proposed options, it MUST NOT be used for Route Origin
   Validation.  I.e. the knob in Section 4 should only be used in very
   well known and controlled circumstances.

   Operators using the specification in Section 4 should be aware that a
   misconfigured neighbor might erroneously send a massive number of
   paths, thus consuming a lot of memory.  Pre-policy filtering such as
   described in [I-D.sas-idr-maxprefix-inbound] SHOULD be used to reduce
   this exposure.

   Internet Exchange Points (IXPs)which provide [RFC7947] Route Servers
   should be aware that some members could be causing an undue Route
   Refresh load on the Route Servers and take appropriate administrative
   and/or technical measures.  IXPs using BGP speakers as route servers
   should ensure that they are not generating excessive route refresh

6.  Security Considerations

   This document describes a denial of service which Route Origin
   Validation or other RPKI policy may place on a BGP neighbor, and
   describes how it may be ameliorated.

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   Otherwise, this document adds no additional security considerations
   to those already described by the referenced documents.

7.  IANA Considerations


8.  Acknowledgements

   The authors wish to thank Ben Maddison, Derek Yeung, John Heasley,
   John Scudder, Matthias Waehlisch, Nick Hilliard, Saku Ytti, and Ties
   de Kock.

9.  References

9.1.  Normative References

              Aelmans, M., Stucchi, M., and J. Snijders, "BGP Maximum
              Prefix Limits Inbound", Work in Progress, Internet-Draft,
              draft-sas-idr-maxprefix-inbound-04, 19 January 2022,

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,

   [RFC7313]  Patel, K., Chen, E., and B. Venkatachalapathy, "Enhanced
              Route Refresh Capability for BGP-4", RFC 7313,
              DOI 10.17487/RFC7313, July 2014,

   [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>.

9.2.  Informative References

              Bush, R. and R. Austein, "The Resource Public Key
              Infrastructure (RPKI) to Router Protocol, Version 2", Work

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              in Progress, Internet-Draft, draft-ietf-sidrops-8210bis-
              10, 16 June 2022, <https://www.ietf.org/archive/id/draft-

              Azimov, A., Bogomazov, E., Bush, R., Patel, K., and J.
              Snijders, "Verification of AS_PATH Using the Resource
              Certificate Public Key Infrastructure and Autonomous
              System Provider Authorization", Work in Progress,
              Internet-Draft, draft-ietf-sidrops-aspa-verification-08,
              25 August 2021, <https://www.ietf.org/archive/id/draft-

   [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,

   [RFC6811]  Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
              Austein, "BGP Prefix Origin Validation", RFC 6811,
              DOI 10.17487/RFC6811, January 2013,

   [RFC7947]  Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
              "Internet Exchange BGP Route Server", RFC 7947,
              DOI 10.17487/RFC7947, September 2016,

   [RFC8205]  Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol
              Specification", RFC 8205, DOI 10.17487/RFC8205, September
              2017, <https://www.rfc-editor.org/info/rfc8205>.

   [RFC8481]  Bush, R., "Clarifications to BGP Origin Validation Based
              on Resource Public Key Infrastructure (RPKI)", RFC 8481,
              DOI 10.17487/RFC8481, September 2018,

Authors' Addresses

   Randy Bush
   IIJ Research Lab & Arrcus, Inc.
   1856 SW Edgewood Dr
   Portland, Oregon 97210
   United States of America

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   Email: randy@psg.com

   Keyur Patel
   Arrcus, Inc.
   2077 Gateway Place, Suite #400
   San Jose, CA 95119
   United States of America
   Email: keyur@arrcus.com

   Philip Smith
   PFS Internet Development Pty Ltd
   PO Box 1908
   Milton QLD 4064
   Email: pfsinoz@gmail.com

   Mark Tinka
   Building 7, Design Quarter District, Leslie Avenue, Magaliessig
   Fourways, Gauteng
   South Africa
   Email: mark@tinka.africa

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