Avoidance for ROA Containing Multiple IP Prefixes
draft-ietf-sidrops-roa-considerations-02

SIDR Operations                                                   Z. Yan
Internet-Draft                                                     CNNIC
Intended status: Informational                                   R. Bush
Expires: 29 October 2022                       Internet Initiative Japan
                                                               G.G. Geng
                                                        Jinan University
                                                                  J. Yao
                                                                   CNNIC
                                                              April 2022

           Avoidance for ROA Containing Multiple IP Prefixes
                draft-ietf-sidrops-roa-considerations-02

Abstract

   In RPKI, the address space holder needs to issue an ROA object when
   authorizing one or more ASes to originate routes to IP prefix(es).
   During ROA issurance process, the address space holder may need to
   specify an origin AS for a list of IP prefixes.  Additionally, the
   address space holder is free to choose to put multiple prefixes into
   a single ROA or issue separate ROAs for each prefix according to the
   current specification.  This memo analyzes some operational problems
   which may arise from ROAs containing multiple IP prefixes and
   recommends avoiding placing multiple IP prefixes in one ROA.

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Copyright Notice

   Copyright (c) 2022 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 and Analysis  . . . . . . . . . . . . . . .   3
   4.  Suggestions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Appendix A.  ROA Analysis . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   In Resource Public Key Infrastructure (RPKI), Route Origin
   Authorization (ROA) is a digitally signed object which identifies
   that a single 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 prefixes.  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 ASes to advertise the
   same set of address prefixes, the holder must issue multiple ROAs,
   one for each AS number.  However, at present there are no mandatory
   requirements describing that the address space holders must issue a
   separate ROA for each prefix or a ROA containing multiple 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 and Analysis

   Currently, there are about 24% ROAs containing two or more prefixes.
   Among them, the average number of prefixes per ROA exceeds 10.

   For ROAs containing multiple prefixes, adding or deleting one <AS,
   ip_prefix> pair, the entire ROA must be withdrawn and reissued, or
   covered by a new ROA.  That is, although aggregating multiple IP
   prefixes can reduce the number of issued ROA, updating an ROA
   containing multiple IP address prefixes will result in redundant
   transmission between RP and BGP routers because in reality just the
   changed IP prefix needs to be updated by the new ROA.  Updating these
   ROAs frequently will increase the convergence time of BGP routers and
   reduce the stability of RPKI and BGP system.

   In addition, ROAs have a long validity period in default, during
   which the prefix ownership is more likely to change (of course,
   resource shrink may happen at any time), which will lead to the
   withdrawal or reissue of the whole set of prefixes aggregated within
   the same ROA.  This will increase the mis-configuration possibility
   and operational complexity [RFC8211].  If one prefix is included in
   the list by mistake, the whole ROA will not be generated
   successfully.

4.  Suggestions

   The following suggestions should be considered during the process of
   ROA issurance:

   1) It's the most important to guarantee the stability and security of
   RPKI and BGP system, and it is recommended to include a single IP
   prefix in each ROA in default.

   2) In some special scenarios, where the resource is very stable or a
   CA has operational problems producing increased number of individual
   ROAs, multiple IP prefixes may be aggregated in one ROA.

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5.  Security Considerations

   This memo does not give rise to additional security risks.

6.  IANA Considerations

   This document does not request any IANA action.

7.  Acknowledgements

   The authors would like to thanks the valuable comments made by
   members of sidrops WG and the list will be updated later.

   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>.

   [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>.

   [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>.

8.2.  Informative References

   [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>.

   [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>.

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Appendix A.  ROA Analysis

   In order to illustrate the situations of the current ROA database,
   the following analysis is made.

    +-------------- -+----------------------+-------------------------+
    | The total      | The number of ROAs   | The number of ROAs with |
    | number of ROAs | with a single prefix | multiple prefixes       |
    +----------------+----------------------+-------------------------+
    | 105542         | 81759                | 23783                   |
    +----------------+----------------------+-------------------------+

                Figure 1: Statistical results of global ROAs

   As shown in Figure. 1, by April 24th 2022, the total number of ROA
   objects issued is about 105542.  Based on the further analysis on
   these ROA objects, it is found that the number of ROAs containing
   only one prefix is about 81759 (77.47% of all ROA objects), and the
   number of ROAs containing two or more prefixes is about 23783 (22.53%
   of all ROA objects).

   In the 23783 ROA objects which each one contains two or more
   prefixes, the number of IP address prefixes are calculated and
   analyzed.  The statistical results are shown in Figure. 2.

    +----------------+----------------+--------------------------------+
    | The number of  | The number of  | The average number of prefixes |
    | prefixes       |  ROAs          |  in each ROA                   |
    +----------------+----------------+--------------------------------+
    | 248693         | 23783          |  10.46                         |
    +----------------+----------------+--------------------------------+

      Figure 2: Statistical results of the ROAs with multiple prefixes

   As described in Figure. 2, there are 248693 IP address prefixes in
   the 23783 ROA objects.  And the average number of prefixes in each
   ROA is 10.46 (248693/23783).  In addition, four types of ROAs are
   analyzed and calculated within the 23783 ROAs: ROAs each contains
   2-10/11-50/51-100/>100 IP address prefixes.  The statistical results
   are presented in Figure. 3.

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    +----------+----------+----------+----------+----------+-------+
    | ROA      | ROA with | ROA with | ROA with | ROA with | Total |
    | types    | 2-10     | 11-50    | 51-100   | >100     | number|
    |          | prefixes | prefixes | prefixes | prefixes |       |
    +----------+----------+----------+----------+----------+-------+
    | The      |  20286   |   2880   |    322   |    295   | 23783 |
    | number   |          |          |          |          |       |
    | of ROAs  |          |          |          |          |       |
    +----------+----------+----------+----------+----------+-------+
    | The      | 85.30%   |  12.11%  |  1.35%   |  1.24%   | 100%  |
    | ratio of |          |          |          |          |       |
    | ROAs     |          |          |          |          |       |
    +----------+----------+----------+----------+----------+-------+
    | The      |  74504   |  59015   |  22244   |  92930   |248693 |
    | number   |          |          |          |          |       |
    | of       |          |          |          |          |       |
    | prefixes |          |          |          |          |       |
    +----------+----------+----------+----------+----------+-------+
    | The      | 29.96%   | 23.73%   |  8.94%   | 37.37%   | 100%  |
    | ratio of |          |          |          |          |       |
    | prefixes |          |          |          |          |       |
    +----------+----------+----------+----------+----------+-------+

            Figure 3: Statistical results of four types of ROAs

   As shown in Figure. 3, taking the first type of ROA as an example,
   there are 20286 ROAs (85.3% of the 23783 ROA objects) which each
   contains 2-10 IP address prefixes, and the total number of IP
   prefixes in these 20286 ROAs is 74504 (29.96% of the 248693
   prefixes).

   It shows that the address space holders tend to issue each ROA object
   with fewer IP prefixes (more than 95% of ROAs containing less than 50
   prefixes), but they still tend to put multiple prefixes into one
   single ROA.

   The longest and shortest validity periods of a single ROA is 28854
   days and 2 days.  In addition, the average validity period of each
   ROA is 707.83 days.

Authors' Addresses

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

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   Randy Bush
   Internet Initiative Japan
   Email: randy@psg.com

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

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

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