Problem Statement and Considerations for ROA containing Multiple Prefixes
draft-ietf-sidrops-roa-considerations-01
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| Authors | Zhiwei Yan , Randy Bush , Guanggang Geng , Jiankang Yao | ||
| Last updated | 2022-04-29 (Latest revision 2021-10-26) | ||
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draft-ietf-sidrops-roa-considerations-01
SIDR Operations Z. Yan
Internet-Draft CNNIC
Intended status: Informational R. Bush
Expires: April 28, 2022 Internet Initiative Japan
G. Geng
Jinan University
J. Yao
CNNIC
October 25, 2021
Problem Statement and Considerations for ROA containing Multiple
Prefixes
draft-ietf-sidrops-roa-considerations-01
Abstract
The address space holder needs to issue an ROA object when it
authorizes one or more ASes to originate routes to IP prefix(es).
During the process of ROA issuance, the address space holder may need
to specify an origin AS for a list of IP prefixes. Besides, the
address space holder has a free choice to put multiple prefixes into
a single ROA or issue separate ROAs for each prefix based on the
current specification. This memo analyzes and presents some
operational problems which may be caused by the ROAs containing
multiple IP prefixes. Some suggestions and considerations also have
been proposed.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 28, 2022.
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Copyright Notice
Copyright (c) 2021 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem statement and Analysis . . . . . . . . . . . . . . . 3
4. Suggestions and Considerations . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Route Origin Authorization (ROA) is a digitally signed object which
is used to identify 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].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 per AS number.
However, at present there are no mandatory requirements in any RFCs
describing that the address space holders must issue a separate ROA
for each prefix or a ROA containing multiple prefixes.
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. The ROAs with
multiple prefixes is a common case that each ROA contains exactly one
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AS number but may contain multiple IP address prefixes in the
operational process of ROA issuance.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Problem statement and Analysis
As mentioned above, the address space holder needs to issue an ROA
object when it authorizes one or more ASes to originate routes to
multiple prefixes. During the process of ROA issuance, the address
space holder always needs to specify an origin AS for a list of IP
prefixes. Besides, the address space holder has a free choice to put
multiple prefixes into a single ROA or issue separate ROAs for each
prefix based on the current specification.
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 |
+----------------+----------------------+-------------------------+
| 87334 | 66379 | 20955 |
+----------------+----------------------+-------------------------+
Figure 1: Statistical results of global ROAs
As shown in Figure. 1, by October 18th 2021, the total number of ROA
objects issued around the world is about 87334. The result is in
accordance with the statistics provided by RIPE NCC and Internet
Multifeed Co. (MF). Based on the further analysis on these ROA
objects, it is found that the number of ROAs containing only one
prefix is about 66379 (76.01% of all ROA objects), and the number of
ROAs containing two or more prefixes is about 20955 (23.99% of all
ROA objects).
In the 20955 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.
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+----------------+----------------+--------------------------------+
| The number of | The number of | The average number of prefixes |
| prefixes | ROAs | in each ROA |
+----------------+----------------+--------------------------------+
| 215425 | 20955 | 10.28 |
+----------------+----------------+--------------------------------+
Figure 2: Statistical results of the ROAs with multiple prefixes
As described in Figure. 2, there are 215425 IP address prefixes in
the 20955 ROA objects. And the average number of prefixes in each
ROA is 10.28 (215425/20955). In addition, four types of ROAs are
analyzed and calculated within the 20955 ROAs: ROAs each contains
2-10/11-50/51-100/>100 IP address prefixes. The statistical results
are presented in Figure. 3.
+----------+----------+----------+----------+----------+-------+
| ROA | ROA with | ROA with | ROA with | ROA with | Total |
| types | 2-10 | 11-50 | 51-100 | >100 | number|
| | prefixes | prefixes | prefixes | prefixes | |
+----------+----------+----------+----------+----------+-------+
| The | 17918 | 2508 | 272 | 257 | 20955 |
| number | | | | | |
| of ROAs | | | | | |
+----------+----------+----------+----------+----------+-------+
| The | 85.51% | 11.97% | 1.30% | 1.22% | 100% |
| ratio of | | | | | |
| ROAs | | | | | |
+----------+----------+----------+----------+----------+-------+
| The | 65744 | 51904 | 18475 | 79302 |215425 |
| number | | | | | |
| of | | | | | |
| prefixes | | | | | |
+----------+----------+----------+----------+----------+-------+
| The | 30.52% | 24.09% | 8.58% | 36.81% | 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 17918 ROAs (85.51% of the 20955 ROA objects) which each
contains 2-10 IP address prefixes, and the total number of IP
prefixes in these 17918 ROAs is 65744 (30.52% of the 215425
prefixes).
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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.
Furthermore, the ROA data of different RIR CAs are analyzed in
Figure. 4.
+---------------+-------+--------+--------+------+--------+------+
| | ARIN | AfriNIC| LACNIC | APNIC| RIPENCC| Total|
+---------------+-------+--------+--------+------+--------+------+
| The number of | 3388 | 486 | 2825 | 6439 | 14163 |25688 |
| active ASNs | | | | | | |
+---------------+-------+--------+--------+------+--------+------+
| The number of | 43156 | 3437 | 16974 | 78325| 139912 |281804|
| prefixes | | | | | | |
+---------------+-------+--------+--------+------+--------+------+
| The number of | 34871 | 2626 | 9581 | 14240| 26016 |87334 |
| ROAs | | | | | | |
+---------------+-------+--------+--------+------+--------+------+
| The average | 1.24 | 1.31 | 1.77 | 5.50 | 5.38 | 3.23 |
| number of | | | | | | |
| prefixes | | | | | | |
| in each ROA | | | | | | |
+---------------+-------+--------+--------+------+--------+------+
| The maximum | 608 | 64 | 292 | 3512 | 4088 | 4088 |
| number of | | | | | | |
| prefixes in | | | | | | |
| a single ROA | | | | | | |
+---------------+-------+--------+--------+------+--------+------+
| The longest | 3653 | 10588 | 28854 | 6373 | 546 |28854 |
| validity time | | | | | | |
| of a single | | | | | | |
| ROA | | | | | | |
+---------------+-------+--------+--------+------+--------+------+
| The shortest | 24 | 45 | 56 | 73 | 255 | 24 |
| validity time | | | | | | |
| of a single | | | | | | |
| ROA | | | | | | |
+---------------+-------+--------+--------+------+--------+------+
| The average |1656.91|1811.59 |1253.17 |353.87| 426.64 |661.50|
| validity time | | | | | | |
| in each ROA | | | | | | |
+---------------+-------+--------+--------+------+--------+------+
Figure 4: Statistical results of RIR CAs
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As shown in Figure 4, the total number of active ASNs on that day (
October 18th, 2021) has reached 25,688. Taking RIPENCC as an
example, it has the highest number of active ASNs and prefixes. And
the average number of prefixes in each ROA is 5.38 (139912 /26016 ).
According to the Figure 4, there are currently a maximum of 4088
prefixes used in a single ROA, while AfriNIC is more conservative,
and the maximum number of prefixes is only 64.
Still taking RIPENCC as an example, the longest and shortest validity
periods of a single ROA in RIPENCC is 546 days and 255 days. In
addition, the average validity period of each ROA in Ripencc is
426.64 days.
The potential influence of operations of ROAs containing multiple IP
prefixes on BGP routers must be considered. For the ROA containing
multiple prefixes, once increase or delete one <AS, ip_prefix> pair
in it, this whole ROA must be withdrawn and reissued. Through
sychronization with repository, Relying Party (RP) fetches a new ROA
object and then notify and send all the <AS, ip_prefix> pairs in this
ROA to BGP routers. That is to say, the update of the ROA containing
multiple IP address prefixes will lead to redundant transmission
between RP and BGP routers. So frequent update of these ROAs will
increase the convergency time of BGP routers and reduce their
performance obviously.
In addition, the validity period of ROA is a long time in default,
the prefix ownership change is more possible during this period, this
will cause the withdraw or re-issurance of the whole set of prefixes
containing within the same ROA. This will increase the mis-
configuration possibility and operational complexity. If one prefix
is contained in the list by mistake, the whole ROA will not be
generated successfully.
4. Suggestions and Considerations
The following suggestions should be considered during the process of
ROA issuance:
1) The issuance of ROAs containing a large number of IP prefixes may
lead to instability of BGP routing more easily than ROAs with fewer
IP prefixes even without mis-configurations.
A ROA which contains a large number of IP prefixes is more instable
and vulnerable to mis-configurations, because any update of these
prefixes may cause the issued ROA to be withdrawn. Besides, since
the misconfigurations of ROAs containing a larger number of IP
address prefixes may lead to much more serious consequences (a large-
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scale network interruption) than ROAs with fewer IP address prefixes,
it is suggested to avoid issuing ROAs with a large number of IP
address prefixes.
2) The number of ROAs containing multiple IP prefixes should be
limited and the number of IP prefixes in each ROA should also be
limited.
The extreme case (a single ROA can only contain one IP address
prefix) may lead to too many ROA objects globally, which may in turn
become a burden for RPs to synchronize and validate all these ROA
objects with the fully deployment of RPKI. So it seems that a
tradeoff between the number of ROAs and the number of IP prefixes in
a single ROA should be considered. However, considering the
stability and security of RPKI and BGP routing system is the most
important target, containing one IP address prefix in a single ROA is
recommended if the CA wants to avoids the potential instability and
risks.
5. Security Considerations
A safeguard scheme to protect and monitor the process of ROA issuance
should be considered. At least, when a ROA should be updated by the
address space holder because of the change of IP address prefix, the
CA GUI should warn the user that the ROA which is being created will
invalidate the current BGP announcement in the global BGP.
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
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[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>.
[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>.
8.2. Informative References
[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>.
Authors' Addresses
Zhiwei Yan
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing, 100190
P.R. China
Email: yanzhiwei@cnnic.cn
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
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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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