Internet Engineering Task Force (IETF) R. Bush
Request for Comments: 8481 Internet Initiative Japan
Updates: 6811 September 2018
Category: Standards Track
ISSN: 2070-1721
Clarifications to BGP Origin Validation Based on Resource Public Key
Infrastructure (RPKI)
Abstract
Deployment of BGP origin validation based on Resource Public Key
Infrastructure (RPKI) is hampered by, among other things, vendor
misimplementations in two critical areas: which routes are validated
and whether policy is applied when not specified by configuration.
This document is meant to clarify possible misunderstandings causing
those misimplementations; it thus updates RFC 6811 by clarifying that
all prefixes should have their validation state set and that policy
must not be applied without operator configuration.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8481.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
3. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 3
4. Evaluate ALL Prefixes . . . . . . . . . . . . . . . . . . . . 3
5. Set State, Don't Act . . . . . . . . . . . . . . . . . . . . 3
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Normative References . . . . . . . . . . . . . . . . . . . . 4
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Deployment of RPKI-based BGP origin validation is hampered by, among
other things, vendor misimplementations in two critical areas: which
routes are validated and whether policy is applied when not specified
by configuration. This document is meant to clarify possible
misunderstandings causing those misimplementations.
When a route is distributed into BGP, the origin validation state is
set to NotFound, Valid, or Invalid per [RFC6811]. Operational
testing has shown that the specifications of that RFC were not
sufficient to avoid divergent implementations. This document
attempts to clarify two areas which seem to cause confusion.
The implementation issues seem not to be about how to validate, i.e.,
how to decide if a route is NotFound, Valid, or Invalid. The issues
seem to be which routes should be evaluated and have their evaluation
state set, and whether to apply policy without operator
configuration.
2. Requirements Language
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. Suggested Reading
It is assumed that the reader understands BGP [RFC4271], the RPKI
[RFC6480], Route Origin Authorizations (ROAs) [RFC6482], and RPKI-
based Prefix Validation [RFC6811].
4. Evaluate ALL Prefixes
Significant Clarification: A router MUST evaluate and set the
validation state of all routes in BGP coming from any source (eBGP, (e.g.,
eBGP, iBGP, or redistribution from static, connected, etc.), static or connected routes),
unless specifically configured otherwise by the operator. Otherwise,
the operator does not have the ability to drop Invalid routes coming
from every potential source and is therefore liable to complaints
from neighbors about propagation of Invalid routes. For this reason,
[RFC6811] says:
When a BGP speaker receives an UPDATE from a neighbor, it SHOULD
perform a lookup as described above for each of the Routes in the
UPDATE message. The lookup SHOULD also be applied to routes that
are redistributed into BGP from another source, such as another
protocol or a locally defined static route.
[RFC6811] goes on to say, "An implementation MAY provide
configuration options to control which routes the lookup is applied
to."
When redistributing into BGP from connected, static, any source (e.g., IGP, iBGP, etc., or
from static or connected routes), there is no AS_PATH in the input to
allow RPKI validation of the originating Autonomous System (AS). In
such cases, the router MUST use the AS of the router's BGP
configuration. If that is ambiguous because of confederation, AS
migration, or other multi-AS configuration, then the router
configuration MUST provide a means of specifying the AS to be used on
the redistribution, either per redistribution or globally.
5. Set State, Don't Act
Significant Clarification: Once routes are evaluated and have their
state set, the operator should be in complete control of any policy
applied based on the evaluation state. Absent specific operator
configuration, policy MUST NOT be applied.
Automatic origin validation policy actions such as those described in
"BGP Prefix Origin Validation State Extended Community" [RFC8097]
MUST NOT be carried out or otherwise applied unless specifically
configured by the operator.
6. Security Considerations
This document does not create security considerations beyond those of
[RFC6811].
7. IANA Considerations
This document has no IANA actions.
8. 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>.
[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,
<https://www.rfc-editor.org/info/rfc4271>.
[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>.
[RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
Austein, "BGP Prefix Origin Validation", RFC 6811,
DOI 10.17487/RFC6811, January 2013,
<https://www.rfc-editor.org/info/rfc6811>.
[RFC8097] Mohapatra, P., Patel, K., Scudder, J., Ward, D., and R.
Bush, "BGP Prefix Origin Validation State Extended
Community", RFC 8097, DOI 10.17487/RFC8097, March 2017,
<https://www.rfc-editor.org/info/rfc8097>.
[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>.
Acknowledgments
Many thanks to John Scudder, who had the patience to give
constructive review multiple times, and Keyur Patel, who noted that
the AS might have to be specified. George Michaelson, Jay
Borkenhagen, John Heasley, and Matthias Waehlisch kindly helped clean
up loose wording.
Author's Address
Randy Bush
Internet Initiative Japan
5147 Crystal Springs
Bainbridge Island, Washington 98110
United States of America
Email: randy@psg.com