Network Working Group R. Bush
Internet-Draft IIJ
Intended status: BCP January 21, 2011
Expires: July 25, 2011
RPKI-Based Origin Validation Operation
draft-ietf-sidr-origin-ops-03
Abstract
Deployment of the RPKI-based BGP origin validation has many
operational considerations. This document attempts to collect and
present them. It is expected to evolve as RPKI-based origin
validation is deployed and the dynamics are better understood.
Requirements Language
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 RFC 2119 [RFC2119].
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
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This Internet-Draft will expire on July 25, 2011.
Copyright Notice
Copyright (c) 2011 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . 3
3. RPKI Distribution and Maintenance . . . . . . . . . . . . . . . 3
4. Within a Network . . . . . . . . . . . . . . . . . . . . . . . 4
5. Routing Policy . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
RPKI-based origin validation relies on widespread propagation of the
Resource Public Key Infrastructure (RPKI) [I-D.ietf-sidr-arch]. How
the RPKI is distributed and maintained globally is a serious concern
from many aspects.
The global RPKI has yet to be deployed, only a testbed exists, and
some beta testing is being done by the IANA and some RIRs. It is
expected to be deployed incrementally over a number of years. It is
thought that origin validation based on the RPKI will deploy over the
next year to five years.
Origin validation only need be done by an AS's border routers and is
designed so that it can be used to protect announcements which are
originated by large providers, upstreams and downstreams, and by
small stub/entetprise/edge routers.
Origin validation has been designed to be deployed on current routers
without hardware upgrade. It should be used by everyone from large
backbones to small stub/entetprise/edge routers.
RPKI-based origin validation has been designed so that, with prudent
local routing policies, there is little risk that normal Internet
routing is threatened by unprudent deployment of the global RPKI, see
Section 5.
2. Suggested Reading
It is assumed that the reader understands BGP, [RFC4271], the RPKI,
see [I-D.ietf-sidr-arch], the RPKI Repository Structure, see
[I-D.ietf-sidr-repos-struct], ROAs, see [I-D.ietf-sidr-roa-format],
the RPKI to Router Protocol, see [I-D.ietf-sidr-rpki-rtr], and RPKI-
based Prefix Validation, see [I-D.ietf-sidr-pfx-validate].
3. RPKI Distribution and Maintenance
The RPKI is a distributed database containing certificates, CRLs,
manifests, ROAs, and Ghostbuster Records as described in
[I-D.ietf-sidr-repos-struct]. Policies and considerations for RPKI
object generation and maintenance are discussed elsewhere.
A local valid cache containing all RPKI data may be gathered from the
global distributed database using the rsync protocol and a validation
tool such as rcynic.
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Validated caches may also be created and maintained from other
validated caches. An operator should take maximum advantage of this
feature to minimize load on the global distributed RPKI database.
As RPKI-based origin validation relies on the availability of RPKI
data, operators will likely want border routers to have one or more
nearby caches.
For redundancy, a router may peer with more than one cache at the
same time. Peering with two or more, one local and others remote, is
recommended.
If an operator or site trusts upstreams to carry their traffic, they
might as well trust the RPKI data those upstreams cache and peer with
of those caches. Note that this places an obligation on those
upstreams to maintain fresh and reliable caches.
A transit provider or a network with peers will want to validate
origins in announcements made by downstreams and peers. They still
may choose to trust the caches provided by their upstreams.
4. Within a Network
Origin validation need only be done by edge routers in a network,
those which border other networks/ASs.
A validating router will use the result of origin validation to
influence local policy within its network, see Section 5. In
deployment this policy should fit into the AS's existing policy,
preferences, etc. This allows a network to incrementally deploy
validation capable border routers.
eBGP speakers which face more critical peers or up/downstreams would
be candidates for the earliest deployment. Validating more critical
received announcements should be considered in partial deployment.
5. Routing Policy
Origin validation based on the RPKI merely marks a received
announcement as having an origin which is Valid, NotFound, or
Invalid. See [I-D.ietf-sidr-pfx-validate]. How this is used in
routing is specified by the operator's local policy.
Local policy using relative preference is suggested to manage the
uncertainty associated with a system in flux, applying local policy
to eliminate the threat of unroutability of prefixes due to ill-
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advised certification policies and/or incorrect certification data.
E.g. until the community feels comfortable relying on RPKI data,
routing on Invalid origin validity, though at a low preference, will
likely be prevalent for a long time.
As origin validation will be rolled out incrementally, coverage will
be incomplete for a long time. Therefore, routing on NotFound
validity state will be advisable for a long time. As the transition
moves forward, the number of BGP announcements with validation state
NotFound should decrease. Hence an operator's policy should not be
overly strict, preferring Valid announcements, attaching a lower
preference to, but still using, NotFound announcements, and giving
very low preference to, but still using, Invalid announcements.
Some may choose to use the large Local-Preference hammer. Others
might choose to let AS-Path rule and set their internal metric, which
comes after AS-Path in the BGP decision process.
When using a metric which is also influenced by other local policy,
the operator should be careful not to create privilege upgrade
vulnerabilities. E.g. if Local Pref is set depending on validity
state, be careful that peer community signaling can not upgrade an
invalid announcement to valid or better.
Announcements with Valid origins SHOULD be preferred over those with
NotFound or Invalid origins.
Announcements with NotFound origins SHOULD be preferred over those
with Invalid origins.
Announcements with Invalid origins MAY be used, but SHOULD be less
preferred than those with Valid or NotFound.
6. Notes
Like the DNS, the global RPKI presents only a loosely consistent
view, depending on timing, updating, fetching, etc. Thus, one cache
or router may have different data about a particular prefix than
another cache or router. There is no 'fix' for this, it is the
nature of distributed data with distributed caches.
There is some uncertainty about the origin AS of aggregates and what,
if any, ROA can be used. The long range solution to this is the
deprecation of AS-SETs, see [I-D.wkumari-deprecate-as-sets].
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7. Security Considerations
As the BGP origin is not signed, origin validation is open to
malicious spoofing. It is only designed to deal with inadvertent
mis-advertisement.
Origin validation does nothing about AS-Path validation and therefore
is open to monkey in the middle path attacks.
The data plane may not follow the control plane.
Be aware of the class of privilege escalation issues discussed in
Section 5 above.
8. IANA Considerations
This document has no IANA Considerations.
9. Acknowledgments
The author wishes to thank Rob Austein, Steve Bellovin, Pradosh
Mohapatra, Chris Morrow, Keyur Patel, Heather and Jason Schiller,
John Scudder, Maureen Stillman, and Dave Ward.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[I-D.ietf-sidr-arch]
Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", draft-ietf-sidr-arch-11 (work in
progress), September 2010.
[I-D.ietf-sidr-repos-struct]
Huston, G., Loomans, R., and G. Michaelson, "A Profile for
Resource Certificate Repository Structure",
draft-ietf-sidr-repos-struct-06 (work in progress),
November 2010.
[I-D.ietf-sidr-roa-format]
Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
Origin Authorizations (ROAs)",
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draft-ietf-sidr-roa-format-09 (work in progress),
November 2010.
[I-D.ietf-sidr-rpki-rtr]
Bush, R. and R. Austein, "The RPKI/Router Protocol",
draft-ietf-sidr-rpki-rtr-07 (work in progress),
January 2011.
[I-D.ietf-sidr-pfx-validate]
Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
Austein, "BGP Prefix Origin Validation",
draft-ietf-sidr-pfx-validate-00 (work in progress),
July 2010.
10.2. Informative References
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[I-D.wkumari-deprecate-as-sets]
Kumari, W., "Deprecation of BGP AS_SET, AS_CONFED_SET.",
draft-wkumari-deprecate-as-sets-01 (work in progress),
September 2010.
Author's Address
Randy Bush
Internet Initiative Japan, Inc.
5147 Crystal Springs
Bainbridge Island, Washington 98110
US
Phone: +1 206 780 0431 x1
Email: randy@psg.com
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