Network Working Group                                            R. Bush
Internet-Draft                                 Internet Initiative Japan
Intended status: BCP                                        May 23, 2011
Expires: November 24, 2011

                 RPKI-Based Origin Validation Operation


   Deployment of 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",
   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 November 24, 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
   ( 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
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   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  . . . . . . . . . . . . . . . . . . . . . . . 5
   5.  Routing Policy  . . . . . . . . . . . . . . . . . . . . . . . . 5
   6.  Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     10.1.  Normative References . . . . . . . . . . . . . . . . . . . 7
     10.2.  Informative References . . . . . . . . . . . . . . . . . . 8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 8

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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 is in very initial stages of deployment, there is no
   root trust anchor, initial testing is being done by the IANA and some
   RIRs, and there is a technical testbed.  It is thought that origin
   validation based on the RPKI will be deployed incrementally 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 down-streams, and by
   small stub/enterprise/edge routers.

   Origin validation has been designed to be deployed on current routers
   without significant 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 what is seen as
   today's normal Internet routing is threatened by imprudent 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], RPKI-based
   Prefix Validation, see [I-D.ietf-sidr-pfx-validate], and Ghostbuster
   Records, see [I-D.ietf-sidr-ghostbusters].

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.  Network operators SHOULD take maximum advantage of
   this feature to minimize load on the global distributed RPKI

   As RPKI-based origin validation relies on the availability of RPKI
   data, operators SHOULD locate caches close to routers that require
   these data and services.  A router can peer with one or more nearby

   For redundancy, a router SHOULD peer with more than one cache at the
   same time.  Peering with two or more, at least one local and others
   remote, is recommended.

   If an operator trusts upstreams to carry their traffic, they SHOULD
   also trust the RPKI data those upstreams cache, and SHOULD peer with
   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 SHOULD validate origins in
   announcements made by upstreams, down-streams, and peers.  They still
   SHOULD trust the caches provided by their upstreams.

   Before issuing a ROA for a block, an operator MUST ensure that any
   sub-allocations from that block which are announced by other ASs,
   e.g. customers, have correct ROAs in play.  Otherwise, issuing a ROA
   for the super-block will cause the announcements of sub-allocations
   with no ROAs to be Invalid.

   Use of RPKI-based origin validation removes any need to originate
   more specifics to protect against mis-origination of a less specific
   prefix.  Having a ROA for the covering prefix should protect it.

   To aid translation of ROAs into efficient search algorithms in
   routers, ROAs SHOULD be as precise as possible, i.e. match prefixes
   as announced in BGP.  E.g. software and operators SHOULD avoid use of
   excessive max length values in ROAs unless operationally necessary.

   One advantage of minimal ROA length is that the forged origin attack
   does not work for sub-prefixes that are not covered by overly long
   max length.  E.g. if, instead of, one issues and, a forged origin attack can not succeed
   against  They must attack the whole /16, which is more
   likely to be noticed.

   Therefore, ROA generation software MUST use the prefix length as the
   max length if the user does not specify a max length.

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   Operators SHOULD be conservative in use of max length in ROAs.  E.g.,
   if a prefix will have only a few sub-prefixes announced, multiple
   ROAs for the specific announcements SHOULD be used as opposed to one
   ROA with a long max length.

   An environment where private address space is announced in eBGP the
   operator MAY have private RPKI objects which cover these private
   spaces.  This will require a trust anchor created and owned by that
   environment, see [I-D.ietf-sidr-ltamgmt].

   Operators issuing ROAs may have customers announce their own prefixes
   and ASs into global eBGP but who do not wish to go though the work to
   manage the relevant certificates and ROAs.  The operator SHOULD
   provision the RPKI data for these customers just as they provision
   many other things for them.

   While a an operator using RPKI data MAY choose any frequency they
   wish for ensuring they have a fresh RPKI cache, if they use RPKI data
   as an input to operational routing decisions, they SHOULD ensure
   local cache freshness at least every four to six hours.

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/down-streams 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 SHOULD be specified by the operator's local policy.

   Local policy using relative preference is suggested to manage the
   uncertainty associated with a system in early deployment, applying
   local policy to eliminate the threat of unroutability of prefixes due

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   to ill-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,
   MAY occur.

   As origin validation will be rolled out incrementally, coverage will
   be incomplete for a long time.  Therefore, routing on NotFound
   validity state SHOULD be done 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 dropping
   or giving very low preference to 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 MAY NOT upgrade an
   invalid announcement to valid or better.

   Announcements with Valid origins SHOULD be preferred over those with
   NotFound or Invalid origins, if the latter are accepted at all.

   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].

   Operators which manage certificates SHOULD have RPKI Ghostbuster
   Records (see [I-D.ietf-sidr-ghostbusters]), signed indirectly by End

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   Entity certificates, for those certificates on which others' routing
   depends for certificate and/or ROA validation.

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

   Origin validation does not address the problem of AS-Path validation.
   Therefore paths are open to manipulation, either malicious or

   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, Sandy Murphy, Keyur Patel, Heather and Jason
   Schiller, John Scudder, Kotikalapudi Sriram, 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.

              Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", draft-ietf-sidr-arch-12 (work in
              progress), February 2011.

              Huston, G., Loomans, R., and G. Michaelson, "A Profile for
              Resource Certificate Repository Structure",

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              draft-ietf-sidr-repos-struct-07 (work in progress),
              February 2011.

              Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
              Origin Authorizations (ROAs)",
              draft-ietf-sidr-roa-format-10 (work in progress),
              February 2011.

              Bush, R. and R. Austein, "The RPKI/Router Protocol",
              draft-ietf-sidr-rpki-rtr-11 (work in progress),
              March 2011.

              Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
              Austein, "BGP Prefix Origin Validation",
              draft-ietf-sidr-pfx-validate-01 (work in progress),
              February 2011.

              Bush, R., "The RPKI Ghostbusters Record",
              draft-ietf-sidr-ghostbusters-03 (work in progress),
              March 2011.

              Kent, S. and M. Reynolds, "Local Trust Anchor Management
              for the Resource Public Key Infrastructure",
              draft-ietf-sidr-ltamgmt-00 (work in progress),
              November 2010.

10.2.  Informative References

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

              Kumari, W., "Deprecation of BGP AS_SET, AS_CONFED_SET.",
              draft-wkumari-deprecate-as-sets-01 (work in progress),
              September 2010.

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Author's Address

   Randy Bush
   Internet Initiative Japan
   5147 Crystal Springs
   Bainbridge Island, Washington  98110

   Phone: +1 206 780 0431 x1

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