Network Working Group                                            T. King
Internet-Draft                                                C. Dietzel
Intended status: Standards Track                                 D. Kopp
Expires: August 12, 2018                                          DE-CIX
                                                         A. Lambrianidis
                                                                  AMS-IX
                                                              A. Fenioux
                                                               France-IX
                                                       February 08, 2018


     Signaling Prefix Origin Validation Results from an RPKI Origin
                  Validating BGP Speaker to BGP Peers
              draft-ietf-sidrops-validating-bgp-speaker-01

Abstract

   This document defines a new BGP transitive extended community, as
   well as its usage, to signal prefix origin validation results from an
   RPKI Origin validating BGP speaker to other BGP peers.  Upon
   reception of prefix origin validation results, peers can use this
   information in their local routing decision process.

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.

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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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 12, 2018.




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Copyright Notice

   Copyright (c) 2018 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  EBGP Prefix Origin Validation Extended Community  . . . . . .   3
   3.  BGP Prefix Origin Validation State Utilized at Validating
       Peers . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Signaling Prefix Origin Validation Results from a Validating
       Peer to Peers . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Operational Recommendations . . . . . . . . . . . . . . . . .   5
     5.1.  Local Routing Decision Process  . . . . . . . . . . . . .   5
     5.2.  Validating Peers Receiving the EBGP Prefix Origin
           Validation State Extended Community . . . . . . . . . . .   5
     5.3.  Information about Validity of a BGP Prefix Origin Not
           Available at a Validating Peer  . . . . . . . . . . . . .   6
     5.4.  Error Handling at Peers . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   RPKI-based prefix origin validation [RFC6480] can be a significant
   operational burden for BGP peers to implement and adopt.  To
   facilitate acceptance and usage of prefix origin validation and
   ultimately increase the security of the Internet routing system,
   Autonomous Systems may provide RPKI-based prefix origin validation at
   certain vantage points.  The result of this prefix origin validation
   is signaled to peers by using the EBGP Prefix Origin Validation State
   Extended Community as introduced in this document.




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   Peers receiving a prefix origin validation result from the validating
   EBGP peer can use this information in their local routing decision
   process for acceptance, rejection, preference, or other traffic
   engineering purposes of a particular route.

2.  EBGP Prefix Origin Validation Extended Community

   The origin validation state extended community is a transitive Four-
   octet AS Specific Extended Community [RFC5668] with the following
   encoding:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       0x02    |TBD1 (Sub-Type)|   Reserved    | Global Admin  :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :        Global Administrator (cont.)           |validationstate|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 1

   The value of the high-order octet of the extended Type field is 0x02,
   which indicates it is transitive.  The value of the low-order octet
   (Sub-Type) of the extended Type field as assigned by IANA is TBD1.
   The Reserved field MUST be set to 0 and ignored upon receipt of this
   community.  The Global Administrator field MUST be set to the AS
   number of the validating BGP speaker conducting the prefix origin
   validation.  The last octet of the extended community is an unsigned
   integer that gives the route's validation state as described in
   Section 4.

   If the validating BGP speaker is configured to support the extensions
   defined in this document, it SHOULD attach the origin validation
   state extended community to BGP UPDATE messages sent to EBGP peers by
   mapping the computed validation state in the last octet of the
   extended community.  A receiving BGP speaker, in the absence of a
   local validation state, SHOULD derive a validation state from the
   last octet of the received extended community, if present.

   An implementation SHOULD NOT send more than one instance of the
   origin validation state extended community.  However, if more than
   one instance is received, an implementation MUST disregard all
   instances other than the one with the numerically greatest validation
   state value.  If the value received is greater than the largest
   specified value (2), the implementation MUST apply a strategy similar
   to attribute discard [RFC7606] by discarding the erroneous community
   and logging the error for further analysis.




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3.  BGP Prefix Origin Validation State Utilized at Validating Peers

   A validating BGP speaker that is aware of a BGP Prefix Origin
   Validation state for a certain route can handle this information in
   one of the following modes of operation:

   Simple Tagging:  The prefix origin validation state is tagged to the
       route as described in Section 2.
       This mode of operation is similar to the traditional BGP decision
       process, moreover, the prefix origin validation state information
       is available for peers.

   Dropping and Tagging:  Routes for which the prefix origin validation
       state is "invalid" (according to [RFC6811]) are dropped by the
       validating BGP speaker.  Routes which show a prefix origin
       validation state of "not found" and "valid" (according to
       [RFC6811]) are tagged accordingly, as discussed in Section 2.
       In this mode of operation, security is rated higher than
       questionable reachability of a prefix.

   Prioritizing and Tagging:  If the validating BGP speaker holds for a
       particular prefix more than one route it removes the set of
       "invalid" routes first and secondly the "not found" routes unless
       the set of routes is empty.  Based on the remaining set of
       routes, the BGP best path selection algorithm is executed.  The
       selected route is marked according to Section 4.  The BGP best
       path selection algorithm is changed by this mode of operation in
       such a way that "valid" routes are preferred even if they are
       unfavorable by the traditional best path selection algorithm.
       This mode promotes prefix origin validation to be the most
       important criterion for the path selection.

   A validating BGP speaker MUST support the Simple Tagging operation
   mode.  Other modes of operation are OPTIONAL.  The mode of operation
   MAY be configured by the validating BGP speaker operator for all
   connected peers, or for each BGP session with a peer separately.

   Path hiding, as originally discussed in [RFC7947], may impact end-to-
   end connectivity for peers receiving prefixes via validating peers,
   if the best path selected contains a prefix with an "invalid" prefix
   origin validation state, and is subsequently dropped, either at the
   peer (Simple Tagging operation mode) or the validating BGP speaker
   itself (Dropping and Tagging operation mode).

   However, these modes of operation might be used in combination with
   [RFC7911] in order to allow a peer to receive all routes and take the
   routing decision by itself.




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4.  Signaling Prefix Origin Validation Results from a Validating Peer to
    Peers

   The EBGP Prefix Origin Validation State Community is utilized for
   signaling prefix origin validation result from a validating BGP
   speaker to other peers.

   This draft proposes an encoding of the prefix origin validation
   result [RFC6811] as follows:

                  +-------+-----------------------------+
                  | Value | Meaning                     |
                  +-------+-----------------------------+
                  |   0   | Lookup result = "valid"     |
                  |   1   | Lookup result = "not found" |
                  |   2   | Lookup result = "invalid"   |
                  +-------+-----------------------------+

                                  Table 1

   This encoding is re-used.  Validating peers providing RPKI-based
   prefix origin validation set the validation state according to the
   prefix origin validation result (see [RFC6811]).

5.  Operational Recommendations

5.1.  Local Routing Decision Process

   A peer receiving prefix origin validation results from the route
   server MAY use the information in its own local routing decision
   process.  The local routing decision process SHOULD apply to the
   rules as described in Section 5 [RFC6811].

   A peer receiving a prefix origin validation result from the route
   server MAY redistribute this information within its own AS.

   In cases where multiple ASes are being administered by the same
   authority, peers MAY also redistribute this information across EBGP
   boundaries of the authority in question.

5.2.  Validating Peers Receiving the EBGP Prefix Origin Validation State
      Extended Community

   A validating BGP speaker receiving routes from peers containing the
   EBGP Prefix Origin Validation State Extended Community MUST remove
   the extended community before the route is re-distributed to its
   peers.  This is required regardless of whether the validating BGP
   speaker is executing prefix origin validation or not.



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   Failure to do so would allow opportunistic peers to advertise routes
   tagged with arbitrary prefix origin validation results via validating
   peers, influencing maliciously the decision process of other, non-
   validating BGP speakers.

5.3.  Information about Validity of a BGP Prefix Origin Not Available at
      a Validating Peer

   In case information about the validity of a BGP prefix origin is not
   available at the validating BGP speaker (e.g., error in the ROA
   cache, CPU overload) the validating BGP speaker MUST NOT add the EBGP
   Prefix Origin Validation State Extended Community to the route.

5.4.  Error Handling at Peers

   A route sent by a validating BGP speaker SHOULD only contain none or
   one EBGP Prefix Origin Validation State Extended Community.

   A peer receiving a route from a validating BGP speaker containing
   more than one EBGP Prefix Origin Validation State Extended Community
   SHOULD only consider the largest value (as described in Table 1) in
   the validation result field and disregard the other values.  Values
   larger than two in the validation result field MUST be disregarded.

6.  IANA Considerations

   IANA is asked to assign a Transitive BGP Opaque Extended Community as
   defined in Section 4 of [RFC7153].

7.  Security Considerations

   All security considerations described in RFC6811 [RFC6811] fully
   apply to this document.

   Additionally, threat agents polluting ROA cache server(s) run by AS
   operators could cause significant operational impact, since multiple
   validating BGP speaker clients could be affected.  Peers should be
   vigilant as to the integrity and authenticity of the origin
   validation results as they are provided by a third party, namely the
   AS operator hosting both the validating BGP speaker as well as any
   ROA cache server(s).

   Therefore, a validating BGP speaker could be misused to spread
   malicious prefix origin validation results.  However, in the case of
   IXPs, peers already trust the route server for the collection,
   filtering (e.g., IRR database filtering), and redistribution of BGP
   routing information to other peers.




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   To facilitate trust and support with peers establishing appropriate
   controls in mitigating the risks mentioned above, AS operators SHOULD
   provide out-of-band means for peers to ensure that the ROA validation
   process has not been compromised or corrupted.

   While being under DDoS attacks, it is a common practice for peers
   connected to other Autonomous Systems and make use of blackholing
   services.  Peers are using blackholing to drop traffic, typically by
   announcing a more specific prefix, which is under attack.  A peer
   SHOULD make sure that this prefix is covered by an appropriate ROA.

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>.

   [RFC5668]  Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS
              Specific BGP Extended Community", RFC 5668,
              DOI 10.17487/RFC5668, October 2009,
              <https://www.rfc-editor.org/info/rfc5668>.

   [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>.

   [RFC7153]  Rosen, E. and Y. Rekhter, "IANA Registries for BGP
              Extended Communities", RFC 7153, DOI 10.17487/RFC7153,
              March 2014, <https://www.rfc-editor.org/info/rfc7153>.

   [RFC7606]  Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
              Patel, "Revised Error Handling for BGP UPDATE Messages",
              RFC 7606, DOI 10.17487/RFC7606, August 2015,
              <https://www.rfc-editor.org/info/rfc7606>.

   [RFC7911]  Walton, D., Retana, A., Chen, E., and J. Scudder,
              "Advertisement of Multiple Paths in BGP", RFC 7911,
              DOI 10.17487/RFC7911, July 2016,
              <https://www.rfc-editor.org/info/rfc7911>.

   [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>.




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8.2.  Informative References

   [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>.

   [RFC7947]  Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
              "Internet Exchange BGP Route Server", RFC 7947,
              DOI 10.17487/RFC7947, September 2016,
              <https://www.rfc-editor.org/info/rfc7947>.

Authors' Addresses

   Thomas King
   DE-CIX Management GmbH
   Lichtstrasse 43i
   Cologne  50825
   DE

   Email: thomas.king@de-cix.net


   Christoph Dietzel
   DE-CIX Management GmbH
   Lichtstrasse 43i
   Cologne  50825
   DE

   Email: christoph.dietzel@de-cix.net


   Daniel Kopp
   DE-CIX Management GmbH
   Lichtstrasse 43i
   Cologne  50825
   DE

   Email: daniel.kopp@de-cix.net


   Aristidis Lambrianidis
   Amsterdam Internet Exchange
   Frederiksplein 42
   Amsterdam  1017 XN
   NL

   Email: aristidis.lambrianidis@ams-ix.net




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   Arnaud Fenioux
   France-IX
   88 Avenue Des Ternes
   Paris  75017
   FR

   Email: ietf@afenioux.fr












































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