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The Resource Public Key Infrastructure (RPKI) to Router Protocol
draft-ietf-sidr-rpki-rtr-rfc6810-bis-04

The information below is for an old version of the document.
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This is an older version of an Internet-Draft that was ultimately published as RFC 8210.
Authors Randy Bush , Rob Austein
Last updated 2015-06-15
Replaces draft-austein-sidr-rpki-rtr-rfc6810bis
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draft-ietf-sidr-rpki-rtr-rfc6810-bis-04
Network Working Group                                            R. Bush
Internet-Draft                                 Internet Initiative Japan
Updates: 6810 (if approved)                                   R. Austein
Intended status: Standards Track                    Dragon Research Labs
Expires: December 17, 2015                                 June 15, 2015

    The Resource Public Key Infrastructure (RPKI) to Router Protocol
                draft-ietf-sidr-rpki-rtr-rfc6810-bis-04

Abstract

   In order to verifiably validate the origin Autonomous Systems and
   Autonomous System Paths of BGP announcements, routers need a simple
   but reliable mechanism to receive Resource Public Key Infrastructure
   (RFC 6480) prefix origin data and router keys from a trusted cache.
   This document describes a protocol to deliver validated prefix origin
   data and router keys to routers.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://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 December 17, 2015.

Copyright Notice

   Copyright (c) 2015 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
   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

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Glossary  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Deployment Structure  . . . . . . . . . . . . . . . . . . . .   4
   4.  Operational Overview  . . . . . . . . . . . . . . . . . . . .   5
   5.  Protocol Data Units (PDUs)  . . . . . . . . . . . . . . . . .   6
     5.1.  Fields of a PDU . . . . . . . . . . . . . . . . . . . . .   6
     5.2.  Serial Notify . . . . . . . . . . . . . . . . . . . . . .   8
     5.3.  Serial Query  . . . . . . . . . . . . . . . . . . . . . .   9
     5.4.  Reset Query . . . . . . . . . . . . . . . . . . . . . . .  10
     5.5.  Cache Response  . . . . . . . . . . . . . . . . . . . . .  10
     5.6.  IPv4 Prefix . . . . . . . . . . . . . . . . . . . . . . .  11
     5.7.  IPv6 Prefix . . . . . . . . . . . . . . . . . . . . . . .  12
     5.8.  End of Data . . . . . . . . . . . . . . . . . . . . . . .  12
     5.9.  Cache Reset . . . . . . . . . . . . . . . . . . . . . . .  13
     5.10. Router Key  . . . . . . . . . . . . . . . . . . . . . . .  14
     5.11. Error Report  . . . . . . . . . . . . . . . . . . . . . .  15
   6.  Protocol Timing Parameters  . . . . . . . . . . . . . . . . .  16
   7.  Protocol Version Negotiation  . . . . . . . . . . . . . . . .  17
   8.  Protocol Sequences  . . . . . . . . . . . . . . . . . . . . .  19
     8.1.  Start or Restart  . . . . . . . . . . . . . . . . . . . .  19
     8.2.  Typical Exchange  . . . . . . . . . . . . . . . . . . . .  20
     8.3.  No Incremental Update Available . . . . . . . . . . . . .  20
     8.4.  Cache Has No Data Available . . . . . . . . . . . . . . .  21
   9.  Transport . . . . . . . . . . . . . . . . . . . . . . . . . .  21
     9.1.  SSH Transport . . . . . . . . . . . . . . . . . . . . . .  23
     9.2.  TLS Transport . . . . . . . . . . . . . . . . . . . . . .  23
     9.3.  TCP MD5 Transport . . . . . . . . . . . . . . . . . . . .  24
     9.4.  TCP-AO Transport  . . . . . . . . . . . . . . . . . . . .  24
   10. Router-Cache Setup  . . . . . . . . . . . . . . . . . . . . .  25
   11. Deployment Scenarios  . . . . . . . . . . . . . . . . . . . .  26
   12. Error Codes . . . . . . . . . . . . . . . . . . . . . . . . .  27
   13. Security Considerations . . . . . . . . . . . . . . . . . . .  28
   14. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  29
   15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  30
   16. References  . . . . . . . . . . . . . . . . . . . . . . . . .  30
     16.1.  Normative References . . . . . . . . . . . . . . . . . .  30
     16.2.  Informative References . . . . . . . . . . . . . . . . .  31
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  32

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1.  Introduction

   In order to verifiably validate the origin Autonomous Systems (ASes)
   and AS paths of BGP announcements, routers need a simple but reliable
   mechanism to receive cryptographically validated Resource Public Key
   Infrastructure (RPKI) [RFC6480] prefix origin data and router keys
   from a trusted cache.  This document describes a protocol to deliver
   validated prefix origin data and router keys to routers.  The design
   is intentionally constrained to be usable on much of the current
   generation of ISP router platforms.

   Section 3 describes the deployment structure, and Section 4 then
   presents an operational overview.  The binary payloads of the
   protocol are formally described in Section 5, and the expected PDU
   sequences are described in Section 8.  The transport protocol options
   are described in Section 9.  Section 10 details how routers and
   caches are configured to connect and authenticate.  Section 11
   describes likely deployment scenarios.  The traditional security and
   IANA considerations end the document.

   The protocol is extensible in order to support new PDUs with new
   semantics, if deployment experience indicates they are needed.  PDUs
   are versioned should deployment experience call for change.

   For an implementation (not interoperability) report on the use of
   this protocol with prefix origin data, see [RFC7128].

1.1.  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]
   only when they appear in all upper case.  They may also appear in
   lower or mixed case as English words, without special meaning.

2.  Glossary

   The following terms are used with special meaning.

   Global RPKI:  The authoritative data of the RPKI are published in a
      distributed set of servers at the IANA, Regional Internet
      Registries (RIRs), National Internet Registries (NIRs), and ISPs;
      see [RFC6481].

   Cache:  A coalesced copy of the published Global RPKI data,
      periodically fetched or refreshed, directly or indirectly, using
      the [RFC5781] protocol or some successor protocol.  Relying party
      software is used to gather and validate the distributed data of

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      the RPKI into a cache.  Trusting this cache further is a matter
      between the provider of the cache and a relying party.

   Serial Number:  A 32-bit strictly increasing unsigned integer which
      wraps from 2^32-1 to 0.  It denotes the logical version of a
      cache.  A cache increments the value when it successfully updates
      its data from a parent cache or from primary RPKI data.  While a
      cache is receiving updates, new incoming data and implicit deletes
      are associated with the new serial but MUST NOT be sent until the
      fetch is complete.  A Serial Number is not commensurate between
      different caches or different protocol versions, nor need it be
      maintained across resets of the cache server.  See [RFC1982] on
      DNS Serial Number Arithmetic for too much detail on the topic.

   Session ID:  When a cache server is started, it generates a session
      identifier to uniquely identify the instance of the cache and to
      bind it to the sequence of Serial Numbers that cache instance will
      generate.  This allows the router to restart a failed session
      knowing that the Serial Number it is using is commensurate with
      that of the cache.

   Payload PDU:  A protocol message which contains data for use by the
      router, as opposed to a PDU which just conveys the semantics of
      this protocol.  Prefixes and Router Keys are examples of payload
      PDUs.

3.  Deployment Structure

   Deployment of the RPKI to reach routers has a three-level structure
   as follows:

   Global RPKI:  The authoritative data of the RPKI are published in a
      distributed set of servers, RPKI publication repositories, e.g.,
      by the IANA, RIRs, NIRs, and ISPs (see [RFC6481]).

   Local Caches:  A local set of one or more collected and verified
      caches.  A relying party, e.g., router or other client, MUST have
      a trust relationship with, and a trusted transport channel to, any
      cache(s) it uses.

   Routers:  A router fetches data from a local cache using the protocol
      described in this document.  It is said to be a client of the
      cache.  There MAY be mechanisms for the router to assure itself of
      the authenticity of the cache and to authenticate itself to the
      cache.

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4.  Operational Overview

   A router establishes and keeps open a connection to one or more
   caches with which it has client/server relationships.  It is
   configured with a semi-ordered list of caches, and establishes a
   connection to the most preferred cache, or set of caches, which
   accept the connections.

   The router MUST choose the most preferred, by configuration, cache or
   set of caches so that the operator may control load on their caches
   and the Global RPKI.

   Periodically, the router sends to the cache the Serial Number of the
   highest numbered data it has received from that cache, i.e., the
   router's current Serial Number, in the form of a Serial Query.  When
   a router establishes a new connection to a cache, or wishes to reset
   a current relationship, it sends a Reset Query.

   The cache responds to the Serial Query with all data records which
   have Serial Numbers greater than that in the router's query.  This
   may be the null set, in which case the End of Data PDU is still sent.
   Note that "greater" MUST take wrap-around into account, see
   [RFC1982].

   When the router has received all data records from the cache, it sets
   its current Serial Number to that of the Serial Number in the End of
   Data PDU.

   When the cache updates its database, it sends a Notify message to
   every currently connected router.  This is a hint that now would be a
   good time for the router to poll for an update, but is only a hint.
   The protocol requires the router to poll for updates periodically in
   any case.

   Strictly speaking, a router could track a cache simply by asking for
   a complete data set every time it updates, but this would be very
   inefficient.  The Serial Number based incremental update mechanism
   allows an efficient transfer of just the data records which have
   changed since last update.  As with any update protocol based on
   incremental transfers, the router must be prepared to fall back to a
   full transfer if for any reason the cache is unable to provide the
   necessary incremental data.  Unlike some incremental transfer
   protocols, this protocol requires the router to make an explicit
   request to start the fallback process; this is deliberate, as the
   cache has no way of knowing whether the router has also established
   sessions with other caches that may be able to provide better
   service.

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   As a cache server must evaluate certificates and ROAs (Route Origin
   Attestations; see [RFC6480]), which are time dependent, servers'
   clocks MUST be correct to a tolerance of approximately an hour.

5.  Protocol Data Units (PDUs)

   The exchanges between the cache and the router are sequences of
   exchanges of the following PDUs according to the rules described in
   Section 8.

   Reserved fields (marked "zero" in PDU diagrams) MUST be zero on
   transmission, and SHOULD be ignored on receipt.

5.1.  Fields of a PDU

   PDUs contain the following data elements:

   Protocol Version:  An eight-bit unsigned integer, currently 1,
      denoting the version of this protocol.

   PDU Type:  An eight-bit unsigned integer, denoting the type of the
      PDU, e.g., IPv4 Prefix, etc.

   Serial Number:  The Serial Number of the RPKI Cache when this set of
      PDUs was received from an upstream cache server or gathered from
      the Global RPKI.  A cache increments its Serial Number when
      completing a rigorously validated update from a parent cache or
      the Global RPKI.

   Session ID:  A 16-bit unsigned integer.  When a cache server is
      started, it generates a Session ID to identify the instance of the
      cache and to bind it to the sequence of Serial Numbers that cache
      instance will generate.  This allows the router to restart a
      failed session knowing that the Serial Number it is using is
      commensurate with that of the cache.  If, at any time, either the
      router or the cache finds the value of the session identifier is
      not the same as the other's, they MUST completely drop the session
      and the router MUST flush all data learned from that cache.

      Note that sessions are specific to a particular protocol version.
      That is: if a cache server supports multiple versions of this
      protocol, happens to use the same Session ID value for multiple
      protocol versions, and further happens to use the same Serial
      Number values for two or more sessions using the same Session ID
      but different Protocol Version values, the serial numbers are not
      commensurate.  The full test for whether serial numbers are
      commensurate requires comparing Protocol Version, Session ID, and
      Serial Number.  To reduce the risk of confusion, cache servers

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      SHOULD NOT use the same Session ID across multiple protocol
      versions, but even if they do, routers MUST treat sessions with
      different Protocol Version fields as separate sessions even if
      they do happen to have the same Session ID.

      Should a cache erroneously reuse a Session ID so that a router
      does not realize that the session has changed (old Session ID and
      new Session ID have same numeric value), the router may become
      confused as to the content of the cache.  The time it takes the
      router to discover it is confused will depend on whether the
      Serial Numbers are also reused.  If the Serial Numbers in the old
      and new sessions are different enough, the cache will respond to
      the router's Serial Query with a Cache Reset, which will solve the
      problem.  If, however, the Serial Numbers are close, the cache may
      respond with a Cache Response, which may not be enough to bring
      the router into sync.  In such cases, it's likely but not certain
      that the router will detect some discrepancy between the state
      that the cache expects and its own state.  For example, the Cache
      Response may tell the router to drop a record which the router
      does not hold, or may tell the router to add a record which the
      router already has.  In such cases, a router will detect the error
      and reset the session.  The one case in which the router may stay
      out of sync is when nothing in the Cache Response contradicts any
      data currently held by the router.

      Using persistent storage for the session identifier or a clock-
      based scheme for generating session identifiers should avoid the
      risk of session identifier collisions.

      The Session ID might be a pseudo-random value, a strictly
      increasing value if the cache has reliable storage, etc.

   Length:  A 32-bit unsigned integer which has as its value the count
      of the bytes in the entire PDU, including the eight bytes of
      header which end with the length field.

   Flags:  The lowest order bit of the Flags field is 1 for an
      announcement and 0 for a withdrawal.  For a Prefix PDU (IPv4 or
      IPv6), the flag indicates whether this PDU announces a new right
      to announce the prefix or withdraws a previously announced right;
      a withdraw effectively deletes one previously announced Prefix PDU
      with the exact same Prefix, Length, Max-Len, and Autonomous System
      Number (ASN).  Similarly, for a Router Key PDU, the flag indicates
      whether this PDU announces a new Router Key or deletes one
      previously announced Router Key PDU with the exact same AS Number,
      subjectKeyIdentifier, and subjectPublicKeyInfo.

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      The remaining bits in the flags field are reserved for future use.
      In protocol version 1, they MUST be 0 on transmission and SHOULD
      be ignored on receipt.

   Prefix Length:  An 8-bit unsigned integer denoting the shortest
      prefix allowed for the prefix.

   Max Length:  An 8-bit unsigned integer denoting the longest prefix
      allowed by the prefix.  This MUST NOT be less than the Prefix
      Length element.

   Prefix:  The IPv4 or IPv6 prefix of the ROA.

   Autonomous System Number:  A 32-bit unsigned integer representing an
      ASN allowed to announce a prefix or associated with a router key.

   Subject Key Identifier:  20-octet Subject Key Identifier (SKI) value
      of a router key, as described in [RFC6487].

   Subject Public Key Info:  a router key's subjectPublicKeyInfo value,
      as described in [I-D.ietf-sidr-bgpsec-algs].  This is the full
      ASN.1 DER encoding of the subjectPublicKeyInfo, including the
      ASN.1 tag and length values of the subjectPublicKeyInfo SEQUENCE.

   Zero:  Fields shown as zero MUST be zero on transmission.  The value
      of such a field SHOULD be ignored on receipt.

5.2.  Serial Notify

   The cache notifies the router that the cache has new data.

   The Session ID reassures the router that the Serial Numbers are
   commensurate, i.e., the cache session has not been changed.

   Upon receipt of a Serial Notify PDU, the router MAY issue an
   immediate Serial Query or Reset Query without waiting for the Refresh
   Interval timer (see Section 6) to expire.

   Serial Notify is the only message that the cache can send that is not
   in response to a message from the router.

   If the router receives a Serial Notify PDU during the initial start-
   up period where the router and cache are still negotiating to agree
   on a protocol version, the router SHOULD simply ignore the Serial
   Notify PDU, even if the Serial Notify PDU is for an unexpected
   protocol version.  See Section 7 for details.

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   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |     Session ID      |
   |    1     |    0     |                     |
   +-------------------------------------------+
   |                                           |
   |                Length=12                  |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |               Serial Number               |
   |                                           |
   `-------------------------------------------'

5.3.  Serial Query

   Serial Query: The router sends Serial Query to ask the cache for all
   all announcements and withdrawals which have occurred since the
   Serial Number specified in the Serial Query.

   The cache replies to this query with a Cache Response PDU
   (Section 5.5) if the cache has a, possibly null, record of the
   changes since the Serial Number specified by the router, followed by
   zero or more payload PDUs and an End Of Data PDU.

   If the cache does not have the data needed to update the router,
   perhaps because its records do not go back to the Serial Number in
   the Serial Query, then it responds with a Cache Reset PDU
   (Section 5.9).

   The Session ID tells the cache what instance the router expects to
   ensure that the Serial Numbers are commensurate, i.e., the cache
   session has not been changed.

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   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |     Session ID      |
   |    1     |    1     |                     |
   +-------------------------------------------+
   |                                           |
   |                 Length=12                 |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |               Serial Number               |
   |                                           |
   `-------------------------------------------'

5.4.  Reset Query

   Reset Query: The router tells the cache that it wants to receive the
   total active, current, non-withdrawn database.  The cache responds
   with a Cache Response PDU (Section 5.5).

   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |         zero        |
   |    1     |    2     |                     |
   +-------------------------------------------+
   |                                           |
   |                 Length=8                  |
   |                                           |
   `-------------------------------------------'

5.5.  Cache Response

   The cache responds with zero or more payload PDUs.  When replying to
   a Serial Query request (Section 5.3), the cache sends the set of
   announcements and withdrawals that have occurred since the Serial
   Number sent by the client router.  When replying to a Reset Query,
   the cache sends the set of all data records it has; in this case, the
   withdraw/announce field in the payload PDUs MUST have the value 1
   (announce).

   In response to a Reset Query, the new value of the Session ID tells
   the router the instance of the cache session for future confirmation.
   In response to a Serial Query, the Session ID being the same
   reassures the router that the Serial Numbers are commensurate, i.e.,
   the cache session has not changed.

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   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |     Session ID      |
   |    1     |    3     |                     |
   +-------------------------------------------+
   |                                           |
   |                 Length=8                  |
   |                                           |
   `-------------------------------------------'

5.6.  IPv4 Prefix

   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |         zero        |
   |    1     |    4     |                     |
   +-------------------------------------------+
   |                                           |
   |                 Length=20                 |
   |                                           |
   +-------------------------------------------+
   |          |  Prefix  |   Max    |          |
   |  Flags   |  Length  |  Length  |   zero   |
   |          |   0..32  |   0..32  |          |
   +-------------------------------------------+
   |                                           |
   |                IPv4 Prefix                |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |         Autonomous System Number          |
   |                                           |
   `-------------------------------------------'

   The lowest order bit of the Flags field is 1 for an announcement and
   0 for a withdrawal.

   In the RPKI, nothing prevents a signing certificate from issuing two
   identical ROAs.  In this case, there would be no semantic difference
   between the objects, merely a process redundancy.

   In the RPKI, there is also an actual need for what might appear to a
   router as identical IPvX PDUs.  This can occur when an upstream
   certificate is being reissued or there is an address ownership
   transfer up the validation chain.  The ROA would be identical in the
   router sense, i.e., have the same {Prefix, Len, Max-Len, ASN}, but a

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   different validation path in the RPKI.  This is important to the
   RPKI, but not to the router.

   The cache server MUST ensure that it has told the router client to
   have one and only one IPvX PDU for a unique {Prefix, Len, Max-Len,
   ASN} at any one point in time.  Should the router client receive an
   IPvX PDU with a {Prefix, Len, Max-Len, ASN} identical to one it
   already has active, it SHOULD raise a Duplicate Announcement Received
   error.

5.7.  IPv6 Prefix

   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |         zero        |
   |    1     |    6     |                     |
   +-------------------------------------------+
   |                                           |
   |                 Length=32                 |
   |                                           |
   +-------------------------------------------+
   |          |  Prefix  |   Max    |          |
   |  Flags   |  Length  |  Length  |   zero   |
   |          |  0..128  |  0..128  |          |
   +-------------------------------------------+
   |                                           |
   +---                                     ---+
   |                                           |
   +---            IPv6 Prefix              ---+
   |                                           |
   +---                                     ---+
   |                                           |
   +-------------------------------------------+
   |                                           |
   |         Autonomous System Number          |
   |                                           |
   `-------------------------------------------'

   Analogous to the IPv4 Prefix PDU, it has 96 more bits and no magic.

5.8.  End of Data

   End of Data: The cache tells the router it has no more data for the
   request.

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   The Session ID and Protocol Version MUST be the same as that of the
   corresponding Cache Response which began the, possibly null, sequence
   of data PDUs.

   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |     Session ID      |
   |    1     |    7     |                     |
   +-------------------------------------------+
   |                                           |
   |                 Length=24                 |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |               Serial Number               |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |              Refresh Interval             |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |               Retry Interval              |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |              Expire Interval              |
   |                                           |
   `-------------------------------------------'

   The Refresh Interval, Retry Interval, and Expire Interval are all
   32-bit elapsed times measured in seconds, and express the timing
   parameters that the cache expects the router to use to decide when
   next to send the cache another Serial Query or Reset Query PDU.  See
   Section 6 for an explanation of the use and the range of allowed
   values for these parameters.

5.9.  Cache Reset

   The cache may respond to a Serial Query informing the router that the
   cache cannot provide an incremental update starting from the Serial
   Number specified by the router.  The router must decide whether to
   issue a Reset Query or switch to a different cache.

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   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |         zero        |
   |    1     |    8     |                     |
   +-------------------------------------------+
   |                                           |
   |                 Length=8                  |
   |                                           |
   `-------------------------------------------'

5.10.  Router Key

   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |          |          |
   | Version  |   Type   |   Flags  |   zero   |
   |     1    |    9     |          |          |
   +-------------------------------------------+
   |                                           |
   |                  Length                   |
   |                                           |
   +-------------------------------------------+
   |                                           |
   +---                                     ---+
   |          Subject Key Identifier           |
   +---                                     ---+
   |                                           |
   +---                                     ---+
   |                (20 octets)                |
   +---                                     ---+
   |                                           |
   +-------------------------------------------+
   |                                           |
   |                 AS Number                 |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |          Subject Public Key Info          |
   |                                           |
   `-------------------------------------------'

   The lowest order bit of the Flags field is 1 for an announcement and
   0 for a withdrawal.

   The cache server MUST ensure that it has told the router client to
   have one and only one Router Key PDU for a unique {SKI, ASN, Subject
   Public Key} at any one point in time.  Should the router client

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   receive a Router Key PDU with a {SKI, ASN, Subject Public Key}
   identical to one it already has active, it SHOULD raise a Duplicate
   Announcement Received error.

   Note that a particular ASN may appear in multiple Router Key PDUs
   with different Subject Public Key values, while a particular Subject
   Public Key value may appear in multiple Router Key PDUs with
   different ASNs.  In the interest of keeping the announcement and
   withdrawal semantics as simple as possible for the router, this
   protocol makes no attempt to compress either of these cases.

   Also note that it is possible, albeit very unlikely, for multiple
   distinct Subject Public Key values to hash to the same SKI.  For this
   reason, implementations MUST compare Subject Public Key values as
   well as SKIs when detecting duplicate PDUs.

5.11.  Error Report

   This PDU is used by either party to report an error to the other.

   Error reports are only sent as responses to other PDUs.

   The Error Code is described in Section 12.

   If the error is generic (e.g., "Internal Error") and not associated
   with the PDU to which it is responding, the Erroneous PDU field MUST
   be empty and the Length of Encapsulated PDU field MUST be zero.

   An Error Report PDU MUST NOT be sent for an Error Report PDU.  If an
   erroneous Error Report PDU is received, the session SHOULD be
   dropped.

   If the error is associated with a PDU of excessive length, i.e., too
   long to be any legal PDU other than another Error Report, or a
   possibly corrupt length, the Erroneous PDU field MAY be truncated.

   The diagnostic text is optional; if not present, the Length of Error
   Text field MUST be zero.  If error text is present, it MUST be a
   string in UTF-8 encoding (see [RFC3269]).

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   0          8          16         24        31
   .-------------------------------------------.
   | Protocol |   PDU    |                     |
   | Version  |   Type   |     Error Code      |
   |    1     |    10    |                     |
   +-------------------------------------------+
   |                                           |
   |                  Length                   |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |       Length of Encapsulated PDU          |
   |                                           |
   +-------------------------------------------+
   |                                           |
   ~           Copy of Erroneous PDU           ~
   |                                           |
   +-------------------------------------------+
   |                                           |
   |           Length of Error Text            |
   |                                           |
   +-------------------------------------------+
   |                                           |
   |              Arbitrary Text               |
   |                    of                     |
   ~          Error Diagnostic Message         ~
   |                                           |
   `-------------------------------------------'

6.  Protocol Timing Parameters

   Since the data the cache distributes via the rpki-rtr protocol are
   retrieved from the Global RPKI system at intervals which are only
   known to the cache, only the cache can really know how frequently it
   makes sense for the router to poll the cache, or how long the data
   are likely to remain valid (or, at least, unchanged).  For this
   reason, as well as to allow the cache some control over the load
   placed on it by its client routers, the End Of Data PDU includes
   three values that allow the cache to communicate timing parameters to
   the router.

   Refresh Interval:  This parameter tells the router how long to wait
      before next attempting to poll the cache, using a Serial Query or
      Reset Query PDU.  The router SHOULD NOT poll the cache sooner than
      indicated by this parameter.  Note that receipt of a Serial Notify
      PDU overrides this interval and allows the router to issue an
      immediate query without waiting for the Refresh Interval to

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      expire.  Countdown for this timer starts upon receipt of the
      containing End Of Data PDU.

      Minimum allowed value:  1 second.

      Maximum allowed value:  86400 seconds (one day).

      Recommended default:  3600 seconds (one hour).

   Retry Interval:  This parameter tells the router how long to wait
      before retrying a failed Serial Query or Reset Query.  The router
      SHOULD NOT retry sooner than indicated by this parameter.  Note
      that a protocol version mismatch overrides this interval: if the
      router needs to downgrade to a lower protocol version number, it
      MAY send the first Serial Query or Reset Query immediately.
      Countdown for this timer starts upon failure of the query, and
      restarts after each subsequent failure until a query succeeds.

      Minimum allowed value:  1 second.

      Maximum allowed value:  7200 seconds (two hours).

      Recommended default:  600 seconds (ten minutes).

   Expire Interval:  This parameter tells the router how long it can
      continue to use the current version of the data while unable to
      perform a successful query.  The router MUST NOT retain the data
      past the time indicated by this parameter.  Countdown for this
      timer starts upon receipt of the containing End Of Data PDU.

      Minimum allowed value:  600 seconds (ten minutes).

      Maximum allowed value:  172800 seconds (two days).

      Recommended default:  7200 seconds (two hours).

   If the router has never issued a successful query against a
   particular cache, it SHOULD retry periodically using the default
   Retry Interval, above.

7.  Protocol Version Negotiation

   A router MUST start each transport session by issuing either a Reset
   Query or a Serial Query.  This query will tell the cache which
   version of this protocol the router implements.

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   If a cache which supports version 1 receives a query from a router
   which specifies version 0, the cache MUST downgrade to protocol
   version 0 [RFC6810] or terminate the session.

   If a router which supports version 1 sends a query to a cache which
   only supports version 0, one of two things will happen.

   1.  The cache may terminate the connection, perhaps with a version 0
       Error Report PDU.  In this case the router MAY retry the
       connection using protocol version 0.

   2.  The cache may reply with a version 0 response.  In this case the
       router MUST either downgrade to version 0 or terminate the
       connection.

   In any of the downgraded combinations above, the new features of
   version 1 will not be available.

   If either party receives a PDU containing an unrecognized Protocol
   Version (neither 0 nor 1) during this negotiation, it MUST either
   downgrade to a known version or terminate the connection, with an
   Error Report PDU unless the received PDU is itself an Error Report
   PDU.

   The router MUST ignore any Serial Notify PDUs it might receive from
   the cache during this initial start-up period, regardless of the
   Protocol Version field in the Serial Notify PDU.  Since Session ID
   and Serial Number values are specific to a particular protocol
   version, the values in the notification are not useful to the router.
   Even if these values were meaningful, the only effect that processing
   the notification would have would be to trigger exactly the same
   Reset Query or Serial Query that the router has already sent as part
   of the not-yet-complete version negotiation process, so there is
   nothing to be gained by processing notifications until version
   negotiation completes.

   Caches SHOULD NOT send Serial Notify PDUs before version negotiation
   completes.  Note, however, that routers must handle such
   notifications (by ignoring them) for backwards compatibility with
   caches serving protocol version 0.

   Once the cache and router have agreed upon a Protocol Version via the
   negotiation process above, that version is stable for the life of the
   session.  See Section 5.1 for a discussion of the interaction between
   Protocol Version and Session ID.

   If either party receives a PDU for a different Protocol Version once
   the above negotiation completes, that party MUST drop the session;

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   unless the PDU containing the unexpected Protocol Version was itself
   an Error Report PDU, the party dropping the session SHOULD send an
   Error Report with an error code of 8 ("Unexpected Protocol Version").

8.  Protocol Sequences

   The sequences of PDU transmissions fall into three conversations as
   follows:

8.1.  Start or Restart

   Cache                         Router
     ~                             ~
     | <----- Reset Query -------- | R requests data (or Serial Query)
     |                             |
     | ----- Cache Response -----> | C confirms request
     | ------- Payload PDU ------> | C sends zero or more
     | ------- Payload PDU ------> |   IPv4 Prefix, IPv6 Prefix,
     | ------- Payload PDU ------> |   or Router Key PDUs
     | ------  End of Data ------> | C sends End of Data
     |                             |   and sends new serial
     ~                             ~

   When a transport session is first established, the router MAY send a
   Reset Query and the cache responds with a data sequence of all data
   it contains.

   Alternatively, if the router has significant unexpired data from a
   broken session with the same cache, it MAY start with a Serial Query
   containing the Session ID from the previous session to ensure the
   Serial Numbers are commensurate.

   This Reset Query sequence is also used when the router receives a
   Cache Reset, chooses a new cache, or fears that it has otherwise lost
   its way.

   The router MUST send either a Reset Query or a Serial Query when
   starting a transport session, in order to confirm that router and
   cache are speaking compatible versions of the protocol.  See
   Section 7 for details on version negotiation.

   To limit the length of time a cache must keep the data necessary to
   generate incremental updates, a router MUST send either a Serial
   Query or a Reset Query periodically.  This also acts as a keep-alive
   at the application layer.  See Section 6 for details on the required
   polling frequency.

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8.2.  Typical Exchange

   Cache                         Router
     ~                             ~
     | -------- Notify ----------> |  (optional)
     |                             |
     | <----- Serial Query ------- | R requests data
     |                             |
     | ----- Cache Response -----> | C confirms request
     | ------- Payload PDU ------> | C sends zero or more
     | ------- Payload PDU ------> |   IPv4 Prefix, IPv6 Prefix,
     | ------- Payload PDU ------> |   or Router Key PDUs
     | ------  End of Data ------> | C sends End of Data
     |                             |   and sends new serial
     ~                             ~

   The cache server SHOULD send a notify PDU with its current Serial
   Number when the cache's serial changes, with the expectation that the
   router MAY then issue a Serial Query earlier than it otherwise might.
   This is analogous to DNS NOTIFY in [RFC1996].  The cache MUST rate
   limit Serial Notifies to no more frequently than one per minute.

   When the transport layer is up and either a timer has gone off in the
   router, or the cache has sent a Notify, the router queries for new
   data by sending a Serial Query, and the cache sends all data newer
   than the serial in the Serial Query.

   To limit the length of time a cache must keep old withdraws, a router
   MUST send either a Serial Query or a Reset Query periodically.  See
   Section 6 for details on the required polling frequency.

8.3.  No Incremental Update Available

   Cache                         Router
     ~                             ~
     | <-----  Serial Query ------ | R requests data
     | ------- Cache Reset ------> | C cannot supply update
     |                             |   from specified serial
     | <------ Reset Query ------- | R requests new data
     | ----- Cache Response -----> | C confirms request
     | ------- Payload PDU ------> | C sends zero or more
     | ------- Payload PDU ------> |   IPv4 Prefix, IPv6 Prefix,
     | ------- Payload PDU ------> |   or Router Key PDUs
     | ------  End of Data ------> | C sends End of Data
     |                             |   and sends new serial
     ~                             ~

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   The cache may respond to a Serial Query with a Cache Reset, informing
   the router that the cache cannot supply an incremental update from
   the Serial Number specified by the router.  This might be because the
   cache has lost state, or because the router has waited too long
   between polls and the cache has cleaned up old data that it no longer
   believes it needs, or because the cache has run out of storage space
   and had to expire some old data early.  Regardless of how this state
   arose, the cache replies with a Cache Reset to tell the router that
   it cannot honor the request.  When a router receives this, the router
   SHOULD attempt to connect to any more preferred caches in its cache
   list.  If there are no more preferred caches, it MUST issue a Reset
   Query and get an entire new load from the cache.

8.4.  Cache Has No Data Available

   Cache                         Router
     ~                             ~
     | <-----  Serial Query ------ | R requests data
     | ---- Error Report PDU ----> | C No Data Available
     ~                             ~

   Cache                         Router
     ~                             ~
     | <-----  Reset Query ------- | R requests data
     | ---- Error Report PDU ----> | C No Data Available
     ~                             ~

   The cache may respond to either a Serial Query or a Reset Query
   informing the router that the cache cannot supply any update at all.
   The most likely cause is that the cache has lost state, perhaps due
   to a restart, and has not yet recovered.  While it is possible that a
   cache might go into such a state without dropping any of its active
   sessions, a router is more likely to see this behavior when it
   initially connects and issues a Reset Query while the cache is still
   rebuilding its database.

   When a router receives this kind of error, the router SHOULD attempt
   to connect to any other caches in its cache list, in preference
   order.  If no other caches are available, the router MUST issue
   periodic Reset Queries until it gets a new usable load from the
   cache.

9.  Transport

   The transport-layer session between a router and a cache carries the
   binary PDUs in a persistent session.

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   To prevent cache spoofing and DoS attacks by illegitimate routers, it
   is highly desirable that the router and the cache be authenticated to
   each other.  Integrity protection for payloads is also desirable to
   protect against monkey-in-the-middle (MITM) attacks.  Unfortunately,
   there is no protocol to do so on all currently used platforms.
   Therefore, as of the writing of this document, there is no mandatory-
   to-implement transport which provides authentication and integrity
   protection.

   To reduce exposure to dropped but non-terminated sessions, both
   caches and routers SHOULD enable keep-alives when available in the
   chosen transport protocol.

   It is expected that, when the TCP Authentication Option (TCP-AO)
   [RFC5925] is available on all platforms deployed by operators, it
   will become the mandatory-to-implement transport.

   Caches and routers MUST implement unprotected transport over TCP
   using a port, rpki-rtr (323); see Section 14.  Operators SHOULD use
   procedural means, e.g., access control lists (ACLs), to reduce the
   exposure to authentication issues.

   Caches and routers SHOULD use TCP-AO, SSHv2, TCP MD5, or IPsec
   transport.

   If unprotected TCP is the transport, the cache and routers MUST be on
   the same trusted and controlled network.

   If available to the operator, caches and routers MUST use one of the
   following more protected protocols.

   Caches and routers SHOULD use TCP-AO transport [RFC5925] over the
   rpki-rtr port.

   Caches and routers MAY use SSHv2 transport [RFC4252] using the normal
   SSH port.  For an example, see Section 9.1.

   Caches and routers MAY use TCP MD5 transport [RFC2385] using the
   rpki-rtr port.  Note that TCP MD5 has been obsoleted by TCP-AO
   [RFC5925].

   Caches and routers MAY use TCP over IPsec transport [RFC4301] using
   the rpki-rtr port.

   Caches and routers MAY use TLS transport [RFC5246] using a port,
   rpki-rtr-tls (324); see Section 14.

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9.1.  SSH Transport

   To run over SSH, the client router first establishes an SSH transport
   connection using the SSHv2 transport protocol, and the client and
   server exchange keys for message integrity and encryption.  The
   client then invokes the "ssh-userauth" service to authenticate the
   application, as described in the SSH authentication protocol
   [RFC4252].  Once the application has been successfully authenticated,
   the client invokes the "ssh-connection" service, also known as the
   SSH connection protocol.

   After the ssh-connection service is established, the client opens a
   channel of type "session", which results in an SSH session.

   Once the SSH session has been established, the application invokes
   the application transport as an SSH subsystem called "rpki-rtr".
   Subsystem support is a feature of SSH version 2 (SSHv2) and is not
   included in SSHv1.  Running this protocol as an SSH subsystem avoids
   the need for the application to recognize shell prompts or skip over
   extraneous information, such as a system message that is sent at
   shell start-up.

   It is assumed that the router and cache have exchanged keys out of
   band by some reasonably secured means.

   Cache servers supporting SSH transport MUST accept RSA and Digital
   Signature Algorithm (DSA) authentication and SHOULD accept Elliptic
   Curve Digital Signature Algorithm (ECDSA) authentication.  User
   authentication MUST be supported; host authentication MAY be
   supported.  Implementations MAY support password authentication.
   Client routers SHOULD verify the public key of the cache to avoid
   monkey-in-the-middle attacks.

9.2.  TLS Transport

   Client routers using TLS transport MUST present client-side
   certificates to authenticate themselves to the cache in order to
   allow the cache to manage the load by rejecting connections from
   unauthorized routers.  In principle, any type of certificate and
   certificate authority (CA) may be used; however, in general, cache
   operators will wish to create their own small-scale CA and issue
   certificates to each authorized router.  This simplifies credential
   rollover; any unrevoked, unexpired certificate from the proper CA may
   be used.

   Certificates used to authenticate client routers in this protocol
   MUST include a subjectAltName extension [RFC5280] containing one or
   more iPAddress identities; when authenticating the router's

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   certificate, the cache MUST check the IP address of the TLS
   connection against these iPAddress identities and SHOULD reject the
   connection if none of the iPAddress identities match the connection.

   Routers MUST also verify the cache's TLS server certificate, using
   subjectAltName dNSName identities as described in [RFC6125], to avoid
   monkey-in-the-middle attacks.  The rules and guidelines defined in
   [RFC6125] apply here, with the following considerations:

      Support for DNS-ID identifier type (that is, the dNSName identity
      in the subjectAltName extension) is REQUIRED in rpki-rtr server
      and client implementations which use TLS.  Certification
      authorities which issue rpki-rtr server certificates MUST support
      the DNS-ID identifier type, and the DNS-ID identifier type MUST be
      present in rpki-rtr server certificates.

      DNS names in rpki-rtr server certificates SHOULD NOT contain the
      wildcard character "*".

      rpki-rtr implementations which use TLS MUST NOT use CN-ID
      identifiers; a CN field may be present in the server certificate's
      subject name, but MUST NOT be used for authentication within the
      rules described in [RFC6125].

      The client router MUST set its "reference identifier" to the DNS
      name of the rpki-rtr cache.

9.3.  TCP MD5 Transport

   If TCP MD5 is used, implementations MUST support key lengths of at
   least 80 printable ASCII bytes, per Section 4.5 of [RFC2385].
   Implementations MUST also support hexadecimal sequences of at least
   32 characters, i.e., 128 bits.

   Key rollover with TCP MD5 is problematic.  Cache servers SHOULD
   support [RFC4808].

9.4.  TCP-AO Transport

   Implementations MUST support key lengths of at least 80 printable
   ASCII bytes.  Implementations MUST also support hexadecimal sequences
   of at least 32 characters, i.e., 128 bits.  Message Authentication
   Code (MAC) lengths of at least 96 bits MUST be supported, per
   Section 5.1 of [RFC5925].

   The cryptographic algorithms and associated parameters described in
   [RFC5926] MUST be supported.

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10.  Router-Cache Setup

   A cache has the public authentication data for each router it is
   configured to support.

   A router may be configured to peer with a selection of caches, and a
   cache may be configured to support a selection of routers.  Each must
   have the name of, and authentication data for, each peer.  In
   addition, in a router, this list has a non-unique preference value
   for each server.  This preference merely denotes proximity, not
   trust, preferred belief, etc.  The client router attempts to
   establish a session with each potential serving cache in preference
   order, and then starts to load data from the most preferred cache to
   which it can connect and authenticate.  The router's list of caches
   has the following elements:

   Preference:  An unsigned integer denoting the router's preference to
      connect to that cache; the lower the value, the more preferred.

   Name:  The IP address or fully qualified domain name of the cache.

   Key:  Any needed public key of the cache.

   MyKey:  Any needed private key or certificate of this client.

   Due to the distributed nature of the RPKI, caches simply cannot be
   rigorously synchronous.  A client may hold data from multiple caches
   but MUST keep the data marked as to source, as later updates MUST
   affect the correct data.

   Just as there may be more than one covering ROA from a single cache,
   there may be multiple covering ROAs from multiple caches.  The
   results are as described in [RFC6811].

   If data from multiple caches are held, implementations MUST NOT
   distinguish between data sources when performing validation.

   When a more preferred cache becomes available, if resources allow, it
   would be prudent for the client to start fetching from that cache.

   The client SHOULD attempt to maintain at least one set of data,
   regardless of whether it has chosen a different cache or established
   a new connection to the previous cache.

   A client MAY drop the data from a particular cache when it is fully
   in sync with one or more other caches.

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   See Section 6 for details on what to do when the client is not able
   to refresh from a particular cache.

   If a client loses connectivity to a cache it is using, or otherwise
   decides to switch to a new cache, it SHOULD retain the data from the
   previous cache until it has a full set of data from one or more other
   caches.  Note that this may already be true at the point of
   connection loss if the client has connections to more than one cache.

11.  Deployment Scenarios

   For illustration, we present three likely deployment scenarios.

   Small End Site:  The small multihomed end site may wish to outsource
      the RPKI cache to one or more of their upstream ISPs.  They would
      exchange authentication material with the ISP using some out-of-
      band mechanism, and their router(s) would connect to the cache(s)
      of one or more upstream ISPs.  The ISPs would likely deploy caches
      intended for customer use separately from the caches with which
      their own BGP speakers peer.

   Large End Site:  A larger multihomed end site might run one or more
      caches, arranging them in a hierarchy of client caches, each
      fetching from a serving cache which is closer to the Global RPKI.
      They might configure fall-back peerings to upstream ISP caches.

   ISP Backbone:  A large ISP would likely have one or more redundant
      caches in each major point of presence (PoP), and these caches
      would fetch from each other in an ISP-dependent topology so as not
      to place undue load on the Global RPKI.

   Experience with large DNS cache deployments has shown that complex
   topologies are ill-advised as it is easy to make errors in the graph,
   e.g., not maintain a loop-free condition.

   Of course, these are illustrations and there are other possible
   deployment strategies.  It is expected that minimizing load on the
   Global RPKI servers will be a major consideration.

   To keep load on Global RPKI services from unnecessary peaks, it is
   recommended that primary caches which load from the distributed
   Global RPKI not do so all at the same times, e.g., on the hour.
   Choose a random time, perhaps the ISP's AS number modulo 60 and
   jitter the inter-fetch timing.

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12.  Error Codes

   This section contains a preliminary list of error codes.  The authors
   expect additions to the list during development of the initial
   implementations.  There is an IANA registry where valid error codes
   are listed; see Section 14.  Errors which are considered fatal SHOULD
   cause the session to be dropped.

   0: Corrupt Data (fatal):  The receiver believes the received PDU to
      be corrupt in a manner not specified by another error code.

   1: Internal Error (fatal):  The party reporting the error experienced
      some kind of internal error unrelated to protocol operation (ran
      out of memory, a coding assertion failed, et cetera).

   2: No Data Available:  The cache believes itself to be in good
      working order, but is unable to answer either a Serial Query or a
      Reset Query because it has no useful data available at this time.
      This is likely to be a temporary error, and most likely indicates
      that the cache has not yet completed pulling down an initial
      current data set from the Global RPKI system after some kind of
      event that invalidated whatever data it might have previously held
      (reboot, network partition, et cetera).

   3: Invalid Request (fatal):  The cache server believes the client's
      request to be invalid.

   4: Unsupported Protocol Version (fatal):  The Protocol Version is not
      known by the receiver of the PDU.

   5: Unsupported PDU Type (fatal):  The PDU Type is not known by the
      receiver of the PDU.

   6: Withdrawal of Unknown Record (fatal):  The received PDU has Flag=0
      but a matching record ({Prefix, Len, Max-Len, ASN} tuple for an
      IPvX PDU, {SKI, ASN, Subject Public Key} tuple for a Router Key
      PDU) does not exist in the receiver's database.

   7: Duplicate Announcement Received (fatal):  The received PDU has
      Flag=1 but a matching record ({Prefix, Len, Max-Len, ASN} tuple
      for an IPvX PDU, {SKI, ASN, Subject Public Key} tuple for a Router
      Key PDU) is already active in the router.

   8: Unexpected Protocol Version (fatal):  The received PDU has a
      Protocol Version field that differs from the protocol version
      negotiated in Section 7.

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13.  Security Considerations

   As this document describes a security protocol, many aspects of
   security interest are described in the relevant sections.  This
   section points out issues which may not be obvious in other sections.

   Cache Validation:  In order for a collection of caches as described
      in Section 11 to guarantee a consistent view, they need to be
      given consistent trust anchors to use in their internal validation
      process.  Distribution of a consistent trust anchor is assumed to
      be out of band.

   Cache Peer Identification:  The router initiates a transport session
      to a cache, which it identifies by either IP address or fully
      qualified domain name.  Be aware that a DNS or address spoofing
      attack could make the correct cache unreachable.  No session would
      be established, as the authorization keys would not match.

   Transport Security:  The RPKI relies on object, not server or
      transport, trust.  That is, the IANA root trust anchor is
      distributed to all caches through some out-of-band means, and can
      then be used by each cache to validate certificates and ROAs all
      the way down the tree.  The inter-cache relationships are based on
      this object security model; hence, the inter-cache transport can
      be lightly protected.

      However, this protocol document assumes that the routers cannot do
      the validation cryptography.  Hence, the last link, from cache to
      router, is secured by server authentication and transport-level
      security.  This is dangerous, as server authentication and
      transport have very different threat models than object security.

      So the strength of the trust relationship and the transport
      between the router(s) and the cache(s) are critical.  You're
      betting your routing on this.

      While we cannot say the cache must be on the same LAN, if only due
      to the issue of an enterprise wanting to off-load the cache task
      to their upstream ISP(s), locality, trust, and control are very
      critical issues here.  The cache(s) really SHOULD be as close, in
      the sense of controlled and protected (against DDoS, MITM)
      transport, to the router(s) as possible.  It also SHOULD be
      topologically close so that a minimum of validated routing data
      are needed to bootstrap a router's access to a cache.

      The identity of the cache server SHOULD be verified and
      authenticated by the router client, and vice versa, before any
      data are exchanged.

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      Transports which cannot provide the necessary authentication and
      integrity (see Section 9) must rely on network design and
      operational controls to provide protection against spoofing/
      corruption attacks.  As pointed out in Section 9, TCP-AO is the
      long-term plan.  Protocols which provide integrity and
      authenticity SHOULD be used, and if they cannot, i.e., TCP is used
      as the transport, the router and cache MUST be on the same
      trusted, controlled network.

14.  IANA Considerations

   This section only discusses updates required in the existing IANA
   protocol registries to accommodate version 1 of this protocol.  See
   [RFC6810] for IANA Considerations from the original (version 0)
   protocol.

   All existing entries in the IANA "rpki-rtr-pdu" registry remain valid
   for protocol version 0.  All of the PDU types allowed in protocol
   version 0 are also allowed in protocol version 1, with the addition
   of the new Router Key PDU.  To reduce the likelihood of confusion,
   the PDU number used by the Router Key PDU in protocol version 1 is
   hereby registered as reserved (and unused) in protocol version 0.

   The policy for adding to the registry is RFC Required per [RFC5226],
   either Standards Track or Experimental.

   Assuming that the registry allows range notation in the Protocol
   Version field, the updated "rpki-rtr-pdu" registry will be:

              Protocol   PDU
              Version    Type  Description
              --------   ----  ---------------
                 0-1       0   Serial Notify
                 0-1       1   Serial Query
                 0-1       2   Reset Query
                 0-1       3   Cache Response
                 0-1       4   IPv4 Prefix
                 0-1       6   IPv6 Prefix
                 0-1       7   End of Data
                 0-1       8   Cache Reset
                  0        9   Reserved
                  1        9   Router Key
                 0-1      10   Error Report
                 0-1     255   Reserved

   All exiting entries in the IANA "rpki-rtr-error" registry remain
   valid for all protocol versions.  Protocol version 1 adds one new
   error code:

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              Error
              Code    Description
              -----   ----------------
                  8   Unexpected Protocol Version

15.  Acknowledgments

   The authors wish to thank Nils Bars, Steve Bellovin, Tim Bruijnzeels,
   Rex Fernando, Richard Hansen, Paul Hoffman, Fabian Holler, Russ
   Housley, Pradosh Mohapatra, Keyur Patel, David Mandelberg, Sandy
   Murphy, Robert Raszuk, Andreas Reuter, Thomas C. Schmidt, John
   Scudder, Ruediger Volk, Matthias Waehlisch, and David Ward.
   Particular thanks go to Hannes Gredler for showing us the dangers of
   unnecessary fields.

   No doubt this list is incomplete.  We apologize to any contributor
   whose name we missed.

16.  References

16.1.  Normative References

   [I-D.ietf-sidr-bgpsec-algs]
              Turner, S., "BGP Algorithms, Key Formats, & Signature
              Formats", draft-ietf-sidr-bgpsec-algs-09 (work in
              progress), January 2015.

   [RFC1982]  Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
              August 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", RFC 2119, BCP 14, March 1997.

   [RFC2385]  Heffernan, A., "Protection of BGP Sessions via the TCP MD5
              Signature Option", RFC 2385, August 1998.

   [RFC3269]  Kermode, R. and L. Vicisano, "Author Guidelines for
              Reliable Multicast Transport (RMT) Building Blocks and
              Protocol Instantiation documents", RFC 3269, April 2002.

   [RFC4252]  Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
              Authentication Protocol", RFC 4252, January 2006.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

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   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226, BCP 26,
              May 2008.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5925]  Touch, J., Mankin, A., and R. Bonica, "The TCP
              Authentication Option", RFC 5925, June 2010.

   [RFC5926]  Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms
              for the TCP Authentication Option (TCP-AO)", RFC 5926,
              June 2010.

   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service Identity
              within Internet Public Key Infrastructure Using X.509
              (PKIX) Certificates in the Context of Transport Layer
              Security (TLS)", RFC 6125, March 2011.

   [RFC6487]  Huston, G., Michaelson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates", RFC 6487, February
              2012.

   [RFC6810]  Bush, R. and R. Austein, "The Resource Public Key
              Infrastructure (RPKI) to Router Protocol", RFC 6810,
              January 2013.

   [RFC6811]  Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
              Austein, "BGP Prefix Origin Validation", RFC 6811, January
              2013.

16.2.  Informative References

   [RFC1996]  Vixie, P., "A Mechanism for Prompt Notification of Zone
              Changes (DNS NOTIFY)", RFC 1996, August 1996.

   [RFC4808]  Bellovin, S., "Key Change Strategies for TCP-MD5", RFC
              4808, March 2007.

   [RFC5781]  Weiler, S., Ward, D., and R. Housley, "The rsync URI
              Scheme", RFC 5781, February 2010.

   [RFC6480]  Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", RFC 6480, February 2012.

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   [RFC6481]  Huston, G., Loomans, R., and G. Michaelson, "A Profile for
              Resource Certificate Repository Structure", RFC 6481,
              February 2012.

   [RFC7128]  Bush, R., Austein, R., Patel, K., Gredler, H., and M.
              Waehlisch, "Resource Public Key Infrastructure (RPKI)
              Router Implementation Report", RFC 7128, February 2014.

Authors' Addresses

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

   Email: randy@psg.com

   Rob Austein
   Dragon Research Labs

   Email: sra@hactrn.net

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