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Internet Open Trading Protocol - IOTP Version 1.0
draft-ietf-trade-iotp-v1.0-protocol-07

The information below is for an old version of the document that is already published as an RFC.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 2801.
Author David Burdett
Last updated 2013-03-02 (Latest revision 1999-11-12)
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Informational
Formats
Additional resources Mailing list discussion
Stream WG state (None)
Document shepherd (None)
IESG IESG state Became RFC 2801 (Informational)
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-ietf-trade-iotp-v1.0-protocol-07
IPv6 Maintenance                                              J. Linkova
Internet-Draft                                                    Google
Updates: 4861 (if approved)                           September 13, 2020
Intended status: Standards Track
Expires: March 17, 2021

Gratuitous Neighbor Discovery: Creating Neighbor Cache Entries on First-
                              Hop Routers
                        draft-ietf-6man-grand-02

Abstract

   Neighbor Discovery (RFC4861) is used by IPv6 nodes to determine the
   link-layer addresses of neighboring nodes as well as to discover and
   maintain reachability information.  This document updates RFC4861 to
   allow routers to proactively create a Neighbor Cache entry when a new
   IPv6 address is assigned to a node.  It also updates RFC4861 and
   recommends nodes to send unsolicited Neighbor Advertisements upon
   assigning a new IPv6 address.  The proposed change will minimize the
   delay and packet loss when a node initiate connections to off-link
   destination from a new IPv6 address.

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 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 March 17, 2021.

Copyright Notice

   Copyright (c) 2020 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

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   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.

quot;
 CurrCodeType
                    "IOTP"

                    New values of CurrCodeType attribute are allocated
                    following review on the IETF Trade mailing list
                    and by the Designated Expert.

 DeliveryData/      "Post"
 DelivMethod
                    "Web"

                    "Email"

                    New values of Delivery Method attribute are
                    allocated following review on the IETF Trade
                    mailing list and by the Designated Expert. This
                    may require the publication of additional
                    documentation to describe how the delivery method
                    is used.

 PackagedContent/   "PCDATA"
 Content
                    "MIME"

                    "MIME:mimetype" (where mimetype must be the same
                    as content-type as defined by [MIME] )

                    "XML"

                    If the Content attribute is of the form
                    "MIME"mimetype", then control of new values for
                    "mimetype" is as defined in [MIME].

                    Otherwise, new values of the Content attribute are
                    allocated following review on the IETF Trade
                    mailing list and by the Designated Expert. This
                    may require the publication of additional
                    documentation to describe how the new attribute is
                    used within a Packaged Content element.

 RelatedTo/         "IotpTransaction"
 RelationshipType
                    "Reference"

                    New values of the RelationshipType attribute are
                    allocated following review on the IETF Trade
                    Working Group mailing list and by the Designated
                    Expert. This may require the publication of
                    additional documentation to describe how the

David Burdett et al.                                        [Page 223]

Internet Draft.                 IOTP/1.0                  October 1999

   Element Type/                     Attribute Values
   Attribute Name
                    delivery method is used.

 Status/            Offer
 StatusType
                    Payment

                    Delivery

                    Authentication

                    Unidentified

                    New values of the Status Type attribute are
                    allocated following:
                     o publication to the IETF Trade Working Group,
                       of an RFC describing the Trading Exchange,
                       Trading Roles and associated components that
                       relate to the Status, and
                     o review of the document on the IETF Trade
                       mailing list and by the Designated Expert.

                      [Note]     The document describing new values
                                 for the Status Type attribute may be
                                 combined with documents that describe
                                 new Trading Roles and types of
                                 signatures (see below).
                      [Note End]

 TradingRole/       "Consumer"
 TradingRole
                    "Merchant"

                    "PaymentHandler"

                    "DeliveryHandler"

                    "DelivTo"

                    "CustCare"

                    New values of the Trading Role attribute are
                    allocated following:
                     o publication to the IETF Trade Working Group,
                       of an RFC describing the Trading Exchange,
                       Trading Roles and associated components that
                       relate to the Trading Role, and
                     o review of the document on the IETF Trade
                       mailing list and by the Designated Expert.

                      [Note]     The document describing new values
                                 for the Trading Role attribute may be

David Burdett et al.                                        [Page 224]

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   Element Type/                     Attribute Values
   Attribute Name
                                 combined with documents that describe
                                 new Status Types (see above) and
                                 types of signatures (see below).
                      [Note End]

 TransId/           "BaselineAuthentication"
 IotpTransType
                    "BaselineDeposit"

                    "BaselinePurchase"

                    "BaselineRefund"

                    "BaselineWithdrawal"

                    "BaselineValueExchange"

                    "BaselineInquiry"

                    "BaselinePing"

                    New values of the IotpTransType attribute are
                    allocated following:
                     o publication to the IETF Trade mailing list, of
                       an RFC describing the new IOTP Transaction, and
                     o review of the document on the IETF Trade
                       Working Group mailing list and by the
                       Designated Expert.

 Attibute/ Content
 (see Signature
                    "OfferResponse"
 Component)         "PaymentResponse"

                    "DeliveryResponse"

                    "AuthenticationRequest"

                    "AuthenticationResponse"

                    "PingRequest"

                    "PingResponse"

                    New values of the code that define the type of a
                    signature are allocated following:
                     o publication to the IETF Trade Working Group,
                       of an RFC describing the Trading Exchange where
                       the signature is being used, and
                     o review of the document on the IETF Trade
                       mailing list and by the Designated Expert.

David Burdett et al.                                        [Page 225]

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   Element Type/                     Attribute Values
   Attribute Name

                     [Note]     The document describing new values
                                 for the types of signatures may be
                                 combined with documents that describe
                                 new Status Types and Trading Roles
                                 (see above).
                      [Note End]

12.2 Codes not controlled by IANA

 In addition to the formal development and registration of codes as
 described above, there is still a need for developers to experiment using
 new IOTP codes. For this reason, "user defined codes" may be used to
 identify additional values for the codes contained within this
 specification without the need for them to be registered with IANA.

 The definition of a user defined code is as follows:

 user_defined_code ::= ( "x-" | "X-" ) NameChar (NameChar)*

   NameChar           NameChar has the same definition as the [XML]
                      definition of NameChar

 Use of domain names (see [DNS]) to make user defined codes unique is
 recommended although this method cannot be relied upon.

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13. Internet Open Trading Protocol Data Type Definition

 This section contains the XML DTD for the Internet Open Trading
 Protocols.

 <!--
 ******************************************************
 *                                                    *
 * INTERNET OPEN TRADING PROTOCOL VERSION 1.0 DTD     *
 * Filename: ietf.org/rfc/rfcxxxx.dtd                 *
 *                                                    *
 * Changes from version 06 (iotp-v1.0-protocol-06.dtd)*
 * 1.  Corrected definition of encoding attrubute of  *
 *     the Value element in Dsig                      *
 * 2.  Updated the name space definition on the       *
 *     IOTP Message element                           *
 *                                                    *
 * Copyright Internet Engineering Task Force 1998,99  *
 *                                                    *
 ******************************************************

 ******************************************************
 * IOTP MESSAGE DEFINITION                            *
 ******************************************************
  -->

 <!ELEMENT IotpMessage
    ( TransRefBlk,
      IotpSignatures?,
      ErrorBlk?,
      ( AuthReqBlk |
        AuthRespBlk |
        AuthStatusBlk |
        CancelBlk |
        DeliveryReqBlk |
        DeliveryRespBlk |
        InquiryReqBlk |
        InquiryRespBlk |
        OfferRespBlk |
        PayExchBlk |
        PayReqBlk |
        PayRespBlk |
        PingReqBlk |
        PingRespBlk |
        TpoBlk |
        TpoSelectionBlk
      )*
    ) >
 <!ATTLIST IotpMessage
   xmlns              CDATA
    'http://ietf.org/rfc/rfcxxxx.txt' >

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 <!--
 ******************************************************
 * TRANSACTION REFERENCE BLOCK DEFINITION             *
 ******************************************************
  -->

 <!ELEMENT TransRefBlk (TransId, MsgId, RelatedTo*) >
 <!ATTLIST TransRefBlk
  ID                 ID      #REQUIRED >

 <!ELEMENT TransId EMPTY >
 <!ATTLIST TransId
  ID                 ID      #REQUIRED
  Version            NMTOKEN #FIXED '1.0'
  IotpTransId        CDATA   #REQUIRED
  IotpTransType      CDATA   #REQUIRED
  TransTimeStamp     CDATA   #REQUIRED >

 <!ELEMENT MsgId EMPTY >
 <!ATTLIST MsgId
  ID                 ID      #REQUIRED
  RespIotpMsg        NMTOKEN #IMPLIED
  xml:lang           NMTOKEN #REQUIRED
  LangPrefList       NMTOKENS #IMPLIED
  CharSetPrefList    NMTOKENS #IMPLIED
  SenderTradingRoleRef NMTOKEN #IMPLIED
  SoftwareId         CDATA   #REQUIRED
  TimeStamp          CDATA   #IMPLIED >

 <!ELEMENT RelatedTo (PackagedContent) >
 <!ATTLIST RelatedTo
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  RelationshipType   NMTOKEN #REQUIRED
  Relation           CDATA   #REQUIRED
  RelnKeyWords       NMTOKENS #IMPLIED >

 <!--
 ******************************************************
 * Packaged Content Common Element                    *
 ******************************************************
  -->

 <!ELEMENT PackagedContent (#PCDATA) >
 <!ATTLIST PackagedContent
  Name             CDATA     #IMPLIED
  Content          NMTOKEN   "PCDATA"

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  Transform (NONE|BASE64)    "NONE" >

 <!--
 ******************************************************
 * TRADING COMPONENTS                                 *
 ******************************************************
  -->
 <!-- PROTOCOL OPTIONS COMPONENT -->
 <!ELEMENT ProtocolOptions EMPTY >
 <!ATTLIST ProtocolOptions
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  ShortDesc          CDATA   #REQUIRED
  SenderNetLocn      CDATA   #IMPLIED
  SecureSenderNetLocn CDATA  #IMPLIED
  SuccessNetLocn     CDATA   #REQUIRED >

 <!-- AUTHENTICATION DATA COMPONENT -->
 <!ELEMENT AuthReq (Algorithm, PackagedContent*)>
 <!ATTLIST AuthReq
  ID                 ID      #REQUIRED
  AuthenticationId   CDATA   #REQUIRED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!-- AUTHENTICATION RESPONSE COMPONENT -->
 <!ELEMENT AuthResp (PackagedContent*) >
 <!ATTLIST AuthResp
  ID                 ID      #REQUIRED
  AuthenticationId   CDATA   #REQUIRED
  SelectedAlgorithmRef NMTOKEN #REQUIRED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!-- TRADING ROLE INFO REQUEST COMPONENT -->
 <!ELEMENT TradingRoleInfoReq EMPTY>
 <!ATTLIST TradingRoleInfoReq
  ID                 ID      #REQUIRED
  TradingRoleList    NMTOKENS #REQUIRED >

 <!-- ORDER COMPONENT -->
 <!ELEMENT Order (PackagedContent*) >
 <!ATTLIST Order
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  OrderIdentifier    CDATA   #REQUIRED
  ShortDesc          CDATA   #REQUIRED
  OkFrom             CDATA   #REQUIRED
  OkTo               CDATA   #REQUIRED
  ApplicableLaw      CDATA   #REQUIRED
  ContentSoftwareId  CDATA   #IMPLIED >

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 <!-- ORGANISATION COMPONENT -->
 <!ELEMENT Org (TradingRole+, ContactInfo?,
      PersonName?, PostalAddress?)>
 <!ATTLIST Org
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  OrgId              CDATA   #REQUIRED
  LegalName          CDATA   #IMPLIED
  ShortDesc          CDATA   #IMPLIED
  LogoNetLocn        CDATA   #IMPLIED >

 <!ELEMENT TradingRole EMPTY >
 <!ATTLIST TradingRole
  ID      ID#REQUIRED
  TradingRole        NMTOKEN #REQUIRED
  IotpMsgIdPrefix    NMTOKEN #REQUIRED
  CancelNetLocn      CDATA   #IMPLIED
  ErrorNetLocn       CDATA   #IMPLIED
  ErrorLogNetLocn  CDATA           #IMPLIED >

 <!ELEMENT ContactInfo EMPTY >
 <!ATTLIST ContactInfo
  xml:lang           NMTOKEN #IMPLIED
  Tel                CDATA   #IMPLIED
  Fax                CDATA   #IMPLIED
  Email              CDATA   #IMPLIED
  NetLocn            CDATA   #IMPLIED >

 <!ELEMENT PersonName EMPTY >
 <!ATTLIST PersonName
  xml:lang           NMTOKEN #IMPLIED
  Title              CDATA   #IMPLIED
  GivenName          CDATA   #IMPLIED
  Initials           CDATA   #IMPLIED
  FamilyName         CDATA   #IMPLIED >

 <!ELEMENT PostalAddress EMPTY >
 <!ATTLIST PostalAddress
  xml:lang           NMTOKEN #IMPLIED
  AddressLine1       CDATA   #IMPLIED
  AddressLine2       CDATA   #IMPLIED
  CityOrTown         CDATA   #IMPLIED
  StateOrRegion      CDATA   #IMPLIED
  PostalCode         CDATA   #IMPLIED
  Country            CDATA   #IMPLIED
  LegalLocation (True | False) 'False' >

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 <!-- BRAND LIST COMPONENT -->
 <!ELEMENT BrandList (Brand+, ProtocolAmount+,
  CurrencyAmount+, PayProtocol+) >
 <!ATTLIST BrandList
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  ShortDesc          CDATA   #REQUIRED
  PayDirection (Debit | Credit) #REQUIRED >

 <!ELEMENT Brand (ProtocolBrand*, PackagedContent*) >
 &Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Solution Requirements . . . . . . . . . . . . . . . . . . . .   5
   4.  Proposed Changes to Neighbor Discovery  . . . . . . . . . . .   6
     4.1.  Nodes Sending Gratuitous Neighbor Advertisements  . . . .   6
     4.2.  Routers Creating Cache Entries Upon Receiving Unsolicited
           Neighbor Advertisements . . . . . . . . . . . . . . . . .   7
   5.  Avoiding Disruption . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Neighbor Cache Entry Exists in Any State Other That
           INCOMPLETE  . . . . . . . . . . . . . . . . . . . . . . .   8
     5.2.  Neighbor Cache Entry is in INCOMPLETE state . . . . . . .   8
     5.3.  Neighbor Cache Entry Does Not Exist . . . . . . . . . . .   8
       5.3.1.  The Rightful Owner Is Not Sending Packets From The
               Address . . . . . . . . . . . . . . . . . . . . . . .   9
       5.3.2.  The Rightful Owner Has Started Sending Packets From
               The Address . . . . . . . . . . . . . . . . . . . . .  10
   6.  Modifications to RFC-Mandated Behavior  . . . . . . . . . . .  11
     6.1.  Modification to RFC4861 Neighbor Discovery for IP version
           6 (IPv6)  . . . . . . . . . . . . . . . . . . . . . . . .  11
       6.1.1.  Modification to the section 7.2.5 . . . . . . . . . .  11
       6.1.2.  Modification to the section 7.2.6 . . . . . . . . . .  12
   7.  Solutions Considered but Discarded  . . . . . . . . . . . . .  12
     7.1.  Do Nothing  . . . . . . . . . . . . . . . . . . . . . . .  13
     7.2.  Change to the Registration-Based Neighbor Discovery . . .  13
     7.3.  Host Sending NS to the Router Address from Its GUA  . . .  13
     7.4.  Host Sending Router Solicitation from its GUA . . . . . .  14
     7.5.  Routers Populating Their Caches by Gleaning From Neighbor
           Discovery Packets . . . . . . . . . . . . . . . . . . . .  15
     7.6.  Initiating Hosts-to-Routers Communication . . . . . . . .  15
     7.7.  Transit Dataplane Traffic From a New Address Triggering
           Address Resolution  . . . . . . . . . . . . . . . . . . .  16
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  17
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     11.2.  Informative References . . . . . . . . . . . . . . . . .  18

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   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   The Neighbor Discovery state machine defined in [RFC4861] assumes
   that communications between IPv6 nodes are in most cases bi-
   directional and if a node A is trying to communicate to its neighbor,
   node B, the return traffic flows could be expected.  So when the node
   A starts the address resolution process, the target node B would also
   create an entry for A address in its neighbor cache.  That entry will
   be used for sending the return traffic to A.

   In particular, section 7.2.5 of [RFC4861] states: "When a valid
   Neighbor Advertisement is received (either solicited or unsolicited),
   the Neighbor Cache is searched for the target's entry.  If no entry
   exists, the advertisement SHOULD be silently discarded.  There is no
   need to create an entry if none exists, since the recipient has
   apparently not initiated any communication with the target."

   While this approach is perfectly suitable for host-to-host on-link
   communications, it does not work so well when a host sends traffic to
   off-link destinations.  After joining the network and receiving a
   Router Advertisement the host populates its neighbor cache with the
   default router IPv6 and link-layer addresses and is able to send
   traffic to off-link destinations.  At the same time the router does
   not have any cache entries for the host global addresses yet and only
   starts address resolution upon receiving the first packet of the
   return traffic flow.  While waiting for the resolution to complete
   routers only keep a very small number of packets in the queue, as
   recommended in Section 7.2.2 [RFC4861].  All subsequent packets
   arriving before the resolution process finishes are likely to be
   dropped.  It might cause user-visible packet loss and performance
   degradation.

1.1.  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.

1.2.  Terminology

   Node: a device that implements IP, [RFC4861].

   Host: any node that is not a router, [RFC4861].

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   ND: Neighbor Discovery, [RFC4861].

   SLAAC: IPv6 Stateless Address Autoconfiguration, [RFC4862].

   NS: Neighbor Solicitation, [RFC4861].

   NA: Neighbor Advertisement, [RFC4861].

   RS: Router Solicitation, [RFC4861].

   RA: Router Advertisement, [RFC4861].

   SLLA: Source link-layer Address, an option in the ND packets
   containing the link-layer address of the sender of the packet
   [RFC4861].

   TLLA: Target link-layer Address, an option in the ND packets
   containing the link-layer address of the target [RFC4861].

   GUA: Global Unicast Address [RFC4291].

   DAD: Duplicate Address Detection, [RFC4862].

   Optimistic DAD: a modification of DAD, [RFC4429].

2.  Problem Statement

   The most typical scenario when the problem may arise is a host
   joining the network, forming a new address and using that address for
   accessing the Internet:

   1.  A host joins the network and receives a Router Advertisement (RA)
       packet from the first-hop router (either a periodic unsolicited
       RA or a response to a Router Solicitation sent by the host).  The
       RA contains information the host needs to perform SLAAC and to
       configure its network stack.  As in most cases the RA also
       contains the link-layer address of the router, the host can
       populate its Neighbor Cache with the router's link-local and
       link-layer addresses.

   2.  The host starts opening connections to off-link destinations.  A
       very common use case is a mobile device sending probes to detect
       the Internet connectivity and/or the presence of a captive portal
       on the network.  To speed up that process many implementations
       use Optimistic DAD which allows them to send probes before the
       DAD process is completed.  At that moment the device neighbor
       cache contains all information required to send those probes
       (such as the default router link-local the link-layer addresses).

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       The router neighbor cache, however, might contain an entry for
       the device link-local address (if the device has been performing
       the address resolution for the router link-local address), but
       there are no entries for the device global addresses.

   3.  Return traffic is received by the first-hop router.  As the
       router does not have any cache entry for the host global address
       yet, the router starts the neighbor discovery process by creating
       an INCOMPLETE cache entry and then sending a Neighbor
       Solicitation to the Solicited Node Multicast Address.  Most
       router implementations buffer only one data packet while
       resolving the packet destination address, so it would drop all
       subsequent packets for the host global address, until the address
       resolution process is completed.

   4.  If the host sends multiple probes in parallel, it would consider
       all but one of them failed.  That leads to user-visible delay in
       connecting to the network, especially if the host implements some
       form of backoff mechanism and does not retransmit the probes as
       soon as possible.

   This scenario illustrates the problem occurring when the device
   connects to the network for the first time or after a timeout long
   enough for the device address to be removed from the router's
   neighbor cache.  However, the same sequence of events happen when the
   host starts using a new global address previously unseen by the
   router, such as a new privacy address [RFC4941] or if the router's
   Neighbor Cache has been flushed.

   While in dual-stack networks this problem might be hidden by Happy
   Eyeballs [RFC8305] it manifests quite clearly in IPv6-only
   environments, especially wireless ones, leading to poor user
   experience and contributing to a negative perception of IPv6-only
   solutions as unstable and non-deployable.

3.  Solution Requirements

   It would be highly desirable to improve the Neighbor Discovery
   mechanics so routers have a usable cache entry for a host address by
   the time the router receives the first packet for that address.  In
   particular:

   o  If the router does not have a Neighbor Cache entry for the
      address, a STALE entry needs to be created.

   o  The solution needs to work for Optimistic addresses as well.
      Devices implementing the Optimistic DAD usually attempt to
      minimize the delay in connecting to the network and therefore are

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      lt;!ATTLIST Brand
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #IMPLIED
  BrandId            CDATA   #REQUIRED
  BrandName          CDATA   #REQUIRED
  BrandLogoNetLocn   CDATA   #REQUIRED
  BrandNarrative     CDATA   #IMPLIED
  ProtocolAmountRefs IDREFS  #REQUIRED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!ELEMENT ProtocolBrand (PackagedContent*) >
 <!ATTLIST ProtocolBrand
  ProtocolId         CDATA   #REQUIRED
  ProtocolBrandId    CDATA   #REQUIRED >

 <!ELEMENT ProtocolAmount (PackagedContent*) >
 <!ATTLIST ProtocolAmount
  ID                 ID      #REQUIRED
  PayProtocolRef     IDREF   #REQUIRED
  CurrencyAmountRefs IDREFS  #REQUIRED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!ELEMENT CurrencyAmount EMPTY >
 <!ATTLIST CurrencyAmount
  ID                 ID      #REQUIRED
  Amount             CDATA   #REQUIRED
  CurrCodeType       NMTOKEN 'ISO4217-A'
  CurrCode           CDATA   #REQUIRED >

 <!ELEMENT PayProtocol (PackagedContent*) >
 <!ATTLIST PayProtocol
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #IMPLIED
  ProtocolId         NMTOKEN #REQUIRED
  ProtocolName       CDATA   #REQUIRED
  ActionOrgRef       NMTOKEN #REQUIRED
  PayReqNetLocn      CDATA   #IMPLIED
  SecPayReqNetLocn   CDATA   #IMPLIED
  ContentSoftwareId  CDATA   #IMPLIED >

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 <!-- BRAND SELECTION COMPONENT -->
 <!ELEMENT BrandSelection (BrandSelBrandInfo?,
      BrandSelProtocolAmountInfo?,
      BrandSelCurrencyAmountInfo?) >
 <!ATTLIST BrandSelection
  ID                 ID      #REQUIRED
  BrandListRef       NMTOKEN #REQUIRED
  BrandRef           NMTOKEN #REQUIRED
  ProtocolAmountRef  NMTOKEN #REQUIRED
  CurrencyAmountRef  NMTOKEN #REQUIRED >

 <!ELEMENT BrandSelBrandInfo (PackagedContent+) >
 <!ATTLIST BrandSelBrandInfo
  ID                 ID      #REQUIRED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!ELEMENT BrandSelProtocolAmountInfo (PackagedContent+) >
 <!ATTLIST BrandSelProtocolAmountInfo
  ID                 ID      #REQUIRED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!ELEMENT BrandSelCurrencyAmountInfo (PackagedContent+) >
 <!ATTLIST BrandSelCurrencyAmountInfo
  ID                 ID      #REQUIRED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!-- PAYMENT COMPONENT -->
 <!ELEMENT Payment EMPTY >
 <!ATTLIST Payment
  ID                 ID      #REQUIRED
  OkFrom             CDATA   #REQUIRED
  OkTo               CDATA   #REQUIRED
  BrandListRef       NMTOKEN #REQUIRED
  SignedPayReceipt (True | False) #REQUIRED
  StartAfterRefs     NMTOKENS #IMPLIED >

 <!-- PAYMENT SCHEME COMPONENT -->
 <!ELEMENT PaySchemeData (PackagedContent+) >
 <!ATTLIST PaySchemeData
  ID                 ID      #REQUIRED
  PaymentRef         NMTOKEN #IMPLIED
  ConsumerPaymentId  CDATA   #IMPLIED
  PaymentHandlerPayId CDATA  #IMPLIED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!-- PAYMENT RECEIPT COMPONENT -->
 <!ELEMENT PayReceipt (PackagedContent*) >
 <!ATTLIST PayReceipt
  ID                 ID      #REQUIRED
  PaymentRef         NMTOKEN #REQUIRED

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  PayReceiptNameRefs NMTOKENS #IMPLIED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!-- PAYMENT NOTE COMPONENT -->
 <!ELEMENT PaymentNote (PackagedContent+) >
 <!ATTLIST PaymentNote
   ID                ID      #REQUIRED
   ContentSoftwareId CDATA   #IMPLIED >

 <!-- DELIVERY COMPONENT -->
 <!ELEMENT Delivery (DeliveryData?, PackagedContent*) >
 <!ATTLIST Delivery
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  DelivExch          (True | False) #REQUIRED
  DelivAndPayResp    (True | False) #REQUIRED
  ActionOrgRef       NMTOKEN #IMPLIED >

 <!ELEMENT DeliveryData (PackagedContent*) >
 <!ATTLIST DeliveryData
  xml:lang           NMTOKEN #IMPLIED
  OkFrom             CDATA   #REQUIRED
  OkTo               CDATA   #REQUIRED
  DelivMethod        NMTOKEN #REQUIRED
  DelivToRef         NMTOKEN #REQUIRED
  DelivReqNetLocn    CDATA   #IMPLIED
  SecDelivReqNetLocn CDATA   #IMPLIED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!-- CONSUMER DELIVERY DATA COMPONENT -->
 <!ELEMENT ConsumerDeliveryData EMPTY >
 <!ATTLIST ConsumerDeliveryData
  ID                 ID      #REQUIRED
  ConsumerDeliveryId CDATA   #REQUIRED >

 <!-- DELIVERY NOTE COMPONENT -->
 <!ELEMENT DeliveryNote (PackagedContent+) >
 <!ATTLIST DeliveryNote
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  DelivHandlerDelivId CDATA  #IMPLIED
  ContentSoftwareId  CDATA   #IMPLIED >

 <!-- STATUS COMPONENT -->
 <!ELEMENT Status EMPTY >
 <!ATTLIST Status
  ID                 ID      #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  StatusType         NMTOKEN #REQUIRED

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  ElRef              NMTOKEN #IMPLIED
  ProcessState (NotYetStarted | InProgress |
      CompletedOk | Failed | ProcessError) #REQUIRED
  CompletionCode     NMTOKEN #IMPLIED
  ProcessReference   CDATA   #IMPLIED
  StatusDesc         CDATA   #IMPLIED >

 <!-- TRADING ROLE DATA COMPONENT -->
 <!ELEMENT TradingRoleData (PackagedContent+) >
 <!ATTLIST TradingRoleData
   ID                ID      #REQUIRED
   OriginatorElRef   NMTOKEN #REQUIRED
   DestinationElRefs NMTOKENS #REQUIRED >

 <!-- INQUIRY TYPE COMPONENT -->
 <!ELEMENT InquiryType EMPTY >
 <!ATTLIST InquiryType
  ID                 ID      #REQUIRED
  Type               NMTOKEN #REQUIRED
  ElRef              NMTOKEN #IMPLIED
  ProcessReference   CDATA   #IMPLIED >

 <!-- ERROR COMPONENT -->
 <!ELEMENT ErrorComp (ErrorLocation+, PackagedContent*) >
 <!ATTLIST ErrorComp
  ID                 NMTOKEN #REQUIRED
  xml:lang           NMTOKEN #REQUIRED
  ErrorCode          NMTOKEN #REQUIRED
  ErrorDesc          CDATA   #REQUIRED
  Severity (Warning|TransientError|HardError) #REQUIRED
  MinRetrySecs       CDATA   #IMPLIED
  SwVendorErrorRef   CDATA   #IMPLIED >

 <!ELEMENT ErrorLocation EMPTY >
 <!ATTLIST ErrorLocation
  ElementType        NMTOKEN #REQUIRED
  IotpMsgRef         NMTOKEN #IMPLIED
  BlkRef             NMTOKEN #IMPLIED
  CompRef            NMTOKEN #IMPLIED
  ElementRef         NMTOKEN #IMPLIED
  AttName            NMTOKEN #IMPLIED >

 <!--
 ******************************************************
 * TRADING BLOCKS                                     *
 ******************************************************
  -->

 <!-- TRADING PROTOCOL OPTIONS BLOCK -->
 &more likely to be affected by the problem described in this
      document.

   o  In case of duplicate addresses present in the network, the
      proposed solution MUST NOT override the existing entry.

   o  In topologies with multiple first-hop routers the cache needs to
      be updated on all of them, as traffic might be asymmetric:
      outgoing flows leaving the network via one router while the return
      traffic enters the segment via another one.

   In addition the solution MUST NOT exacerbate issues described in
   [RFC6583] and MUST be compatible with the recommendations provided in
   [RFC6583].

4.  Proposed Changes to Neighbor Discovery

   The following changes are proposed to minimize the delay in creating
   new entries in a router neighbor cache

   o  A node sends unsolicited NAs upon assigning a new IPv6 address to
      its interface.

   o  A router creates a new cache entry upon receiving an unsolicited
      NA from a host.

   The following sections discuss these changes in more detail.

4.1.  Nodes Sending Gratuitous Neighbor Advertisements

   The section 7.2.6 of [RFC4861] discusses using unsolicited Neighbor
   Advertisement to inform node neighbors of the new link-layer address
   quickly.  The same mechanism could be used to notify the node
   neighbors about the new network-layer address as well: the node can
   send gratuitous unsolicited Neighbor Advertisements upon assigning a
   new IPv6 address to its interface.

   To minimize the potential disruption in case of duplicate addresses
   the node should not set the Override flag for a preferred address and
   must not set the Override flag if the address is in Optimistic
   [RFC4429] state.

   As the main purpose of sending unsolicited NAs upon configuring a new
   address is to proactively create a Neighbor Cache entry on the first-
   hop routers, the gratuitous NAs are sent to all-routers multicast
   address (ff02::2).  Limiting the recipients to routers only would
   help reduce the multicast noise level.  If the link-layer devices are

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   performing MLD snooping [RFC4541] then those unsolicited NAs will be
   only sent to onlink routers instead of being flooded to all nodes.

   It should be noted that the proposed mechanism does not cause any
   significant increase in the multicast traffic.  The additional
   multicast unsolicited NA would proactively create a STALE cache entry
   on routers as discussed below.  When the router receives the return
   traffic flows it does not need to send multicast NSes to the
   solicited node multicast address but would be sending unicast NSes
   instead.  Therefore total amount of multicast traffic should not
   increase.

4.2.  Routers Creating Cache Entries Upon Receiving Unsolicited Neighbor
      Advertisements

   The section 7.2.5 of [RFC4861] states: "When a valid Neighbor
   Advertisement is received (either solicited or unsolicited), the
   Neighbor Cache is searched for the target's entry.  If no entry
   exists, the advertisement SHOULD be silently discarded.  There is no
   need to create an entry if none exists, since the recipient has
   apparently not initiated any communication with the target".

   The reasoning behind dropping unsolicited Neighbor Advertisements
   ("the recipient has apparently not initiated any communication with
   the target") is valid for onlink host-to-host communication but, as
   discussed above, it does not really apply for the scenario when the
   host is announcing its address to routers.  Therefore it would be
   beneficial to allow routers creating new entries upon receiving an
   unsolicited Neighbor Advertisement.

   This document updates [RFC4861] so that routers create a new Neighbor
   Cache entry upon receiving an unsolicited Neighbor Advertisement.
   The proposed changes do not modify routers behaviour specified in
   [RFC4861] for the scenario when the corresponding Neighbor Cache
   entry already exists.

5.  Avoiding Disruption

   If nodes following the recommendations in this document are using the
   DAD mechanism defined in [RFC4862], they would send unsolicited NA as
   soon as the address changes the state from tentative to preferred
   (after its uniqueness has been verified).  However nodes willing to
   minimize network stack configuration delays might be using optimistic
   addresses, which means there is a possibility of the address not
   being unique on the link.  The section 2.2 of [RFC4429] discusses
   measures to ensure that ND packets from the optimistic address do not
   override any existing neighbor cache entries as it would cause
   traffic interruption of the rightful address owner in case of address

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   conflict.  As nodes willing to speed up their network stack
   configuration are most likely to be affected by the problem outlined
   in this document it seems reasonable for such hosts to advertise
   their optimistic addresses by sending unsolicited NAs.  The main
   question to consider is the potential risk of overriding the cache
   entry for the rightful address owner if the optimistic address
   happens to be duplicated.

   The following sections are discussing the address collision scenario
   when a node sends an unsolicited NA for an address in the Optimistic
   state, while another node has the same address assigned already.

5.1.  Neighbor Cache Entry Exists in Any State Other That INCOMPLETE

   If the router Neighbor Cache entry for the target address already
   exists in any state other than INCOMPLETE, then as per section 7.2.5
   of [RFC4861] an unsolicited NA with the Override flag cleared would
   change the entry state from REACHABLE to STALE but would not update
   the entry in any other way.  Therefore even if the host sends an
   unsolicited NA from the its Optimistic address the router cache entry
   would not be updated with the new Link-Layer address and no impact to
   the traffic for the rightful address owner is expected.

5.2.  Neighbor Cache Entry is in INCOMPLETE state

   Another corner case is the INCOMPLETE cache entry for the address.
   If the host sends an unsolicited NA from the Optimistic address it
   would update the entry with the host link-layer address and set the
   entry to the STALE state.  As the INCOMPLETE entry means that the
   router has started the ND process for the address and the multicast
   NS has been sent, the rightful owner is expected to reply with
   solicited NA with the Override flag set.  Upon receiving a solicited
   NA with the Override flag the cache entry will be updated with the
   TLLA supplied and (as the NA has the Solicited flag set), the entry
   state will be set to REACHABLE.  It would recover the cache entry and
   set the link-layer address to the one of the rightful owner.  The
   only potential impact would be for packets arriving to the router
   after the unsolicited NA from the host but before the rightful owner
   responded with the solicited NA.  Those packets would be sent to the
   host with the optimistic address instead of its rightful owner.
   However those packets would have been dropped anyway as until the
   solicited NA is received the router can not send the traffic.

5.3.  Neighbor Cache Entry Does Not Exist

   There are two distinct scenarios which can lead to the situation when
   the router does not have a NC entry for the IPv6 address:

lt;!ELEMENT TpoBlk ( ProtocolOptions, BrandList*, Org* ) >

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 <!ATTLIST TpoBlk
  ID                 ID      #REQUIRED >

 <!-- TPO SELECTION BLOCK -->
 <!ELEMENT TpoSelectionBlk (BrandSelection+) >
 <!ATTLIST TpoSelectionBlk
  ID                 ID      #REQUIRED >

 <!-- OFFER RESPONSE BLOCK -->
 <!ELEMENT OfferRespBlk (Status, Order?, Payment*,
              Delivery?, TradingRoleData*) >
 <!ATTLIST OfferRespBlk
  ID                 ID      #REQUIRED >

 <!-- AUTHENTICATION REQUEST BLOCK -->
 <!ELEMENT AuthReqBlk (AuthReq*, TradingRoleInfoReq?) >
 <!ATTLIST AuthReqBlk
  ID                 ID      #REQUIRED >

 <!-- AUTHENTICATION RESPONSE BLOCK -->
 <!ELEMENT AuthRespBlk (AuthResp?, Org*) >
 <!ATTLIST AuthRespBlk
  ID                 ID      #REQUIRED >

 <!-- AUTHENTICATION STATUS BLOCK -->
 <!ELEMENT AuthStatusBlk (Status) >
 <!ATTLIST AuthStatusBlk
  ID                 ID      #REQUIRED >

 <!-- PAYMENT REQUEST BLOCK -->
 <!ELEMENT PayReqBlk (Status+, BrandList, BrandSelection,
      Payment, PaySchemeData?, Org*, TradingRoleData*) >
 <!ATTLIST PayReqBlk
  ID                 ID      #REQUIRED >

 <!-- PAYMENT EXCHANGE BLOCK -->
 <!ELEMENT PayExchBlk (PaySchemeData) >
 <!ATTLIST PayExchBlk
  ID                 ID      #REQUIRED >

 <!-- PAYMENT RESPONSE BLOCK -->
 <!ELEMENT PayRespBlk (Status, PayReceipt?, PaySchemeData?,
      PaymentNote?, TradingRoleData*) >
 <!ATTLIST PayRespBlk
  ID                 ID      #REQUIRED >

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 <!-- DELIVERY REQUEST BLOCK -->
 <!ELEMENT DeliveryReqBlk (Status+, Order, Org*, Delivery,
      ConsumerDeliveryData?, TradingRoleData*) >
 <!ATTLIST DeliveryReqBlk
  ID                 ID      #REQUIRED >

 <!-- DELIVERY RESPONSE BLOCK -->
 <!ELEMENT DeliveryRespBlk (Status, DeliveryNote) >
 <!ATTLIST DeliveryRespBlk
  ID                 ID      #REQUIRED >

 <!-- INQUIRY REQUEST BLOCK -->
 <!ELEMENT InquiryReqBlk ( InquiryType, PaySchemeData? ) >
 <!ATTLIST InquiryReqBlk
  ID                 ID      #REQUIRED >

 <!-- INQUIRY RESPONSE BLOCK -->
 <!ELEMENT InquiryRespBlk (Status, PaySchemeData?) >
 <!ATTLIST InquiryRespBlk
  ID                 ID      #REQUIRED
  LastReceivedIotpMsgRef NMTOKEN #IMPLIED
  LastSentIotpMsgRef NMTOKEN #IMPLIED >

 <!-- PING REQUEST BLOCK -->
 <!ELEMENT PingReqBlk (Org*)>
 <!ATTLIST PingReqBlk
  ID                 ID      #REQUIRED>

 <!-- PING RESPONSE BLOCK -->
 <!ELEMENT PingRespBlk (Org+)>
 <!ATTLIST PingRespBlk
  ID                 ID      #REQUIRED
  PingStatusCode (Ok | Busy | Down) #REQUIRED
  SigVerifyStatusCode (Ok | NotSupported | Fail) #IMPLIED
  xml:lang           NMTOKEN #IMPLIED
  PingStatusDesc     CDATA   #IMPLIED>

 <!-- ERROR BLOCK -->
 <!ELEMENT ErrorBlk (ErrorComp+, PaySchemeData*) >
 <!ATTLIST ErrorBlk
  ID                 ID      #REQUIRED >

 <!-- CANCEL BLOCK -->
 <!ELEMENT CancelBlk (Status) >
 <!ATTLIST CancelBlk
  ID                 ID      #REQUIRED >

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 <!--
 ******************************************************
 * IOTP SIGNATURES BLOCK DEFINITION                   *
 ******************************************************
 -->

 <!ELEMENT IotpSignatures (Signature+ ,Certificate*) >
 <!ATTLIST IotpSignatures
     ID        ID        #IMPLIED
 >

 <!--
 ******************************************************
 * IOTP SIGNATURE COMPONENT DEFINITION                *
 ******************************************************
 -->

 <!ELEMENT Signature (Manifest, Value+) >
 <!ATTLIST Signature
     ID         ID        #IMPLIED
 >

 <!ELEMENT Manifest
     (       Algorithm+,
             Digest+,
             Attribute*,
             OriginatorInfo,
             RecipientInfo+
     )
 >

 <!ATTLIST Manifest
     LocatorHRefBase       CDATA             #IMPLIED
 >

 <!ELEMENT Algorithm (Parameter*) >
 <!ATTLIST Algorithm
     ID                     ID                #REQUIRED
     type            (digest|signature)      #IMPLIED
     name                  NMTOKEN           #REQUIRED
 >

 <!ELEMENT Digest (Locator, Value) >
 <!ATTLIST Digest
     DigestAlgorithmRef    IDREF             #REQUIRED
 >

 <!ELEMENT Attribute ( ANY ) >
 <!ATTLIST Attribute
     type                   NMTOKEN           #REQUIRED
     critical            ( true | false )     #REQUIRED

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 >

 <!ELEMENT OriginatorInfo ANY >
 <!ATTLIST OriginatorInfo
     OriginatorRef           NMTOKEN          #IMPLIED
 >

 <!ELEMENT RecipientInfo ANY >
 <!ATTLIST RecipientInfo
     SignatureAlgorithmRef   IDREF            #REQUIRED
     SignatureValueRef       IDREF            #IMPLIED
     SignatureCertRef        IDREF            #IMPLIED
     RecipientRefs           NMTOKENS         #IMPLIED
 >

 <!ELEMENT KeyIdentifier EMPTY>
 <!ATTLIST KeyIdentifier
     value                    CDATA           #REQUIRED
 >

 <!ELEMENT Parameter ANY >
 <!ATTLIST Parameter
     type                     CDATA           #REQUIRED
 >

 <!--
 ******************************************************
 * IOTP CERTIFICATE COMPONENT DEFINITION              *
 ******************************************************
 -->

 <!ELEMENT Certificate
  (  IssuerAndSerialNumber,  ( Value | Locator ) )
 >

 <!ATTLIST Certificate
     ID                        ID                #IMPLIED
     type                      NMTOKEN           #REQUIRED
 >

 <!ELEMENT IssuerAndSerialNumber EMPTY >
 <!ATTLIST IssuerAndSerialNumber
     issuer                     CDATA            #REQUIRED
     number                     CDATA            #REQUIRED
 >

 <!--
 ******************************************************
 * IOTP SHARED COMPONENT DEFINITION                   *
 ******************************************************
 -->
 <!ELEMENT Value ( #PCDATA ) >
 <!ATTLIST Value

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     ID               ID           #IMPLIED
     encoding    (base64|none)    'base64'
 >

 <!ELEMENT Locator EMPTY>
 <!ATTLIST Locator
     xml:link        CDATA         #FIXED        'simple'
     href            CDATA         #REQUIRED
 >

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14. Glossary

 This section contains a glossary of some of the terms used within this
 specification in alphabetical order.

        NAME                            DESCRIPTION

 Authenticator      The Organisation which is requesting the
                    authentication of another Organisation, and

 Authenticatee      The Organisation being authenticated by an
                    Authenticator

 Business Error     See Status Component.

 Brand              A Brand is the mark which identifies a particular
                    type of Payment Instrument. A list of Brands are
                    the payment options which are presented by the
                    Merchant to the Consumer and from which the
                    Consumer makes a selection. Each Brand may have a
                    different Payment Handler. Examples of Brands
                    include:
                     o payment association and proprietary Brands,
                       for example MasterCard, Visa, American Express,
                       Diners Club, American Express, Mondex,
                       GeldKarte, CyberCash, etc.
                     o Promotional Brands (see below). These include:
                     o store Brands, where the Payment Instrument is
                       issued to a Consumer by a particular Merchant,
                       for example Walmart, Sears, or Marks and
                       Spencer (UK)
                     o coBrands, for example American Advantage Visa,
                       where an a company uses their own Brand in
                       conjunction with, typically, a payment
                       association Brand.

 Consumer           The Organisation which is to receive the benefit
                    of and typically pay for the goods or services.

 ContentSoftwareId  This contains information which identifies the
                    software which generated the content of the
                    element. Its purpose is to help resolve
                    interoperability problems that might occur as a
                    result of incompatibilities between messages
                    produced by different software. It is a single
                    text string in the language defined by xml:lang.
                    It must contain, as a minimum:
                     o the name of the software manufacturer
                     o the name of the software
                     o the version of the software, and
                     o the build of the software

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        NAME                            DESCRIPTION

                    It is recommended that this attribute is included
                    whenever the software which generated the content
                    cannot be identified from the SoftwareId attribute
                    on the Message Id Component (see section 3.3.2)

 Customer Care      An Organisation that is providing customer care
 Provider           typically on behalf of a Merchant. Examples of
                    customer care include, responding to problems
                    raised by a Consumer arising from an IOTP
                    Transaction that the Consumer took part in.

 Delivery Handler   The Organisation that directly delivers the goods
                    or services to the Consumer on behalf of the
                    Merchant. Delivery can be in the form of either
                    digital goods (e.g. a [MIME] message), or
                    physically delivered using the post or a courier.

 Document Exchange  A Document Exchange consists of a set of IOTP
                    Messages exchanged between two parties that
                    implement part or all of two Trading Exchanges
                    simultaneously in order to minimise the number of
                    actual IOTP Messages which must be sent over the
                    Internet.

                    Document Exchanges are combined together in
                    sequence to implement a particular IOTP
                    Transaction.

 Dual Brand         A Dual Brand means that a single Payment
                    Instrument may be used as if it were two separate
                    Brands. For example there could be a single
                    Japanese "UC" MasterCard which can be used as
                    either a UC card or a regular MasterCard. The UC
                    card Brand and the MasterCard Brand could each
                    have their own separate Payment Handlers. This
                    means that:
                     o the Merchant treats, for example "UC" and
                       "MasterCard" as two separate Brands when
                       offering a list of Brands to the Consumer,
                     o the Consumer chooses a Brand, for example
                       either "UC" or "MasterCard,
                     o the Consumer IOTP aware application determines
                       which Payment Instrument(s) match the chosen
                       Brand, and selects, perhaps with user
                       assistance, the correct Payment Instrument to
                       use.

 Error Block        An Error Block reports that a Technical Error was
                    found in an IOTP Message that was previously
                    received. Typically Technical Errors are caused by
                    errors in the XML which has been received or some

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        NAME                            DESCRIPTION
                    technical failure of the processing of the IOTP
                    Message. Frequently the generation or receipt of
                    an Error Block will result in failure of the IOTP
                    Transaction. They are distinct from Business
                    Errors, reported in a Status Component, which can
                    also cause failure of an IOTP Transaction.

 Exchange Block     An Exchange Block is sent between the two Trading
                    Roles involved in a Trading Exchange. It contains
                    one or more Trading Components. Exchange Blocks
                    are always sent after a Request Block and before a
                    Response Block in a Trading Exchange. The content
                    of an Exchange Block is dependent on the type of
                    Trading Exchange being carried out.

 IOTP Message       An IOTP Message is the outermost wrapper for the
                    document(s) which are sent between Trading Roles
                    that are taking part in a trade. It is a well
                    formed XML document. The documents it contains
                    consist of:
                     o a Transaction Reference Block to uniquely
                       identify the IOTP Transaction of which the IOTP
                       Message is part,
                     o an optional Signature Block to digitally sign
                       the Trading Blocks or Trading Components
                       associated with the IOTP Transaction
                     o an optional Error Block to report on technical
                       errors contained in a previously received IOTP
                       Message, and
                     o a collection of IOTP Trading Blocks which
                       carries the data required to carry out an IOTP
                       Transaction.

 IOTP Transaction   An instance of an Internet Open Trading Protocol
                    Transaction consists of a set of IOTP Messages
                    transferred between Trading Roles. The rules for
                    what may be contained in the IOTP Messages is
                    defined by the Transaction Type of the IOTP
                    Transaction.

 IOTP Transaction   A Transaction Type identifies the type an of IOTP
 Type               Transaction. Examples of Transaction Type include:
                    Purchase, Refund, Authentication, Withdrawal,
                    Deposit (of electronic cash). The Transaction Type
                    specifies for an IOTP Transaction:
                     o the Trading Exchanges which may be included in
                       the transaction,
                     o how those Trading Exchanges may be combined to
                       meet the business needs of the transaction
                     o which Trading Blocks may be included in the
                       IOTP Messages that make up the transaction
                     o Consult this specification for the rules that

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        NAME                            DESCRIPTION
                       apply for each Transaction Type.

 Merchant           The Organisation from whom the service or goods
                    are being obtained, who is legally responsible for
                    providing the goods or services and receives the
                    benefit of any payment made

 Merchant Customer  The Organisation that is involved with customer
 Care Provider      dispute negotiation and resolution on behalf of
                    the Merchant

 Organisation       A company or individual that takes part in a Trade
                    as a Trading Role. The Organisations may take one
                    or more of the roles involved in the Trade

 Payment Handler    The Organisation that physically receives the
                    payment from the Consumer on behalf of the
                    Merchant

 Payment            A Payment Instrument is the means by which
 Instrument         Consumer pays for goods or services offered by a
                    Merchant. It can be, for example:
                     o a credit card such as MasterCard or Visa;
                     o a debit card such as MasterCard's Maestro;
                     o a smart card based electronic cash Payment
                       Instrument such as a Mondex Card, a GeldKarte
                       card or a Visa Cash card
                     o a software based electronic payment account
                       such as a CyberCash's CyberCoin or DigiCash
                       account.

                    All Payment Instruments have a number, typically
                    an account number, by which the Payment Instrument
                    can be identified.

 Promotional Brand  A Promotional Brand means that, if the Consumer
                    pays with that Brand, then the Consumer will
                    receive some additional benefit which can be
                    received in two ways:
                     o at the time of purchase. For example if a
                       Consumer pays with a "Walmart MasterCard" at a
                       Walmart web site, then a 5% discount might
                       apply, which means the Consumer actually pays
                       less,
                     o from their Payment Instrument (card) issuer
                       when the payment appears on their statement.
                       For example loyalty points in a frequent flyer
                       scheme could be awarded based on the total
                       payments made with the Payment Instrument since
                       the last statement was issued.

                    Each Promotional Brand should be identified as a

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        NAME                            DESCRIPTION
                    separate Brand in the list of Brands offered by
                    the Merchant.

 Receipt Component  A Receipt Component is a record of the successful
                    completion of a Trading Exchange. Examples of
                    Receipt Components include: Payment Receipts, and
                    Delivery Notes. It's content may dependent on the
                    technology used to perform the Trading Exchange.
                    For example a Secure Electronic Transaction (SET)
                    payment receipt consists of SET payment messages
                    which record the result of the payment.

 Request Block      A Request Block is Trading Block that contains a
                    request for a Trading Exchange to start. The
                    Trading Components in a Request Block may be
                    signed by a Signature Block so that their
                    authenticity may be checked and to determine that
                    the Trading Exchange being requested is
                    authorised. Authorisation for a Trading Exchange
                    to start can be provided by the signatures
                    contained on Receipt Components contained in
                    Response Blocks resulting from previously
                    completed Trading Exchanges.  Examples of Request
                    Blocks are Payment Request and Delivery Request

 Response Block     A Response Block is a Trading Block that indicates
                    that a Trading Exchange is complete. It is sent by
                    the Trading Role that received a Request Block to
                    the Trading Role that sent the Request Block. The
                    Response Block contains a Status Component that
                    contains information about the completion of the
                    Trading Exchange, for example it indicates whether
                    or not the Trading Exchange completed
                    successfully. For some Trading Exchanges the
                    Response Block contains a Receipt Component that
                    forms a record of the Trading Exchange. Receipt
                    Components may be digitally signed using a
                    Signature Block to make completion non-refutable.
                    Examples of Response Blocks include Offer
                    Response, Payment Response and Delivery Response.

 Signature Block    A Signature Block is a Trading Block that contains
                    one or more digital signatures in the form of
                    Signature Components. A Signature Component may
                    digitally sign any Block or Component in any IOTP
                    Message in the same IOTP Transaction.

 Status Component   A Status Component contains information that
                    describes the state of a Trading Exchange.

                    Before the Trading Exchange is complete the Status
                    Component can indicate information about how the

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        NAME                            DESCRIPTION
                    Trading Exchange is progressing.

                    Once a Trading Exchange is complete the Status
                    Component can only indicate the success of the
                    Trading Exchange or that a Business Error has
                    occurred.

                    A Business Error indicates that continuation with
                    the Trading Exchange was not possible because of
                    some business rule or logic, for example,
                    "insufficient funds available", rather than any
                    Technical Error associated with the content or
                    format of the IOTP Messages in the IOTP
                    Transaction.

 Technical Error    See Error Block.

 Trading Block      A Trading Block consists of one or more Trading
                    Components. One or more Trading Blocks may be
                    contained within the IOTP Messages which are
                    physically sent in the form of [XML] documents
                    between the different Trading Roles that are
                    taking part in a trade. Trading Blocks are of
                    three main types:
                     o a Request Block,
                     o an Exchange Block, or a
                     o a Response Block

 Trading Component  A Trading Component is a collection of XML
                    elements and attributes. Trading Components are
                    the child elements of the Trading Blocks. Examples
                    of Trading Components are: Offer, Brand List,
                    Payment Receipt, Delivery [information], Payment
                    Amount [information]

 Trading Exchange   A Trading Exchange consists of the exchange,
                    between two Trading Roles, of a sequence of
                    documents. The documents may be in the form of
                    Trading Blocks or they may be transferred by some
                    other means, for example through entering data
                    into a web page. Each Trading Exchange consists of
                    three main parts:
                     o the sending of a Request Block by one Trading
                       Role (the initiator) to another Trading Role
                       (the recipient),
                     o the optional exchange of one or more Exchange
                       Blocks between the recipient and the initiator,
                       until eventually,
                     o the Trading Role that received the Request
                       Block sends a Response Block to the initiator.

                    A Trading Exchange is designed to implement a

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        NAME                            DESCRIPTION
                    useful service of some kind. Examples of Trading
                    Exchanges/services are:
                     o Offer, which results in a Consumer receiving
                       an offer from a Merchant to carry out a
                       business transaction of some kind,
                     o Payment, where a Consumer makes a payment to a
                       Payment Handler,
                     o Delivery, where a Consumer requests, and
                       optionally obtains, delivery of goods or
                       services from a Delivery Handler, and
                     o Authentication, where any Trading Role may
                       request and receive information about another
                       Trading Role.

 Trading Role       A Trading Role identifies the different ways in
                    which Organisations can participate in a trade.
                    There are five Trading Roles: Consumer, Merchant,
                    Payment Handler, Delivery Handler, and Merchant
                    Customer Care Provider.

 Transaction        A Transaction Reference Block identifies an IOTP
 Reference Block    Transaction. It contains data that identifies:
                     o the Transaction Type,
                     o the IOTP Transaction uniquely, through a
                       globally unique transaction identifier
                     o the IOTP Message uniquely within the IOTP
                       Transaction, through a message identifier

                    The Transaction Reference Block may also contain
                    references to other transactions which may or may
                    not be IOTP Transactions

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15. Copyrights

 Copyright (C) The Internet Society (1998). All Rights Reserved.

 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it or
 assist in its implementation may be prepared, copied, published and
 distributed, in whole or in part, without restriction of any kind,
 provided that the above copyright notice and this paragraph are included
 on all such copies and derivative works. However, this document itself
 may not be modified in any way, such as by removing the copyright notice
 or references to the Internet Society or other Internet organisations,
 except as needed for the purpose of developing Internet standards in
 which case the procedures for copyrights defined in the Internet
 Standards process must be followed, or as required to translate it into
 languages other than English.

 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.

 This document and the information contained herein is provided on an AS
 IS basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE
 DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
 ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
 PARTICULAR PURPOSE.

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16. References

 This section contains references to related documents identified in this
 specification.

 [Base64]    Base64 Content-Transfer-Encoding. A method of
             transporting binary data defined by MIME. See: RFC 2045:
             Multipurpose Internet Mail Extensions (MIME) Part One:
             Format of Internet Message Bodies. N. Freed & N.
             Borenstein. November 1996.

 [DOM-HASH]  A method for generating hashes of all or part of an XML
             tree based on the DOM of that tree. See, currently,
             http://www.ietf.org/internet-drafts/draft-ietf-trade-
             hiroshi-dom-hash-*.txt

 [DNS]       See RFC 1034: Domain names - concepts and facilities.
             P.V. Mockapetris. Nov-01-1987, and RFC 1035: Domain names
             - implementation and specification. P.V. Mockapetris.
             Nov-01-1987.

 [DSA]       The Digital Signature Algorithm (DSA) published by the
             National Institute of Standards and Technology (NIST) in
             the Digital Signature Standard (DSS), which is a part of
             the US government's Capstone project.

 [ECCDSA]    Elliptic Curve Cryptosystems Digital Signature Algorithm
             (ECCDSA). Elliptic curve cryptosystems are analogues of
             public-key cryptosystems such as RSA in which modular
             multiplication is replaced by the elliptic curve addition
             operation. See: V. S. Miller. Use of elliptic curves in
             cryptography. In Advances in Cryptology - Crypto '85,
             pages 417-426, Springer-Verlag, 1986.

 [HMAC]      See RFC 2104 HMAC: Keyed-Hashing for Message
             Authentication. H. Krawczyk, M. Bellare, R. Canetti.
             February 1997

 [HTML]      Hyper Text Mark Up Language. The Hypertext Mark-up
             Language (HTML) is a simple mark-up language used to
             create hypertext documents that are platform independent.
             See RFC 1866 and the World Wide Web (W3C) consortium web
             site at: http://www.w3.org/MarkUp/

 [HTTP]      Hyper Text Transfer Protocol versions 1.0 and 1.1. See
             RFC 1945: Hypertext Transfer Protocol -- HTTP/1.0. T.
             Berners-Lee, R. Fielding & H. Frystyk. May 1996. and RFC
             2068: Hypertext Transfer Protocol -- HTTP/1.1. R.
             Fielding, J. Gettys, J. Mogul, H. Frystyk, T. Berners-
             Lee. January 1997.

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 [IANA]      The Internet Assigned Numbers Authority. The organisation
             responsible for co-ordinating the names and numbers
             associated with the Internet. See http://www.iana.org/.

 [ISO4217]   ISO 4217: Codes for the Representation of Currencies.
             Available from ANSI or ISO.

 [IOTPDSIG]  A document that describes how data contained in IOTP
             messages may be digitally signed. See, currently,
             http://www.ietf.org/internet-drafts/draft-ietf-trade-
             iotp-v1.0-dsig-*.txt.

 [MD5]       R.L. Rivest. RFC 1321: The MD5 Message-Digest Algorithm.

 [MIME]      Multipurpose Internet Mail Extensions. See RFC822,
             RFC2045, RFC2046, RFC2047, RFC2048 and RFC2049.

 [OPS]       Open Profiling Standard. A proposed standard which
             provides a framework with built-in privacy safeguards for
             the trusted exchange of profile information between
             individuals and web sites.  Being developed by Netscape
             and Microsoft amongst others.

 [RFC822]    See RFC 822: The Standard for the Format of ARPA Internet
             Messages. 13 August 1982, David H Crocker. 13 August
             1982.

 [RFC1738]   See RFC 1738: Uniform Resource Locators (URL), ed. T.
             Berners-Lee, L. Masinter, M. McCahill. 1994.

 [RFC2434]   See RFC 2434. Guidelines for Writing an IANA
             Considerations Section in RFCs. T. Narten and H.
             Alvestrand

 [RSA]       RSA is a public-key cryptosystem for both encryption and
             authentication supported by RSA Data Security Inc. See:
             R. L. Rivest, A. Shamir, and L.M. Adleman. A method for
             obtaining digital signatures and public-key
             cryptosystems. Communications of the ACM, 21(2): 120-126,
             February 1978.

 [SCCD]      Secure Channel Credit Debit. A method of conducting a
             credit or debit card payment where unauthorised access to
             account information is prevented through use of secure
             channel transport mechanisms such as SSL/TLS. An IOTP
             supplement describing how SCCD works is under
             development.

 [SET]       Secure Electronic Transaction Specification, Version 1.0,
             May 31, 1997. Supports credit and debit card payments
             using certificates at the Consumer and Merchant to help
             ensure authenticity.
             Download from: <http://www.setco.org>.

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 [SSL/TLS]   SSL is a standard developed by Netscape for encrypting
             data over IP networks. See
             http://home.netscape.com/eng/ssl3/index.html. TLS is the
             likely successor to SSL being developed by the IETF. See
             http://www.ietf.org/internet-drafts/draft-ietf-tls-
             protocol-05.txt

 [SHA1]      [FIPS-180-1]"Secure Hash Standard", National Institute of
             Standards and Technology, US Department Of Commerce,
             April 1995. Also known as: 59 Fed Reg. 35317 (1994). See
             http://www.itl.nist.gov/div897/pubs/fip180-1.htm

 [UTC]       Universal Time Co-ordinated. A method of defining time
             absolutely relative to Greenwich Mean Time (GMT).
             Typically of the form:  "CCYY-MM-DDTHH:MM:SS.sssZ+n"
             where the "+n" defines the number of hours from GMT. See
             ISO DIS8601.

 [UTF16]     The Unicode Standard, Version 2.0.  The Unicode
             Consortium, Reading, Massachusetts. See ISO/IEC 10646 1
             Proposed Draft Amendment 1

 [X.509]     ITU Recommendation X.509 1993 | ISO/IEC 9594-8: 1995,
             Including Draft Amendment 1: Certificate Extensions
             (Version 3 Certificate)

 [XML        Recommendation for Namespaces in XML, World Wide Web
 Namespace]  Consortium, 14 January 1999, "http://www.w3.org/TR/REC-
             xml-names"

 [XML]       Extensible Mark Up Language. A W3C recommendation. See
             http://www.w3.org/TR/1998/REC-xml-19980210 for the 10
             February 1998 version.

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17. Author's Address

 The author of this document is:

 David Burdett
 Commerce One
 1600 Riviera Ave, Suite 200
 Walnut Creek
 California 94596
 USA

 Tel: +1 (925) 941 4422

 Email: david.burdett@commerceone.com

 The author of this document particularly wants to thank Mondex
 International Limited (www.mondex.com) for the tremendous support
 provided in the formative stages of the development of this
 specification.

 In addition the author appreciates the following contributors to this
 protocol (in alphabetic order of company) without which it could not have
 been developed.
   - Phillip Mullarkey, British Telecom plc
   - Andrew Marchewka, Canadian Imperial Bank of Commerce
   - Brian Boesch, CyberCash Inc.
   - Tom Arnold, CyberSource
   - Terry Allen, Commerce One (formally Veo Systems)
   - Richard Brown, GlobeSet Inc.
   - Peter Chang, Hewlett Packard
   - Masaaki Hiroya, Hitachi Ltd
   - Yoshiaki Kawatsura, Hitachi Ltd
   - Donald Eastlake 3rd, International Business Machines (formerly
     CyberCash Inc).
   - Mark Linehan, International Business Machines
   - Jonathan Sowler, JCP Computer Services Ltd
   - John Wankmueller, MasterCard International
   - Steve Fabes, Mondex International Ltd
   - Surendra Reddy, Oracle Corporation
   - Akihiro Nakano, Plat Home, Inc. (ex Hitachi Ltd)
   - Chris Smith, Royal Bank of Canada
   - Hans Bernhard-Beykirch, SIZ (IT Development and Coordination Centre
     of the German Savings Banks Organisation)
   - W. Reid Carlisle, Spyrus (ex Citibank Universal Card Services,
     formally AT&T Universal Card Services)
   - Efrem Lipkin, Sun Microsystems
   - Tony Lewis, Visa International

 The author would also like to thank the following organisations for their
 support:
   - Amino Communications
   - DigiCash

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   - Fujitsu
   - General Information Systems
   - Globe Id Software
   - Hyperion
   - InterTrader
   - Nobil I T Corp
   - Mercantec
   - Netscape
   - Nippon Telegraph and Telephone Corporation
   - Oracle Corporation
   - Smart Card Integrations Ltd.
   - Spyrus
   - Verifone
   - Unisource nv
   - Wells Fargo Bank

 File name: [draft-ietf-trade-iotp-v1.0-protocol-07.txt]
 Expires:   April 2000

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