Attribute-Value Pairs For Provisioning Customer Equipment Supporting IPv4-Over-IPv6 Transitional Solutions
draft-zhou-dime-4over6-provisioning-04

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Document Type Active Internet-Draft (individual)
Authors Cathy Zhou  , Tom Taylor  , Qiong Sun  , Mohamed Boucadair 
Last updated 2014-09-16
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Internet Engineering Task Force                                  C. Zhou
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                               T. Taylor
Expires: March 20, 2015                             PT Taylor Consulting
                                                                  Q. Sun
                                                           China Telecom
                                                            M. Boucadair
                                                          France Telecom
                                                      September 16, 2014

  Attribute-Value Pairs For Provisioning Customer Equipment Supporting
                 IPv4-Over-IPv6 Transitional Solutions
                 draft-zhou-dime-4over6-provisioning-04

Abstract

   During the transition from IPv4 to IPv6, customer equipment may have
   to support one of the various transition methods that have been
   defined for carrying IPv4 packets over IPv6.  This document
   enumerates the information that needs to be provisioned on a customer
   edge router to support a list of transition techniques based on
   tunneling IPv4 in IPv6, with a view to defining reusable components
   for a reasonable transition path between these techniques.  To the
   extent that the provisioning is done dynamically, AAA support is
   needed to provide the information to the network server responsible
   for passing the information to the customer equipment.  This document
   specifies Diameter (RFC 6733) attribute-value pairs to be used for
   that purpose.

Status of This Memo

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   This Internet-Draft will expire on March 20, 2015.

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Copyright Notice

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   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Description of the Parameters Required By Each Transition
       Method  . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Parameters For Dual-Stack Lite (DS-Lite)  . . . . . . . .   4
     2.2.  Light Weight IPv4 Over IPv6 (LW4over6)  . . . . . . . . .   5
     2.3.  Port Set Specification  . . . . . . . . . . . . . . . . .   5
     2.4.  Mapping of Address and Port with Encapsulation (MAP-E)  .   6
     2.5.  Parameters For Multicast  . . . . . . . . . . . . . . . .   7
     2.6.  Summary and Discussion  . . . . . . . . . . . . . . . . .   7
   3.  Attribute-Value Pair Definitions  . . . . . . . . . . . . . .   8
     3.1.  Common Prefix Data Format . . . . . . . . . . . . . . . .   8
     3.2.  Border-Router-Name AVP  . . . . . . . . . . . . . . . . .   9
     3.3.  64-Multicast-Attributes AVP . . . . . . . . . . . . . . .   9
       3.3.1.  ASM-Prefix64 AVP  . . . . . . . . . . . . . . . . . .   9
       3.3.2.  SSM-Prefix64 AVP  . . . . . . . . . . . . . . . . . .  10
       3.3.3.  Unicast-Prefix64 AVP  . . . . . . . . . . . . . . . .  10
     3.4.  Tunnel-Source-Pref-Or-Addr AVP  . . . . . . . . . . . . .  10
     3.5.  Port-Set-Identifier . . . . . . . . . . . . . . . . . . .  10
     3.6.  LW4over6-Binding  . . . . . . . . . . . . . . . . . . . .  11
     3.7.  MAP-E-Attributes  . . . . . . . . . . . . . . . . . . . .  12
     3.8.  MAP-Mapping-Rule  . . . . . . . . . . . . . . . . . . . .  13
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

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1.  Introduction

   A number of transition technologies have been defined to allow IPv4
   packets to pass between hosts and IPv4 networks over an intervening
   IPv6 network while minimizing the number of public IPv4 addresses
   that need to be consumed by the hosts.  Different operators will
   deploy different technologies, and sometimes one operator will use
   more than one technology, depending on what is supported by the
   available equipment and upon other factors both technical and
   economic.

   Each technique requires the provisioning of some subscriber-specific
   information on the customer edge device.  The provisioning may be by
   DHCPv6 [RFC3315] or by some other method.  This document is
   indifferent to the specific provisioning technique used, but assumes
   a deployment in which that information is managed by AAA
   (Authentication, Authorization, and Accounting) servers.  It further
   assumes that this information is delivered to intermediate network
   nodes for onward provisioning using the Diameter protocol [RFC6733].

   As described below, in the particular case where the Light Weight
   IPv4 Over IPv6 (LW4o6) [I-D.ietf-softwire-lw4over6] transition method
   has been deployed, per-subscriber-site information almost identical
   to that passed to the subscriber site [I-D.ietf-softwire-map-dhcp] or
   collected from it [I-D.fsc-softwire-dhcp4o6-saddr-opt] also needs to
   be delivered to the border router serving that site.  The Diameter
   protocol may be used for this purpose too.

   This document analyzes the information required to configure the
   customer edge equipment for the following set of transition methods:

   o  Dual-Stack Lite (DS-Lite) [RFC6333],

   o  Light Weight IPv4 Over IPv6 (LW4over6)
      [I-D.ietf-softwire-lw4over6], and

   o  Mapping of Address and Port with Encapsulation (MAP-E)
      [I-D.ietf-softwire-map].

   [I-D.softwire-dslite-multicast] specifies a generic solution for
   delivery of IPv4 multicast services to IPv4 clients over an IPv6
   multicast network.  The solution was developed with DS-Lite in mind
   but it is however not limited to DS-Lite.  As such, it applies also
   for LW4over6 and MAP-E.  This document analyzes the information
   required to configure the customer edge equipment for the support of
   multicast in the context of DS-Lite, MAP, and LW4over6 in particular.

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   On the basis of those analyses it specifies a number of attribute-
   value pairs (AVPs) to allow the necessary subscriber-site-specific
   configuration information to be carried in Diameter.

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 [RFC2119].

   The abbreviation "CE" denotes the equipment at the customer edge that
   terminates the customer end of an IPv6 transitional tunnel.  This
   will usually be a router, but could be a host directly connected to
   the network.

   The term "tunnel source address" is used to denote the IPv6 source
   address used in the outer header of packets sent from the CE through
   an LW4over6 transitional tunnel to the border router.

2.  Description of the Parameters Required By Each Transition Method

   This section reviews the parameters that need to be provisioned for
   each of the transition methods listed above.  This enumeration
   provides the justification for the AVPs defined in the next section.

   A means is required to indicate which transition method(s) a given
   subscriber is allowed to use.  The approach taken in this document is
   to specify grouped AVPs specific to LW4over6 and MAP-E.  The operator
   can control which of these two transition methods a given subscriber
   uses by ensuring that AAA passes only the grouped AVP relevant to
   that method.  A grouped AVP is unnecessary for Dual-Stack Lite, since
   (as the next section indicates) AAA has to provide only one
   parameter.  Hence the absence of either of the grouped AVPs indicates
   that the subscriber equipment will use Dual-Stack Lite.  Provisioning
   of multicast is an orthogonal activity, since it is independent of
   the transition method.

2.1.  Parameters For Dual-Stack Lite (DS-Lite)

   DS-Lite is documented in [RFC6333].  The Basic Bridging BroadBand
   (B4) element at the customer premises needs to be provisioned with
   the IPv6 address of the AFTR (border router).  Optionally, it could
   also be configured with the IPv4 address of the B4 interface facing
   the tunnel, where the default value in the absence of provisioning is
   192.0.0.2 and valid values are 192.0.0.2 through 192.0.0.7.
   Provisioning this information through AAA is problematic because it
   is most likely used in a case where multiple B4 instances occupy the
   same device.  This document therefore assumes that the B4 interface

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   address is determined by other means (implementation-dependent or
   static assignment).

2.2.  Light Weight IPv4 Over IPv6 (LW4over6)

   Light Weight IPv4 Over IPv6 (LW4over6) is documented in
   [I-D.ietf-softwire-lw4over6].  LW4over6 requires four items to be
   provisioned to the customer equipment:

   o  IPv6 address of the border router.

   o  IPv6 prefix used by the CE to construct the tunnel source address.
      In the terminology of [I-D.ietf-softwire-lw4over6], this is the
      IPv6 Binding Prefix.

   o  an IPv4 address to be used on the external side of the CE; and

   o  if the IPv4 address is shared, a specification of the port set the
      subscriber site is allowed to use.  Please see the description in
      Section 2.3.  For LW4over6, all three of the parameters 'a', 'k',
      and PSID described in that section are required.  The default
      value of the offset parameter 'a' is 0.

   As discussed in Section 4 of [I-D.ietf-softwire-lw4over6], it is
   necessary to synchronize this configuration with corresponding per-
   subscriber configuration at the border router.  The border router
   information consists of the same public IPv4 address and port set
   parameters that are passed to the CE, bound together with the full
   /128 IPv6 address (not just the Binding Prefix) configured as the
   tunnel source address at the CE.

   [I-D.fsc-softwire-dhcp4o6-saddr-opt] proposes a means whereby a
   DHCPv6 server can influence the choice of this address and collect it
   from the CE.  Depending on the provisioning architecture deployed in
   a given network, it is possible that the tunnel source address is
   passed to AAA as an intermediate step before the binding information
   is passed on to the border router.

2.3.  Port Set Specification

   When an external IPv4 address is shared, LW4over6 and MAP-E restrict
   the CE to use of a subset of all available ports on the external
   side.  Both transition methods use the the algorithm defined in
   Appendix B of [I-D.ietf-softwire-map] to derive the values of the
   port numbers in the port set.  This algorithm features three
   parameters, describing the positioning and value of the Port Set
   Identifier (PSID) within each port number of the generated set:

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   o  an offset 'a' from the beginning of the port number to the first
      bit of the PSID;

   o  the length 'k' of the PSID within the port number, in bits; and

   o  the value of the PSID itself.

2.4.  Mapping of Address and Port with Encapsulation (MAP-E)

   Mapping of Address and Port with Encapsulation (MAP-E) is described
   in [I-D.ietf-softwire-map].  MAP-E requires the provisioning of the
   following per-subscriber information at the customer edge device:

   o  the IPv6 address of one or more border routers, or in MAP-E
      terminology, MAP border relays.

   o  the unique End-user IPv6 prefix for the customer edge device.
      This may be provided by AAA or acquired by other means.

   o  the Basic Mapping Rule for the customer edge device.  This
      includes the following parameters:

      *  the rule IPv6 prefix and length;

      *  the rule IPv4 prefix and length.  A prefix length of 0
         indicates that the entire IPv4 address or prefix is coded in
         the Extended Address (EA) bits of the End-user IPv6 prefix
         rather than in the mapping rule.

      *  the number of EA bits included in the End-user IPv6 prefix;

      *  port set parameters giving the set of ports the CE is allowed
         to use when the IPv4 address is shared.  Please see the
         description of these parameters in Section 2.3.  At a minimum,
         the offset parameter 'a' is required.  For MAP-E this has the
         default value 6.  The parameters 'k' and PSID are needed if
         they cannot be derived from the mapping rule information and
         the EA bits (final case of Section 5.2 of
         [I-D.ietf-softwire-map]).

   o  whether the device is to operate in mesh or hub-and-spoke mode;

   o  in mesh mode only, zero or more Forwarding Mapping Rules,
      described by the same set of parameters as the Basic Mapping Rule;

   As indicated in Section 5, bullet 1 of the MAP-E document, a MAP CE
   can be provisioned with multiple End-user IPv6 prefixes, each
   associated with its own Basic Mapping Rule.  This does not change the

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   basic requirement for representation of the corresponding information
   in the form of Diameter AVPs, but adds a potential requirement for
   multiple instances of this information to be present in the Diameter
   message, differing in the value of the End-user IPv6 prefix (in
   contrast to the Forward Mapping Rule instances).

   The border router needs to be configured with the superset of the
   Mapping Rules passed to the customer sites it serves.  Since this
   requirement does not require direct coordination with CE
   configuration in the way LW4over6 does, it is out of scope of the
   present document.  However, the AVPs defined here may be useful if a
   separate Diameter application is used to configure the border router.

2.5.  Parameters For Multicast

   [I-D.softwire-dslite-multicast] specifies a generic solution for
   delivery of IPv4 multicast services to IPv4 clients over an IPv6
   multicast network.  The solution can be in particular deployed in a
   DS-Lite context, but is also adaptable to LW4over6 and MAP-E.
   [I-D.ietf-softwire-multicast-prefix-option] specifies how DHCPv6
   [RFC3315] can be used to provision multicast-related information,
   particularly:

   o  ASM_mPrefix64: the IPv6 multicast prefix to be used to synthesize
      the IPv4-embedded IPv6 addresses of the multicast groups in the
      ASM mode.

   o  SSM_mPrefix64: the IPv6 multicast prefix to be used to synthesize
      the IPv4-embedded IPv6 addresses of the multicast groups in the
      SSM mode.

   o  uPrefix64: the IPv6 unicast prefix to be used in SSM mode for
      constructing the IPv4-embedded IPv6 addresses representing the
      IPv4 multicast sources in the IPv6 domain. uPrefix64 may also be
      used to extract the IPv4 address from the received multicast data
      flows.  The address mapping follows the guidelines documented in
      [RFC6052].

2.6.  Summary and Discussion

   It appears that two items are common to the different transition
   methods and the corresponding AVPs to carry them can be reused:

   o  a representation of the IPv6 address of a border router;

   o  A set of prefixes for delivery of multicast services to IPv4
      clients over an IPv6 multicast network.

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   [RFC6519] sets a precedent for representation of the IPv6 address of
   a border router as an FQDN.  This can be dereferenced to one or more
   IP addresses by the provisioning system before being passed to the
   customer equipment, or left as an FQDN as it as in [RFC6334].

   The remaining requirements are transition-method-specific:

   o  for LW4over6, a representation of a binding between (1) either the
      IPv6 Binding Prefix or a full /128 IPv6 address, (2) a public IPv4
      address, and (3) (if the IPv4 address is shared) a port set
      identifier;

   o  for MAP-E, a representation of the unique End-user IPv6 prefix for
      the CE, if not provided by other means;

   o  for MAP-E, a representation of a Mapping Rule;

   o  for MAP-E, an indication of whether mesh mode or hub-and-spoke
      mode is to be used.

3.  Attribute-Value Pair Definitions

   This section provides the specifications for the AVPs needed to meet
   the requirements summarized in Section 2.6.  Within the context of
   their usage, all of these AVPs MUST have the M bit set and the V bit
   cleared.

3.1.  Common Prefix Data Format

   A number of the AVPs in this section convey prefixes, and in one case
   either a prefix or a full address.  They all have the same format.
   Rather than repeat the format in each case, it is specified once here
   and referred to henceforward as the common prefix data format.

   The common prefix data format is an extension of the Address data
   format defined in Section 4.3.1 of [RFC6733].  Like the Address data
   format, it is derived from the OctetString basic AVP format.  As well
   as an AddressType, it contains a PrefixLength field.  The detailed
   specification is as follows:

   o  As with the Address data format, the first two octets represent
      the AddressType, which contains an Address Family, defined in
      [IANAADFAM].

   o  The next two octets are interpreted as a 16-bit unsigned integer
      representing the PrefixLength.

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   o  The remaining octets present the prefix or address, most
      significant octet first.  If the prefix does not extend to an
      octet boundary, the low-order bits of the final octet MUST be
      padded with zeroes.

3.2.  Border-Router-Name AVP

   Following on the precedent set by [RFC6334] and [RFC6519], this
   document identifies a border router using an FQDN rather than an
   address.  The Border-Router-Name AVP (AVP Code TBD01) is of type
   OctetString.  The rules for encoding the FQDN are the same as those
   for the FQDN variant of the derived type DiameterIdentity
   (Section 4.3.1 of [RFC6733]).

3.3.  64-Multicast-Attributes AVP

   The 64-Multicast-Attributes AVP (AVP Code TBD13) is of type Grouped.
   It contains the multicast-related prefixes needed for providing IPv4
   multicast over IPv6 using DS-Lite, MAP-E, or LW4over6, as specified
   in [I-D.softwire-dslite-multicast].

   The syntax is shown in Figure 1.

           64-Multicast-Attributes  ::= < AVP Header: TBD13 >
                          [ ASM-Prefix64 ]
                          [ SSM-Prefix64 ]
                          [ Unicast-Prefix64 ]
                         *[ AVP ]

                   Figure 1: 64-Multicast-Attributes AVP

   If either ASM-Prefix64 or SSM-Prefix64 or both are present, Unicast-
   Prefix64 MUST also be present.

3.3.1.  ASM-Prefix64 AVP

   The ASM-Prefix64 AVP (AVP Code TBD14) conveys the value of
   ASM_mPrefix64 as identified in Section 2.1 and specified in
   [I-D.softwire-dslite-multicast].  The ASM-Prefix64 AVP uses the
   common prefix data format.  The AddressType field MUST be set to 2
   (IPv6).  Valid prefix lengths in the PrefixLength field are from 24
   to 96.  The conveyed multicast IPv6 prefix MUST belong to the ASM
   range.

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3.3.2.  SSM-Prefix64 AVP

   The SSM-Prefix64 AVP (AVP Code TBD14) conveys the value of
   SSM_mPrefix64 as identified in Section 2.1 and specified in
   [I-D.softwire-dslite-multicast].  The SSM-Prefix64 AVP uses the
   common prefix data format.  The AddressType field MUST be set to 2
   (IPv6).  See the next paragraph regarding the PrefixLength field.
   The conveyed multicast IPv6 prefix MUST belong to the SSM range.

   Note that Section 6 of [RFC3306] requires that bits 33-95 of an SSM
   address in the FF3x range be set to zero, meaning that the prefix
   length for an SSM prefix is effectively 96.  However, Section 1 of
   [RFC4607] suggests that the lower limit of 32 bits be preserved to
   allow potential future use of bits 33-95.  Hence applications SHOULD
   accept prefix lengths between 32 and 96 inclusive.

3.3.3.  Unicast-Prefix64 AVP

   The Unicast-Prefix64 AVP (AVP Code TBD15) conveys the value of
   uPrefix64 as identified in Section 2.1 and specified in
   [I-D.softwire-dslite-multicast].  The Unicast-Prefix64 AVP uses the
   common prefix data format.  The AddressType field MUST be set to 2
   (IPv6).  As specified by [RFC6052], valid values in the PrefixLength
   field are 32, 48, 56, 64 and 96.

3.4.  Tunnel-Source-Pref-Or-Addr AVP

   The Tunnel-Source-Pref-Or-Addr AVP (AVP Code TBD02) conveys either
   the IPv6 Binding Prefix or the tunnel source address on the CE, as
   described in Section 2.2.  The Tunnel-Source-Pref-Or-Addr AVP uses
   the common prefix data format.  The AddressType field MUST be set to
   2 (IPv6).  Valid values in the PrefixLength field are from 0 to 128
   (full address).

   This AVP is defined separately from the LW4over6-Binding AVP (which
   includes it) to provide flexibility in the transport of the tunnel
   source address from the provisioning system to AAA.

3.5.  Port-Set-Identifier

   The Port-Set-Identifier AVP (AVP Code TBD03) is a structured
   OctetString with four octets of data, hence a total AVP length of 12.
   The description of the structure which follows refers to refers to
   the parameters described in Section 2.3.

   o  The first (high-order) octet is the Offset field.  It is
      interpreted as an 8-bit unsigned integer giving the offset 'a'
      from the beginning of a port number to the beginning of the port

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      set identifier (PSID) to which that port belongs.  Valid values
      are from 0 to 15.

   o  The next octet, the PSIDLength, is also interpreted as an 8-bit
      unsigned integer and gives the length 'k' in bits of the port set
      identifier (PSID).  Valid values are from 0 to (16 - a).  A value
      of 0 indicates that the PSID is not present (probable case for
      MAP-E, see Section 2.4), and the PSIDValue field MUST be ignored.

   o  The final two octets contain the PSIDValue field.  They give the
      value of the PSID itself, right-justified within the field.  That
      is, the value of the PSID occupies the 'k' lowest-order bits of
      the PSIDValue field.

3.6.  LW4over6-Binding

   The LW4over6-Binding AVP (AVP Code TBD04) is of type Grouped.  It
   contains the elements of configuration that constitute the binding
   between an LW4over6 tunnel and IPv4 packets sent through that tunnel,
   as described in Section 2.2.

                    LW4over6-Binding  ::= < AVP Header: TBD04 >
                             { Tunnel-Source-Pref-Or-Addr }
                             { LW4over6-External-IPv4-Addr }
                             [ Port-Set-Identifier ]
                            *[ AVP ]

                                 Figure 2

   The Tunnel-Source-Pref-Or-Addr AVP is defined in Section 3.4 and
   provides either the Binding Prefix or the full IPv6 tunnel source
   address.  This AVP MUST be present.

   The LW4over6-External-IPv4-Addr AVP (AVP Code TBD05) uses the Address
   derived data format defined in Section 4.3.1 of [RFC6733].  It
   provides the CE's external IPv4 address within the LW4over6 tunnel
   associated with the given binding.  The AddressType field MUST be set
   to 1 (IPv4), and the total length of the AVP MUST be 14 octets.  This
   AVP MUST be present.

   The Port-Set-Identifier AVP is defined in Section 3.5.  It identifies
   the specific set of ports assigned to the LW4over6 tunnel, when the
   IPv4 address is being shared.

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3.7.  MAP-E-Attributes

   The MAP-E-Attributes AVP (AVP Code TBD06) is of type Grouped.  It
   contains the configuration data identified in Section 2.4 for all of
   the mapping rules (Basic and Forwarding) in a single MAP domain.
   Multiple instances of this AVP will be present if the CE belongs to
   multiple MAP domains.

                    MAP-E-Attributes  ::= < AVP Header: TBD06 >
                           1*{ Border-Router-Name }
                           1*{ MAP-Mapping-Rule }
                             [ MAP-Mesh-Mode ]
                             [ MAP-End-User-IPv6-Prefix ]
                            *[ AVP ]

                                 Figure 3

   The Border-Router-Name AVP is defined in Section 3.2.  It provides
   the FQDN of a MAP border relay at the edge of the MAP domain to which
   the containing MAP-E-Attributes AVP relates.  At least one instance
   of this AVP MUST be present.

   The MAP-Mapping-Rule AVP is defined in Section 3.8.  At least one
   instance of this AVP MUST be present.  If the MAP-E domain supports
   mesh mode (indicated by the presence of the MAP-Mesh-Mode AVP),
   additional MAP-Mapping-Rule instances MAY be present.  If the MAP-E
   domain is operating in hub-and-spoke mode, additional MAP-Mapping-
   Rule instances MUST NOT be present.

   The MAP-Mesh-Mode AVP (AVP Code TBD07) uses the OctetString data
   format but has no data.  Hence the AVP length is always 8.  The
   absence of the mesh mode indicator attribute indicates that the CE is
   required to operate in hub-and-spoke mode.

   The MAP-End-User-IPv6-Prefix AVP (AVP Code TBD08) provides the End-
   user IPv6 prefix assigned to the CE for the MAP domain to which the
   containing MAP-E-Attributes AVP relates.  It uses the common prefix
   data format defined in Section 3.1.  The AddressType field MUST have
   the value 2 (IPv6).  Valid values of the PrefixLength field range
   from 0 to 128.

   The MAP-End-User-IPv6-Prefix AVP is optional because, depending on
   deployment, the End-user IPv6 prefix may be provided by AAA or by
   other means.  If multiple instances of the MAP-E-Attributes AVP
   containing the MAP-End-User-IPv6-Prefix AVP are present, each
   instance of the latter MUST have a different value.

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3.8.  MAP-Mapping-Rule

   The MAP-Mapping-Rule AVP (AVP Code TBD09) is of type Grouped, and is
   used only in conjunction with MAP-based transition methods.  Mapping
   rules are required both by the MAP border relay and by the CE.  The
   components of the MAP-Mapping-Rule AVP provide the contents of a
   mapping rule as described in Section 2.4.

   The syntax of the MAP-Mapping-Rule AVP is as follows:

            MAP-Mapping-Rule  ::= < AVP Header: TBD09 >
                             { Rule-IPv4-Addr-Or-Prefix }
                             { Rule-IPv6-Prefix    }
                             { EA-Field-Length     }
                             { Port-Set-Identifier }
                            *[ AVP ]

                                 Figure 4

   The Rule-IPv4-Addr-Or-Prefix AVP (AVP Code TBD10) conveys the rule
   IPv4 prefix and length as described in Section 2.4.  It uses the
   common prefix data format defined in Section 3.1.  The AddressType
   field MUST have the value 1 (IPv4).  Valid values of the PrefixLength
   field range from 0 to 32, based on the different cases identified in
   Section 5.2 of [I-D.ietf-softwire-map].  This AVP MUST be present.

   The Rule-IPv6-Prefix AVP (AVP Code TBD11) conveys the rule IPv6
   prefix and length as described in Section 2.4.  It uses the common
   prefix data format defined in Section 3.1.  The AddressType field
   MUST have the value 2 (IPv6).  The minimum valid PrefixLength is 0.
   If the MAP-End-User-IPv6-Prefix AVP is present in the MAP-
   E-Attributes AVP that encapsulates both that AVP and the MAP-Mapping-
   Rule AVP instance to which the Rule-IPv6-Prefix AVP belongs, then the
   maximum value of the latter's PrefixLength field is given by the
   value of the PrefixLength field in the MAP-End-User-IPv6-Prefix AVP.
   Otherwise it is 128.  This AVP MUST be present.

   The EA-Field-Length AVP (AVP Code TBD12) is of type Unsigned32.
   Valid values range from 0 to 48.  See Section 5.2 of
   [I-D.ietf-softwire-map] for a description of the use of this
   parameter in deriving IPv4 address and port number configuration.
   This AVP MUST be present.

   The Port-Set-Identifier AVP provides information to identify the
   specific set of ports assigned to the CE.  For more information see
   Section 2.4and Section 2.3.  The Port-Set-Identifier AVP is defined
   in Section 3.5.  It MUST be present.

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4.  Acknowledgements

   Huawei Technologies funded Tom Taylor's work on earlier versions of
   this document.

5.  IANA Considerations

   This memo requests to IANA to register the following Diameter AVP
   codes:

          +-------+-----------------------------+---------------+
          |  Code | Attribute Name              | Reference     |
          +-------+-----------------------------+---------------+
          | TBD01 | Border-Router-Name          | This document |
          | TBD02 | Tunnel-Source-Pref-Or-Addr  | This document |
          | TBD03 | Port-Set-Identifier         | This document |
          | TBD04 | LW4over6-Binding            | This document |
          | TBD05 | LW4over6-External-IPv4-Addr | This document |
          | TBD06 | MAP-E-Attributes            | This document |
          | TBD07 | MAP-Mesh-Mode               | This document |
          | TBD08 | MAP-End-User-IPv6-Prefix    | This document |
          | TBD09 | MAP-Mapping-Rule            | This document |
          | TBD10 | Rule-IPv4-Addr-Or-Prefix    | This document |
          | TBD11 | Rule-IPv6-Prefix            | This document |
          | TBD12 | EA-Field-Length             | This document |
          | TBD13 | 64-Multicast-Attributes     | This document |
          | TBD14 | ASM-Prefix64                | This document |
          | TBD15 | SSM-Prefix64                | This document |
          | TBD16 | Unicast-Prefix64            | This document |
          +-------+-----------------------------+---------------+

                                  Table 1

6.  Security Considerations

   The AVPs defined in this document face two threats, both dependent on
   man-in-the-middle attacks on the Diameter delivery path.  The more
   serious threat is denial of service through modification of the AVP
   contents leading to misconfiguration.  The lesser threat is
   disclosure of subscriber addresses allowing the attacker to track
   subscriber activity.

   Diameter security is currently provided on a hop-by-hop basis (see
   Section 2.2 of [RFC6733]).  The Diameter end-to-end security problem
   has not been solved, so man-in-the-middle attacks on Diameter peers
   along the path are possible.  The present document does not propose
   to solve that general problem, but simply warn that it exists.

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7.  References

7.1.  Normative References

   [I-D.ietf-softwire-lw4over6]
              Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
              Farrer, "Lightweight 4over6: An Extension to the DS-Lite
              Architecture (work in progress)", March 2014.

   [I-D.ietf-softwire-map]
              Troan, O., Dec, W., Li, X., Bao, C., Matsushima, S.,
              Murakami, T., and T. Taylor, "Mapping of Address and Port
              with Encapsulation (MAP) (work in progress)", January
              2014.

   [I-D.softwire-dslite-multicast]
              Qin, J., Boucadair, M., Jacquenet, C., Lee, Y., and Q.
              Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients
              over an IPv6 Multicast Network (work in progress)", March
              2014.

   [IANAADFAM]
              IANA, "Address Family Numbers",
              <http://www.iana.org/assignments/address-family- numbers>.

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

   [RFC3306]  Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6
              Multicast Addresses", RFC 3306, August 2002.

   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, August 2011.

   [RFC6733]  Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
              "Diameter Base Protocol", RFC 6733, October 2012.

7.2.  Informative References

   [I-D.fsc-softwire-dhcp4o6-saddr-opt]
              Farrer, I., Sun, Q., and Y. Cui, "DHCPv4 over DHCPv6
              Source Address Option (Work in progress)", June 2014.

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   [I-D.ietf-softwire-map-dhcp]
              Mrugalski, T., Troan, O., Farrer, I., Perrault, S., Dec,
              W., Bao, C., Yeh, L., and X. Deng, "DHCPv6 Options for
              configuration of Softwire Address and Port Mapped Clients
              (Work in progress)", March 2014.

   [I-D.ietf-softwire-multicast-prefix-option]
              Boucadair, M., Qin, J., Tsou, T., and X. Deng, "DHCPv6
              Option for IPv4-Embedded Multicast and Unicast IPv6
              Prefixes", draft-ietf-softwire-multicast-prefix-option-07
              (work in progress), September 2014.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC4607]  Holbrook, H. and B. Cain, "Source-Specific Multicast for
              IP", RFC 4607, August 2006.

   [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
              Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
              October 2010.

   [RFC6334]  Hankins, D. and T. Mrugalski, "Dynamic Host Configuration
              Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite",
              RFC 6334, August 2011.

   [RFC6519]  Maglione, R. and A. Durand, "RADIUS Extensions for Dual-
              Stack Lite", RFC 6519, February 2012.

Authors' Addresses

   Cathy Zhou
   Huawei Technologies
   Bantian, Longgang District
   Shenzhen  518129
   P.R. China

   Email: cathy.zhou@huawei.com

   T. Taylor
   PT Taylor Consulting
   Ottawa
   Canada

   Email: tom.taylor.stds@gmail.com

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   Qiong Sun
   China Telecom
   P.R.China

   Phone: 86 10 58552936
   Email: sunqiong@ctbri.com.cn

   M. Boucadair
   France Telecom
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com

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