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rfc:bcp:bcp153

[Note that this file is a concatenation of more than one RFC.]

Internet Engineering Task Force (IETF) J. Weil Request for Comments: 6598 Time Warner Cable BCP: 153 V. Kuarsingh Updates: 5735 Rogers Communications Category: Best Current Practice C. Donley ISSN: 2070-1721 CableLabs

                                                       C. Liljenstolpe
                                                         Telstra Corp.
                                                            M. Azinger
                                               Frontier Communications
                                                            April 2012
         IANA-Reserved IPv4 Prefix for Shared Address Space

Abstract

 This document requests the allocation of an IPv4 /10 address block to
 be used as Shared Address Space to accommodate the needs of Carrier-
 Grade NAT (CGN) devices.  It is anticipated that Service Providers
 will use this Shared Address Space to number the interfaces that
 connect CGN devices to Customer Premises Equipment (CPE).
 Shared Address Space is distinct from RFC 1918 private address space
 because it is intended for use on Service Provider networks.
 However, it may be used in a manner similar to RFC 1918 private
 address space on routing equipment that is able to do address
 translation across router interfaces when the addresses are identical
 on two different interfaces.  Details are provided in the text of
 this document.
 This document details the allocation of an additional special-use
 IPv4 address block and updates RFC 5735.

Status of This Memo

 This memo documents an Internet Best Current Practice.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 BCPs is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6598.

Weil, et al. Best Current Practice [Page 1] RFC 6598 Shared Address Space Request April 2012

IESG Note

 A number of operators have expressed a need for the special-purpose
 IPv4 address allocation described by this document.  During
 deliberations, the IETF community demonstrated very rough consensus
 in favor of the allocation.
 While operational expedients, including the special-purpose address
 allocation described in this document, may help solve a short-term
 operational problem, the IESG and the IETF remain committed to the
 deployment of IPv6.

Copyright Notice

 Copyright (c) 2012 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Table of Contents

 1. Introduction ....................................................3
 2. Requirements Language ...........................................3
 3. Alternatives to Shared Address Space ............................3
 4. Use of Shared CGN Space .........................................4
 5. Risk ............................................................5
    5.1. Analysis ...................................................5
    5.2. Empirical Data .............................................6
 6. Security Considerations .........................................7
 7. IANA Considerations .............................................8
 8. References ......................................................8
    8.1. Normative References .......................................8
    8.2. Informative References .....................................9
 Appendix A. Acknowledgments .......................................10

Weil, et al. Best Current Practice [Page 2] RFC 6598 Shared Address Space Request April 2012

1. Introduction

 IPv4 address space is nearly exhausted.  However, ISPs must continue
 to support IPv4 growth until IPv6 is fully deployed.  To that end,
 many ISPs will deploy a Carrier-Grade NAT (CGN) device, such as that
 described in [RFC6264].  Because CGNs are used on networks where
 public address space is expected, and currently available private
 address space causes operational issues when used in this context,
 ISPs require a new IPv4 /10 address block.  This address block will
 be called the "Shared Address Space" and will be used to number the
 interfaces that connect CGN devices to Customer Premises Equipment
 (CPE).
 Shared Address Space is similar to [RFC1918] private address space in
 that it is not globally routable address space and can be used by
 multiple pieces of equipment.  However, Shared Address Space has
 limitations in its use that the current [RFC1918] private address
 space does not have.  In particular, Shared Address Space can only be
 used in Service Provider networks or on routing equipment that is
 able to do address translation across router interfaces when the
 addresses are identical on two different interfaces.
 This document requests the allocation of an IPv4 /10 address block to
 be used as Shared Address Space.  In conversations with many ISPs, a
 /10 is the smallest block that will allow them to deploy CGNs on a
 regional basis without requiring nested CGNs.  For instance, as
 described in [ISP-SHARED-ADDR], a /10 is sufficient to service Points
 of Presence in the Tokyo area.
 This document details the allocation of an additional special-use
 IPv4 address block and updates [RFC5735].

2. Requirements Language

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119 [RFC2119].

3. Alternatives to Shared Address Space

 The interfaces that connect CGN devices to CPE might conceivably be
 numbered from any of the following address spaces:
 o  legitimately assigned globally unique address space
 o  usurped globally unique address space (i.e., squat space)

Weil, et al. Best Current Practice [Page 3] RFC 6598 Shared Address Space Request April 2012

 o  [RFC1918] space
 o  Shared Address Space
 A Service Provider can number the interfaces in question from
 legitimately assigned globally unique address space.  While this
 solution poses the fewest problems, it is impractical because
 globally unique IPv4 address space is in short supply.  While the
 Regional Internet Registries (RIRs) have enough address space to
 allocate a single /10 to be shared by all Service Providers, they do
 not have enough address space to make a unique assignment to each
 Service Provider.
 Service Providers MUST NOT number the interfaces in question from
 usurped globally unique address space (i.e., squat space).  If a
 Service Provider leaks advertisements for squat space into the global
 Internet, the legitimate holders of that address space may be
 adversely impacted, as would those wishing to communicate with them.
 Even if the Service Provider did not leak advertisements for squat
 space, the Service Provider and its subscribers might lose
 connectivity to the legitimate holders of that address space.
 A Service Provider can number the interfaces in question from
 [RFC1918] space if at least one of the following conditions is true:
 o  The Service Provider knows that the CPE/NAT works correctly when
    the same [RFC1918] address block is used on both its inside and
    outside interfaces.
 o  The Service Provider knows that the [RFC1918] address block that
    it uses to number interfaces between the CGN and CPE is not used
    on the subscriber side of the CPE.
 Unless at least one of the conditions above is true, the Service
 Provider cannot safely use [RFC1918] address space and must resort to
 Shared Address Space.  This is typically the case in an unmanaged
 service, where subscribers provide their own CPE and number their own
 internal network.

4. Use of Shared CGN Space

 Shared Address Space is IPv4 address space designated for Service
 Provider use with the purpose of facilitating CGN deployment.  Also,
 Shared Address Space can be used as additional non-globally routable
 space on routing equipment that is able to do address translation
 across router interfaces when the addresses are identical on two
 different interfaces.

Weil, et al. Best Current Practice [Page 4] RFC 6598 Shared Address Space Request April 2012

 Devices MUST be capable of performing address translation when
 identical Shared Address Space ranges are used on two different
 interfaces.
 Packets with Shared Address Space source or destination addresses
 MUST NOT be forwarded across Service Provider boundaries.  Service
 Providers MUST filter such packets on ingress links.  One exception
 to this paragraph's proscription is in the case of business
 relationships, such as hosted CGN services.
 When running a single DNS infrastructure, Service Providers MUST NOT
 include Shared Address Space in zone files.  When running a split DNS
 infrastructure, Service Providers MUST NOT include Shared Address
 Space in external-facing zone files.
 Reverse DNS queries for Shared Address Space addresses MUST NOT be
 forwarded to the global DNS infrastructure.  DNS Providers SHOULD
 filter requests for Shared Address Space reverse DNS queries on
 recursive nameservers.  This is done to avoid having to set up
 something similar to AS112.net for [RFC1918] private address space
 that a host has incorrectly sent for a DNS that reverse-maps queries
 on the public Internet [RFC6304].
 Because CGN service requires non-overlapping address space on each
 side of the home NAT and CGN, entities using Shared Address Space for
 purposes other than for CGN service, as described in this document,
 are likely to experience problems implementing or connecting to CGN
 service at such time as they exhaust their supply of public IPv4
 addresses.

5. Risk

5.1. Analysis

 Some existing applications discover the outside address of their
 local CPE, determine whether the address is reserved for special use,
 and behave differently based on that determination.  If a new IPv4
 address block is reserved for special use and that block is used to
 number CPE outside interfaces, some of the above-mentioned
 applications may fail.
 For example, assume that an application requires its peer (or some
 other device) to initiate an incoming connection directly with its
 CPE's outside address.  That application discovers the outside
 address of its CPE and determines whether that address is reserved
 for special use.  If the address is reserved for special use, the
 application rightly concludes that the address is not reachable from

Weil, et al. Best Current Practice [Page 5] RFC 6598 Shared Address Space Request April 2012

 the global Internet and behaves in one manner.  If the address is not
 reserved for special use, the application assumes that the address is
 reachable from the global Internet and behaves in another manner.
 While the assumption that a non-special-use address is reachable from
 the global Internet is generally safe, it is not always true (e.g.,
 when the CPE outside interface is numbered from globally unique
 address space but that address is not advertised to the global
 Internet as when it is behind a CGN).  Such an assumption could cause
 certain applications to behave incorrectly in those cases.

5.2. Empirical Data

 The primary motivation for the allocation of Shared Address Space is
 as address space for CGNs; the use and impact of CGNs has been
 previously described in [RFC6269] and [NAT444-IMPACTS].  Some of the
 services adversely impacted by CGNs are as follows:
 1.  Console gaming -- some games fail when two subscribers using the
     same outside public IPv4 address try to connect to each other.
 2.  Video streaming -- performance is impacted when using one of
     several popular video-streaming technologies to deliver multiple
     video streams to users behind particular CPE routers.
 3.  Peer-to-peer -- some peer-to-peer applications cannot seed
     content due to the inability to open incoming ports through the
     CGN.  Likewise, some SIP client implementations cannot receive
     incoming calls unless they first initiate outgoing traffic or
     open an incoming port through the CGN using the Port Control
     Protocol (PCP) [PCP-BASE] or a similar mechanism.
 4.  Geo-location -- geo-location systems identify the location of the
     CGN server, not the end host.
 5.  Simultaneous logins -- some websites (particularly banking and
     social-networking websites) restrict the number of simultaneous
     logins per outside public IPv4 address.
 6.  6to4 -- 6to4 requires globally reachable addresses and will not
     work in networks that employ addresses with limited topological
     span, such as those employing CGNs.
 Based on testing documented in [NAT444-IMPACTS], the CGN impacts on
 items 1-5 above are comparable regardless of whether globally unique,
 Shared Address Space, or [RFC1918] addresses are used.  There is,
 however, a difference between the three alternatives in the treatment
 of 6to4.

Weil, et al. Best Current Practice [Page 6] RFC 6598 Shared Address Space Request April 2012

 As described in [RFC6343], CPE routers do not attempt to initialize
 6to4 tunnels when they are configured with [RFC1918] or [RFC5735] WAN
 addresses.  When configured with globally unique or Shared Address
 Space addresses, such devices may attempt to initiate 6to4, which
 would fail.  Service Providers can mitigate this issue using 6to4
 Provider Managed Tunnels [6to4-PMT] or blocking the route to
 192.88.99.1 and generating an IPv4 'destination unreachable' message
 [RFC6343].  When the address range is well-defined, as with Shared
 Address Space, CPE router vendors can include Shared Address Space in
 their list of special-use addresses (e.g., [RFC5735]) and treat
 Shared Address Space similarly to [RFC1918] space.  When the CGN-CPE
 address range is not well-defined, as in the case of globally unique
 space, it will be more difficult for CPE router vendors to mitigate
 this issue.
 Thus, when comparing the use of [RFC1918] and Shared Address Space,
 Shared Address Space poses an additional impact on 6to4 connectivity,
 which can be mitigated by Service Provider or CPE router vendor
 action.  On the other hand, the use of [RFC1918] address space poses
 more of a challenge vis-a-vis Shared Address Space when the
 subscriber and Service Provider use overlapping [RFC1918] space,
 which will be outside the Service Provider's control in the case of
 unmanaged service.  Service Providers have indicated that it is more
 challenging to mitigate the possibility of overlapping [RFC1918]
 address space on both sides of the CPE router than it is to mitigate
 the 6to4 impacts of Shared Address Space.

6. Security Considerations

 Similar to other [RFC5735] special-use IPv4 addresses, Shared Address
 Space does not directly raise security issues.  However, the Internet
 does not inherently protect against abuse of these addresses.
 Attacks have been mounted that depend on the unexpected use of
 similar special-use addresses.  Network operators are encouraged to
 review this document and determine what security policies should be
 associated with this address block within their specific operating
 environments.  They should consider including Shared Address Space in
 Ingress Filter lists [RFC3704], unless their Internet service
 incorporates a CGN.

Weil, et al. Best Current Practice [Page 7] RFC 6598 Shared Address Space Request April 2012

 To mitigate potential misuse of Shared Address Space, except where
 required for hosted CGN service or a similar business relationship,
 o  routing information about Shared Address Space networks MUST NOT
    be propagated across Service Provider boundaries.  Service
    Providers MUST filter incoming advertisements regarding Shared
    Address Space.
 o  packets with Shared Address Space source or destination addresses
    MUST NOT be forwarded across Service Provider boundaries.  Service
    Providers MUST filter such packets on ingress links.
 o  Service Providers MUST NOT include Shared Address Space in
    external-facing DNS zone files.
 o  reverse DNS queries for Shared Address Space addresses MUST NOT be
    forwarded to the global DNS infrastructure.
 o  DNS Providers SHOULD filter requests for Shared Address Space
    reverse DNS queries on recursive nameservers.

7. IANA Considerations

 IANA has recorded the allocation of an IPv4 /10 for use as Shared
 Address Space.
 The Shared Address Space address range is 100.64.0.0/10.

8. References

8.1. Normative References

 [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., de Groot, G.,
            and E. Lear, "Address Allocation for Private Internets",
            BCP 5, RFC 1918, February 1996.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC5735]  Cotton, M. and L. Vegoda, "Special Use IPv4 Addresses",
            BCP 153, RFC 5735, January 2010.

Weil, et al. Best Current Practice [Page 8] RFC 6598 Shared Address Space Request April 2012

8.2. Informative References

 [6to4-PMT] Kuarsingh, V., Ed., Lee, Y., and O. Vautrin, "6to4
            Provider Managed Tunnels", Work in Progress,
            February 2012.
 [ISP-SHARED-ADDR]
            Yamagata, I., Miyakawa, S., Nakagawa, A., Yamaguchi, J.,
            and H. Ashida, "ISP Shared Address", Work in Progress,
            January 2012.
 [NAT444-IMPACTS]
            Donley, C., Howard, L., Kuarsingh, V., Berg, J., and J.
            Doshi, "Assessing the Impact of Carrier-Grade NAT on
            Network Applications", Work in Progress, November 2011.
 [PCP-BASE] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
            P. Selkirk, "Port Control Protocol (PCP)", Work
            in Progress, March 2012.
 [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
            Networks", BCP 84, RFC 3704, March 2004.
 [RFC6264]  Jiang, S., Guo, D., and B. Carpenter, "An Incremental
            Carrier-Grade NAT (CGN) for IPv6 Transition", RFC 6264,
            June 2011.
 [RFC6269]  Ford, M., Ed., Boucadair, M., Durand, A., Levis, P., and
            P. Roberts, "Issues with IP Address Sharing", RFC 6269,
            June 2011.
 [RFC6304]  Abley, J. and W. Maton, "AS112 Nameserver Operations",
            RFC 6304, July 2011.
 [RFC6343]  Carpenter, B., "Advisory Guidelines for 6to4 Deployment",
            RFC 6343, August 2011.

Weil, et al. Best Current Practice [Page 9] RFC 6598 Shared Address Space Request April 2012

Appendix A. Acknowledgments

 Thanks to the following people (in alphabetical order) for their
 guidance and feedback:
    Stan Barber
    John Brzozowski
    Isaiah Connell
    Greg Davies
    Owen DeLong
    Kirk Erichsen
    Wes George
    Chris Grundemann
    Tony Hain
    Philip Matthews
    John Pomeroy
    Barbara Stark
    Jean-Francois Tremblay
    Leo Vegoda
    Steven Wright
    Ikuhei Yamagata

Weil, et al. Best Current Practice [Page 10] RFC 6598 Shared Address Space Request April 2012

Authors' Addresses

 Jason Weil
 Time Warner Cable
 13820 Sunrise Valley Drive
 Herndon, VA  20171
 USA
 EMail: jason.weil@twcable.com
 Victor Kuarsingh
 Rogers Communications
 8200 Dixie Road
 Brampton, ON  L6T 0C1
 Canada
 EMail: victor.kuarsingh@gmail.com
 Chris Donley
 CableLabs
 858 Coal Creek Circle
 Louisville, CO  80027
 USA
 EMail: c.donley@cablelabs.com
 Christopher Liljenstolpe
 Telstra Corp.
 7/242 Exhibition Street
 Melbourne, VIC  316
 Australia
 Phone: +61 3 8647 6389
 EMail: cdl@asgaard.org
 Marla Azinger
 Frontier Communications
 Vancouver, WA
 USA
 Phone: +1.360.513.2293
 EMail: marla.azinger@frontiercorp.com

Weil, et al. Best Current Practice [Page 11]

Internet Engineering Task Force (IETF) M. Cotton Request for Comments: 6890 L. Vegoda BCP: 153 ICANN Obsoletes: 4773, 5156, 5735, 5736 R. Bonica, Ed. Category: Best Current Practice Juniper Networks ISSN: 2070-1721 B. Haberman

                                                                   JHU
                                                            April 2013
               Special-Purpose IP Address Registries

Abstract

 This memo reiterates the assignment of an IPv4 address block
 (192.0.0.0/24) to IANA.  It also instructs IANA to restructure its
 IPv4 and IPv6 Special-Purpose Address Registries.  Upon
 restructuring, the aforementioned registries will record all special-
 purpose address blocks, maintaining a common set of information
 regarding each address block.
 This memo obsoletes RFCs 4773, 5156, 5735, and 5736.

Status of This Memo

 This memo documents an Internet Best Current Practice.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 BCPs is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6890.

Cotton, et al. Best Current Practice [Page 1] RFC 6890 Special-Purpose Address Registries April 2013

Copyright Notice

 Copyright (c) 2013 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Table of Contents

 1. Introduction ....................................................2
 2. IANA Considerations .............................................3
    2.1. Assignment of an IPv4 Address Block to IANA ................3
    2.2. Restructuring of the IPv4 and IPv6 Special-Purpose
         Address ....................................................4
         2.2.1. Information Requirements ............................4
         2.2.2. IPv4 Special-Purpose Address Registry Entries .......6
         2.2.3. IPv6 Special-Purpose Address Registry Entries ......14
 3. Security Considerations ........................................20
 4. Acknowledgements ...............................................20
 5. Informative References .........................................20

1. Introduction

 In order to support new protocols and practices, the IETF
 occasionally reserves an address block for a special purpose.  For
 example, [RFC1122] reserves an IPv4 address block (0.0.0.0/8) to
 represent the local (i.e., "this") network.  Likewise, [RFC4291]
 reserves an IPv6 address block (fe80::/10) to represent link-scoped
 unicast addresses.
 Periodically, the IETF publishes an RFC that catalogs special-purpose
 address blocks.  Currently, [RFC5735] catalogs all IPv4 special-
 purpose address blocks and [RFC5156] catalogs all IPv6 special-
 purpose address blocks.
 [RFC5736] assigns an IPv4 address block (192.0.0.0/24) to IANA and
 instructs IANA to allocate special-purpose address blocks from this
 space.  [RFC5736] also instructs IANA to create an IPv4 Special-
 Purpose Address Registry that records allocations from this address

Cotton, et al. Best Current Practice [Page 2] RFC 6890 Special-Purpose Address Registries April 2013

 space.  However, [RFC5736] does not instruct IANA to record special-
 purpose address block reservations from outside of the aforementioned
 space in the IPv4 Special-Purpose Address Registry.
 Likewise, [RFC2928] assigns an IPv6 address block (2001:0000::/23) to
 IANA and instructs IANA to allocate special-purpose address blocks
 from this space.  [RFC4773] instructs IANA to create an IPv6 Special-
 Purpose Address Registry that records allocations from this address
 space.  However, [RFC4773] does not instruct IANA to record special-
 purpose address block reservations from outside of the aforementioned
 space in the IPv6 Special-Purpose Address Registry.
 This memo reiterates the assignment of an IPv4 address block
 (192.0.0.0/24) to IANA.  It also instructs IANA to restructure its
 IPv4 and IPv6 Special-Purpose Address Registries.  Specifically, this
 memo instructs IANA to record all special-purpose address blocks in
 the aforementioned registries.  These include, but are not limited
 to, IPv4 allocations from 192.0.0.0/24 and IPv6 allocations from
 2001:0000::/23.  Furthermore, this memo defines:
 o  a common set of information that the registries will maintain
    regarding each special-purpose address block
 o  a common set of requirements for future entries
 When the aforementioned registries include all special-purpose
 address blocks, [RFC5735] and [RFC5156] will become redundant with
 the registries.  Therefore, this memo obsoletes [RFC5735] and
 [RFC5156].  Because this memo reiterates the assignment of
 192.0.0.0/24 to IANA, and because it restructures the IPv4 Special-
 Purpose Address Registry, it obsoletes [RFC5736].  Finally, because
 this memo restructures the IPv6 Special-Purpose Address Registry, it
 obsoletes [RFC4773].

2. IANA Considerations

2.1. Assignment of an IPv4 Address Block to IANA

 Table 7 of this document records the assignment of an IPv4 address
 block (192.0.0.0/24) to IANA for IETF protocol assignments.  This
 address allocation to IANA is intended to support IETF protocol
 assignments.  A more general view of the roles of IANA with respect
 to address allocation functions is documented in Sections 4.1 and 4.3
 [RFC2860].
 IANA has designated special-purpose address blocks in compliance with
 [RFC2860].

Cotton, et al. Best Current Practice [Page 3] RFC 6890 Special-Purpose Address Registries April 2013

2.2. Restructuring of the IPv4 and IPv6 Special-Purpose Address

    Registries
 IANA has restructured the following registries:
    o  IPv4 Special-Purpose Address Registry
    o  IPv6 Special-Purpose Address Registry
 The IPv4 Special-Purpose Address Registry records all IPv4 special-
 purpose address blocks.  These reservations include, but are not
 limited to, allocations from the 192.0.0.0/24 address block.
 Likewise, the IPv6 Special-Purpose Address Registry records all IPv6
 special-purpose address blocks.  These reservations include, but are
 not limited to, allocations from the 2001:0000::/23 address block.
 Section 2.2.1 of this document describes information that both
 registries will maintain for each entry.  Initially, IANA has
 populated the IPv4 Special-Purpose Address Registry with information
 taken from Section 2.2.2 of this document.  Likewise, IANA has
 populated the IPv6 Special-Purpose Address Registry with information
 taken from Section 2.2.3 of this document.
 IANA will update the aforementioned registries as requested in the
 "IANA Considerations" section of a document that has passed IETF
 Review [RFC5226].  The "IANA Considerations" section must include all
 of the information specified in Section 2.2.1 of this document.

2.2.1. Information Requirements

 The IPv4 and IPv6 Special-Purpose Address Registries maintain the
 following information regarding each entry:
 o  Address Block - A block of IPv4 or IPv6 addresses that has been
    registered for a special purpose.
 o  Name - A descriptive name for the special-purpose address block.
 o  RFC - The RFC through which the special-purpose address block was
    requested.
 o  Allocation Date - The date upon which the special-purpose address
    block was allocated.
 o  Termination Date - The date upon which the allocation is to be
    terminated.  This field is applicable for limited-use allocations
    only.

Cotton, et al. Best Current Practice [Page 4] RFC 6890 Special-Purpose Address Registries April 2013

 o  Source - A boolean value indicating whether an address from the
    allocated special-purpose address block is valid when used as the
    source address of an IP datagram that transits two devices.
 o  Destination - A boolean value indicating whether an address from
    the allocated special-purpose address block is valid when used as
    the destination address of an IP datagram that transits two
    devices.
 o  Forwardable - A boolean value indicating whether a router may
    forward an IP datagram whose destination address is drawn from the
    allocated special-purpose address block between external
    interfaces.
 o  Global - A boolean value indicating whether an IP datagram whose
    destination address is drawn from the allocated special-purpose
    address block is forwardable beyond a specified administrative
    domain.
 o  Reserved-by-Protocol - A boolean value indicating whether the
    special-purpose address block is reserved by IP, itself.  This
    value is "TRUE" if the RFC that created the special-purpose
    address block requires all compliant IP implementations to behave
    in a special way when processing packets either to or from
    addresses contained by the address block.
 If the value of "Destination" is FALSE, the values of "Forwardable"
 and "Global" must also be false.

Cotton, et al. Best Current Practice [Page 5] RFC 6890 Special-Purpose Address Registries April 2013

2.2.2. IPv4 Special-Purpose Address Registry Entries

 Tables 1 though 16, below, represent entries with which IANA has
 initially populated the IPv4 Special-Purpose Address Registry.
            +----------------------+----------------------------+
            | Attribute            | Value                      |
            +----------------------+----------------------------+
            | Address Block        | 0.0.0.0/8                  |
            | Name                 | "This host on this network"|
            | RFC                  | [RFC1122], Section 3.2.1.3 |
            | Allocation Date      | September 1981             |
            | Termination Date     | N/A                        |
            | Source               | True                       |
            | Destination          | False                      |
            | Forwardable          | False                      |
            | Global               | False                      |
            | Reserved-by-Protocol | True                       |
            +----------------------+----------------------------+
                  Table 1: "This host on this network"
                  +----------------------+---------------+
                  | Attribute            | Value         |
                  +----------------------+---------------+
                  | Address Block        | 10.0.0.0/8    |
                  | Name                 | Private-Use   |
                  | RFC                  | [RFC1918]     |
                  | Allocation Date      | February 1996 |
                  | Termination Date     | N/A           |
                  | Source               | True          |
                  | Destination          | True          |
                  | Forwardable          | True          |
                  | Global               | False         |
                  | Reserved-by-Protocol | False         |
                  +----------------------+---------------+
                     Table 2: Private-Use Networks

Cotton, et al. Best Current Practice [Page 6] RFC 6890 Special-Purpose Address Registries April 2013

               +----------------------+----------------------+
               | Attribute            | Value                |
               +----------------------+----------------------+
               | Address Block        | 100.64.0.0/10        |
               | Name                 | Shared Address Space |
               | RFC                  | [RFC6598]            |
               | Allocation Date      | April 2012           |
               | Termination Date     | N/A                  |
               | Source               | True                 |
               | Destination          | True                 |
               | Forwardable          | True                 |
               | Global               | False                |
               | Reserved-by-Protocol | False                |
               +----------------------+----------------------+
                     Table 3: Shared Address Space
            +----------------------+----------------------------+
            | Attribute            | Value                      |
            +----------------------+----------------------------+
            | Address Block        | 127.0.0.0/8                |
            | Name                 | Loopback                   |
            | RFC                  | [RFC1122], Section 3.2.1.3 |
            | Allocation Date      | September 1981             |
            | Termination Date     | N/A                        |
            | Source               | False [1]                  |
            | Destination          | False [1]                  |
            | Forwardable          | False [1]                  |
            | Global               | False [1]                  |
            | Reserved-by-Protocol | True                       |
            +----------------------+----------------------------+
            [1] Several protocols have been granted exceptions to this
                rule.  For examples, see [RFC4379] and [RFC5884].
                           Table 4: Loopback

Cotton, et al. Best Current Practice [Page 7] RFC 6890 Special-Purpose Address Registries April 2013

                  +----------------------+----------------+
                  | Attribute            | Value          |
                  +----------------------+----------------+
                  | Address Block        | 169.254.0.0/16 |
                  | Name                 | Link Local     |
                  | RFC                  | [RFC3927]      |
                  | Allocation Date      | May 2005       |
                  | Termination Date     | N/A            |
                  | Source               | True           |
                  | Destination          | True           |
                  | Forwardable          | False          |
                  | Global               | False          |
                  | Reserved-by-Protocol | True           |
                  +----------------------+----------------+
                          Table 5: Link Local
                  +----------------------+---------------+
                  | Attribute            | Value         |
                  +----------------------+---------------+
                  | Address Block        | 172.16.0.0/12 |
                  | Name                 | Private-Use   |
                  | RFC                  | [RFC1918]     |
                  | Allocation Date      | February 1996 |
                  | Termination Date     | N/A           |
                  | Source               | True          |
                  | Destination          | True          |
                  | Forwardable          | True          |
                  | Global               | False         |
                  | Reserved-by-Protocol | False         |
                  +----------------------+---------------+
                     Table 6: Private-Use Networks

Cotton, et al. Best Current Practice [Page 8] RFC 6890 Special-Purpose Address Registries April 2013

          +----------------------+---------------------------------+
          | Attribute            | Value                           |
          +----------------------+---------------------------------+
          | Address Block        | 192.0.0.0/24 [2]                |
          | Name                 | IETF Protocol Assignments       |
          | RFC                  | Section 2.1 of this document    |
          | Allocation Date      | January 2010                    |
          | Termination Date     | N/A                             |
          | Source               | False                           |
          | Destination          | False                           |
          | Forwardable          | False                           |
          | Global               | False                           |
          | Reserved-by-Protocol | False                           |
          +----------------------+---------------------------------+
            [2] Not usable unless by virtue of a more specific
                reservation.
                  Table 7: IETF Protocol Assignments
           +----------------------+--------------------------------+
           | Attribute            | Value                          |
           +----------------------+--------------------------------+
           | Address Block        | 192.0.0.0/29                   |
           | Name                 | DS-Lite                        |
           | RFC                  | [RFC6333]                      |
           | Allocation Date      | June 2011                      |
           | Termination Date     | N/A                            |
           | Source               | True                           |
           | Destination          | True                           |
           | Forwardable          | True                           |
           | Global               | False                          |
           | Reserved-by-Protocol | False                          |
           +----------------------+--------------------------------+
                           Table 8: DS-Lite

Cotton, et al. Best Current Practice [Page 9] RFC 6890 Special-Purpose Address Registries April 2013

            +----------------------+----------------------------+
            | Attribute            | Value                      |
            +----------------------+----------------------------+
            | Address Block        | 192.0.2.0/24               |
            | Name                 | Documentation (TEST-NET-1) |
            | RFC                  | [RFC5737]                  |
            | Allocation Date      | January 2010               |
            | Termination Date     | N/A                        |
            | Source               | False                      |
            | Destination          | False                      |
            | Forwardable          | False                      |
            | Global               | False                      |
            | Reserved-by-Protocol | False                      |
            +----------------------+----------------------------+
                          Table 9: TEST-NET-1
                +----------------------+--------------------+
                | Attribute            | Value              |
                +----------------------+--------------------+
                | Address Block        | 192.88.99.0/24     |
                | Name                 | 6to4 Relay Anycast |
                | RFC                  | [RFC3068]          |
                | Allocation Date      | June 2001          |
                | Termination Date     | N/A                |
                | Source               | True               |
                | Destination          | True               |
                | Forwardable          | True               |
                | Global               | True               |
                | Reserved-by-Protocol | False              |
                +----------------------+--------------------+
                     Table 10: 6to4 Relay Anycast

Cotton, et al. Best Current Practice [Page 10] RFC 6890 Special-Purpose Address Registries April 2013

                  +----------------------+----------------+
                  | Attribute            | Value          |
                  +----------------------+----------------+
                  | Address Block        | 192.168.0.0/16 |
                  | Name                 | Private-Use    |
                  | RFC                  | [RFC1918]      |
                  | Allocation Date      | February 1996  |
                  | Termination Date     | N/A            |
                  | Source               | True           |
                  | Destination          | True           |
                  | Forwardable          | True           |
                  | Global               | False          |
                  | Reserved-by-Protocol | False          |
                  +----------------------+----------------+
                    Table 11: Private-Use Networks
                  +----------------------+---------------+
                  | Attribute            | Value         |
                  +----------------------+---------------+
                  | Address Block        | 198.18.0.0/15 |
                  | Name                 | Benchmarking  |
                  | RFC                  | [RFC2544]     |
                  | Allocation Date      | March 1999    |
                  | Termination Date     | N/A           |
                  | Source               | True          |
                  | Destination          | True          |
                  | Forwardable          | True          |
                  | Global               | False         |
                  | Reserved-by-Protocol | False         |
                  +----------------------+---------------+
        Table 12: Network Interconnect Device Benchmark Testing

Cotton, et al. Best Current Practice [Page 11] RFC 6890 Special-Purpose Address Registries April 2013

            +----------------------+----------------------------+
            | Attribute            | Value                      |
            +----------------------+----------------------------+
            | Address Block        | 198.51.100.0/24            |
            | Name                 | Documentation (TEST-NET-2) |
            | RFC                  | [RFC5737]                  |
            | Allocation Date      | January 2010               |
            | Termination Date     | N/A                        |
            | Source               | False                      |
            | Destination          | False                      |
            | Forwardable          | False                      |
            | Global               | False                      |
            | Reserved-by-Protocol | False                      |
            +----------------------+----------------------------+
                         Table 13: TEST-NET-2
            +----------------------+----------------------------+
            | Attribute            | Value                      |
            +----------------------+----------------------------+
            | Address Block        | 203.0.113.0/24             |
            | Name                 | Documentation (TEST-NET-3) |
            | RFC                  | [RFC5737]                  |
            | Allocation Date      | January 2010               |
            | Termination Date     | N/A                        |
            | Source               | False                      |
            | Destination          | False                      |
            | Forwardable          | False                      |
            | Global               | False                      |
            | Reserved-by-Protocol | False                      |
            +----------------------+----------------------------+
                         Table 14: TEST-NET-3

Cotton, et al. Best Current Practice [Page 12] RFC 6890 Special-Purpose Address Registries April 2013

               +----------------------+----------------------+
               | Attribute            | Value                |
               +----------------------+----------------------+
               | Address Block        | 240.0.0.0/4          |
               | Name                 | Reserved             |
               | RFC                  | [RFC1112], Section 4 |
               | Allocation Date      | August 1989          |
               | Termination Date     | N/A                  |
               | Source               | False                |
               | Destination          | False                |
               | Forwardable          | False                |
               | Global               | False                |
               | Reserved-by-Protocol | True                 |
               +----------------------+----------------------+
                   Table 15: Reserved for Future Use
               +----------------------+----------------------+
               | Attribute            | Value                |
               +----------------------+----------------------+
               | Address Block        | 255.255.255.255/32   |
               | Name                 | Limited Broadcast    |
               | RFC                  | [RFC0919], Section 7 |
               | Allocation Date      | October 1984         |
               | Termination Date     | N/A                  |
               | Source               | False                |
               | Destination          | True                 |
               | Forwardable          | False                |
               | Global               | False                |
               | Reserved-by-Protocol | False                |
               +----------------------+----------------------+
                      Table 16: Limited Broadcast

Cotton, et al. Best Current Practice [Page 13] RFC 6890 Special-Purpose Address Registries April 2013

2.2.3. IPv6 Special-Purpose Address Registry Entries

 Tables 17 through 28, below, represent entries with which the IANA
 has initially populated the IPv6 Special-Purpose Address Registry.
                 +----------------------+------------------+
                 | Attribute            | Value            |
                 +----------------------+------------------+
                 | Address Block        | ::1/128          |
                 | Name                 | Loopback Address |
                 | RFC                  | [RFC4291]        |
                 | Allocation Date      | February 2006    |
                 | Termination Date     | N/A              |
                 | Source               | False            |
                 | Destination          | False            |
                 | Forwardable          | False            |
                 | Global               | False            |
                 | Reserved-by-Protocol | True             |
                 +----------------------+------------------+
                      Table 17: Loopback Address
               +----------------------+---------------------+
               | Attribute            | Value               |
               +----------------------+---------------------+
               | Address Block        | ::/128              |
               | Name                 | Unspecified Address |
               | RFC                  | [RFC4291]           |
               | Allocation Date      | February 2006       |
               | Termination Date     | N/A                 |
               | Source               | True                |
               | Destination          | False               |
               | Forwardable          | False               |
               | Global               | False               |
               | Reserved-by-Protocol | True                |
               +----------------------+---------------------+
                     Table 18: Unspecified Address

Cotton, et al. Best Current Practice [Page 14] RFC 6890 Special-Purpose Address Registries April 2013

              +----------------------+---------------------+
              | Attribute            | Value               |
              +----------------------+---------------------+
              | Address Block        | 64:ff9b::/96        |
              | Name                 | IPv4-IPv6 Translat. |
              | RFC                  | [RFC6052]           |
              | Allocation Date      | October 2010        |
              | Termination Date     | N/A                 |
              | Source               | True                |
              | Destination          | True                |
              | Forwardable          | True                |
              | Global               | True                |
              | Reserved-by-Protocol | False               |
              +----------------------+---------------------+
                Table 19: IPv4-IPv6 Translation Address
               +----------------------+---------------------+
               | Attribute            | Value               |
               +----------------------+---------------------+
               | Address Block        | ::ffff:0:0/96       |
               | Name                 | IPv4-mapped Address |
               | RFC                  | [RFC4291]           |
               | Allocation Date      | February 2006       |
               | Termination Date     | N/A                 |
               | Source               | False               |
               | Destination          | False               |
               | Forwardable          | False               |
               | Global               | False               |
               | Reserved-by-Protocol | True                |
               +----------------------+---------------------+
                     Table 20: IPv4-Mapped Address

Cotton, et al. Best Current Practice [Page 15] RFC 6890 Special-Purpose Address Registries April 2013

            +----------------------+----------------------------+
            | Attribute            | Value                      |
            +----------------------+----------------------------+
            | Address Block        | 100::/64                   |
            | Name                 | Discard-Only Address Block |
            | RFC                  | [RFC6666]                  |
            | Allocation Date      | June 2012                  |
            | Termination Date     | N/A                        |
            | Source               | True                       |
            | Destination          | True                       |
            | Forwardable          | True                       |
            | Global               | False                      |
            | Reserved-by-Protocol | False                      |
            +----------------------+----------------------------+
                     Table 21: Discard-Only Prefix
            +----------------------+---------------------------+
            | Attribute            | Value                     |
            +----------------------+---------------------------+
            | Address Block        | 2001::/23                 |
            | Name                 | IETF Protocol Assignments |
            | RFC                  | [RFC2928]                 |
            | Allocation Date      | September 2000            |
            | Termination Date     | N/A                       |
            | Source               | False[1]                  |
            | Destination          | False[1]                  |
            | Forwardable          | False[1]                  |
            | Global               | False[1]                  |
            | Reserved-by-Protocol | False                     |
            +----------------------+---------------------------+
           [1] Unless allowed by a more specific allocation.
                  Table 22: IETF Protocol Assignments

Cotton, et al. Best Current Practice [Page 16] RFC 6890 Special-Purpose Address Registries April 2013

                  +----------------------+----------------+
                  | Attribute            | Value          |
                  +----------------------+----------------+
                  | Address Block        | 2001::/32      |
                  | Name                 | TEREDO         |
                  | RFC                  | [RFC4380]      |
                  | Allocation Date      | January 2006   |
                  | Termination Date     | N/A            |
                  | Source               | True           |
                  | Destination          | True           |
                  | Forwardable          | True           |
                  | Global               | False          |
                  | Reserved-by-Protocol | False          |
                  +----------------------+----------------+
                           Table 23: TEREDO
                  +----------------------+----------------+
                  | Attribute            | Value          |
                  +----------------------+----------------+
                  | Address Block        | 2001:2::/48    |
                  | Name                 | Benchmarking   |
                  | RFC                  | [RFC5180]      |
                  | Allocation Date      | April 2008     |
                  | Termination Date     | N/A            |
                  | Source               | True           |
                  | Destination          | True           |
                  | Forwardable          | True           |
                  | Global               | False          |
                  | Reserved-by-Protocol | False          |
                  +----------------------+----------------+
                        Table 24: Benchmarking

Cotton, et al. Best Current Practice [Page 17] RFC 6890 Special-Purpose Address Registries April 2013

                  +----------------------+---------------+
                  | Attribute            | Value         |
                  +----------------------+---------------+
                  | Address Block        | 2001:db8::/32 |
                  | Name                 | Documentation |
                  | RFC                  | [RFC3849]     |
                  | Allocation Date      | July 2004     |
                  | Termination Date     | N/A           |
                  | Source               | False         |
                  | Destination          | False         |
                  | Forwardable          | False         |
                  | Global               | False         |
                  | Reserved-by-Protocol | False         |
                  +----------------------+---------------+
                        Table 25: Documentation
                   +----------------------+--------------+
                   | Attribute            | Value        |
                   +----------------------+--------------+
                   | Address Block        | 2001:10::/28 |
                   | Name                 | ORCHID       |
                   | RFC                  | [RFC4843]    |
                   | Allocation Date      | March 2007   |
                   | Termination Date     | March 2014   |
                   | Source               | False        |
                   | Destination          | False        |
                   | Forwardable          | False        |
                   | Global               | False        |
                   | Reserved-by-Protocol | False        |
                   +----------------------+--------------+
                           Table 26: ORCHID

Cotton, et al. Best Current Practice [Page 18] RFC 6890 Special-Purpose Address Registries April 2013

                  +----------------------+---------------+
                  | Attribute            | Value         |
                  +----------------------+---------------+
                  | Address Block        | 2002::/16 [2] |
                  | Name                 | 6to4          |
                  | RFC                  | [RFC3056]     |
                  | Allocation Date      | February 2001 |
                  | Termination Date     | N/A           |
                  | Source               | True          |
                  | Destination          | True          |
                  | Forwardable          | True          |
                  | Global               | N/A [2]       |
                  | Reserved-by-Protocol | False         |
                  +----------------------+---------------+
                    [2] See [RFC3056] for details.
                            Table 27: 6to4
                   +----------------------+--------------+
                   | Attribute            | Value        |
                   +----------------------+--------------+
                   | Address Block        | fc00::/7     |
                   | Name                 | Unique-Local |
                   | RFC                  | [RFC4193]    |
                   | Allocation Date      | October 2005 |
                   | Termination Date     | N/A          |
                   | Source               | True         |
                   | Destination          | True         |
                   | Forwardable          | True         |
                   | Global               | False        |
                   | Reserved-by-Protocol | False        |
                   +----------------------+--------------+
                        Table 28: Unique-Local

Cotton, et al. Best Current Practice [Page 19] RFC 6890 Special-Purpose Address Registries April 2013

              +----------------------+-----------------------+
              | Attribute            | Value                 |
              +----------------------+-----------------------+
              | Address Block        | fe80::/10             |
              | Name                 | Linked-Scoped Unicast |
              | RFC                  | [RFC4291]             |
              | Allocation Date      | February 2006         |
              | Termination Date     | N/A                   |
              | Source               | True                  |
              | Destination          | True                  |
              | Forwardable          | False                 |
              | Global               | False                 |
              | Reserved-by-Protocol | True                  |
              +----------------------+-----------------------+
                    Table 29: Linked-Scoped Unicast

3. Security Considerations

 Security of the Internet's routing system relies on the ability to
 authenticate an assertion of unique control of an address block.
 Measures to authenticate such assertions rely on validation that the
 address block forms part of an existing allocated address block and
 that there is a trustable and unique reference in the IANA address
 registries.
 The proposed registry is intended to provide an authoritative source
 of information regarding the currency and intended purpose of special
 purpose address blocks that are designated from the IANA-administered
 Special-Purpose registry.  This is a small step towards the creation
 of a comprehensive registry framework that can be used as a trust
 point for commencing a chain of address validation.  Consideration
 should be given to IANA registry publication formats that are machine
 parsable.  Additionally, consideration should be given to the use of
 file signatures and associated certificate mechanisms to allow
 applications to confirm that the registry contents are current and
 that they have been published by the IANA.

4. Acknowledgements

 The authors thank Geoff Huston and Randy Bush for their helpful
 comments.  The authors also express their gratitude to an anonymous
 donor, without whom this document would not have been written.

5. Informative References

 [RFC0919]  Mogul, J., "Broadcasting Internet Datagrams", STD 5, RFC
            919, October 1984.

Cotton, et al. Best Current Practice [Page 20] RFC 6890 Special-Purpose Address Registries April 2013

 [RFC1112]  Deering, S., "Host extensions for IP multicasting", STD 5,
            RFC 1112, August 1989.
 [RFC1122]  Braden, R., Ed., "Requirements for Internet Hosts -
            Communication Layers", STD 3, RFC 1122, October 1989.
 [RFC1918]  Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
            and E. Lear, "Address Allocation for Private Internets",
            BCP 5, RFC 1918, February 1996.
 [RFC2544]  Bradner, S. and J. McQuaid, "Benchmarking Methodology for
            Network Interconnect Devices", RFC 2544, March 1999.
 [RFC2860]  Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
            Understanding Concerning the Technical Work of the
            Internet Assigned Numbers Authority", RFC 2860, June 2000.
 [RFC2928]  Hinden, R., Deering, S., Fink, R., and T. Hain, "Initial
            IPv6 Sub-TLA ID Assignments", RFC 2928, September 2000.
 [RFC3056]  Carpenter, B. and K. Moore, "Connection of IPv6 Domains
            via IPv4 Clouds", RFC 3056, February 2001.
 [RFC3068]  Huitema, C., "An Anycast Prefix for 6to4 Relay Routers",
            RFC 3068, June 2001.
 [RFC3849]  Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix
            Reserved for Documentation", RFC 3849, July 2004.
 [RFC3927]  Cheshire, S., Aboba, B., and E. Guttman, "Dynamic
            Configuration of IPv4 Link-Local Addresses", RFC 3927, May
            2005.
 [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
            Addresses", RFC 4193, October 2005.
 [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
            Architecture", RFC 4291, February 2006.
 [RFC4379]  Kompella, K. and G. Swallow, "Detecting Multi-Protocol
            Label Switched (MPLS) Data Plane Failures", RFC 4379,
            February 2006.
 [RFC4380]  Huitema, C., "Teredo: Tunneling IPv6 over UDP through
            Network Address Translations (NATs)", RFC 4380, February
            2006.

Cotton, et al. Best Current Practice [Page 21] RFC 6890 Special-Purpose Address Registries April 2013

 [RFC4773]  Huston, G., "Administration of the IANA Special Purpose
            IPv6 Address Block", RFC 4773, December 2006.
 [RFC4843]  Nikander, P., Laganier, J., and F. Dupont, "An IPv6 Prefix
            for Overlay Routable Cryptographic Hash Identifiers
            (ORCHID)", RFC 4843, April 2007.
 [RFC5156]  Blanchet, M., "Special-Use IPv6 Addresses", RFC 5156,
            April 2008.
 [RFC5180]  Popoviciu, C., Hamza, A., Van de Velde, G., and D.
            Dugatkin, "IPv6 Benchmarking Methodology for Network
            Interconnect Devices", RFC 5180, May 2008.
 [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", BCP 26, RFC 5226,
            May 2008.
 [RFC5735]  Cotton, M. and L. Vegoda, "Special Use IPv4 Addresses",
            RFC 5735, January 2010.
 [RFC5736]  Huston, G., Cotton, M., and L. Vegoda, "IANA IPv4 Special
            Purpose Address Registry", RFC 5736, January 2010.
 [RFC5737]  Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks
            Reserved for Documentation", RFC 5737, January 2010.
 [RFC5884]  Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
            "Bidirectional Forwarding Detection (BFD) for MPLS Label
            Switched Paths (LSPs)", RFC 5884, June 2010.
 [RFC6052]  Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
            Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
            October 2010.
 [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
            Stack Lite Broadband Deployments Following IPv4
            Exhaustion", RFC 6333, August 2011.
 [RFC6598]  Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and
            M. Azinger, "IANA-Reserved IPv4 Prefix for Shared Address
            Space", BCP 153, RFC 6598, April 2012.
 [RFC6666]  Hilliard, N. and D. Freedman, "A Discard Prefix for IPv6",
            RFC 6666, August 2012.

Cotton, et al. Best Current Practice [Page 22] RFC 6890 Special-Purpose Address Registries April 2013

Authors' Addresses

 Michelle Cotton
 Internet Corporation for Assigned Names and Numbers (ICANN)
 12025 Waterfront Drive, Suite 300
 Los Angeles, CA 90094-2536
 USA
 Phone: +310-823-9358
 EMail: michelle.cotton@icann.org
 URI:   http://www.icann.org/
 Leo Vegoda
 Internet Corporation for Assigned Names and Numbers (ICANN)
 12025 Waterfront Drive, Suite 300
 Los Angeles, CA 90094-2536
 USA
 Phone: +310-823-9358
 EMail: leo.vegoda@icann.org
 URI:   http://www.icann.org/
 Ronald P Bonica (editor)
 Juniper Networks
 2251 Corporate Park Drive
 Herndon, VA 20171
 USA
 EMail: rbonica@juniper.net
 Brian Haberman
 Johns Hopkins University (JHU) Applied Physics Lab
 11100 Johns Hopkins Road
 Laurel, MD 20723-6099
 USA
 EMail: brian@innovationslab.net

Cotton, et al. Best Current Practice [Page 23]

Internet Engineering Task Force (IETF) R. Bonica Request for Comments: 8190 Juniper Networks BCP: 153 M. Cotton Updates: 6890 PTI Category: Best Current Practice B. Haberman ISSN: 2070-1721 Johns Hopkins University

                                                             L. Vegoda
                                                                 ICANN
                                                             June 2017
        Updates to the Special-Purpose IP Address Registries

Abstract

 This memo updates the IANA IPv4 and IPv6 Special-Purpose Address
 Registries to address issues raised by the definition of a "global"
 prefix.  It also corrects several errors in registry entries to
 ensure the integrity of the IANA Special-Purpose Address Registries.
 This memo updates RFC 6890.

Status of This Memo

 This memo documents an Internet Best Current Practice.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 BCPs is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc8190.

Bonica, et al. Best Current Practice [Page 1] RFC 8190 Special-Purpose Address Registries June 2017

Copyright Notice

 Copyright (c) 2017 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
 2.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   2.1.  Definition of Globally Reachable  . . . . . . . . . . . .   3
   2.2.  Updates to the IPv4 Special-Purpose Address Registry  . .   4
   2.3.  Updates to the IPv6 Special-Purpose Address Registry  . .   4
 3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
 4.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
   4.2.  Informative References  . . . . . . . . . . . . . . . . .   5
 Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   5
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

Bonica, et al. Best Current Practice [Page 2] RFC 8190 Special-Purpose Address Registries June 2017

1. Introduction

 In order to support new protocols and practices, the IETF
 occasionally reserves an address block for a special purpose.  For
 example, [RFC1122] reserves an IPv4 address block (0.0.0.0/8) to
 represent the local (i.e., "this") network.  Likewise, [RFC4291]
 reserves an IPv6 address block (fe80::/10) for link-local unicast
 addresses.
 Several issues have been raised with the documentation of some of the
 special-purpose address blocks in [RFC6890].  Specifically, the
 definition of "global" provided in [RFC6890] was misleading as it
 slightly differed from the generally accepted definition of "global
 scope" (i.e., the ability to forward beyond the boundaries of an
 administrative domain, described as "global unicast" in the IPv6
 addressing architecture [RFC4291]).
 This memo updates the definition of "global" from [RFC6890] for the
 IPv4 and IPv6 Special-Purpose Address Registries, augments the fields
 contained within the registries in order to address the confusion
 raised by the definition of "global", and corrects some errors in
 some of the entries in the Special-Purpose Address Registries.
 This memo updates [RFC6890].

2. IANA Considerations

2.1. Definition of Globally Reachable

 [RFC6890] defined the term "global" without taking into consideration
 the multiple uses of the term.  Specifically, IP addresses can be
 global in terms of allocation scope as well as global in terms of
 routing/reachability.  To address this ambiguity, the use of the term
 "global" defined in [RFC6890] is replaced with "globally reachable".
 The following definition replaces the definition of "global" in the
 IANA Special-Purpose Address Registries:
 o  Globally Reachable - A boolean value indicating whether an IP
    datagram whose destination address is drawn from the allocated
    special-purpose address block is forwardable beyond a specified
    administrative domain.
 The same relationship between the value of "Destination" and the
 values of "Forwardable" and "Global" described in [RFC6890] holds for
 "Globally Reachable".  If the value of "Destination" is FALSE, the
 values of "Forwardable" and "Globally Reachable" must also be FALSE.

Bonica, et al. Best Current Practice [Page 3] RFC 8190 Special-Purpose Address Registries June 2017

 The "Global" columns in the IPv4 Special-Purpose Address Registry
 (https://www.iana.org/assignments/iana-ipv4-special-registry) and the
 IPv6 Special-Purpose Address Registry
 (https://www.iana.org/assignments/iana-ipv6-special-registry) have
 been renamed to "Globally Reachable".

2.2. Updates to the IPv4 Special-Purpose Address Registry

 o  Limited Broadcast prefix (255.255.255.255/32) - The Reserved-by-
    Protocol value has changed from False to True.  This change was
    made to align the registry with reservation of the limited
    broadcast address with Section 7 of [RFC919].

2.3. Updates to the IPv6 Special-Purpose Address Registry

 The following changes to the "IPv6 Special-Purpose Address Registry"
 involved the insertion of two new footnotes.  These additions
 required that the footnotes be renumbered.
 o  TEREDO prefix (2001::/32) - The Globally Reachable value has
    changed from False to "N/A [2]".  The [2] footnote now states:
  • See Section 5 of [RFC4380] for details.
 o  EID Space for LISP (2001:5::/32) - All footnotes have been
    incremented by 1.
 o  6to4 (2002::/16) - All footnotes have been incremented by 1.
 o  Unique-Local (fc00::/7) - The Globally Reachable value has changed
    from False to "False [7]".  The [7] footnote now states:
  • See [RFC4193] for more details on the routability of Unique-

Local addresses. The Unique-Local prefix is drawn from the

       IPv6 Global Unicast Address range but is specified as not
       globally routed.

3. Security Considerations

 This document does not raise any security issues beyond those
 discussed in [RFC6890].

Bonica, et al. Best Current Practice [Page 4] RFC 8190 Special-Purpose Address Registries June 2017

4. References

4.1. Normative References

 [RFC6890]  Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
            "Special-Purpose IP Address Registries", BCP 153,
            RFC 6890, DOI 10.17487/RFC6890, April 2013,
            <http://www.rfc-editor.org/info/rfc6890>.

4.2. Informative References

 [RFC919]   Mogul, J., "Broadcasting Internet Datagrams", STD 5,
            RFC 919, DOI 10.17487/RFC0919, October 1984,
            <http://www.rfc-editor.org/info/rfc919>.
 [RFC1122]  Braden, R., Ed., "Requirements for Internet Hosts -
            Communication Layers", STD 3, RFC 1122,
            DOI 10.17487/RFC1122, October 1989,
            <http://www.rfc-editor.org/info/rfc1122>.
 [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
            Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,
            <http://www.rfc-editor.org/info/rfc4193>.
 [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
            Architecture", RFC 4291, DOI 10.17487/RFC4291, February
            2006, <http://www.rfc-editor.org/info/rfc4291>.
 [RFC4380]  Huitema, C., "Teredo: Tunneling IPv6 over UDP through
            Network Address Translations (NATs)", RFC 4380,
            DOI 10.17487/RFC4380, February 2006,
            <http://www.rfc-editor.org/info/rfc4380>.

Acknowledgements

 Brian Carpenter and C.M. Heard provided useful comments on initial
 draft versions of this document.  Daniel Migault provided an in-depth
 review that helped strengthen the text within the document.  Amanda
 Baber and Sabrina Tanamal asked questions which resulted in the
 authors simplifying the document.

Bonica, et al. Best Current Practice [Page 5] RFC 8190 Special-Purpose Address Registries June 2017

Authors' Addresses

 Ronald Bonica
 Juniper Networks
 Email: rbonica@juniper.net
 Michelle Cotton
 PTI, an affiliate of ICANN
 12025 Waterfront Drive, Suite 300
 Los Angeles, CA  90094-2536
 United States of America
 Phone: +1-424-254-5300
 Email: michelle.cotton@iana.org
 Brian Haberman
 Johns Hopkins University
 Email: brian@innovationslab.net
 Leo Vegoda
 ICANN
 Email: leo.vegoda@icann.org

Bonica, et al. Best Current Practice [Page 6]

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