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Internet Engineering Task Force (IETF)                         A. BrandtRequest for Comments: 7428                                      J. BuronCategory: Standards Track                                  Sigma DesignsISSN: 2070-1721                                            February 2015Transmission of IPv6 Packets over ITU-T G.9959 NetworksAbstract   This document describes the frame format for transmission of IPv6   packets as well as a method of forming IPv6 link-local addresses and   statelessly autoconfigured IPv6 addresses on ITU-T G.9959 networks.Status of This Memo   This is an Internet Standards Track document.   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   Internet Standards is available inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7428.Copyright Notice   Copyright (c) 2015 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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.Brandt & Buron               Standards Track                    [Page 1]

RFC 7428                    IPv6 over G.9959               February 2015Table of Contents1. Introduction ....................................................21.1. Terms Used .................................................31.2. Requirements Language ......................................42. G.9959 Parameters to Use for IPv6 Transport .....................52.1. Addressing Mode ............................................52.2. IPv6 Multicast Support .....................................62.3. G.9959 MAC PDU Size and IPv6 MTU ...........................62.4. Transmission Status Indications ............................72.5. Transmission Security ......................................73. 6LoWPAN Adaptation Layer and Frame Format .......................73.1. Dispatch Header ............................................84. 6LoWPAN Addressing ..............................................9      4.1. Stateless Address Autoconfiguration of Routable IPv6           Addresses ..................................................94.2. IPv6 Link-Local Address ...................................104.3. Unicast Address Mapping ...................................104.4. On the Use of Neighbor Discovery Technologies .............114.4.1. Prefix and CID Management (Route-Over) .............114.4.2. Prefix and CID Management (Mesh-Under) .............115. Header Compression .............................................126. Security Considerations ........................................137. Privacy Considerations .........................................148. References .....................................................148.1. Normative References ......................................148.2. Informative References ....................................16Appendix A. G.9959 6LoWPAN Datagram Example .......................17   Acknowledgements ..................................................21   Authors' Addresses ................................................211.  Introduction   The ITU-T G.9959 recommendation [G.9959] targets low-power Personal   Area Networks (PANs).  This document defines the frame format for   transmission of IPv6 [RFC2460] packets as well as the formation of   IPv6 link-local addresses and statelessly autoconfigured IPv6   addresses on G.9959 networks.   The general approach is to adapt elements of [RFC4944] to G.9959   networks.  G.9959 provides a Segmentation and Reassembly (SAR) layer   for transmission of datagrams larger than the G.9959 Media Access   Control Protocol Data Unit (MAC PDU).   [RFC6775] updates [RFC4944] by specifying IPv6 over Low-Power   Wireless Personal Area Network (6LoWPAN) optimizations for IPv6   Neighbor Discovery (ND) (originally defined by [RFC4861]).  This   document limits the use of [RFC6775] to prefix and Context IDBrandt & Buron               Standards Track                    [Page 2]

RFC 7428                    IPv6 over G.9959               February 2015   assignment.  An Interface Identifier (IID) may be constructed from a   G.9959 link-layer address, leading to a "link-layer-derived IPv6   address".  If using that method, Duplicate Address Detection (DAD) is   not needed.  Alternatively, IPv6 addresses may be assigned centrally   via DHCP, leading to a "non-link-layer-derived IPv6 address".   Address registration is only needed in certain cases.   In addition to IPv6 application communication, the frame format   defined in this document may be used by IPv6 routing protocols such   as the Routing Protocol for Low-Power and Lossy Networks (RPL)   [RFC6550] or Reactive Discovery of Point-to-Point Routes in Low-Power   and Lossy Networks (P2P-RPL) [RFC6997] to implement IPv6 routing over   G.9959 networks.   The encapsulation frame defined by this specification may optionally   be transported via mesh routing below the 6LoWPAN layer.  Mesh-under   and route-over routing protocol specifications are out of scope for   this document.1.1.  Terms Used   6LoWPAN: IPv6 over Low-Power Wireless Personal Area Network   ABR: Authoritative 6LoWPAN Border Router (Authoritative 6LBR)      [RFC6775]   Ack: Acknowledgement   AES: Advanced Encryption Standard   CID: Context Identifier [RFC6775]   DAD: Duplicate Address Detection [RFC6775]   DHCPv6: Dynamic Host Configuration Protocol for IPv6 [RFC3315]   EUI-64: Extended Unique Identifier [EUI64]   G.9959: Short range narrow-band digital radiocommunication      transceiver [G.9959]   GHC: Generic Header Compression [RFC7400]   HomeID: G.9959 Link-Layer Network Identifier   IID: Interface IdentifierBrandt & Buron               Standards Track                    [Page 3]

RFC 7428                    IPv6 over G.9959               February 2015   Link-layer-derived address: IPv6 address constructed on the basis of      link-layer address information   MAC: Media Access Control   Mesh-under: Forwarding via mesh routing below the 6LoWPAN layer   MTU: Maximum Transmission Unit   ND: Neighbor Discovery [RFC4861] [RFC6775]   NodeID: G.9959 Link-Layer Node Identifier   Non-link-layer-derived address: IPv6 address assigned by a managed      process, e.g., DHCPv6   P2P-RPL: Reactive Discovery of Point-to-Point Routes in Low-Power and      Lossy Networks [RFC6997]   PAN: Personal Area Network   PDU: Protocol Data Unit   PHY: Physical Layer   RA: Router Advertisement [RFC4861] [RFC6775]   Route-over: Forwarding via IP routing above the 6LoWPAN layer   RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks [RFC6550]   SAR: G.9959 Segmentation and Reassembly   ULA: Unique Local Address [RFC4193]1.2.  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 [RFC2119].Brandt & Buron               Standards Track                    [Page 4]

RFC 7428                    IPv6 over G.9959               February 20152.  G.9959 Parameters to Use for IPv6 Transport   This section outlines properties applying to the PHY and MAC layers   of G.9959 and how to use these for IPv6 transport.2.1.  Addressing Mode   G.9959 defines how a unique 32-bit HomeID network identifier is   assigned by a network controller and how an 8-bit NodeID host   identifier is allocated to each node.  NodeIDs are unique within the   network identified by the HomeID.  The G.9959 HomeID represents an   IPv6 subnet that is identified by one or more IPv6 prefixes.   An IPv6 host MUST construct its link-local IPv6 address from the   link-layer-derived IID in order to facilitate IP header compression   as described in [RFC6282].   A node interface MAY support the M flag of the RA message for the   construction of routable IPv6 addresses.  A cost-optimized node   implementation may save memory by skipping support for the M flag.   The M flag MUST be interpreted as defined in Figure 1.    +--------+--------+---------------------------------------------+    | M flag | M flag |  Required node behavior                     |    | support| value  |                                             |    +--------+--------+---------------------------------------------+    | No     |(ignore)| Node MUST use link-layer-derived addressing |    +--------+--------+---------------------------------------------+    | Yes    |    0   | Node MUST use link-layer-derived addressing |    |        +--------+---------------------------------------------+    |        |    1   | Node MUST use DHCPv6-based addressing, and  |    |        |        | node MUST comply fully with [RFC6775]       |    +--------+--------+---------------------------------------------+              Figure 1: RA M Flag Support and Interpretation   A node that uses DHCPv6-based addressing MUST comply fully with the   text of [RFC6775].   If DHCPv6-based addressing is used, the DHCPv6 client must use a   DHCPv6 Unique Identifier (DUID) of type DUID-UUID, as described in   [RFC6355].  The Universally Unique Identifier (UUID) used in the   DUID-UUID must be generated as specified in[RFC4122], Section 4.5,   starting at the third paragraph in that section (the 47-bit random   number-based UUID).  The DUID must be stored persistently by the node   as specified inSection 3 of [RFC6355].Brandt & Buron               Standards Track                    [Page 5]

RFC 7428                    IPv6 over G.9959               February 2015   A word of caution: since HomeIDs and NodeIDs are handed out by a   network controller function during inclusion, identifier validity and   uniqueness are limited by the lifetime of the network membership.   This can be cut short by a mishap occurring at the network   controller.  Having a single point of failure at the network   controller suggests that high-reliability network deployments may   benefit from a redundant network controller function.   This warning applies to link-layer-derived addressing as well as to   non-link-layer-derived addressing deployments.2.2.  IPv6 Multicast Support   [RFC3819] recommends that IP subnetworks support (subnet-wide)   multicast.  G.9959 supports direct-range IPv6 multicast, while   subnet-wide multicast is not supported natively by G.9959.  Subnet-   wide multicast may be provided by an IP routing protocol or a mesh   routing protocol operating below the 6LoWPAN layer.  Routing protocol   specifications are out of scope for this document.   IPv6 multicast packets MUST be carried via G.9959 broadcast.   As per [G.9959], this is accomplished as follows:   1.  The destination HomeID of the G.9959 MAC PDU MUST be the HomeID       of the network.   2.  The destination NodeID of the G.9959 MAC PDU MUST be the       broadcast NodeID (0xff).   G.9959 broadcast MAC PDUs are only intercepted by nodes within the   network identified by the HomeID.2.3.  G.9959 MAC PDU Size and IPv6 MTU   IPv6 packets MUST be transmitted using G.9959 transmission profile R3   or higher.   [RFC2460] specifies that any link that cannot convey a 1280-octet   packet in one piece must provide link-specific fragmentation and   reassembly at a layer below IPv6.   G.9959 provides segmentation and reassembly for payloads up to   1350 octets.  IPv6 header compression [RFC6282] improves the chances   that a short IPv6 packet can fit into a single G.9959 frame.   Therefore,Section 3 of this document specifies that [RFC6282] MUST   be supported.  With the mandatory link-layer security enabled, a   G.9959 R3 MAC PDU may accommodate 6LoWPAN datagrams of up toBrandt & Buron               Standards Track                    [Page 6]

RFC 7428                    IPv6 over G.9959               February 2015   130 octets without triggering G.9959 segmentation and reassembly.   Longer 6LoWPAN datagrams will lead to the transmission of multiple   G.9959 PDUs.2.4.  Transmission Status Indications   The G.9959 MAC layer provides native acknowledgement and   retransmission of MAC PDUs.  The G.9959 SAR layer does the same for   larger datagrams.  A mesh routing layer may provide a similar feature   for routed communication.  An IPv6 routing stack communicating over   G.9959 may utilize link-layer status indications such as delivery   confirmation and Ack timeout from the MAC layer.2.5.  Transmission Security   Implementations claiming conformance with this document MUST enable   G.9959 shared network key security.   The shared network key is intended to address security requirements   in the home at the normal level of security requirements.  For   applications with high or very high requirements for confidentiality   and/or integrity, additional application-layer security measures for   end-to-end authentication and encryption may need to be applied.   (The availability of the network relies on the security properties of   the network key in any case.)3.  6LoWPAN Adaptation Layer and Frame Format   The 6LoWPAN encapsulation formats defined in this section are carried   as payload in the G.9959 MAC PDU.  IPv6 header compression [RFC6282]   MUST be supported by implementations of this specification.  Further,   implementations MAY support Generic Header Compression (GHC)   [RFC7400].  A node implementing [RFC7400] MUST probe its peers for   GHC support before applying GHC.   All 6LoWPAN datagrams transported over G.9959 are prefixed by a   6LoWPAN encapsulation header stack.  The 6LoWPAN payload follows this   encapsulation header stack.  Each header in the header stack contains   a header type followed by zero or more header fields.  An IPv6 header   stack may contain, in the following order, addressing, hop-by-hop   options, routing, fragmentation, destination options, and, finally,   payload [RFC2460].  The 6LoWPAN header format is structured the same   way.  Currently, only one payload option is defined for the G.9959   6LoWPAN header format.Brandt & Buron               Standards Track                    [Page 7]

RFC 7428                    IPv6 over G.9959               February 2015   The definition of 6LoWPAN headers consists of the dispatch value, the   definition of the header fields that follow, and their ordering   constraints relative to all other headers.  Although the header stack   structure provides a mechanism to address future demands on the   6LoWPAN adaptation layer, it is not intended to provide general-   purpose extensibility.   An example of a complete G.9959 6LoWPAN datagram can be found inAppendix A.3.1.  Dispatch Header   The Dispatch Header is shown below:     0                   1                   2                   3     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    | 6LoWPAN CmdCls|   Dispatch    |  Type-specific header         |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                    Figure 2: Dispatch Type and Header   6LoWPAN CmdCls: 6LoWPAN Command Class identifier.  This field MUST      carry the value 0x4F [G.9959].  The value is assigned by the ITU-T      and specifies that the following bits are a 6LoWPAN encapsulated      datagram.  6LoWPAN protocols MUST ignore the G.9959 frame if the      6LoWPAN Command Class identifier deviates from 0x4F.   Dispatch: Identifies the header type immediately following the      Dispatch Header.   Type-specific header: A header determined by the Dispatch Header.   The dispatch value may be treated as an unstructured namespace.  Only   a few symbols are required to represent current 6LoWPAN   functionality.  Although some additional savings could be achieved by   encoding additional functionality into the dispatch byte, these   measures would tend to constrain the ability to address future   alternatives.Brandt & Buron               Standards Track                    [Page 8]

RFC 7428                    IPv6 over G.9959               February 2015              +------------+--------------------+-----------+              | Pattern    | Header Type        | Reference |              +------------+--------------------+-----------+              | 01  1xxxxx | 6LoWPAN_IPHC       | [RFC6282] |              +------------+--------------------+-----------+              Other IANA-assigned 6LoWPAN dispatch values do not              apply to this document.                         Figure 3: Dispatch Values   6LoWPAN_IPHC: IPv6 Header Compression.  Refer to [RFC6282].4.  6LoWPAN Addressing   IPv6 addresses may be autoconfigured from IIDs that may again be   constructed from link-layer address information to save memory in   devices and to facilitate efficient IP header compression as per   [RFC6282].  Link-layer-derived addresses have a static nature and may   involuntarily expose private usage data on public networks.  Refer toSection 7.   A NodeID is mapped into an IEEE EUI-64 identifier as follows:                        IID = 0000:00ff:fe00:YYXX                 Figure 4: Constructing a Compressible IID   where XX carries the G.9959 NodeID and YY is a 1-byte value chosen by   the individual node.  The default YY value MUST be zero.  A node MAY   use values of YY other than zero to form additional IIDs in order to   instantiate multiple IPv6 interfaces.  The YY value MUST be ignored   when computing the corresponding NodeID (the XX value) from an IID.   The method of constructing IIDs from the link-layer address obviously   does not support addresses assigned or constructed by other means.  A   node MUST NOT compute the NodeID from the IID if the first 6 bytes of   the IID do not comply with the format defined in Figure 4.  In that   case, the address resolution mechanisms of [RFC6775] apply.4.1.  Stateless Address Autoconfiguration of Routable IPv6 Addresses   The IID defined above MUST be used whether autoconfiguring a ULA IPv6   address [RFC4193] or a globally routable IPv6 address [RFC3587] in   G.9959 subnets.Brandt & Buron               Standards Track                    [Page 9]

RFC 7428                    IPv6 over G.9959               February 20154.2.  IPv6 Link-Local Address   The IPv6 link-local address [RFC4291] for a G.9959 interface is   formed by appending the IID defined above to the IPv6 link-local   prefix fe80::/64.   The "Universal/Local" (U/L) bit MUST be set to zero in keeping with   the fact that this is not a globally unique value [EUI64].   The resulting link-local address is formed as follows:        10 bits            54 bits                  64 bits     +----------+-----------------------+----------------------------+     |1111111010|         (zeros)       | Interface Identifier (IID) |     +----------+-----------------------+----------------------------+                     Figure 5: IPv6 Link-Local Address4.3.  Unicast Address Mapping   The address resolution procedure for mapping IPv6 unicast addresses   into G.9959 link-layer addresses follows the general description inSection 7.2 of [RFC4861].  The Source/Target Link-layer Address   option MUST have the following form when the link layer is G.9959.                      0                   1                      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                     |     Type      |    Length=1   |                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                     |     0x00      |    NodeID     |                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                     |            Padding            |                     +-                             -+                     |          (All zeros)          |                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                  Figure 6: IPv6 Unicast Address Mapping   Option fields:   Type:  The value 1 signifies the Source Link-layer address.  The      value 2 signifies the Destination Link-layer address.   Length:  This is the length of this option (including the Type and      Length fields) in units of 8 octets.  The value of this field is      always 1 for G.9959 NodeIDs.Brandt & Buron               Standards Track                   [Page 10]

RFC 7428                    IPv6 over G.9959               February 2015   NodeID:  This is the G.9959 NodeID to which the actual interface      currently responds.  The link-layer address may change if the      interface joins another network at a later time.4.4.  On the Use of Neighbor Discovery Technologies   [RFC4861] specifies how IPv6 nodes may resolve link-layer addresses   from IPv6 addresses via the use of link-local IPv6 multicast.   [RFC6775] is an optimization of [RFC4861], specifically targeting   6LoWPAN networks.  [RFC6775] defines how a 6LoWPAN node may register   IPv6 addresses with an authoritative border router (ABR).  Mesh-under   networks MUST NOT use [RFC6775] address registration.  However,   [RFC6775] address registration MUST be used if the first 6 bytes of   the IID do not comply with the format defined in Figure 4.4.4.1.  Prefix and CID Management (Route-Over)   In route-over environments, IPv6 hosts MUST use [RFC6775] address   registration.  A node implementation for route-over operation MAY use   [RFC6775] mechanisms for obtaining IPv6 prefixes and corresponding   header compression context information [RFC6282].  [RFC6775] route-   over requirements apply with no modifications.4.4.2.  Prefix and CID Management (Mesh-Under)   An implementation for mesh-under operation MUST use [RFC6775]   mechanisms for managing IPv6 prefixes and corresponding header   compression context information [RFC6282].  [RFC6775] Duplicate   Address Detection (DAD) MUST NOT be used, since the link-layer   inclusion process of G.9959 ensures that a NodeID is unique for a   given HomeID.   With this exception and the specific redefinition of the RA Router   Lifetime value 0xFFFF (refer toSection 4.4.2.3), the text of the   following subsections is in compliance with [RFC6775].4.4.2.1.  Prefix Assignment Considerations   As stated by [RFC6775], an ABR is responsible for managing   prefix(es).  Global routable prefixes may change over time.  It is   RECOMMENDED that a ULA prefix is assigned to the 6LoWPAN subnet to   facilitate stable site-local application associations based on IPv6   addresses.  A node MAY support the M flag of the RA message.  This   influences the way IPv6 addresses are assigned.  Refer toSection 2.1   for details.Brandt & Buron               Standards Track                   [Page 11]

RFC 7428                    IPv6 over G.9959               February 20154.4.2.2.  Robust and Efficient CID Management   The 6LoWPAN Context Option (6CO) is used according to [RFC6775] in an   RA to disseminate Context IDs (CIDs) to use for compressing prefixes.   One or more prefixes and corresponding Context IDs MUST be assigned   during initial node inclusion.   When updating context information, a CID may have its lifetime set to   zero to obsolete it.  The CID MUST NOT be reused immediately; rather,   the next vacant CID should be assigned.  Header compression based on   CIDs MUST NOT be used for RA messages carrying context information.   An expired CID and the associated prefix MUST NOT be reset but rather   must be retained in receive-only mode if there is no other current   need for the CID value.  This will allow an ABR to detect if a   sleeping node without a clock uses an expired CID, and in response,   the ABR MUST return an RA with fresh context information to the   originator.4.4.2.3.  Infinite Prefix Lifetime Support for Island-Mode Networks   Nodes MUST renew the prefix and CID according to the lifetime   signaled by the ABR.  [RFC6775] specifies that the maximum value of   the RA Router Lifetime field MAY be up to 0xFFFF.  This document   further specifies that the value 0xFFFF MUST be interpreted as   infinite lifetime.  This value MUST NOT be used by ABRs.  Its use is   only intended for a sleeping network controller -- for instance, a   battery-powered remote control being master for a small island-mode   network of light modules.5.  Header Compression   IPv6 header compression [RFC6282] MUST be implemented, and GHC   [RFC7400] compression for higher layers MAY be implemented.  This   section will simply identify substitutions that should be made when   interpreting the text of [RFC6282] and [RFC7400].   In general, the following substitutions should be made:   o  Replace "802.15.4" with "G.9959".   o  Replace "802.15.4 short address" with "<Interface><G.9959      NodeID>".   o  Replace "802.15.4 PAN ID" with "G.9959 HomeID".Brandt & Buron               Standards Track                   [Page 12]

RFC 7428                    IPv6 over G.9959               February 2015   When a 16-bit address is called for (i.e., an IEEE 802.15.4 "short   address"), it MUST be formed by prepending an Interface label byte to   the G.9959 NodeID:                      0                   1                      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                     |   Interface   |    NodeID     |                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   A transmitting node may be sending to an IPv6 destination address   that can be reconstructed from the link-layer destination address.   If the Interface number is zero (the default value), all IPv6 address   bytes may be elided.  Likewise, the Interface number of a fully   elided IPv6 address (i.e., SAM/DAM=11) may be reconstructed to the   value zero by a receiving node.   64-bit 802.15.4 address details do not apply.6.  Security Considerations   The method of derivation of Interface Identifiers from 8-bit NodeIDs   preserves uniqueness within the network.  However, there is no   protection from duplication through forgery.  Neighbor Discovery in   G.9959 links may be susceptible to threats as detailed in [RFC3756].   G.9959 networks may feature mesh routing.  This implies additional   threats due to ad hoc routing as per [KW03].  G.9959 provides   capability for link-layer security.  G.9959 nodes MUST use link-layer   security with a shared key.  Doing so will alleviate the majority of   threats stated above.  A sizable portion of G.9959 devices is   expected to always communicate within their PAN (i.e., within their   subnet, in IPv6 terms).  In response to cost and power consumption   considerations, these devices will typically implement the minimum   set of features necessary.  Accordingly, security for such devices   may rely on the mechanisms defined at the link layer by G.9959.   G.9959 relies on the Advanced Encryption Standard (AES) for   authentication and encryption of G.9959 frames and further employs   challenge-response handshaking to prevent replay attacks.   It is also expected that some G.9959 devices (e.g., billing and/or   safety-critical products) will implement coordination or integration   functions.  These may communicate regularly with IPv6 peers outside   the subnet.  Such IPv6 devices are expected to secure their end-to-   end communications with standard security mechanisms (e.g., IPsec,   Transport Layer Security (TLS), etc.).Brandt & Buron               Standards Track                   [Page 13]

RFC 7428                    IPv6 over G.9959               February 20157.  Privacy Considerations   IP addresses may be used to track devices on the Internet; such   devices can in turn be linked to individuals and their activities.   Depending on the application and the actual use pattern, this may be   undesirable.  To impede tracking, globally unique and non-changing   characteristics of IP addresses should be avoided, e.g., by   frequently changing the global prefix and avoiding unique link-layer-   derived IIDs in addresses.   Some link layers use a 48-bit or 64-bit link-layer address that   uniquely identifies the node on a global scale, regardless of global   prefix changes.  The risk of exposing a G.9959 device from its   link-layer-derived IID is limited because of the short 8-bit   link-layer address.   While intended for central address management, DHCPv6 address   assignment also decouples the IPv6 address from the link-layer   address.  Addresses may be made dynamic by the use of a short DHCP   lease period and an assignment policy that makes the DHCP server hand   out a fresh IP address every time.  For enhanced privacy, the   DHCP-assigned addresses should be logged only for the duration of the   lease, provided the implementation also allows logging for longer   durations as per the operational policies.   It should be noted that privacy and frequently changing address   assignments come at a cost.  Non-link-layer-derived IIDs require the   use of address registration.  Further, non-link-layer-derived IIDs   cannot be compressed; this leads to longer datagrams and increased   link-layer segmentation.  Finally, frequent prefix changes   necessitate more Context Identifier updates; this not only leads to   increased traffic but also may affect the battery lifetime of   sleeping nodes.8.  References8.1.  Normative References   [G.9959]   International Telecommunication Union, "Short range              narrow-band digital radiocommunication transceivers - PHY              and MAC layer specifications", ITU-T Recommendation              G.9959, January 2015,              <http://www.itu.int/rec/T-REC-G.9959>.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997,              <http://www.rfc-editor.org/info/rfc2119>.Brandt & Buron               Standards Track                   [Page 14]

RFC 7428                    IPv6 over G.9959               February 2015   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6              (IPv6) Specification",RFC 2460, December 1998,              <http://www.rfc-editor.org/info/rfc2460>.   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally              Unique IDentifier (UUID) URN Namespace",RFC 4122,              July 2005, <http://www.rfc-editor.org/info/rfc4122>.   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast              Addresses",RFC 4193, October 2005,              <http://www.rfc-editor.org/info/rfc4193>.   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing              Architecture",RFC 4291, February 2006,              <http://www.rfc-editor.org/info/rfc4291>.   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,              "Neighbor Discovery for IP version 6 (IPv6)",RFC 4861,              September 2007, <http://www.rfc-editor.org/info/rfc4861>.   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,              "Transmission of IPv6 Packets over IEEE 802.15.4              Networks",RFC 4944, September 2007,              <http://www.rfc-editor.org/info/rfc4944>.   [RFC6282]  Hui, J. and P. Thubert, "Compression Format for IPv6              Datagrams over IEEE 802.15.4-Based Networks",RFC 6282,              September 2011, <http://www.rfc-editor.org/info/rfc6282>.   [RFC6355]  Narten, T. and J. Johnson, "Definition of the UUID-Based              DHCPv6 Unique Identifier (DUID-UUID)",RFC 6355,              August 2011, <http://www.rfc-editor.org/info/rfc6355>.   [RFC6775]  Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann,              "Neighbor Discovery Optimization for IPv6 over Low-Power              Wireless Personal Area Networks (6LoWPANs)",RFC 6775,              November 2012, <http://www.rfc-editor.org/info/rfc6775>.   [RFC7400]  Bormann, C., "6LoWPAN-GHC: Generic Header Compression for              IPv6 over Low-Power Wireless Personal Area Networks              (6LoWPANs)",RFC 7400, November 2014,              <http://www.rfc-editor.org/info/rfc7400>.Brandt & Buron               Standards Track                   [Page 15]

RFC 7428                    IPv6 over G.9959               February 20158.2.  Informative References   [EUI64]    IEEE, "Guidelines for 64-bit Global Identifier              (EUI-64TM)", November 2012, <http://standards.ieee.org/regauth/oui/tutorials/EUI64.html>.   [KW03]     Karlof, C. and D. Wagner, "Secure Routing in Sensor              Networks: Attacks and Countermeasures", Elsevier Ad Hoc              Networks Journal, Special Issue on Sensor Network              Applications and Protocols, vol. 1, issues 2-3,              September 2003.   [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,              <http://www.rfc-editor.org/info/rfc3315>.   [RFC3587]  Hinden, R., Deering, S., and E. Nordmark, "IPv6 Global              Unicast Address Format",RFC 3587, August 2003,              <http://www.rfc-editor.org/info/rfc3587>.   [RFC3756]  Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor              Discovery (ND) Trust Models and Threats",RFC 3756,              May 2004, <http://www.rfc-editor.org/info/rfc3756>.   [RFC3819]  Karn, P., Bormann, C., Fairhurst, G., Grossman, D.,              Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L.              Wood, "Advice for Internet Subnetwork Designers",BCP 89,RFC 3819, July 2004,              <http://www.rfc-editor.org/info/rfc3819>.   [RFC6550]  Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R.,              Levis, P., Pister, K., Struik, R., Vasseur, JP., and R.              Alexander, "RPL: IPv6 Routing Protocol for Low-Power and              Lossy Networks",RFC 6550, March 2012,              <http://www.rfc-editor.org/info/rfc6550>.   [RFC6997]  Goyal, M., Baccelli, E., Philipp, M., Brandt, A., and J.              Martocci, "Reactive Discovery of Point-to-Point Routes in              Low-Power and Lossy Networks",RFC 6997, August 2013,              <http://www.rfc-editor.org/info/rfc6997>.Brandt & Buron               Standards Track                   [Page 16]

RFC 7428                    IPv6 over G.9959               February 2015Appendix A.  G.9959 6LoWPAN Datagram Example   This example outlines each individual bit of a sample IPv6 UDP packet   arriving to a G.9959 node from a host in the Internet via a PAN   border router.   In the G.9959 PAN, the complete frame has the following fields.   G.9959:     +------+---------+----------+---+-----+----------...     |HomeID|SrcNodeID|FrmControl|Len|SeqNo|DestNodeID|     +------+---------+----------+---+-----+----------+-...   6LoWPAN:     ...+--------------+----------------+-----------------------...        |6LoWPAN CmdCls|6LoWPAN_IPHC Hdr|Compressed IPv6 headers|       ...-------------+----------------+-----------------------+-...   IPv6, TCP/UDP, App payload:       ...+-------------------------+------------+-----------+          |Uncompressed IPv6 headers|TCP/UDP/ICMP|App payload|         ...------------------------+------------+-----------+   The frame comes from the source IPv6 address   2001:0db8:ac10:ef01::ff:fe00:1206.  The source prefix   2001:0db8:ac10:ef01/64 is identified by the IPHC CID = 3.   The frame is delivered in direct range from the gateway that has   source NodeID = 1.  The Interface Identifier (IID) ff:fe00:1206 is   recognized as a link-layer-derived address and is compressed to the   16-bit value 0x1206.   The frame is sent to the destination IPv6 address   2001:0db8:27ef:42ca::ff:fe00:0004.  The destination prefix   2001:0db8:27ef:42ca/64 is identified by the IPHC CID = 2.   The IID ff:fe00:0004 is recognized as a link-layer-derived address.   Thanks to the link-layer-derived addressing rules, the sender knows   that this is to be sent to G.9959 NodeID = 4, targeting the IPv6   interface instance number 0 (the default).   To reach the 6LoWPAN stack of the G.9959 node (skipping the G.9959   header fields), the first octet must be the 6LoWPAN Command Class   (0x4F).Brandt & Buron               Standards Track                   [Page 17]

RFC 7428                    IPv6 over G.9959               February 2015        0        0 1 2 3 4 5 6 7 8       +-+-+-+-+-+-+-+-...       |     0x4F      |       +-+-+-+-+-+-+-+-+-...   The Dispatch Header bits '011' advertise a compressed IPv6 header.        0                   1        0 1 2 3 4 5 6 7 8 9 0       +-+-+-+-+-+-+-+-+-+-+-...       |     0x4F      |0 1 1       +-+-+-+-+-+-+-+-+-+-+-+-...   The following bits encode the first IPv6 header fields:   TF = '11'   : Traffic Class and Flow Label are elided   NH = '1'    : Next Header is elided   HLIM = '10' : Hop limit is 64         0                   1         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...        |     0x4F      |0 1 1 1 1 1 1 0|        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...   CID = '1'   : CI data follows the DAM field   SAC = '1'   : Src addr uses stateful, context-based compression   SAM = '10'  : Use src CID and 16 bits for link-layer-derived addr   M = '0'     : Dest addr is not a multicast addr   DAC = '1'   : Dest addr uses stateful, context-based compression   DAM = '11'  : Use dest CID and dest NodeID to link-layer-derived addr        0                   1                   2        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...       |     0x4F      |0 1 1 1 1 1 1 0|1 1 1 0 0 1 1 1|       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...Brandt & Buron               Standards Track                   [Page 18]

RFC 7428                    IPv6 over G.9959               February 2015   Address compression context identifiers:   SCI =  0x3   DCI =  0x2          2           3          4 5 6 7 8 9 0 1      ...+-+-+-+-+-+-+-+-...         |  0x3  |  0x2  |        ...+-+-+-+-+-+-+-+-...   IPv6 header fields:   (skipping "version" field)   (skipping "Traffic Class")   (skipping "flow label")   (skipping "payload length")   IPv6 header address fields:   SrcIP = 0x1206 : Use SCI and 16 least significant bits of   link-layer-derived address   (skipping DestIP ) - completely reconstructed from dest NodeID                        and DCI          2           3                   4          4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7      ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...         |  0x3  |  0x2  |     0x12      |     0x06      |        ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...   Next Header encoding for the UDP header:   Dispatch = '11110': Next Header dispatch code for UDP header   C =      '0'      : 16-bit checksum carried inline   P =      '00'     : Both src port and dest port are carried in-line          4   5          8 9 0 1 2 3 4 5      ...+-+-+-+-+-+-+-+-...         |1 1 1 1 0|0|0 0|        ...+-+-+-+-+-+-+-+-...Brandt & Buron               Standards Track                   [Page 19]

RFC 7428                    IPv6 over G.9959               February 2015 UDP header fields: src port  = 0x1234 dest port = 0x5678     5       6                   7                   8     6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...    |     0x12      |     0x34      |     0x56      |     0x78      |   ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-.. (skipping "length") checksum = ....  (actual checksum value depends on                   the actual UDP payload)                                1        8   9                   0        8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3    ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...       |         (UDP checksum)        |      ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... Add your own UDP payload here...Brandt & Buron               Standards Track                   [Page 20]

RFC 7428                    IPv6 over G.9959               February 2015Acknowledgements   Thanks to the authors ofRFC 4944 andRFC 6282, and members of the   IETF 6LoWPAN working group; this document borrows extensively from   their work.  Thanks to Erez Ben-Tovim, Erik Nordmark, Kerry Lynn,   Michael Richardson, and Tommas Jess Christensen for useful comments.   Thanks to Carsten Bormann for extensive feedback that improved this   document significantly.  Thanks to Brian Haberman for pointing out   unclear details.Authors' Addresses   Anders Brandt   Sigma Designs   Emdrupvej 26A, 1.   Copenhagen O  2100   Denmark   EMail: anders_brandt@sigmadesigns.com   Jakob Buron   Sigma Designs   Emdrupvej 26A, 1.   Copenhagen O  2100   Denmark   EMail: jakob_buron@sigmadesigns.comBrandt & Buron               Standards Track                   [Page 21]

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