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Versions: 00 01

6Lo Working Group                                     L. Del Carpio Vega
Internet-Draft                                                 M. Robles
Intended status: Standards Track                             R. Morabito
Expires: April 21, 2016                                         Ericsson
                                                        October 19, 2015


                           IPv6 over 802.11ah
                     draft-delcarpio-6lo-wlanah-01

Abstract

   IEEE 802.11 is an established Wireless LAN (WLAN) technology which
   provides radio connectivity to a wide range of devices.  The IEEE
   802.11ah amendment defines a WLAN system operating at sub 1 GHz
   license-exempt bands designed to operate with low-rate/low-power
   consumption.  This amendment supports large number of stations and
   extends the radio coverage to several hundreds of meters.  This
   document describes how IPv6 is transported over 802.11ah using
   6LoWPAN techniques.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 21, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   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.  Terminology and Language Requirements . . . . . . . . . . . .   3
   3.  Overview of 802.11ah  . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Link Layer Topology of 802.11ah . . . . . . . . . . . . .   4
     3.2.  Device Addressing and Frame Structure . . . . . . . . . .   5
     3.3.  Protocol Version 0  . . . . . . . . . . . . . . . . . . .   6
     3.4.  Protocol Version 1  . . . . . . . . . . . . . . . . . . .   6
     3.5.  Link Layer Control  . . . . . . . . . . . . . . . . . . .   7
     3.6.  Ad Hoc Mode and Extended Service Set  . . . . . . . . . .   8
     3.7.  Relation with other 802.11 Versions . . . . . . . . . . .   9
   4.  Uses Cases  . . . . . . . . . . . . . . . . . . . . . . . . .   9
   5.  6LoWPAN over 802.11ah . . . . . . . . . . . . . . . . . . . .   9
   6.  Stateless Address Autoconfiguration . . . . . . . . . . . . .  11
   7.  Neighbour Discovery in 802.11ah . . . . . . . . . . . . . . .  12
   8.  Header Compression  . . . . . . . . . . . . . . . . . . . . .  12
   9.  Fragmentation . . . . . . . . . . . . . . . . . . . . . . . .  13
   10. Multicast at IP Level . . . . . . . . . . . . . . . . . . . .  13
   11. Internet Connection . . . . . . . . . . . . . . . . . . . . .  13
   12. Management of the Network . . . . . . . . . . . . . . . . . .  13
   13. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  14
   15. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   16. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     16.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     16.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   IEEE 802.11 [IEEE802.11], also known as Wi-Fi, is an established
   Wireless LAN (WLAN) technology operating in unlicensed Industrial,
   Scientific and Medical (ISM) bands.  Its IEEE 802.11ah [IEEE802.11ah]
   amendment is tailored for Internet of Things (IoT) use-cases and at
   the moment of writing this draft it is in the final stages of IEEE
   standardization.

   IEEE 802.11ah operates in the Sub-1 GHz spectrum which helps reducing
   the power consumption.  It also supports a larger number of stations
   on a single Basic Service Set (BSS) and it provides power-saving
   mechanisms that allow radio stations to sleep in order to save power.




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   However, the system achieves lower throughput compared to 802.11n/ac
   amendments.

   IEEE 802.11 specifies only the MAC and PHY layers of the radio
   technology.  In other words, 802.11 does not specify a networking
   layer but it is compatible with commonly used internet protocol such
   as IPv4 and IPv6.  As 802.11ah is a low-rate/low-power technology,
   the communication protocols used above MAC should also take power-
   efficiency into consideration.  This motivates the introduction of
   6LoWPAN techniques [RFC4944] [RFC6282] for efficient transport of
   IPv6 packets over IEEE 802.11ah radio networks.

   This document specifies how to use 6LoWPAN techniques for 802.11ah.

2.  Terminology and Language Requirements

   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].

   Terminology from 802.11ah:

   Station (STA): defined in 802.11-2012 [IEEE802.11-2012] as a wireless
   station which is an addressable unit.

   Sensor-STA: defined in 802.11ah as a device having low-power
   consumption requirements.  This device might be a battery operated
   device.

   Non-sensor STA: defined in 802.11ah as device which usually does not
   have low-power consumption requirements.

   In this document, any type STA (sensor STA/non-sensor STA) is
   associated with a 6LoWPAN Node(6LN).

   Access Point (AP): entity maintaining the WLAN Basic Service Set
   (BSS) and it is associated with the 6LoWPAN Border Router (6LBR).  It
   is assumed that APs are connected to the power-line.

   The terms 6LoWPAN Router (6LR) and 6LoWPAN Border Router (6LBR) are
   defined as in [RFC6775] and in this context 6LoWPAN Nodes (6LN) do
   not refer to a router (Access Point), just to a host (STA).

3.  Overview of 802.11ah

   The IEEE 802.11 technology uses the unlicensed spectrum in different
   ISM bands, using CSMA/CA techniques.  Specifically 802.11ah is
   designed to operate in ISM band below Sub-1 Ghz with a basic



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   bandwidth of 1Mhz/2Mhz (depending of configuration).  The system is
   formed by an Access Point (AP) which maintains a Basic Service Set
   (BSS) and stations (STAs).  STAs are connected to the AP in a star
   topology.

   The 802.11ah is more energy efficient compared to other conventional
   802.11 technologies because of it uses mechanisms which allow STAs to
   doze periodically and STAs request downlink data when switching to
   active mode i.e.  Traffic Indication Map (TIM) operation, non-TIM
   operation, Target Wakeup Time (TWT)

   An exemplary deployment of a 802.11ah BSS may include a large number
   of STAs associated to a BSS where STAs are sleeping (dozing) most of
   the time and they may monitor periodic beacon-frame transmissions
   containing Traffic Indication Maps (TIM).  Data packets intended to
   STAs cannot be delivered when STAs sleep, thus the TIM indicates
   which STAs have downlink data buffered at the AP.  After reading the
   TIM, STAs request their buffered data by transmitting a Power-Saving
   Poll (PS-Poll) frame to the AP.  After the downlink data is
   delivered, STAs enter into sleep mode again.  For uplink data
   delivery, STAs might transmit as soon as their data is available.

   There might be STAs that do not monitor constantly the TIM and
   request downlink data sporadically after waking up.

3.1.  Link Layer Topology of 802.11ah

   The 802.11ah defines a star topology at L2 link connectivity, where
   the STAs are connected to the AP and any communication between STAs
   passes through the AP.  It also includes L2 relays to extend the
   range of the system.  As in other 802.11 amendments, the ad-hoc
   topology is also suported.  Finally, the 802.11 standard does not
   define its own networking layer but is compatible with commonly used
   protocols e.g.  IPv4, IPv6 via the Link Layer Control.

















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                      +---+
                      |STA|
                      +-+-+
         +---+          |
         |STA+------+   |
         +---+      |   |
                    +---+---+    +---+
                    |   AP  +----+STA|
                    ++-----++    +---+
          +----+     |      |
          |STA +-----+      |
          +----+          +-+--+
                          |STA |
                          +----+


                    Figure 1: Star Link Layer Topology

   It is important to note that the communication link is unidirectional
   at any given point in time and that the medium is shared by CSMA/CA
   techniques which avoid that two or more STAs utilize the medium
   simultaneously.

3.2.  Device Addressing and Frame Structure

   The 802.11 physical transmission is composed by a preamble which is
   used to prepare a receiver for frame decoding, basic physical layer
   information, and the physical layer payload which encapsulates the
   MAC Protocol Data Unit (MPDU).

   There can be different classes of MAC frames in 802.11, the MAC data
   frame is the only one carrying higher layer data.  Other frames are
   control and management frames which are used to maintain MAC layer
   functions.  In general in 802.11 MAC addresses use the EUI-48 bit
   address space.

   A MAC data frame in 802.11 is composed by a MAC header, a MAC payload
   and a Frame Check Sequence (FCS) which are encoded in an MPDU.  The
   MAC payload carries Link Layer Control PDUs which encapsulates, for
   example, IP packets.  There are two protocol versions for MAC frame
   formats, the Protocol Version 0 (PV0) which is the default format of
   802.11 and it is inherited to 802.11ah and the Protocol Version 1
   (PV1) which has less overhead that PV0 and can be optionally
   supported by 802.11ah non-sensor STA and it is mandatory supported
   for 802.11ah sensor STA.

   In 802.11ah, the maximum size of the MSDU (MAC payload) is given by
   the maximum size of a A-MSDU which is constrained by the maximum size



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   of the A-MPDU of 7991 bytes.  This maximum of the A-MPDU is
   independent of Protocol Version.

   In addition, segmentation at 802.11 MAC layer level is supported if
   required.

3.3.  Protocol Version 0

   The elements of the MAC data frame with PV0 are defined in
   802.11-2012, Section 8.2 [IEEE802.11-2012]  and are depicted in the
   picture below.


   +-------+--------+----+----+----+------+----+-----+----+-------+---+
   + Frame +Duration+ A1 + A2 + A3 + Seq. + A4 + QoS + HT + Frame +FCS+
   +Control+   /ID  +    +    +    + Ctrl +    + Crl +Crl + Body  +   +
   +-------+--------+----+----+----+------+----+-----+----+-------+---+
        2      2      6     6   6    2     6/0    2     4    0-7951  4


                          Figure 2: MAC frame PV0

   Frame Control: contains information relevant in link layer such as
   the Protocol Version, frame type and subtype, Power Management,
   Fragmentation Information, among others.

   A1, A2, A3: indicate the recipient, the transmitter and the BSSID
   which in infraestructure mode is the value of the STA contained in
   the AP (AP MAC address in practice).  They follow 48-bits MAC address
   format.

   A4, Sequence control, QoS control, HT control: The meaning of these
   field are out of scope of this draft.  Please refer to 802.11-2012,
   Section 8.2.4 [IEEE802.11-2012] for further information.

   Frame Body: is of variable-length field and contains the MAC payload
   for example L3 packets.

   FCS: The Frame Check Sequence field is a 32-bit field containing a
   32-bit CRC which is calculated over all the fields of the MAC header
   and the Frame Body field

3.4.  Protocol Version 1

   The MAC header for the PV1 format is at least formed by a Frame
   Control field and the address fields.  Other fields are optional.
   Please refer to 802.11-2012, Section 8.8.1 [IEEE802.11ah] for further
   information.



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       +---------------+-------+--------+---------------------+
       + Frame Control +   A1  +   A2   + Frame Body +  FCS   +
       +---------------+-------+--------+---------------------+
        Bytes:  2         6/2     2/6      0-7951         4


                    Figure 3: MAC frame PV1 of 802.11ah

   Frame control: see above.

   A1, A2: indicates the recipient and the transmitter respectively of
   the frame and it contains the 6-bytes MAC address or the Short ID
   (2-bytes) provided by the AP after association in a given BSS.  Short
   ID includes the Association Identifier (AID) field which is used in
   TIM and power-saving mode.

   Frame Body: The minimum length for non-data frames is 0 bytes.  The
   maximum length of A-MSDU is constrained by the maximum size of the
   A-MPDU of 7991 bytes.

3.5.  Link Layer Control

   The Logical Link Control (LLC) layers works as the interface between
   higher layers, for example IP, and the 802.11 MAC.  It supports
   higher layer protocol discrimination via the EtherType value
   utilizing the LLC SNAP or RFC1042.


           +----------------------------------------------------+
           | DSAP | SSAP | CTL    | OUI      | Ethertype  | SDU |
           | 0xAA | 0xAA | 0x03=UI| 00+00+00 |            |     |
           +----------------------------------------------------+

          Figure 4: Format of LPD compatible with current 802.11
                              recommendations

   Examples of EtherTypes are 0x0800 and 0x8DD, which are used to
   identify IPv4 and IPv6, respectively.













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                           +-----------------------+
                           |     Upper Layer       |
                           +-----------------------+
                           |        802 LLC        |
                           +-----------------------+
                           | MAC Layer (802.11ah)  |
                           +-----------------------+
                           | PHY Layer (802.11ah)  |
                           +-----------------------+

                       Figure 5: WLAN Protocol Stack

3.6.  Ad Hoc Mode and Extended Service Set

   The standard allows to connect devices through ad-hoc mechanisms.  In
   this mode the devices are connected using implementation specific
   protocols e.g. between two STAs or between two APs and the power-
   saving mechanism of 802.11ah cannot be used (as AP-STA hierarchy is
   required).  The following figure describes STAs connected to AP
   through 802.11ah and connections between APs are not based on
   802.11ah, but are implementation specific.

   +---+     +---+           +----+      +-----+
   |STA+-----+AP +-----------+AP  +------+STA  |
   +---+     +--++           +--+-+      +-----+
                |               |
                |               |
                |           +---+-+      +-----+
                +-----------+AP   +------+STA  |
                            +-----+      +-----+

                        Figure 6: WLAN Ad Hoc Mode

   In an Extented Service Set(ESS), the connections between Base Service
   Station (BSS) happen through a distribution system.  The distribution
   system (DS) maybe realised by a different technology or it can be
   composed by AP connections.

   +------------------+                         +------------------+
   | +---+     +---+  |                         | +----+    +----+ |
   | |STA+-----+AP +------------ DS -----------+AP  +----+STA | |
   | +---+     +---+  |                         | +----+    +----+ |
   +----------+-------+                         +------------------+
         BSS  |                                         | BSS
              +--------------->  ESS  <-----------------+


                       Figure 7: WLAN Protocol Stack



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3.7.  Relation with other 802.11 Versions

   In principle, the 6Lo stack might be used for other 802.11 versions
   such as 802.11b, 802.11n and 802.11ac, due to these standards support
   LLC compatibility.  LLC 6lo indentifier would be the same for all
   mentioned WiFi versions.

4.  Uses Cases

   [RFC7548] defines use cases for the management of constrained
   networks: Environmental Monitoring, Infrastructure Monitoring,
   Industrial Applications, Energy Management, Medical Applications,
   Building Automation, Home Automation, Transport Applications,
   Community Network Applications and Field Operations.  These uses
   cases are apply as well to 802.11ah.

   As a starting point in 802.11ah specification work, the Task Group AH
   proposed the following use-case categories
   [ReferenceUseCase802.11ah]:

   - Sensor and Meters, where large number of sensor deliver data
   through 802.11ah connectivity

   - Backhaul Sensor and meter data, where 802.11ah STA can be either
   directly integrated with a sensor or it will aggregate data from
   other tree of wireless sensors and then deliver 802.11ah connectivity

   - Extended Range Wi-Fi, where the typical range of the Wi-Fi
   connection will extended due to the use of lower frequencies and
   other techniques.

5.  6LoWPAN over 802.11ah

   IPv4 and IPv6 are compatible with 802.11ah via the LLC.  However,
   802.11ah technology presents a trade-off between energy consumption
   and link bitrate.  Consequently, 6LoWPAN techniques are beneficial to
   reduce the overhead of transmissions, save energy and improve
   throughput.  With 6LoWPAN, the nodes, i.e. 6LN, 6LBR, are co-located
   on the same devices with 802.11 features.  The typical 802.11ah
   network uses a star topology where the 6LBR functionally is co-
   located with the AP.  6LNs are co-located with STAs and are connected
   to the 6LBR through 802.11ah links.  As mesh topology at MAC level is
   not defined by the 802.11ah standard, 6LBR is the only router present
   in the network.  Thus, there is no presence of 6LR.







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              +---------+
              |+-------+|                      +---------+
              ||  6LN  ||  802.11ah            |+-------+|
              |+-------+|                      ||  6LN  ||
              |+-------++------------+---------|+-------+|
              ||  STA  ||            |         |+-------+|
              |+-------+|            |         ||  STA  ||
              +---------+            |         |+-------+|
                6LN-STA              |         +---------+
                               +-----+-----+
                               |+----+----+|
                               ||  6LBR   ||
                               |+---------+|
                 +---------+   |           |    +---------+
                 |+-------+|   |+---------++    ++-------+|
                 ||  6LN  ||   ||   AP    ||    ||  6LN  ||
                 |+-------+|   |+---------+|    |+-------+|
                 |+-------++---+----+------+    |         |
                 ||  STA  ||        |  6LBR-AP  |+-------+|
                 |+-------+|        |           ||  STA  ||
                 +--------+|        |           |+-------+|
                 +---------+        +-----------+---------+

                        Figure 8: Network Topology

   There exists the possibility to have a 802.11ah relay node at L2 to
   extend the range of an AP.  This however is an L2 feature and it is
   experienced as a single hop by the 6LoWPAN network.  In case there is
   need to connect wirelessly several APs and ad hoc solution needs to
   be considered.

   Devices in this kind of networks, not necessarily have constrained
   resources (memory, CPU, etc), but the radio link capacity is limited.
   It might be that APs are connected to mains power and STAs might be
   for example battery operated sensors.  Therefore 6LoWPAN techniques
   might be good to support transmission of IPv6 packets over 802.11ah
   battery operated devices.  Related to performance gain, a reduction
   in air-time is achieved if the stack is compressed.  The
   communication 6LN-6LN is not supported directly using link-local
   addresses, it is done through the 6LBR using the shared prefix used
   on the subnet.  This specification requires IPv6 header compression
   format specified in [RFC6282].

   The Figure below shows the stack for PHY/MAC and IPv6 including
   6LoWPAN






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            +---------------------+
            |    Upper Layers     |
            +---------------------+
            |       IPv6          |
            +---------------------+
            |      6LoWPAN        |
            +---------------------+
            |      802 LLC        |
            +---------------------+
            | MAC Layer(802.11ah) |
            +---------------------+
            | PHY Layer(802.11ah) |
            +---------------------+

                   Figure 9: Protocol Stack with 6LoWPAN

6.  Stateless Address Autoconfiguration

   The IPv6 link local address follows Section 5.3 of [RFC4862] based on
   the 48-bit MAC device address.

   To get the 64-bit Interface Identifier (IID) RFC 7136 [RFC7136] MUST
   be followed.  Section 5 of this RFC states:

   "For all unicast addresses, except those that start with the binary
   value 000, Interface IDs are required to be 64 bits long.  If derived
   from an IEEE MAC-layer address, they must be constructed in Modified
   EUI-64 format."

                   10 bits        54 bits             64 bits
              +----------+-----------------+----------------------+
              |1111111010|       0         | Interface Identifier |
              +----------+-----------------+----------------------+

                    Figure 10: IPv6 link local address

   Following Appendix-A of RFC 4291 [RFC4291] the IID is formed
   inserting two octets, with hexadecimal values of 0xFF and 0xFE in the
   middle of the 48-bit MAC.  The IID would be as follow where "a" is a
   bit of the 48 MAC address.

   |0              1|1              3|3              4|4              6|
   |0              5|6              1|2              7|8              3|
   +----------------+----------------+----------------+----------------+
   |aaaaaaaaaaaaaaaa|aaaaaaaa11111111|11111110aaaaaaaa|aaaaaaaaaaaaaaaa|
   +----------------+----------------+----------------+----------------+

                     Figure 11: Modified EUI-64 format



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   For non-link-local addresses a 64-bit IID MAY be formed by utilizing
   the 48-bit MAC device address.  Random IID can be generated for 6LN
   using alternative methods such as [I-D.ietf-6man-default-iids].

7.  Neighbour Discovery in 802.11ah

   Neighbour Discovery approach for 6LoWPAN [RFC6775] is applicable to
   802.11ah topologies.  Related to Host-initiated process, use of
   Address Registration Option (ARO), through the Neighbour Solicitation
   (NS) and Neighbour Advertisement (NA).  Router Solicitation and
   Router Advertisement are applicable as well following [RFC6775].

   As the topology is star, Multihop Distribution of prefix and 6LoWPAN
   header compression; and Multihop Duplicated Address Detection (DAD)
   mechanism are not applicable, since this technology does not cover
   multihop topology.

8.  Header Compression

   For header compression, the rules proposed in [RFC6282] are
   applicable.  Section 3.1.1 mentions the base Encoding principle
   applicable to 802.11ah.

   0                                       1
   0   1   2   3   4   5   6   7   8   9   0   1   2   3   4   5
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
   | 0 | 1 | 1 |  TF   |NH | HLIM  |CID|SAC|  SAM  | M |DAC|  DAM  |
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

                   Figure 12: LOWPAN_IPHC base Encoding

   TF: Traffic Class; Flow Label; For 802.11ah case would apply this
   field as defined in [RFC6282].

   NH: Next Header; as defined in [RFC6282].

   HLIM: Hop Limit; as star topology the common value would be HLIM=1.

   CID: Context Identifier Extension; as defined in [RFC6282].

   SAC: Source Address Compression; as defined in [RFC6282].

   SAM: Source Address Mode; In this case, the combinations for 16-bits
   are not applicable to this technology since 802.11 uses 48-bits for
   addresses.

   M: Multicast Compression; as defined in [RFC6282].




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   DAC: Destination Address Compression; as defined in [RFC6282].

   DAM: Destination Address Mode.  In this case, the combinations for
   16-bits are not applicable to this technology since 802.11 uses
   48-bits for addresses.

9.  Fragmentation

   802.11ah perform fragmentation at L2, thus the fragmentation at L3
   would be not necessary.

10.  Multicast at IP Level

   802.11ah supports broadcast and multicast at link layer level, both
   can be used to carry multicast IP transmission depending on the
   system's configuration.  TBD: add an example.

11.  Internet Connection

   For Internet connection, the 6LBR acts as router and forwarding
   packets between 6LNs to and from Internet.

          +-----+
          | 6LN +--------+
          +-----+        |
                         |         +-----------+
                    +----+----+    |           |
                    |         |    |  Internet |
             +------+  6LBR   +----+           |
          +--+--+   |         |    |           |
          | 6LN |   +----+----+    +-----------+
          +-----+        |
                      +--+--+
                      | 6LN |
                      +-----+

               Figure 13: Internet connection of 6Lo network

12.  Management of the Network

   TBD: how LightWeight Machine to Machine (LWM2M) or CoAP Management
   Interface (COMI) [I-D.vanderstok-core-comi] aspects can be applied to
   this technology, considering [RFC7547]








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13.  IANA Considerations

   There are no IANA considerations related to this document.

14.  Security Considerations

   The security considerations defined in [RFC4944] and its update
   [RFC6282] can be assumed valid for the 802.11ah case as well.
   Indeed, the transmission of IPv6 over 802.11ah links meets all the
   requirements for security as for IEEE 802.15.4.  The standard IEEE
   802.11ah defines all those aspects related with Link Layer security.
   As well as for other existing WiFi solutions, 802.11ah Link Layer
   supports security mechanism such as WPA, WPS, 802.1X.  To have a
   deeper understanding on how the Key Management processes are handled
   in 802.11ah, please refer to [TBD]

   Implementations defined in [I-D.ietf-6man-default-iids], [RFC3972],
   [RFC4941], or [RFC5535], can be considered, for example, as methods
   to support non-link local addresses.

   For what concerns privacy issues, the draft
   [I-D.thaler-6lo-privacy-considerations] introduces a series of
   recommendations which can be applied in order to overcome possible
   privacy threats in the particular case of technologies designed for
   IPv6 over networks of resource-constrained nodes.

15.  Acknowledgements

   This work is partially funded by the FP7 Marie Curie Initial Training
   Network (ITN) METRICS project (grant agreement No. 607728).

   The authors are thankful to the members of IEEE Task Group AH for
   their valuable comments.

16.  References

16.1.  Normative References

   [IEEE802.11ah]
              Institute of Electrical and Electronics Engineers (IEEE),
              "Wireless LAN Medium Access Control (MAC) and Physical
              Layer (PHY) Specifications: Amendment- Sub 1 GHz License-
              Exempt Operation", January 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.



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   [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>.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,
              <http://www.rfc-editor.org/info/rfc4862>.

   [RFC6282]  Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
              Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
              DOI 10.17487/RFC6282, September 2011,
              <http://www.rfc-editor.org/info/rfc6282>.

   [RFC6775]  Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
              Bormann, "Neighbor Discovery Optimization for IPv6 over
              Low-Power Wireless Personal Area Networks (6LoWPANs)",
              RFC 6775, DOI 10.17487/RFC6775, November 2012,
              <http://www.rfc-editor.org/info/rfc6775>.

   [RFC7136]  Carpenter, B. and S. Jiang, "Significance of IPv6
              Interface Identifiers", RFC 7136, DOI 10.17487/RFC7136,
              February 2014, <http://www.rfc-editor.org/info/rfc7136>.

16.2.  Informative References

   [I-D.ietf-6lo-btle]
              Nieminen, J., Savolainen, T., Isomaki, M., Patil, B.,
              Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low
              Energy", draft-ietf-6lo-btle-17 (work in progress), August
              2015.

   [I-D.ietf-6man-default-iids]
              Gont, F., Cooper, A., Thaler, D., and S. LIU,
              "Recommendation on Stable IPv6 Interface Identifiers",
              draft-ietf-6man-default-iids-08 (work in progress),
              October 2015.

   [I-D.thaler-6lo-privacy-considerations]
              Thaler, D., "Privacy Considerations for IPv6 over Networks
              of Resource-Constrained Nodes", draft-thaler-6lo-privacy-
              considerations-01 (work in progress), October 2015.

   [I-D.vanderstok-core-comi]
              Stok, P., Bierman, A., Schoenwaelder, J., and A. Sehgal,
              "CoAP Management Interface", draft-vanderstok-core-comi-08
              (work in progress), October 2015.




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   [IEEE802-2014]
              Institute of Electrical and Electronics Engineers (IEEE),
              "IEEE Standard for Local and Metropolitan Area Networks:
              Overview and Architecture", 2014.

   [IEEE802.11]
              Institute of Electrical and Electronics Engineers (IEEE),
              "Wireless LAN", 2011.

   [IEEE802.11-2012]
              Institute of Electrical and Electronics Engineers (IEEE),
              "Wireless LAN Medium Access Control (MAC) and Physical
              Layer (PHY) Specifications", 2012.

   [ReferenceUseCase802.11ah]
              Institute of Electrical and Electronics Engineers (IEEE),
              "Potential compromise of 80211ah use case", 2012.

   [RFC3972]  Aura, T., "Cryptographically Generated Addresses (CGA)",
              RFC 3972, DOI 10.17487/RFC3972, March 2005,
              <http://www.rfc-editor.org/info/rfc3972>.

   [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>.

   [RFC4941]  Narten, T., Draves, R., and S. Krishnan, "Privacy
              Extensions for Stateless Address Autoconfiguration in
              IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
              <http://www.rfc-editor.org/info/rfc4941>.

   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
              "Transmission of IPv6 Packets over IEEE 802.15.4
              Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
              <http://www.rfc-editor.org/info/rfc4944>.

   [RFC5535]  Bagnulo, M., "Hash-Based Addresses (HBA)", RFC 5535,
              DOI 10.17487/RFC5535, June 2009,
              <http://www.rfc-editor.org/info/rfc5535>.

   [RFC7547]  Ersue, M., Ed., Romascanu, D., Schoenwaelder, J., and U.
              Herberg, "Management of Networks with Constrained Devices:
              Problem Statement and Requirements", RFC 7547,
              DOI 10.17487/RFC7547, May 2015,
              <http://www.rfc-editor.org/info/rfc7547>.






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   [RFC7548]  Ersue, M., Ed., Romascanu, D., Schoenwaelder, J., and A.
              Sehgal, "Management of Networks with Constrained Devices:
              Use Cases", RFC 7548, DOI 10.17487/RFC7548, May 2015,
              <http://www.rfc-editor.org/info/rfc7548>.

Authors' Addresses

   Luis Felipe Del Carpio Vega
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: felipe.del.carpio@ericsson.com


   Maria Ines Robles
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: maria.ines.robles@ericsson.com


   Roberto Morabito
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: roberto.morabito@ericsson.com



















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