[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-robles-roll-useofrplinfo) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

ROLL Working Group                                             M. Robles
Internet-Draft                                                     Aalto
Updates: 6553, 6550, 8138 (if approved)                    M. Richardson
Intended status: Standards Track                                     SSW
Expires: July 27, 2019                                        P. Thubert
                                                                   Cisco
                                                        January 23, 2019


 Using RPL Option Type, Routing Header for Source Routes  and IPv6-in-
                IPv6 encapsulation in the RPL Data Plane
                    draft-ietf-roll-useofrplinfo-24

Abstract

   This document looks at different data flows through LLN (Low-Power
   and Lossy Networks) where RPL (IPv6 Routing Protocol for Low-Power
   and Lossy Networks) is used to establish routing.  The document
   enumerates the cases where RFC 6553 (RPL Option Type), RFC 6554
   (Routing Header for Source Routes) and IPv6-in-IPv6 encapsulation is
   required in data plane.  This analysis provides the basis on which to
   design efficient compression of these headers.  This document updates
   RFC 6553 adding a change to the RPL Option Type.  Additionally, this
   document updates RFC 6550 to indicate about this change and updates
   RFC8138 as well to consider the new Option Type when RPL Option is
   decompressed.

Status of This Memo

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

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

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

   This Internet-Draft will expire on July 27, 2019.








Robles, et al.            Expires July 27, 2019                 [Page 1]


Internet-Draft               RPL-data-plane                 January 2019


Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   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  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Terminology and Requirements Language . . . . . . . . . . . .   5
   3.  Updates to RFC6553, RFC6550 and RFC 8138  . . . . . . . . . .   5
     3.1.  Updates to RFC 6553 . . . . . . . . . . . . . . . . . . .   5
     3.2.  Updates to RFC 8138 . . . . . . . . . . . . . . . . . . .   8
     3.3.  Updates to RFC 6550: Indicating the new RPI in the
           DODAG Configuration Option Flag.  . . . . . . . . . . . .   9
   4.  Sample/reference topology . . . . . . . . . . . . . . . . . .  10
   5.  Use cases . . . . . . . . . . . . . . . . . . . . . . . . . .  12
   6.  Storing mode  . . . . . . . . . . . . . . . . . . . . . . . .  15
     6.1.  Storing Mode: Interaction between Leaf and Root . . . . .  16
       6.1.1.  SM: Example of Flow from RPL-aware-leaf to root . . .  17
       6.1.2.  SM: Example of Flow from root to RPL-aware-leaf . . .  18
       6.1.3.  SM: Example of Flow from root to not-RPL-aware-leaf .  18
       6.1.4.  SM: Example of Flow from not-RPL-aware-leaf to root .  19
     6.2.  Storing Mode: Interaction between Leaf and Internet.  . .  20
       6.2.1.  SM: Example of Flow from RPL-aware-leaf to Internet .  20
       6.2.2.  SM: Example of Flow from Internet to RPL-aware-leaf .  21
       6.2.3.  SM: Example of Flow from not-RPL-aware-leaf to
               Internet  . . . . . . . . . . . . . . . . . . . . . .  22
       6.2.4.  SM: Example of Flow from Internet to non-RPL-aware-
               leaf. . . . . . . . . . . . . . . . . . . . . . . . .  23
     6.3.  Storing Mode: Interaction between Leaf and Leaf . . . . .  24
       6.3.1.  SM: Example of Flow from RPL-aware-leaf to RPL-aware-
               leaf  . . . . . . . . . . . . . . . . . . . . . . . .  25
       6.3.2.  SM: Example of Flow from RPL-aware-leaf to non-RPL-
               aware-leaf  . . . . . . . . . . . . . . . . . . . . .  26
       6.3.3.  SM: Example of Flow from not-RPL-aware-leaf to RPL-
               aware-leaf  . . . . . . . . . . . . . . . . . . . . .  27
       6.3.4.  SM: Example of Flow from not-RPL-aware-leaf to not-



Robles, et al.            Expires July 27, 2019                 [Page 2]


Internet-Draft               RPL-data-plane                 January 2019


               RPL-aware-leaf  . . . . . . . . . . . . . . . . . . .  28
   7.  Non Storing mode  . . . . . . . . . . . . . . . . . . . . . .  29
     7.1.  Non-Storing Mode: Interaction between Leaf and Root . . .  31
       7.1.1.  Non-SM: Example of Flow from RPL-aware-leaf to root .  32
       7.1.2.  Non-SM: Example of Flow from root to RPL-aware-leaf .  32
       7.1.3.  Non-SM: Example of Flow from root to not-RPL-aware-
               leaf  . . . . . . . . . . . . . . . . . . . . . . . .  33
       7.1.4.  Non-SM: Example of Flow from not-RPL-aware-leaf to
               root  . . . . . . . . . . . . . . . . . . . . . . . .  34
     7.2.  Non-Storing Mode: Interaction between Leaf and Internet .  35
       7.2.1.  Non-SM: Example of Flow from RPL-aware-leaf to
               Internet  . . . . . . . . . . . . . . . . . . . . . .  35
       7.2.2.  Non-SM: Example of Flow from Internet to RPL-aware-
               leaf  . . . . . . . . . . . . . . . . . . . . . . . .  36
       7.2.3.  Non-SM: Example of Flow from not-RPL-aware-leaf to
               Internet  . . . . . . . . . . . . . . . . . . . . . .  37
       7.2.4.  Non-SM: Example of Flow from Internet to not-RPL-
               aware-leaf  . . . . . . . . . . . . . . . . . . . . .  38
     7.3.  Non-Storing Mode: Interaction between Leafs . . . . . . .  39
       7.3.1.  Non-SM: Example of Flow from RPL-aware-leaf to RPL-
               aware-leaf  . . . . . . . . . . . . . . . . . . . . .  39
       7.3.2.  Non-SM: Example of Flow from RPL-aware-leaf to not-
               RPL-aware-leaf  . . . . . . . . . . . . . . . . . . .  41
       7.3.3.  Non-SM: Example of Flow from not-RPL-aware-leaf to
               RPL-aware-leaf  . . . . . . . . . . . . . . . . . . .  42
       7.3.4.  Non-SM: Example of Flow from not-RPL-aware-leaf to
               not-RPL-aware-leaf  . . . . . . . . . . . . . . . . .  43
   8.  Operational Considerations of supporting
       not-RPL-aware-leaves  . . . . . . . . . . . . . . . . . . . .  43
   9.  Operational considerations of introducing 0x23  . . . . . . .  44
     9.1.  Has deployment been discussed?  . . . . . . . . . . . . .  45
     9.2.  Has installation and initial setup been discussed?? . . .  45
     9.3.  Has the migration path been discussed?  . . . . . . . . .  45
     9.4.  Have the Requirements on other protocols and
           functional components been discussed? . . . . . . . . . .  45
     9.5.  Has the impact on network operation been discussed? . . .  45
     9.6.  Have suggestions for verifying correct operation been
           discussed?  . . . . . . . . . . . . . . . . . . . . . . .  45
     9.7.  Has management interoperability been discussed? . . . . .  45
     9.8.  Are there fault or threshold conditions that should be
           reported? . . . . . . . . . . . . . . . . . . . . . . . .  46
     9.9.  Is configuration discussed? . . . . . . . . . . . . . . .  46
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  46
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  46
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  49
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  49
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  49
     13.2.  Informative References . . . . . . . . . . . . . . . . .  50



Robles, et al.            Expires July 27, 2019                 [Page 3]


Internet-Draft               RPL-data-plane                 January 2019


   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  52

1.  Introduction

   RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks)
   [RFC6550] is a routing protocol for constrained networks.  RFC 6553
   [RFC6553] defines the "RPL option" (RPI), carried within the IPv6
   Hop-by-Hop header to quickly identify inconsistencies (loops) in the
   routing topology.  RFC 6554 [RFC6554] defines the "RPL Source Route
   Header" (RH3), an IPv6 Extension Header to deliver datagrams within a
   RPL routing domain, particularly in non-storing mode.

   These various items are referred to as RPL artifacts, and they are
   seen on all of the data-plane traffic that occurs in RPL routed
   networks; they do not in general appear on the RPL control plane
   traffic at all which is mostly hop-by-hop traffic (one exception
   being DAO messages in non-storing mode).

   It has become clear from attempts to do multi-vendor
   interoperability, and from a desire to compress as many of the above
   artifacts as possible that not all implementors agree when artifacts
   are necessary, or when they can be safely omitted, or removed.

   An interim meeting went through the 24 cases defined here to discover
   if there were any shortcuts, and this document is the result of that
   discussion.  This document clarifies examples that intend to
   illustrate the result of the normative language in RFC8200 and
   RFC6553.  In other words, the examples are intended to be normative
   explanation of the results of executing that language.

   A Routing Header Dispatch for 6LoWPAN (6LoRH)([RFC8138]) defines a
   mechanism for compressing RPL Option information and Routing Header
   type 3 [RFC6554], as well as an efficient IPv6-in-IPv6 technique.

1.1.  Overview

   The rest of the document is organized as follows: Section 2 describes
   the used terminology.  Section 3 describes the updates to RFC6553,
   RFC6550 and RFC 8138.  Section 4 provides the reference topology used
   for the uses cases.  Section 5 describes the uses cases included.
   Section 6 describes the storing mode cases and section 7 the non-
   storing mode cases.  Section 8 describes the operational
   considerations for the proposed change on RPL Option type.  Section 9
   depicts the 6LoRH Compression cases, section 10 the IANA
   considerations and then section 11 describes the security aspects.






Robles, et al.            Expires July 27, 2019                 [Page 4]


Internet-Draft               RPL-data-plane                 January 2019


2.  Terminology and Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119], [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   Terminology defined in [RFC7102] applies to this document: LBR, LLN,
   RPL, RPL Domain and ROLL.

   RPL-node: A device which implements RPL, thus the device is RPL-
   aware.  Please note that the device can be found inside the LLN or
   outside LLN.  In this document a RPL-node which is a leaf of a
   (Destination Oriented Directed Acyclic Graph) DODAG is called RPL-
   aware-leaf (Raf).

   RPL-not-capable: A device which does not implement RPL, thus the
   device is not-RPL-aware.  Please note that the device can be found
   inside the LLN.  In this document a not-RPL-aware node which is a
   leaf of a DODAG is called not-RPL-aware-leaf (~Raf).

   6LN: [RFC6775] defines it as: "A 6LoWPAN node is any host or router
   participating in a LoWPAN.  This term is used when referring to
   situations in which either a host or router can play the role
   described.".  In this document, a 6LN acts as a leaf.

   6LR, 6LBR are defined in [RFC6775].

   Flag Day: A transition that involves have a network with different
   values of RPL Option Type.  Thus the network do not work correctly.

   Hop-by-hop IPv6-in-IPv6 headers: The term "hop-by-hop IPv6-in-IPv6"
   header refers to: adding a header that originates from a node to an
   adjacent node, using the addresses (usually the GUA or ULA, but could
   use the link-local addresses) of each node.  If the packet must
   traverse multiple hops, then it must be decapsulated at each hop, and
   then re-encapsulated again in a similar fashion.

3.  Updates to RFC6553, RFC6550 and RFC 8138

3.1.  Updates to RFC 6553

   This modification is required to be able to send, for example, IPv6
   packets from a RPL-aware-leaf to a not-RPL-aware node through
   Internet (see Section 6.2.1), without requiring IPv6-in-IPv6
   encapsulation.




Robles, et al.            Expires July 27, 2019                 [Page 5]


Internet-Draft               RPL-data-plane                 January 2019


   [RFC6553] states as shown below, that in the Option Type field of the
   RPL Option header, the two high order bits must be set to '01' and
   the third bit is equal to '1'.  The first two bits indicate that the
   IPv6 node must discard the packet if it doesn't recognize the option
   type, and the third bit indicates that the Option Data may change in
   route.  The remaining bits serve as the option type.


          Hex Value     Binary Value
                        act  chg  rest     Description        Reference
          ---------     ---  ---  -------  -----------------  ----------
            0x63         01    1   00011   RPL Option         [RFC6553]


                   Figure 1: Option Type in RPL Option.

   Recent changes in [RFC8200] (section 4, page 8), states: "it is now
   expected that nodes along a packet's delivery path only examine and
   process the Hop-by-Hop Options header if explicitly configured to do
   so".  Processing of the Hop-by-Hop Options header (by IPv6
   intermediate nodes) is now optional, but if they are configured to
   process the header, and if such nodes encounter an option with the
   first two bits set to 01, they will drop the packet (if they conform
   to [RFC8200]).  Host systems should do the same, irrespective of the
   configuration.

   Based on that, if an IPv6 (intermediate) node (RPL-not-capable)
   receives a packet with an RPL Option, it should ignore the HBH RPL
   option (skip over this option and continue processing the header).
   This is relevant, as it was mentioned previously, in the case that
   there is a flow from RPL-aware-leaf to Internet (see Section 6.2.1).

   Thus, this document updates the Option Type field to: the two high
   order bits MUST be set to '00' and the third bit is equal to '1'.
   The first two bits indicate that the IPv6 node MUST skip over this
   option and continue processing the header ([RFC8200] Section 4.2) if
   it doesn't recognize the option type, and the third bit continues to
   be set to indicate that the Option Data may change en route.  The
   remaining bits serve as the option type and remain as 0x3.  This
   ensures that a packet that leaves the RPL domain of an LLN (or that
   leaves the LLN entirely) will not be discarded when it contains the
   [RFC6553] RPL Hop-by-Hop option known as RPI.

   This is a significant update to [RFC6553].  [RFCXXXX] represents this
   document.






Robles, et al.            Expires July 27, 2019                 [Page 6]


Internet-Draft               RPL-data-plane                 January 2019


          Hex Value     Binary Value
                        act  chg  rest     Description        Reference
          ---------     ---  ---  -------  -----------------  ----------
            0x23         00    1   00011   RPL Option         [RFCXXXX]


               Figure 2: Revised Option Type in RPL Option.

   This change creates a flag day for existing networks which are
   currently using 0x63 as the RPI value.  A move to 0x23 will not be
   understood by those networks.  It is suggested that implementations
   accept both 0x63 and 0x23 when processing.

   In the cases where a forwarding node is forwarding traffic that is
   not addressed directly to it (such as when the outer IPv6-in-IPv6
   header is not a Link-Local address), then RFC8200 forbids changing
   the RPI type code when forwarding.

   When forwarding traffic that is wrapped in Link-Local IPv6-in-IPv6
   headers, the forwarding node is in effect originating new packets,
   and it MAY make a choice as to whether to use the old (0x63) RPI Type
   code, or the new (0x23) RPI Type code.  In that situation,
   implementations SHOULD use the same value as was received.  This
   allows to the network to be incrementally upgraded, and in some cases
   may allow the DODAG root to know which parts of the network are
   upgraded.

   A network which is switching from straight 6lowpan compression
   mechanism to those described in [RFC8138] will experience a flag day
   in the data compression anyway, and if possible this change can be
   deployed at the same time.

   The change of RPI option type from 0x63 to 0x23, makes all [RFC8200]
   Section 4.2 compliant nodes tolerant of the RPL artifacts.  There is
   therefore no longer a necessity to remove the artifacts when sending
   traffic to the Internet.  This change clarifies when to use an IPv6-
   in-IPv6 header, and how to address them: The Hop-by-Hop Options
   Header containing the RPI option SHOULD always be added when 6LRs
   originate packets (without IPv6-in-IPv6 headers), and IPv6-in-IPv6
   headers SHOULD always be added when a 6LR find that it needs to
   insert a Hop-by-Hop Options Header containing the RPI option.  The
   IPv6-in-IPv6 header is to be addressed to the RPL root when on the
   way up, and to the end-host when on the way down.

   Non-constrained uses of RPL are not in scope of this document, and
   applicability statements for those uses MAY provide different advice,
   E.g.  [I-D.ietf-anima-autonomic-control-plane].




Robles, et al.            Expires July 27, 2019                 [Page 7]


Internet-Draft               RPL-data-plane                 January 2019


   In the non-storing case, dealing with non-RPL aware leaf nodes is
   much easier as the 6LBR (DODAG root) has complete knowledge about the
   connectivity of all DODAG nodes, and all traffic flows through the
   root node.

   The 6LBR can recognize non-RPL aware leaf nodes because it will
   receive a DAO about that node from the 6LR immediately above that
   non-RPL aware node.  This means that the non-storing mode case can
   avoid ever using hop-by-hop IPv6-in-IPv6 headers for traffic
   originating from the root to leafs.

   The non-storing mode case does not require the type change from 0x63
   to 0x23, as the root can always create the right packet.  The type
   change does not adversely affect the non-storing case.

3.2.  Updates to RFC 8138

   RPI-6LoRH header provides a compressed form for the RPL RPI [RFC8138]
   in section 6.  A node that is decompressing this header MUST
   decompress using the RPL RPI option type that is currently active:
   that is, a choice between 0x23 (new) and 0x63 (old).  The node will
   know which to use based upon the presence of the DODAG Configuration
   Option described in the next section.  E.g.  If the network is in
   0x23 mode (by DIO option), then it should be decompressed to 0x23.

   [RFC8138] section 7 documents how to compress the IPv6-in-IPv6
   header.

   There are potential significant advantages to having a single code
   path that always processes IPv6-in-IPv6 headers with no options.

   In Storing Mode, for the examples of Flow from RPL-aware-leaf to non-
   RPL-aware-leaf and non-RPL-aware-leaf to non-RPL-aware-leaf comprise
   an IPv6-in-IPv6 and RPI compression headers.  The use of the IPv6-in-
   IPv6 header is MANDATORY in this case, and it SHOULD be compressed
   with [RFC8138] section 7.


   +--+-----+---+--------------+-----------+-----------+-----------+
   |1 | 0|0 |TSE| 6LoRH Type 6 | Hop Limit | RPI-6LoRH |LOWPAN IPHC|
   +--+-----+---+--------------+-----------+-----------+-----------+


                  Figure 3: Critical IPv6-in-IPv6 (RPI).







Robles, et al.            Expires July 27, 2019                 [Page 8]


Internet-Draft               RPL-data-plane                 January 2019


3.3.  Updates to RFC 6550: Indicating the new RPI in the DODAG
      Configuration Option Flag.

   In order to avoid a Flag Day caused by lack of interoperation between
   new RPI (0x23) and old RPI (0x63) nodes, this section defines a flag
   in the DIO Configuration Option, to indicate when then new RPI value
   can be safely used.  Without this, there could be a mix of new nodes
   (which understand 0x23 and 0x63), and old nodes (which understand
   0x63 only).  A new node would not know if it was safe to use 0x23.

   This is done via a DODAG Configuration Option flag which will
   propagate through the network.  If the flag is received with a value
   zero (which is the default), then new nodes will remain in RFC6553
   Compatible Mode; originating traffic with the old-RPI (0x63) value.

   As stated in [RFC6550] the DODAG Configuration option is present in
   DIO messages.  The DODAG Configuration option distributes
   configuration information.  It is generally static, and does not
   change within the DODAG.  This information is configured at the DODAG
   root and distributed throughout the DODAG with the DODAG
   Configuration option.  Nodes other than the DODAG root do not modify
   this information when propagating the DODAG Configuration option.

   The DODAG Configuration Option has a Flag field which is modified by
   this document.  Currently, the DODAG Configuration Option in
   [RFC6550] states: "the unused bits MUST be initialize to zero by the
   sender and MUST be ignored by the receiver".

   Bit number three of the flag field in the DODAG Configuration option
   is to be used as follows:


                +------------+-----------------+---------------+
                | Bit number |   Description   |   Reference   |
                +------------+-----------------+---------------+
                |      3     | RPI 0x23 enable | This document |
                +------------+-----------------+---------------+


    Figure 4: DODAG Configuration Option Flag to indicate the RPI-flag-
                                   day.

   In case of rebooting, the node (6LN or 6LR) does not remember if the
   flag is set, so DIO messages would be set with the flag unset until a
   DIO is received with the flag set.






Robles, et al.            Expires July 27, 2019                 [Page 9]


Internet-Draft               RPL-data-plane                 January 2019


4.  Sample/reference topology

   A RPL network in general is composed of a 6LBR (6LoWPAN Border
   Router), Backbone Router (6BBR), 6LR (6LoWPAN Router) and 6LN
   (6LoWPAN Node) as leaf logically organized in a DODAG structure.

   Figure 4 shows the reference RPL Topology for this document.  The
   letters above the nodes are there so that they may be referenced in
   subsequent sections.  In the figure, 6LR represents a full router
   node.  The 6LN is a RPL aware router, or host (as a leaf).
   Additionally, for simplification purposes, it is supposed that the
   6LBR has direct access to Internet, thus the 6BBR is not present in
   the figure.

   The 6LN leaves (Raf - "RPL aware leaf"-) marked as (F, H and I) are
   RPL nodes with no children hosts.

   The leafs marked as ~Raf "not-RPL aware leaf" (G and J) are devices
   which do not speak RPL at all (not-RPL-aware), but uses Router-
   Advertisements, 6LowPAN DAR/DAC and efficient-ND only to participate
   in the network [RFC6775].  In the document these leafs (G and J) are
   also referred to as an IPv6 node.

   The 6LBR ("A") in the figure is the root of the Global DODAG.



























Robles, et al.            Expires July 27, 2019                [Page 10]


Internet-Draft               RPL-data-plane                 January 2019


                     +------------+
                     |  INTERNET  ----------+
                     |            |         |
                     +------------+         |
                                            |
                                            |
                                            |
                                          A |
                                      +-------+
                                      |6LBR   |
                          +-----------|(root) |-------+
                          |           +-------+       |
                          |                           |
                          |                           |
                          |                           |
                          |                           |
                          | B                         |C
                      +---|---+                   +---|---+
                      |  6LR  |                   |  6LR  |
            +-------->|       |--+             +---       ---+
            |         +-------+  |             |  +-------+  |
            |                    |             |             |
            |                    |             |             |
            |                    |             |             |
            |                    |             |             |
            | D                  |  E          |             |
          +-|-----+          +---|---+         |             |
          |  6LR  |          |  6LR  |         |             |
          |       |    +------       |         |             |
          +---|---+    |     +---|---+         |             |
              |        |         |             |             |
              |        |         +--+          |             |
              |        |            |          |             |
              |        |            |          |             |
              |        |            |        I |          J  |
           F  |        | G          | H        |             |
        +-----+-+    +-|-----+  +---|--+   +---|---+     +---|---+
        |  Raf  |    | ~Raf  |  | Raf  |   |  Raf  |     | ~Raf  |
        |  6LN  |    |  6LN  |  | 6LN  |   |  6LN  |     |  6LN  |
        +-------+    +-------+  +------+   +-------+     +-------+



                    Figure 5: A reference RPL Topology.

   RPL defines the RPL Control messages (control plane), a new ICMPv6
   [RFC4443] message with Type 155.  DIS (DODAG Information
   Solicitation), DIO (DODAG Information Object) and DAO (Destination



Robles, et al.            Expires July 27, 2019                [Page 11]


Internet-Draft               RPL-data-plane                 January 2019


   Advertisement Object) messages are all RPL Control messages but with
   different Code values.  A RPL Stack is shown in Figure 5.

   +--------------+
   | Upper Layers |
   |              |
   +--------------+
   |   RPL        |
   |              |
   +--------------+
   |   ICMPv6     |
   |              |
   +--------------+
   |   IPv6       |
   |              |
   +--------------+
   |   6LoWPAN    |
   |              |
   +--------------+
   |   PHY-MAC    |
   |              |
   +--------------+

                           Figure 6: RPL Stack.

   RPL supports two modes of Downward traffic: in storing mode (RPL-SM),
   it is fully stateful; in non-storing (RPL-NSM), it is fully source
   routed.  A RPL Instance is either fully storing or fully non-storing,
   i.e. a RPL Instance with a combination of storing and non-storing
   nodes is not supported with the current specifications at the time of
   writing this document.

5.  Use cases

   In the data plane a combination of RFC6553, RFC6554 and IPv6-in-IPv6
   encapsulation are going to be analyzed for a number of representative
   traffic flows.

   This document assumes that the LLN is using the no-drop RPI option
   (0x23).

   The uses cases describe the communication between RPL-aware-nodes,
   with the root (6LBR), and with Internet.  This document also describe
   the communication between nodes acting as leaves that do not
   understand RPL, but are part of the LLN.  these nodes are named as
   not-RPL-aware-leaf, mentioned previously.  (e.g.  Section 6.1.4 Flow
   from not-RPL-aware-leaf to root) This document describes also how is
   the communication inside of the LLN when it has the final destination



Robles, et al.            Expires July 27, 2019                [Page 12]


Internet-Draft               RPL-data-plane                 January 2019


   addressed outside of the LLN e.g. with destination to Internet.
   (e.g.  Section 6.2.3 Flow from not-RPL-aware-leaf to Internet)

   The uses cases comprise as follow:

   Interaction between Leaf and Root:

      RPL-aware-leaf to root

      root to RPL-aware-leaf

      not-RPL-aware-leaf to root

      root to not-RPL-aware-leaf

   Interaction between Leaf and Internet:

      RPL-aware-leaf to Internet

      Internet to RPL-aware-leaf

      not-RPL-aware-leaf to Internet

      Internet to not-RPL-aware-leaf

   Interaction between Leafs:

      RPL-aware-leaf to RPL-aware-leaf (storing and non-storing)

      RPL-aware-leaf to not-RPL-aware-leaf (non-storing)

      not-RPL-aware-leaf to RPL-aware-leaf (storing and non-storing)

      not-RPL-aware-leaf to not-RPL-aware-leaf (non-storing)

   This document is consistent with the rule that a Header cannot be
   inserted or removed on the fly inside an IPv6 packet that is being
   routed.  This is a fundamental precept of the IPv6 architecture as
   outlined in [RFC8200].  Extensions may not be added or removed except
   by the sender or the receiver.

   However, unlike [RFC6553], the Hop-by-Hop Option Header used for the
   RPI artifact has the first two bits set to '00'.  This means that the
   RPI artifact will be ignored when received by a host or router that
   does not understand that option ( Section 4.2 [RFC8200]).

   This means that when the no-drop RPI option code 0x23 is used, a
   packet that leaves the RPL domain of an LLN (or that leaves the LLN



Robles, et al.            Expires July 27, 2019                [Page 13]


Internet-Draft               RPL-data-plane                 January 2019


   entirely) will not be discarded when it contains the [RFC6553] RPL
   Hop-by-Hop option known as RPI.  Thus, the RPI Hop-by-Hop option is
   left in place even if the end host does not understand it.

   NOTE: There is some possible security risk when the RPI information
   is released to the Internet.  At this point this is a theoretical
   situation; no clear attack has been described.  At worst, it is clear
   that the RPI option would waste some network bandwidth when it
   escapes.  This is traded off against the savings in the LLN by not
   having to encapsulate the packet in order to remove the artifact.

   As the rank information in the RPI artifact is changed at each hop,
   it will typically be zero when it arrives at the DODAG root.  The
   DODAG root SHOULD force it to zero when passing the packet out to the
   Internet.  The Internet will therefore not see any SenderRank
   information.

   Despite being legal to leave the RPI artifact in place, an
   intermediate router that needs to add an extension header (RH3 or RPI
   Option) MUST still encapsulate the packet in an (additional) outer IP
   header.  The new header is placed after this new outer IP header.

   A corollary is that an RH3 or RPI Option can only be removed by an
   intermediate router if it is placed in an encapsulating IPv6 Header,
   which is addressed TO the intermediate router.  When it does so, the
   whole encapsulating header must be removed.  (A replacement may be
   added).  This sometimes can result in outer IP headers being
   addressed to the next hop router using link-local address.

   Both RPI and RH3 headers may be modified in very specific ways by
   routers on the path of the packet without the need to add to remove
   an encapsulating header.  Both headers were designed with this
   modification in mind, and both the RPL RH3 and the RPL option are
   marked mutable but recoverable: so an IPsec AH security header can be
   applied across these headers, but it can not secure the values which
   mutate.

   RPI MUST be present in every single RPL data packet.  There is one
   exception in non-storing mode: when a packet is going down from the
   root the RPI MAY be omitted.  The rational is that in a downward non-
   storing mode, the entire route is written, so there can be no loops
   by construction, nor any confusion about which forwarding table to
   use (as the root has already made all routing decisions).  However,
   there are still cases, such as in 6tisch, where the instanceID
   portion of the RPI header may still be needed [RFC8180] to pick an
   appropriate priority or channel at each hop.





Robles, et al.            Expires July 27, 2019                [Page 14]


Internet-Draft               RPL-data-plane                 January 2019


   Prior to [RFC8138], there was significant interest in removing the
   RPI for downward flows in non-storing mode.  The exception covered a
   very small number of cases, and causes significant interoperability
   challenges, yet costed significant code and testing complexity.  The
   ability to compress the RPI down to three bytes or less removes much
   of the pressure to optimize this any further
   [I-D.ietf-anima-autonomic-control-plane].

   The earlier examples are more extensive to make sure that the process
   is clear, while later examples are more concise.

6.  Storing mode

   In storing mode (fully stateful), the sender can determine if the
   destination is inside the LLN by looking if the destination address
   is matched by the DIO's Prefix Information Option (PIO) option.

   The following table itemizes which headers are needed in each of the
   following scenarios.  It indicate if an IPv6-in-IPv6 header MUST be
   inserted, and whether the destination address of the IPv6-in-IPv6
   header is the next hop, or the final target address.  There are these
   possible situations: hop-by-hop necessary (indicated by "hop"), or
   final target address possible (indicated by "tgt").  In all cases hop
   by hop MAY be used rather than the final target address.

   In cases where no IPv6-in-IPv6 header is needed, the column states as
   "No".

   In all cases the RPI headers are needed, since it identifies
   inconsistencies (loops) in the routing topology.  In all cases the
   RH3 is not needed because it is not used in storing mode.

   In each case, 6LR_i are the intermediate routers from source to
   destination.  "1 <= i <= n", n is the number of routers (6LR) that
   the packet go through from source (6LN) to destination.

   The leaf can be a router 6LR or a host, both indicated as 6LN (see
   Figure 5).













Robles, et al.            Expires July 27, 2019                [Page 15]


Internet-Draft               RPL-data-plane                 January 2019


   +---------------------+--------------+------------+--------------+
   | Interaction between |   Use Case   |IPv6-in-IPv6| v6-in-v6 dst |
   +---------------------+--------------+------------+--------------+
   |                     |  Raf to root |    No      |      No      |
   +                     +--------------+------------+--------------+
   |     Leaf - Root     |  root to Raf |    No      |      No      |
   +                     +--------------+------------+--------------+
   |                     | root to ~Raf |    No      |      No      |
   +                     +--------------+------------+--------------+
   |                     | ~Raf to root |   MUST     |     root     |
   +---------------------+--------------+------------+--------------+
   |                     |  Raf to Int  |    No      |      No      |
   +                     +--------------+------------+--------------+
   |   Leaf - Internet   |  Int to Raf  |   MUST     |  tgt (Raf)   |
   +                     +--------------+------------+--------------+
   |                     |  ~Raf to Int |   MUST     |     root     |
   +                     +--------------+------------+--------------+
   |                     |  Int to ~Raf |   MUST     |      hop     |
   +---------------------+--------------+------------+--------------+
   |                     |  Raf to Raf  |    No      |      No      |
   +                     +--------------+------------+--------------+
   |                     |  Raf to ~Raf |    No      |      No      |
   +     Leaf - Leaf     +--------------+------------+--------------+
   |                     |  ~Raf to Raf |   MUST     |   tgt (Raf)  |
   +                     +--------------+------------+--------------+
   |                     | ~Raf to ~Raf |    Yes     |      hop     |
   +---------------------+--------------+------------+--------------+



           Figure 7: IPv6-in-IPv6 encapsulation in Storing mode.

6.1.  Storing Mode: Interaction between Leaf and Root

   In this section is described the communication flow in storing mode
   (SM) between,

      RPL-aware-leaf to root

      root to RPL-aware-leaf

      not-RPL-aware-leaf to root

      root to not-RPL-aware-leaf







Robles, et al.            Expires July 27, 2019                [Page 16]


Internet-Draft               RPL-data-plane                 January 2019


6.1.1.  SM: Example of Flow from RPL-aware-leaf to root

   In storing mode, RFC 6553 (RPI) is used to send RPL Information
   instanceID and rank information.

   As stated in Section 16.2 of [RFC6550] a RPL-aware-leaf node does not
   generally issue DIO messages; a leaf node accepts DIO messages from
   upstream.  (When the inconsistency in routing occurs, a leaf node
   will generate a DIO with an infinite rank, to fix it).  It may issue
   DAO and DIS messages though it generally ignores DAO and DIS
   messages.

   In this case the flow comprises:

   RPL-aware-leaf (6LN) --> 6LR_i --> root(6LBR)

   For example, a communication flow could be: Node F --> Node E -->
   Node B --> Node A root(6LBR)

   As it was mentioned in this document 6LRs, 6LBR are always full-
   fledged RPL routers.

   The 6LN (Node F) inserts the RPI header, and sends the packet to 6LR
   (Node E) which decrements the rank in RPI and sends the packet up.
   When the packet arrives at 6LBR (Node A), the RPI is removed and the
   packet is processed.

   No IPv6-in-IPv6 header is required.

   The RPI header can be removed by the 6LBR because the packet is
   addressed to the 6LBR.  The 6LN must know that it is communicating
   with the 6LBR to make use of this scenario.  The 6LN can know the
   address of the 6LBR because it knows the address of the root via the
   DODAGID in the DIO messages.

                +-------------------+-----+-------+------+
                | Header            | 6LN | 6LR_i | 6LBR |
                +-------------------+-----+-------+------+
                | Inserted headers  | RPI | --    | --   |
                | Removed headers   | --  | --    | RPI  |
                | Re-added headers  | --  | --    | --   |
                | Modified headers  | --  | RPI   | --   |
                | Untouched headers | --  | --    | --   |
                +-------------------+-----+-------+------+

    Table 1: Storing: Summary of the use of headers from RPL-aware-leaf
                                  to root




Robles, et al.            Expires July 27, 2019                [Page 17]


Internet-Draft               RPL-data-plane                 January 2019


6.1.2.  SM: Example of Flow from root to RPL-aware-leaf

   In this case the flow comprises:

   root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)

   For example, a communication flow could be: Node A root(6LBR) -->
   Node B --> Node D --> Node F

   In this case the 6LBR inserts RPI header and sends the packet down,
   the 6LR is going to increment the rank in RPI (it examines the
   instanceID to identify the right forwarding table), the packet is
   processed in the 6LN and the RPI removed.

   No IPv6-in-IPv6 header is required.

                +-------------------+------+-------+------+
                | Header            | 6LBR | 6LR_i | 6LN  |
                +-------------------+------+-------+------+
                | Inserted headers  | RPI  | --    | --   |
                | Removed headers   | --   | --    | RPI  |
                | Re-added headers  | --   | --    | --   |
                | Modified headers  | --   | RPI   | --   |
                | Untouched headers | --   | --    | --   |
                +-------------------+------+-------+------+

     Table 2: Storing: Summary of the use of headers from root to RPL-
                                aware-leaf

6.1.3.  SM: Example of Flow from root to not-RPL-aware-leaf

   In this case the flow comprises:

   root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)

   For example, a communication flow could be: Node A root(6LBR) -->
   Node B --> Node E --> Node G

   As the RPI extension can be ignored by the not-RPL-aware leaf, this
   situation is identical to the previous scenario.











Robles, et al.            Expires July 27, 2019                [Page 18]


Internet-Draft               RPL-data-plane                 January 2019


           +-------------------+------+-------+----------------+
           | Header            | 6LBR | 6LR_i | IPv6           |
           +-------------------+------+-------+----------------+
           | Inserted headers  | RPI  | --    | --             |
           | Removed headers   | --   | --    | --             |
           | Re-added headers  | --   | --    | --             |
           | Modified headers  | --   | RPI   | --             |
           | Untouched headers | --   | --    | RPI (Ignored)  |
           +-------------------+------+-------+----------------+

   Table 3: Storing: Summary of the use of headers from root to not-RPL-
                                aware-leaf

6.1.4.  SM: Example of Flow from not-RPL-aware-leaf to root

   In this case the flow comprises:

   not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)

   For example, a communication flow could be: Node G --> Node E -->
   Node B --> Node A root(6LBR)

   When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E),
   the 6LR_1 will insert a RPI header, encapsuladed in a IPv6-in-IPv6
   header.  The IPv6-in-IPv6 header can be addressed to the next hop
   (Node B), or to the root (Node A).  The root removes the header and
   processes the packet.
























Robles, et al.            Expires July 27, 2019                [Page 19]


Internet-Draft               RPL-data-plane                 January 2019


   +---------+-----+---------------+------------------+----------------+
   | Header  | IPv | 6LR_1         | 6LR_i            | 6LBR           |
   |         | 6   |               |                  |                |
   +---------+-----+---------------+------------------+----------------+
   | Inserte | --  | IPv6-in-      | IPv6-in-         | --             |
   | d       |     | IPv6(RPI)     | IPv6(RPI)(1)     |                |
   | headers |     |               |                  |                |
   | Removed | --  | --            | --               | IPv6-in-       |
   | headers |     |               |                  | IPv6(RPI)      |
   | Re-     | --  | --            | IPv6-in-         | --             |
   | added   |     |               | IPv6(RPI)(1)     |                |
   | headers |     |               |                  |                |
   | Modifie | --  | --            | IPv6-in-         | --             |
   | d       |     |               | IPv6(RPI)(2)     |                |
   | headers |     |               |                  |                |
   | Untouch | --  | --            | --               | --             |
   | ed      |     |               |                  |                |
   | headers |     |               |                  |                |
   +---------+-----+---------------+------------------+----------------+

    Table 4: Storing: Summary of the use of headers from not-RPL-aware-
   leaf to root.  (1) Case where the IPv6-in-IPv6 header is addressed to
     the next hop (Node B). (2) Case where the IPv6-in-IPv6 header is
                      addressed to the root (Node A)

6.2.  Storing Mode: Interaction between Leaf and Internet.

   In this section is described the communication flow in storing mode
   (SM) between,

      RPL-aware-leaf to Internet

      Internet to RPL-aware-leaf

      not-RPL-aware-leaf to Internet

      Internet to not-RPL-aware-leaf

6.2.1.  SM: Example of Flow from RPL-aware-leaf to Internet

   RPL information from RFC 6553 may go out to Internet as it will be
   ignored by nodes which have not been configured to be RPI aware.

   In this case the flow comprises:

   RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet





Robles, et al.            Expires July 27, 2019                [Page 20]


Internet-Draft               RPL-data-plane                 January 2019


   For example, the communication flow could be: Node F --> Node D -->
   Node B --> Node A root(6LBR) --> Internet

   No IPv6-in-IPv6 header is required.

   Note: In this use case it is used a node as leaf, but this use case
   can be also applicable to any RPL-node type (e.g. 6LR)

       +-------------------+------+-------+------+----------------+
       | Header            | 6LN  | 6LR_i | 6LBR | Internet       |
       +-------------------+------+-------+------+----------------+
       | Inserted headers  | RPI  | --    | --   | --             |
       | Removed headers   | --   | --    | --   | --             |
       | Re-added headers  | --   | --    | --   | --             |
       | Modified headers  | --   | RPI   | --   | --             |
       | Untouched headers | --   | --    | RPI  | RPI (Ignored)  |
       +-------------------+------+-------+------+----------------+

    Table 5: Storing: Summary of the use of headers from RPL-aware-leaf
                                to Internet

6.2.2.  SM: Example of Flow from Internet to RPL-aware-leaf

   In this case the flow comprises:

   Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)

   For example, a communication flow could be: Internet --> Node A
   root(6LBR) --> Node B --> Node D --> Node F

   When the packet arrives from Internet to 6LBR the RPI header is added
   in a outer IPv6-in-IPv6 header and sent to 6LR, which modifies the
   rank in the RPI.  When the packet arrives at 6LN the RPI header is
   removed and the packet processed.

















Robles, et al.            Expires July 27, 2019                [Page 21]


Internet-Draft               RPL-data-plane                 January 2019


   +---------+--------+---------------+---------------+----------------+
   | Header  | Intern | 6LBR          | 6LR_i         | 6LN            |
   |         | et     |               |               |                |
   +---------+--------+---------------+---------------+----------------+
   | Inserte | --     | IPv6-in-      | --            | --             |
   | d       |        | IPv6(RPI)     |               |                |
   | headers |        |               |               |                |
   | Removed | --     | --            | --            | IPv6-in-       |
   | headers |        |               |               | IPv6(RPI)      |
   | Re-     | --     | --            | --            | --             |
   | added   |        |               |               |                |
   | headers |        |               |               |                |
   | Modifie | --     | --            | IPv6-in-      | --             |
   | d       |        |               | IPv6(RPI)     |                |
   | headers |        |               |               |                |
   | Untouch | --     | --            | --            | --             |
   | ed      |        |               |               |                |
   | headers |        |               |               |                |
   +---------+--------+---------------+---------------+----------------+

   Table 6: Storing: Summary of the use of headers from Internet to RPL-
                                aware-leaf

6.2.3.  SM: Example of Flow from not-RPL-aware-leaf to Internet

   In this case the flow comprises:

   not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->
   Internet

   For example, a communication flow could be: Node G --> Node E -->
   Node B --> Node A root(6LBR) --> Internet

   The 6LR_1 (i=1) node will add an IPv6-in-IPv6(RPI) header addressed
   either to the root, or hop-by-hop such that the root can remove the
   RPI header before passing upwards.  The IPv6-in-IPv6 addressed to the
   root cause less processing overhead.  On the other hand, with hop-by-
   hop the intermediate routers can check the routing tables for a
   better routing path, thus it could be more efficient and faster.
   Implementation should decide which approach to take.

   The originating node will ideally leave the IPv6 flow label as zero
   so that the packet can be better compressed through the LLN.  The
   6LBR will set the flow label of the packet to a non-zero value when
   sending to the Internet.






Robles, et al.            Expires July 27, 2019                [Page 22]


Internet-Draft               RPL-data-plane                 January 2019


   +-------+----+-------------+---------------+---------------+--------+
   | Heade | IP | 6LR_1       | 6LR_i         | 6LBR          | Intern |
   | r     | v6 |             | [i=2,..,n]_   |               | et     |
   +-------+----+-------------+---------------+---------------+--------+
   | Inser | -- | IPv6-in-    | IPv6-in-      | --            | --     |
   | ted h |    | IPv6(RPI)   | IPv6(RPI)(2)  |               |        |
   | eader |    |             |               |               |        |
   | s     |    |             |               |               |        |
   | Remov | -- | --          | IPv6-in-      | IPv6-in-      | --     |
   | ed he |    |             | IPv6(RPI)(2)  | IPv6(RPI)(1)  |        |
   | aders |    |             |               |               |        |
   | Re-   | -- | --          | --            | --            | --     |
   | added |    |             |               |               |        |
   | heade |    |             |               |               |        |
   | rs    |    |             |               |               |        |
   | Modif | -- | --          | IPv6-in-      | --            | --     |
   | ied h |    |             | IPv6(RPI)(1)  |               |        |
   | eader |    |             |               |               |        |
   | s     |    |             |               |               |        |
   | Untou | -- | --          | --            | --            | --     |
   | ched  |    |             |               |               |        |
   | heade |    |             |               |               |        |
   | rs    |    |             |               |               |        |
   +-------+----+-------------+---------------+---------------+--------+

    Table 7: Storing: Summary of the use of headers from not-RPL-aware-
     leaf to Internet.  (1) Case when packet is addressed to the root.
             (2) Case when the packet is addressed hop-by-hop.

6.2.4.  SM: Example of Flow from Internet to non-RPL-aware-leaf.

   In this case the flow comprises:

   Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)

   For example, a communication flow could be: Internet --> Node A
   root(6LBR) --> Node B --> Node E --> Node G

   The 6LBR will have to add an RPI header within an IPv6-in-IPv6
   header.  The IPv6-in-IPv6 is addressed to the not-RPL-aware-leaf,
   leaving the RPI inside.

   Note that there is a requirement that the final node be able to
   remove one or more IPv6-in-IPv6 headers which are all addressed to
   it, mentioned in [I-D.thubert-roll-unaware-leaves] :






Robles, et al.            Expires July 27, 2019                [Page 23]


Internet-Draft               RPL-data-plane                 January 2019


   "RPL data packets are often encapsulated using IP in IP.  The 6LN
   MUST be able to decapsulate a packet when it is the destination of
   the outer header and process correctly the inner header."

   The 6LBR MAY set the flow label on the inner IPv6-in-IPv6 header to
   zero in order to aid in compression.

   +--------+---------+---------------+---------------+----------------+
   | Header | Interne | 6LBR          | 6LR_i         | IPv6           |
   |        | t       |               |               |                |
   +--------+---------+---------------+---------------+----------------+
   | Insert | --      | IPv6-in-      | --            | --             |
   | ed hea |         | IPv6(RPI)     |               |                |
   | ders   |         |               |               |                |
   | Remove | --      | --            | --            | IPv6-in-       |
   | d head |         |               |               | IPv6(RPI)- RPI |
   | ers    |         |               |               | (Ignored)      |
   | Re-    | --      | --            | --            | --             |
   | added  |         |               |               |                |
   | header |         |               |               |                |
   | s      |         |               |               |                |
   | Modifi | --      | --            | IPv6-in-      | --             |
   | ed hea |         |               | IPv6(RPI)     |                |
   | ders   |         |               |               |                |
   | Untouc | --      | --            | --            | --             |
   | hed he |         |               |               |                |
   | aders  |         |               |               |                |
   +--------+---------+---------------+---------------+----------------+

   Table 8: Storing: Summary of the use of headers from Internet to non-
                              RPL-aware-leaf

6.3.  Storing Mode: Interaction between Leaf and Leaf

   In this section is described the communication flow in storing mode
   (SM) between,

      RPL-aware-leaf to RPL-aware-leaf

      RPL-aware-leaf to not-RPL-aware-leaf

      not-RPL-aware-leaf to RPL-aware-leaf

      not-RPL-aware-leaf to not-RPL-aware-leaf







Robles, et al.            Expires July 27, 2019                [Page 24]


Internet-Draft               RPL-data-plane                 January 2019


6.3.1.  SM: Example of Flow from RPL-aware-leaf to RPL-aware-leaf

   In [RFC6550] RPL allows a simple one-hop optimization for both
   storing and non-storing networks.  A node may send a packet destined
   to a one-hop neighbor directly to that node.  See section 9 in
   [RFC6550].

   When the nodes are not directly connected, then in storing mode, the
   flow comprises:

   6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> 6LN

   For example, a communication flow could be: Node F --> Node D -->
   Node B --> Node E --> Node H

   6LR_ia (Node D) are the intermediate routers from source to the
   common parent (6LR_x) (Node B) In this case, "1 <= ia <= n", n is the
   number of routers (6LR) that the packet go through from 6LN (Node F)
   to the common parent (6LR_x).

   6LR_id (Node E) are the intermediate routers from the common parent
   (6LR_x) (Node B) to destination 6LN (Node H).  In this case, "1 <= id
   <= m", m is the number of routers (6LR) that the packet go through
   from the common parent (6LR_x) to destination 6LN.

   It is assumed that the two nodes are in the same RPL Domain (that
   they share the same DODAG root).  At the common parent (Node B), the
   direction of RPI is changed (from increasing to decreasing the rank).

   While the 6LR nodes will update the RPI, no node needs to add or
   remove the RPI, so no IPv6-in-IPv6 headers are necessary.  This may
   be done regardless of where the destination is, as the included RPI
   will be ignored by the receiver.


















Robles, et al.            Expires July 27, 2019                [Page 25]


Internet-Draft               RPL-data-plane                 January 2019


   +---------------+--------+--------+---------------+--------+--------+
   | Header        | 6LN    | 6LR_ia | 6LR_x (common | 6LR_id | 6LN    |
   |               | src    |        | parent)       |        | dst    |
   +---------------+--------+--------+---------------+--------+--------+
   | Inserted      | RPI    | --     | --            | --     | --     |
   | headers       |        |        |               |        |        |
   | Removed       | --     | --     | --            | --     | RPI    |
   | headers       |        |        |               |        |        |
   | Re-added      | --     | --     | --            | --     | --     |
   | headers       |        |        |               |        |        |
   | Modified      | --     | RPI    | RPI           | RPI    | --     |
   | headers       |        |        |               |        |        |
   | Untouched     | --     | --     | --            | --     | --     |
   | headers       |        |        |               |        |        |
   +---------------+--------+--------+---------------+--------+--------+

   Table 9: Storing: Summary of the use of headers for RPL-aware-leaf to
                              RPL-aware-leaf

6.3.2.  SM: Example of Flow from RPL-aware-leaf to non-RPL-aware-leaf

   In this case the flow comprises:

   6LN --> 6LR_ia --> common parent (6LR_x) --> 6LR_id --> not-RPL-aware
   6LN (IPv6)

   For example, a communication flow could be: Node F --> Node D -->
   Node B --> Node E --> Node G

   6LR_ia are the intermediate routers from source (6LN) to the common
   parent (6LR_x) In this case, "1 <= ia <= n", n is the number of
   routers (6LR) that the packet go through from 6LN to the common
   parent (6LR_x).

   6LR_id (Node E) are the intermediate routers from the common parent
   (6LR_x) (Node B) to destination not-RPL-aware 6LN (IPv6) (Node G).
   In this case, "1 <= id <= m", m is the number of routers (6LR) that
   the packet go through from the common parent (6LR_x) to destination
   6LN.

   This situation is identical to the previous situation Section 6.3.1










Robles, et al.            Expires July 27, 2019                [Page 26]


Internet-Draft               RPL-data-plane                 January 2019


   +-----------+------+--------+---------------+--------+--------------+
   | Header    | 6LN  | 6LR_ia | 6LR_x(common  | 6LR_id | IPv6         |
   |           | src  |        | parent)       |        |              |
   +-----------+------+--------+---------------+--------+--------------+
   | Inserted  | RPI  | --     | --            | --     | --           |
   | headers   |      |        |               |        |              |
   | Removed   | --   | --     | --            | --     | --           |
   | headers   |      |        |               |        |              |
   | Re-added  | --   | --     | --            | --     | --           |
   | headers   |      |        |               |        |              |
   | Modified  | --   | RPI    | RPI           | RPI    | --           |
   | headers   |      |        |               |        |              |
   | Untouched | --   | --     | --            | --     | RPI(Ignored) |
   | headers   |      |        |               |        |              |
   +-----------+------+--------+---------------+--------+--------------+

    Table 10: Storing: Summary of the use of headers for RPL-aware-leaf
                           to non-RPL-aware-leaf

6.3.3.  SM: Example of Flow from not-RPL-aware-leaf to RPL-aware-leaf

   In this case the flow comprises:

   not-RPL-aware 6LN (IPv6) --> 6LR_ia --> common parent (6LR_x) -->
   6LR_id --> 6LN

   For example, a communication flow could be: Node G --> Node E -->
   Node B --> Node D --> Node F

   6LR_ia (Node E) are the intermediate routers from source (not-RPL-
   aware 6LN (IPv6)) (Node G) to the common parent (6LR_x) (Node B).  In
   this case, "1 <= ia <= n", n is the number of routers (6LR) that the
   packet go through from source to the common parent.

   6LR_id (Node D) are the intermediate routers from the common parent
   (6LR_x) (Node B) to destination 6LN (Node F).  In this case, "1 <= id
   <= m", m is the number of routers (6LR) that the packet go through
   from the common parent (6LR_x) to destination 6LN.

   The 6LR_ia (ia=1) (Node E) receives the packet from the the IPv6 node
   (Node G) and inserts and the RPI header encapsulated in IPv6-in-IPv6
   header.  The IPv6-in-IPv6 header is addressed to the destination 6LN
   (Node F).








Robles, et al.            Expires July 27, 2019                [Page 27]


Internet-Draft               RPL-data-plane                 January 2019


   +-------+----+------------+-------------+-------------+-------------+
   | Heade | IP | 6LR_ia     | common      | 6LR_id      | 6LN         |
   | r     | v6 |            | parent      |             |             |
   |       |    |            | (6LRx)      |             |             |
   +-------+----+------------+-------------+-------------+-------------+
   | Inser | -- | IPv6-in-   | --          | --          | --          |
   | ted h |    | IPv6(RPI)  |             |             |             |
   | eader |    |            |             |             |             |
   | s     |    |            |             |             |             |
   | Remov | -- | --         | --          | --          | IPv6-in-    |
   | ed he |    |            |             |             | IPv6(RPI)   |
   | aders |    |            |             |             |             |
   | Re-   | -- | --         | --          | --          | --          |
   | added |    |            |             |             |             |
   | heade |    |            |             |             |             |
   | rs    |    |            |             |             |             |
   | Modif | -- | --         | IPv6-in-    | IPv6-in-    | --          |
   | ied h |    |            | IPv6(RPI)   | IPv6(RPI)   |             |
   | eader |    |            |             |             |             |
   | s     |    |            |             |             |             |
   | Untou | -- | --         | --          | --          | --          |
   | ched  |    |            |             |             |             |
   | heade |    |            |             |             |             |
   | rs    |    |            |             |             |             |
   +-------+----+------------+-------------+-------------+-------------+

   Table 11: Storing: Summary of the use of headers from not-RPL-aware-
                          leaf to RPL-aware-leaf

6.3.4.  SM: Example of Flow from not-RPL-aware-leaf to not-RPL-aware-
        leaf

   In this case the flow comprises:

   not-RPL-aware 6LN (IPv6 src)--> 6LR_1--> 6LR_ia --> 6LR_id --> not-
   RPL-aware 6LN (IPv6 dst)

   For example, a communication flow could be: Node G --> Node E -->
   Node B --> Node A (root) --> Node C --> Node J

   Internal nodes 6LR_ia (e.g: Node E or Node B) are the intermediate
   routers from the not-RPL-aware source (Node G) to the root (6LBR)
   (Node A).  In this case, "1 < ia <= n", n is the number of routers
   (6LR) that the packet go through from IPv6 src to the root.

   6LR_id (C) are the intermediate routers from the root (Node A) to the
   destination Node J.  In this case, "1 <= id <= m", m is the number of




Robles, et al.            Expires July 27, 2019                [Page 28]


Internet-Draft               RPL-data-plane                 January 2019


   routers (6LR) that the packet go through from the root to destination
   (IPv6 dst).

   Note that this flow is identical to Section 6.3.3, except for where
   the IPv6-in-IPv6 header is inserted.

   The 6LR_1 (Node E) receives the packet from the the IPv6 node (Node
   G) and inserts the RPI header (RPI), encapsulated in an IPv6-in-IPv6
   header.  The IPv6-in-IPv6 header is addressed to the final
   destination (Node J).

   +-------+----+------------+-------------+-------------+-------------+
   | Heade | IP | 6LR_1      | 6LR_ia      | 6LR_m       | IPv6 dst    |
   | r     | v6 |            |             |             |             |
   |       | sr |            |             |             |             |
   |       | c  |            |             |             |             |
   +-------+----+------------+-------------+-------------+-------------+
   | Inser | -- | IPv6-in-   | --          | --          | --          |
   | ted h |    | IPv6(RPI)  |             |             |             |
   | eader |    |            |             |             |             |
   | s     |    |            |             |             |             |
   | Remov | -- | --         | --          | --          | IPv6-in-    |
   | ed he |    |            |             |             | IPv6(RPI),  |
   | aders |    |            |             |             | RPI Ignored |
   | Re-   | -- | --         | --          | --          | --          |
   | added |    |            |             |             |             |
   | heade |    |            |             |             |             |
   | rs    |    |            |             |             |             |
   | Modif | -- | --         | IPv6-in-    | IPv6-in-    | --          |
   | ied h |    |            | IPv6(RPI)   | IPv6(RPI)   |             |
   | eader |    |            |             |             |             |
   | s     |    |            |             |             |             |
   | Untou | -- | --         | --          | --          | --          |
   | ched  |    |            |             |             |             |
   | heade |    |            |             |             |             |
   | rs    |    |            |             |             |             |
   +-------+----+------------+-------------+-------------+-------------+

   Table 12: Storing: Summary of the use of headers from not-RPL-aware-
                        leaf to non-RPL-aware-leaf

7.  Non Storing mode

   In Non Storing Mode (Non SM) (fully source routed), the 6LBR (DODAG
   root) has complete knowledge about the connectivity of all DODAG
   nodes, and all traffic flows through the root node.  Thus, there is
   no need for all nodes to know about the existence of non-RPL aware




Robles, et al.            Expires July 27, 2019                [Page 29]


Internet-Draft               RPL-data-plane                 January 2019


   nodes.  Only the 6LBR needs to act if compensation is necessary for
   non-RPL aware receivers.

   The following table summarizes what headers are needed in the
   following scenarios, and indicates when the RPI, RH3 and IPv6-in-IPv6
   header are to be inserted.  There are these possible situations:
   target destination address possible (indicated by "tgt"), to a 6LR,
   to a 6LN or to the root.  In cases where no IPv6-in-IPv6 header is
   needed, the column states as "No".

   The leaf can be a router 6LR or a host, both indicated as 6LN
   (Figure 3).  In the Figure the (1) indicates a 6tisch case [RFC8180],
   where the instanceID portion of the RPI header may still be needed to
   pick an appropriate priority or channel at each hop.





































Robles, et al.            Expires July 27, 2019                [Page 30]


Internet-Draft               RPL-data-plane                 January 2019


   +-----------------+--------------+-----+-----+----------+----------+
   |   Interaction   |   Use Case   | RPI | RH3 | v6-in-v6 | v6-in-v6 |
   |      between    |              |     |     |          |    dst   |
   +-----------------+--------------+-----+-----+----------+----------+
   |                 |  Raf to root | Yes | No  |    No    |    No    |
   +                 +--------------+-----+-----+----------+----------+
   |   Leaf - Root   |  root to Raf | Opt | Yes |    No    |    No    |
   +                 +--------------+-----+-----+----------+----------+
   |                 | root to ~Raf |No(1)| Yes |   MUST   |    6LR   |
   +                 +--------------+-----+-----+----------+----------+
   |                 | ~Raf to root | Yes | No  |   MUST   |   root   |
   +-----------------+--------------+-----+-----+----------+----------+
   |                 |  Raf to Int  | Yes | No  |   MUST   |   root   |
   +                 +--------------+-----+-----+----------+----------+
   | Leaf - Internet |  Int to Raf  |No(1)| Yes |   MUST   |    tgt   |
   +                 +--------------+-----+-----+----------+----------+
   |                 |  ~Raf to Int | Yes | No  |   MUST   |   root   |
   +                 +--------------+-----+-----+----------+----------+
   |                 |  Int to ~Raf |No(1)| Yes |   MUST   |    6LR   |
   +-----------------+--------------+-----+-----+----------+----------+
   |                 |  Raf to Raf  | Yes | Yes |   MUST   | root/tgt |
   +                 +--------------+-----+-----+----------+----------+
   |                 |  Raf to ~Raf | Yes | Yes |   MUST   | root/6LR |
   +   Leaf - Leaf   +--------------+-----+-----+----------+----------+
   |                 |  ~Raf to Raf | Yes | Yes |   MUST   | root/6LN |
   +                 +--------------+-----+-----+----------+----------+
   |                 | ~Raf to ~Raf | Yes | Yes |   MUST   | root/6LR |
   +-----------------+--------------+-----+-----+----------+----------+

   (1)-6tisch networks may need the RPI information.


   Figure 8: Headers needed in Non-Storing mode: RPI, RH3, IPv6-in-IPv6
                              encapsulation.

7.1.  Non-Storing Mode: Interaction between Leaf and Root

   In this section is described the communication flow in Non Storing
   Mode (Non-SM) between,

      RPL-aware-leaf to root

      root to RPL-aware-leaf

      not-RPL-aware-leaf to root

      root to not-RPL-aware-leaf




Robles, et al.            Expires July 27, 2019                [Page 31]


Internet-Draft               RPL-data-plane                 January 2019


7.1.1.  Non-SM: Example of Flow from RPL-aware-leaf to root

   In non-storing mode the leaf node uses default routing to send
   traffic to the root.  The RPI header MUST be included since contains
   the rank information, which is used to avoid/detect loops.

   RPL-aware-leaf (6LN) --> 6LR_i --> root(6LBR)

   For example, a communication flow could be: Node F --> Node D -->
   Node B --> Node A (root)

   6LR_i are the intermediate routers from source to destination.  In
   this case, "1 <= i <= n", n is the number of routers (6LR) that the
   packet go through from source (6LN) to destination (6LBR).

   This situation is the same case as storing mode.

                +-------------------+-----+-------+------+
                | Header            | 6LN | 6LR_i | 6LBR |
                +-------------------+-----+-------+------+
                | Inserted headers  | RPI | --    | --   |
                | Removed headers   | --  | --    | RPI  |
                | Re-added headers  | --  | --    | --   |
                | Modified headers  | --  | RPI   | --   |
                | Untouched headers | --  | --    | --   |
                +-------------------+-----+-------+------+

   Table 13: Non Storing: Summary of the use of headers from RPL-aware-
                               leaf to root

7.1.2.  Non-SM: Example of Flow from root to RPL-aware-leaf

   In this case the flow comprises:

   root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)

   For example, a communication flow could be: Node A (root) --> Node B
   --> Node D --> Node F

   6LR_i are the intermediate routers from source to destination.  In
   this case, "1 <= i <= n", n is the number of routers (6LR) that the
   packet go through from source (6LBR) to destination (6LN).

   The 6LBR inserts an RH3, and a RPI header.  No IPv6-in-IPv6 header is
   necessary as the traffic originates with an RPL aware node, the 6LBR.
   The destination is known to RPL-aware because, the root knows the
   whole topology in non-storing mode.




Robles, et al.            Expires July 27, 2019                [Page 32]


Internet-Draft               RPL-data-plane                 January 2019


    +-------------------+-----------------+-------+------------------+
    | Header            | 6LBR            | 6LR_i | 6LN              |
    +-------------------+-----------------+-------+------------------+
    | Inserted headers  | (opt: RPI), RH3 | --    | --               |
    | Removed headers   | --              | --    | RH3, (opt: RPI)  |
    | Re-added headers  | --              | --    | --               |
    | Modified headers  | --              | RH3   | --               |
    | Untouched headers | --              | --    | --               |
    +-------------------+-----------------+-------+------------------+

     Table 14: Non Storing: Summary of the use of headers from root to
                              RPL-aware-leaf

7.1.3.  Non-SM: Example of Flow from root to not-RPL-aware-leaf

   In this case the flow comprises:

   root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)

   For example, a communication flow could be: Node A (root) --> Node B
   --> Node E --> Node G

   6LR_i are the intermediate routers from source to destination.  In
   this case, "1 <= i <= n", n is the number of routers (6LR) that the
   packet go through from source (6LBR) to destination (IPv6).

   In 6LBR the RH3 is added, it is modified at each intermediate 6LR
   (6LR_1 and so on) and it is fully consumed in the last 6LR (6LR_n),
   but left there.  If RPI is left by the previous 6LR, then the IPv6
   node which does not understand the RPI, will ignore it (following
   RFC8200), thus encapsulation is not necessary.  Due the complete
   knowledge of the topology at the root, the 6LBR may optionally
   address the IPv6-in-IPv6 header to the last 6LR, such that it is
   removed prior to the IPv6 node.  Please see Section 8 for
   clarification of use of IPv6-in-IPv6 encapsulation.
















Robles, et al.            Expires July 27, 2019                [Page 33]


Internet-Draft               RPL-data-plane                 January 2019


   +---------------+-------------+--------------+------------+---------+
   | Header        | 6LBR        | 6LR_i(i=1)   | 6LR_n(i=n) | IPv6    |
   +---------------+-------------+--------------+------------+---------+
   | Inserted      | (opt: RPI), | --           | --         | --      |
   | headers       | RH3         |              |            |         |
   | Removed       | --          | --           | RH3        | --      |
   | headers       |             |              |            |         |
   | Re-added      | --          | --           | --         | --      |
   | headers       |             |              |            |         |
   | Modified      | --          | (opt: RPI),  | (opt: RPI) | --      |
   | headers       |             | RH3          |            |         |
   | Untouched     | --          | --           | --         | opt:    |
   | headers       |             |              |            | RPI     |
   +---------------+-------------+--------------+------------+---------+

     Table 15: Non Storing: Summary of the use of headers from root to
                            not-RPL-aware-leaf

7.1.4.  Non-SM: Example of Flow from not-RPL-aware-leaf to root

   In this case the flow comprises:

   not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i --> root (6LBR)

   For example, a communication flow could be: Node G --> Node E -->
   Node B --> Node A (root)

   6LR_i are the intermediate routers from source to destination.  In
   this case, "1 < i <= n", n is the number of routers (6LR) that the
   packet go through from source (IPv6) to destination (6LBR).  For
   example, 6LR_1 (i=1) is the router that receives the packets from the
   IPv6 node.

   In this case the RPI is added by the first 6LR (6LR1) (Node E),
   encapsulated in an IPv6-in-IPv6 header, and is modified in the
   following 6LRs.  The RPI and entire packet is consumed by the root.















Robles, et al.            Expires July 27, 2019                [Page 34]


Internet-Draft               RPL-data-plane                 January 2019


   +---------+-----+----------------+----------------+-----------------+
   | Header  | IPv | 6LR_1          | 6LR_i          | 6LBR            |
   |         | 6   |                |                |                 |
   +---------+-----+----------------+----------------+-----------------+
   | Inserte | --  | IPv6-in-       | --             | --              |
   | d       |     | IPv6(RPI)      |                |                 |
   | headers |     |                |                |                 |
   | Removed | --  | --             | --             | IPv6-in-        |
   | headers |     |                |                | IPv6(RPI)       |
   | Re-     | --  | --             | --             | --              |
   | added   |     |                |                |                 |
   | headers |     |                |                |                 |
   | Modifie | --  | --             | IPv6-in-       | --              |
   | d       |     |                | IPv6(RPI)      |                 |
   | headers |     |                |                |                 |
   | Untouch | --  | --             | --             | --              |
   | ed      |     |                |                |                 |
   | headers |     |                |                |                 |
   +---------+-----+----------------+----------------+-----------------+

    Table 16: Non Storing: Summary of the use of headers from not-RPL-
                            aware-leaf to root

7.2.  Non-Storing Mode: Interaction between Leaf and Internet

   This section will describe the communication flow in Non Storing Mode
   (Non-SM) between:

      RPL-aware-leaf to Internet

      Internet to RPL-aware-leaf

      not-RPL-aware-leaf to Internet

      Internet to not-RPL-aware-leaf

7.2.1.  Non-SM: Example of Flow from RPL-aware-leaf to Internet

   In this case the flow comprises:

   RPL-aware-leaf (6LN) --> 6LR_i --> root (6LBR) --> Internet

   For example, a communication flow could be: Node F --> Node D -->
   Node B --> Node A --> Internet

   6LR_i are the intermediate routers from source to destination.  In
   this case, "1 <= i <= n", n is the number of routers (6LR) that the
   packet go through from source (6LN) to 6LBR.



Robles, et al.            Expires July 27, 2019                [Page 35]


Internet-Draft               RPL-data-plane                 January 2019


   This case is identical to storing-mode case.

   The IPv6 flow label should be set to zero to aid in compression, and
   the 6LBR will set it to a non-zero value when sending towards the
   Internet.

       +-------------------+------+-------+------+----------------+
       | Header            | 6LN  | 6LR_i | 6LBR | Internet       |
       +-------------------+------+-------+------+----------------+
       | Inserted headers  | RPI  | --    | --   | --             |
       | Removed headers   | --   | --    | --   | --             |
       | Re-added headers  | --   | --    | --   | --             |
       | Modified headers  | --   | RPI   | --   | --             |
       | Untouched headers | --   | --    | RPI  | RPI (Ignored)  |
       +-------------------+------+-------+------+----------------+

   Table 17: Non Storing: Summary of the use of headers from RPL-aware-
                             leaf to Internet

7.2.2.  Non-SM: Example of Flow from Internet to RPL-aware-leaf

   In this case the flow comprises:

   Internet --> root (6LBR) --> 6LR_i --> RPL-aware-leaf (6LN)

   For example, a communication flow could be: Internet --> Node A
   (root) --> Node B --> Node D --> Node F

   6LR_i are the intermediate routers from source to destination.  In
   this case, "1 <= i <= n", n is the number of routers (6LR) that the
   packet go through from 6LBR to destination(6LN).

   The 6LBR must add an RH3 header.  As the 6LBR will know the path and
   address of the target node, it can address the IPv6-in-IPv6 header to
   that node.  The 6LBR will zero the flow label upon entry in order to
   aid compression.















Robles, et al.            Expires July 27, 2019                [Page 36]


Internet-Draft               RPL-data-plane                 January 2019


   +-----------+----------+--------------+--------------+--------------+
   | Header    | Internet | 6LBR         | 6LR_i        | 6LN          |
   +-----------+----------+--------------+--------------+--------------+
   | Inserted  | --       | IPv6-in-IPv6 | --           | --           |
   | headers   |          | (RH3,RPI)    |              |              |
   | Removed   | --       | --           | --           | IPv6-in-IPv6 |
   | headers   |          |              |              | (RH3,RPI)    |
   | Re-added  | --       | --           | --           | --           |
   | headers   |          |              |              |              |
   | Modified  | --       | --           | IPv6-in-IPv6 | --           |
   | headers   |          |              | (RH3,RPI)    |              |
   | Untouched | --       | --           | --           | --           |
   | headers   |          |              |              |              |
   +-----------+----------+--------------+--------------+--------------+

   Table 18: Non Storing: Summary of the use of headers from Internet to
                              RPL-aware-leaf

7.2.3.  Non-SM: Example of Flow from not-RPL-aware-leaf to Internet

   In this case the flow comprises:

   not-RPL-aware-leaf (IPv6) --> 6LR_1 --> 6LR_i -->root (6LBR) -->
   Internet

   For example, a communication flow could be: Node G --> Node E -->
   Node B --> Node A --> Internet

   6LR_i are the intermediate routers from source to destination.  In
   this case, "1 < i <= n", n is the number of routers (6LR) that the
   packet go through from source(IPv6) to 6LBR. e.g 6LR_1 (i=1).

   In this case the flow label is recommended to be zero in the IPv6
   node.  As RPL headers are added in the IPv6 node packet, the first
   6LR (6LR_1) will add a RPI header inside a new IPv6-in-IPv6 header.
   The IPv6-in-IPv6 header will be addressed to the root.  This case is
   identical to the storing-mode case (see Section 6.2.3).














Robles, et al.            Expires July 27, 2019                [Page 37]


Internet-Draft               RPL-data-plane                 January 2019


   +---------+-----+------------+-------------+-------------+----------+
   | Header  | IPv | 6LR_1      | 6LR_i       | 6LBR        | Internet |
   |         | 6   |            | [i=2,..,n]_ |             |          |
   +---------+-----+------------+-------------+-------------+----------+
   | Inserte | --  | IPv6-in-   | --          | --          | --       |
   | d       |     | IPv6 (RPI) |             |             |          |
   | headers |     |            |             |             |          |
   | Removed | --  | --         | --          | IPv6-in-    | --       |
   | headers |     |            |             | IPv6 (RPI)  |          |
   | Re-     | --  | --         | --          | --          | --       |
   | added   |     |            |             |             |          |
   | headers |     |            |             |             |          |
   | Modifie | --  | --         | IPv6-in-    | --          | --       |
   | d       |     |            | IPv6 (RPI)  |             |          |
   | headers |     |            |             |             |          |
   | Untouch | --  | --         | --          | --          | --       |
   | ed      |     |            |             |             |          |
   | headers |     |            |             |             |          |
   +---------+-----+------------+-------------+-------------+----------+

    Table 19: Non Storing: Summary of the use of headers from not-RPL-
                          aware-leaf to Internet

7.2.4.  Non-SM: Example of Flow from Internet to not-RPL-aware-leaf

   In this case the flow comprises:

   Internet --> root (6LBR) --> 6LR_i --> not-RPL-aware-leaf (IPv6)

   For example, a communication flow could be: Internet --> Node A
   (root) --> Node B --> Node E --> Node G

   6LR_i are the intermediate routers from source to destination.  In
   this case, "1 < i <= n", n is the number of routers (6LR) that the
   packet go through from 6LBR to not-RPL-aware-leaf (IPv6).

   The 6LBR must add an RH3 header inside an IPv6-in-IPv6 header.  The
   6LBR will know the path, and will recognize that the final node is
   not an RPL capable node as it will have received the connectivity DAO
   from the nearest 6LR.  The 6LBR can therefore make the IPv6-in-IPv6
   header destination be the last 6LR.  The 6LBR will set to zero the
   flow label upon entry in order to aid compression.









Robles, et al.            Expires July 27, 2019                [Page 38]


Internet-Draft               RPL-data-plane                 January 2019


   +---------+--------+------------+------------+---------------+------+
   | Header  | Intern | 6LBR       | 6LR_1      | 6LR_i(i=2,.., | IPv6 |
   |         | et     |            |            | n)            |      |
   +---------+--------+------------+------------+---------------+------+
   | Inserte | --     | IPv6-in-   | --         | --            | --   |
   | d       |        | IPv6 (RH3, |            |               |      |
   | headers |        | RPI)       |            |               |      |
   | Removed | --     | --         | --         | IPv6-in-IPv6  | --   |
   | headers |        |            |            | (RH3,RPI)(1)  |      |
   | Re-     | --     | --         | --         | --            | --   |
   | added   |        |            |            |               |      |
   | headers |        |            |            |               |      |
   | Modifie | --     | --         | IPv6-in-   | IPv6-in-IPv6  | --   |
   | d       |        |            | IPv6       | (RH3, RPI)    |      |
   | headers |        |            | (RH3,RPI)  |               |      |
   | Untouch | --     | --         | --         | --            | --   |
   | ed      |        |            |            |               |      |
   | headers |        |            |            |               |      |
   +---------+--------+------------+------------+---------------+------+

   Table 20: NonStoring: Summary of the use of headers from Internet to
         non-RPL-aware-leaf (1) The last 6LR before the IPv6 node.

7.3.  Non-Storing Mode: Interaction between Leafs

   In this section is described the communication flow in Non Storing
   Mode (Non-SM) between,

      RPL-aware-leaf to RPL-aware-leaf

      RPL-aware-leaf to not-RPL-aware-leaf

      not-RPL-aware-leaf to RPL-aware-leaf

      not-RPL-aware-leaf to not-RPL-aware-leaf

7.3.1.  Non-SM: Example of Flow from RPL-aware-leaf to RPL-aware-leaf

   In this case the flow comprises:

   6LN src --> 6LR_ia --> root (6LBR) --> 6LR_id --> 6LN dst

   For example, a communication flow could be: Node F --> Node D -->
   Node B --> Node A (root) --> Node B --> Node E --> Node H

   6LR_ia are the intermediate routers from source to the root In this
   case, "1 <= ia <= n", n is the number of routers (6LR) that the
   packet go through from 6LN to the root.



Robles, et al.            Expires July 27, 2019                [Page 39]


Internet-Draft               RPL-data-plane                 January 2019


   6LR_id are the intermediate routers from the root to the destination.
   In this case, "1 <= ia <= m", m is the number of the intermediate
   routers (6LR).

   This case involves only nodes in same RPL Domain.  The originating
   node will add a RPI header to the original packet, and send the
   packet upwards.

   The originating node SHOULD put the RPI into an IPv6-in-IPv6 header
   addressed to the root, so that the 6LBR can remove that header.  If
   it does not, then additional resources are wasted on the way down to
   carry the useless RPI option.

   The 6LBR will need to insert an RH3 header, which requires that it
   add an IPv6-in-IPv6 header.  It SHOULD be able to remove the RPI, as
   it was contained in an IPv6-in-IPv6 header addressed to it.
   Otherwise, there MAY be a RPI header buried inside the inner IP
   header, which should get ignored.

   Networks that use the RPL P2P extension [RFC6997] are essentially
   non-storing DODAGs and fall into this scenario or scenario
   Section 7.1.2, with the originating node acting as 6LBR.

   +---------+------------+-------+-------------+--------+-------------+
   | Header  | 6LN src    | 6LR_i | 6LBR        | 6LR_id | 6LN dst     |
   |         |            | a     |             |        |             |
   +---------+------------+-------+-------------+--------+-------------+
   | Inserte | IPv6-in-   | --    | IPv6-in-    | --     | --          |
   | d       | IPv6       |       | IPv6        |        |             |
   | headers | (RPI1)     |       | (RH3->6LN,  |        |             |
   |         |            |       | opt RPI2)   |        |             |
   | Removed | --         | --    | IPv6-in-    | --     | IPv6-in-    |
   | headers |            |       | IPv6 (RPI1) |        | IPv6 (RH3,  |
   |         |            |       |             |        | opt RPI2)   |
   | Re-     | --         | --    | --          | --     | --          |
   | added   |            |       |             |        |             |
   | headers |            |       |             |        |             |
   | Modifie | --         | RPI1  | --          | RPI2   | --          |
   | d       |            |       |             |        |             |
   | headers |            |       |             |        |             |
   | Untouch | --         | --    | --          | --     | --          |
   | ed      |            |       |             |        |             |
   | headers |            |       |             |        |             |
   +---------+------------+-------+-------------+--------+-------------+

    Table 21: Non Storing: Summary of the use of headers for RPL-aware-
                          leaf to RPL-aware-leaf




Robles, et al.            Expires July 27, 2019                [Page 40]


Internet-Draft               RPL-data-plane                 January 2019


7.3.2.  Non-SM: Example of Flow from RPL-aware-leaf to not-RPL-aware-
        leaf

   In this case the flow comprises:

   6LN --> 6LR_ia --> root (6LBR) --> 6LR_id --> not-RPL-aware (IPv6)

   For example, a communication flow could be: Node F --> Node D -->
   Node B --> Node A (root) --> Node B --> Node E --> Node G

   6LR_ia are the intermediate routers from source to the root In this
   case, "1 <= ia <= n", n is the number of intermediate routers (6LR)

   6LR_id are the intermediate routers from the root to the destination.
   In this case, "1 <= ia <= m", m is the number of the intermediate
   routers (6LR).

   As in the previous case, the 6LN will insert a RPI (RPI_1) header
   which MUST be in an IPv6-in-IPv6 header addressed to the root so that
   the 6LBR can remove this RPI.  The 6LBR will then insert an RH3
   inside a new IPv6-in-IPv6 header addressed to the 6LR_id.  The RPI is
   optional from 6LBR to 6LR_id (RPI_2).

   +---------+-----------+-----------+------------+------------+-------+
   | Header  | 6LN       | 6LR_1     | 6LBR       | 6LR_id     | IPv6  |
   +---------+-----------+-----------+------------+------------+-------+
   | Inserte | IPv6-in-  | --        | IPv6-in-   | --         | --    |
   | d       | IPv6      |           | IPv6 (RH3, |            |       |
   | headers | (RPI1)    |           | opt RPI_2) |            |       |
   | Removed | --        | --        | IPv6-in-   | IPv6-in-   | --    |
   | headers |           |           | IPv6       | IPv6 (RH3, |       |
   |         |           |           | (RPI_1)    | opt RPI_2) |       |
   | Re-     | --        | --        | --         | --         | --    |
   | added   |           |           |            |            |       |
   | headers |           |           |            |            |       |
   | Modifie | --        | IPv6-in-  | --         | IPv6-in-   | --    |
   | d       |           | IPv6      |            | IPv6 (RH3, |       |
   | headers |           | (RPI_1)   |            | opt RPI_2) |       |
   | Untouch | --        | --        | --         | --         | opt   |
   | ed      |           |           |            |            | RPI_2 |
   | headers |           |           |            |            |       |
   +---------+-----------+-----------+------------+------------+-------+

   Table 22: Non Storing: Summary of the use of headers from RPL-aware-
                        leaf to not-RPL-aware-leaf






Robles, et al.            Expires July 27, 2019                [Page 41]


Internet-Draft               RPL-data-plane                 January 2019


7.3.3.  Non-SM: Example of Flow from not-RPL-aware-leaf to RPL-aware-
        leaf

   In this case the flow comprises:

   not-RPL-aware 6LN (IPv6) --> 6LR_ia --> root (6LBR) --> 6LR_id -->
   6LN

   For example, a communication flow could be: Node G --> Node E -->
   Node B --> Node A (root) --> Node B --> Node E --> Node H

   6LR_ia are the intermediate routers from source to the root.  In this
   case, "1 <= ia <= n", n is the number of intermediate routers (6LR)

   6LR_id are the intermediate routers from the root to the destination.
   In this case, "1 <= ia <= m", m is the number of the intermediate
   routers (6LR).

   This scenario is mostly identical to the previous one.  The RPI is
   added by the first 6LR (6LR_1) inside an IPv6-in-IPv6 header
   addressed to the root.  The 6LBR will remove this RPI, and add it's
   own IPv6-in-IPv6 header containing an RH3 header and optional RPI
   (RPI_2).

   +---------+-----+------------+------------+------------+------------+
   | Header  | IPv | 6LR_1      | 6LBR       | 6LR_id     | 6LN        |
   |         | 6   |            |            |            |            |
   +---------+-----+------------+------------+------------+------------+
   | Inserte | --  | IPv6-in-   | IPv6-in-   | --         | --         |
   | d       |     | IPv6       | IPv6 (RH3, |            |            |
   | headers |     | (RPI_1)    | opt RPI_2) |            |            |
   | Removed | --  | --         | IPv6-in-   | --         | IPv6-in-   |
   | headers |     |            | IPv6       |            | IPv6 (RH3, |
   |         |     |            | (RPI_1)    |            | opt RPI_2) |
   | Re-     | --  | --         | --         | --         | --         |
   | added   |     |            |            |            |            |
   | headers |     |            |            |            |            |
   | Modifie | --  | --         | --         | IPv6-in-   | --         |
   | d       |     |            |            | IPv6 (RH3, |            |
   | headers |     |            |            | opt RPI_2) |            |
   | Untouch | --  | --         | --         | --         | --         |
   | ed      |     |            |            |            |            |
   | headers |     |            |            |            |            |
   +---------+-----+------------+------------+------------+------------+

    Table 23: Non Storing: Summary of the use of headers from not-RPL-
                       aware-leaf to RPL-aware-leaf




Robles, et al.            Expires July 27, 2019                [Page 42]


Internet-Draft               RPL-data-plane                 January 2019


7.3.4.  Non-SM: Example of Flow from not-RPL-aware-leaf to not-RPL-
        aware-leaf

   In this case the flow comprises:

   not-RPL-aware 6LN (IPv6 src)--> 6LR_ia --> root (6LBR) --> 6LR_id -->
   not-RPL-aware (IPv6 dst)

   For example, a communication flow could be: Node G --> Node E -->
   Node B --> Node A (root) --> Node C --> Node J

   6LR_ia are the intermediate routers from source to the root.  In this
   case, "1 <= ia <= n", n is the number of intermediate routers (6LR)

   6LR_id are the intermediate routers from the root to the destination.
   In this case, "1 <= ia <= m", m is the number of the intermediate
   routers (6LR).

   This scenario is the combination of the previous two cases.

   +----------+-----+-------------+--------------+--------------+------+
   | Header   | IPv | 6LR_1       | 6LBR         | 6LR_id       | IPv6 |
   |          | 6   |             |              |              | dst  |
   |          | src |             |              |              |      |
   +----------+-----+-------------+--------------+--------------+------+
   | Inserted | --  | IPv6-in-    | IPv6-in-IPv6 | --           | --   |
   | headers  |     | IPv6        | (RH3, opt    |              |      |
   |          |     | (RPI_1)     | RPI_2)       |              |      |
   | Removed  | --  | --          | IPv6-in-IPv6 | IPv6-in-IPv6 | --   |
   | headers  |     |             | (RPI_1)      | (RH3, opt    |      |
   |          |     |             |              | RPI_2)       |      |
   | Re-added | --  | --          | --           | --           | --   |
   | headers  |     |             |              |              |      |
   | Modified | --  | --          | --           | --           | --   |
   | headers  |     |             |              |              |      |
   | Untouche | --  | --          | --           | --           | --   |
   | d        |     |             |              |              |      |
   | headers  |     |             |              |              |      |
   +----------+-----+-------------+--------------+--------------+------+

    Table 24: Non Storing: Summary of the use of headers from not-RPL-
                     aware-leaf to not-RPL-aware-leaf

8.  Operational Considerations of supporting not-RPL-aware-leaves

   Roughly half of the situations described in this document involve
   leaf ("host") nodes that do not speak RPL.  These nodes fall into two
   further categories: ones that drop a packet that have RPI or RH3



Robles, et al.            Expires July 27, 2019                [Page 43]


Internet-Draft               RPL-data-plane                 January 2019


   headers, and ones that continue to process a packet that has RPI and/
   or RH3 headers.

   [RFC8200] provides for new rules that suggest that nodes that have
   not been configured (explicitly) to examine Hop-by-Hop headers,
   should ignore those headers, and continue processing the packet.
   Despite this, and despite the switch from 0x63 to 0x23, there may be
   hosts that are pre-RFC8200, or simply intolerant.  Those hosts will
   drop packets that continue to have RPL artifacts in them.  In
   general, such hosts can not be easily supported in RPL LLNs.

   There are some specific cases where it is possible to remove the RPL
   artifacts prior to forwarding the packet to the leaf host.  The
   critical thing is that the artifacts have been inserted by the RPL
   root inside an IPv6-in-IPv6 header, and that the header has been
   addressed to the 6LR immediately prior to the leaf node.  In that
   case, in the process of removing the IPv6-in-IPv6 header, the
   artifacts can also be removed.

   The above case occurs whenever traffic originates from the outside
   the LLN (the "Internet" cases above), and non-storing mode is used.
   In non-storing mode, the RPL root knows the exact topology (as it
   must be create the RH3 header), and therefore knows what the 6LR
   prior to the leaf --- the 6LR_n.

   Traffic originating from the RPL root (such as when the data
   collection system is co-located on the RPL root), does not require an
   IPv6-in-IPv6 header (in either mode), as the packet is originating at
   the root, and the root can insert the RPI and RH3 headers directly
   into the packet, as it is formed.  Such a packet is slightly smaller,
   but only can be sent to nodes (whether RPL aware or not), that will
   tolerate the RPL artifacts.

   An operator that finds itself with a lot of traffic from the RPL root
   to RPL-not-aware-leaves, will have to do IPv6-in-IPv6 encapsulation
   if the leaf is not tolerant of the RPL artifacts.  Such an operator
   could otherwise omit this unnecessary header if it was certain of the
   properties of the leaf.

   As storing mode can not know the final path of the traffic,
   intolerant (that drop packets with RPL artifacts) leaf nodes can not
   be supported.

9.  Operational considerations of introducing 0x23

   This section describes the operational considerations





Robles, et al.            Expires July 27, 2019                [Page 44]


Internet-Draft               RPL-data-plane                 January 2019


9.1.  Has deployment been discussed?

   There are no known multivendor deployments outside of the research
   groups!  All known deployments of RPL are in market verticals, with a
   single vendor providing all components.  Research groups typically
   are using Contiki, RiotOS, or OpenWSN., and these are easily adapted
   to 0x23 functionality.  Compatibility issue of RPL Option type not
   seems to be quite relevant for research groups.

9.2.  Has installation and initial setup been discussed??

   During bootstrapping the node get the DIO with the information of RPL
   Option Type and Indicating the new RPI in the DODAG Configuration
   Option Flag.  The DODAG root is in charge to configure the current
   network to the new value gradually, through DIO messages and when all
   the nodes are set with the new value.  The DODAG should change to a
   new DODAG version.  Not able to send data plane messages.  Should
   drop the packet.  In case of rebooting, the node does not remember
   the RPL Option Type.  Thus, the DIO is sent with flag indicating the
   new RPI value.

9.3.  Has the migration path been discussed?

   TBD

9.4.  Have the Requirements on other protocols and functional components
      been discussed?

   It allows to send packets to non-RPL nodes, the 0x23?..

   TBD

9.5.  Has the impact on network operation been discussed?

   Missconfiguration in case that a node join.

   TBD

9.6.  Have suggestions for verifying correct operation been discussed?

   TBD

9.7.  Has management interoperability been discussed?

   TBD






Robles, et al.            Expires July 27, 2019                [Page 45]


Internet-Draft               RPL-data-plane                 January 2019


9.8.  Are there fault or threshold conditions that should be reported?

   TBD

9.9.  Is configuration discussed?

   TBD

10.  IANA Considerations

   This document updates the registration made in [RFC6553] Destination
   Options and Hop-by-Hop Options registry from 0x63 to 0x23.

   [RFCXXXX] represents this document.


  Hex Value  Binary Value
             act  chg  rest     Description              Reference
  ---------  ---  ---  -------  -----------------       ----------
   0x23      00    1   00011   RPL Option                [RFCXXXX]
   0x63      01    1   00011   RPL Option(DEPRECATED) [RFC6553][RFCXXXX]


                   Figure 9: Option Type in RPL Option.

   The DODAG Configuration Option Flags in the DODAG Configuration
   option is updated as follows:


                 +------------+-----------------+---------------+
                 | Bit number |   Description   |   Reference   |
                 +------------+-----------------+---------------+
                 |      3     | RPI 0x23 enable | This document |
                 +------------+-----------------+---------------+


   Figure 10: DODAG Configuration Option Flag to indicate the RPI-flag-
                                   day.

11.  Security Considerations

   The security considerations covered in [RFC6553] and [RFC6554] apply
   when the packets are in the RPL Domain.

   The IPv6-in-IPv6 mechanism described in this document is much more
   limited than the general mechanism described in [RFC2473].  The
   willingness of each node in the LLN to decapsulate packets and




Robles, et al.            Expires July 27, 2019                [Page 46]


Internet-Draft               RPL-data-plane                 January 2019


   forward them could be exploited by nodes to disguise the origin of an
   attack.

   While a typical LLN may be a very poor origin for attack traffic (as
   the networks tend to be very slow, and the nodes often have very low
   duty cycles) given enough nodes, they could still have a significant
   impact, particularly if the attack was on another LLN!  Additionally,
   some uses of RPL involve large backbone ISP scale equipment
   [I-D.ietf-anima-autonomic-control-plane], which may be equipped with
   multiple 100Gb/s interfaces.

   Blocking or careful filtering of IPv6-in-IPv6 traffic entering the
   LLN as described above will make sure that any attack that is mounted
   must originate from compromised nodes within the LLN.  The use of
   BCP38 filtering at the RPL root on egress traffic will both alert the
   operator to the existence of the attack, as well as drop the attack
   traffic.  As the RPL network is typically numbered from a single
   prefix, which is itself assigned by RPL, BCP38 filtering involves a
   single prefix comparison and should be trivial to automatically
   configure.

   There are some scenarios where IPv6-in-IPv6 traffic should be allowed
   to pass through the RPL root, such as the IPv6-in-IPv6 mediated
   communications between a new Pledge and the Join Registrar/
   Coordinator (JRC) when using [I-D.ietf-anima-bootstrapping-keyinfra]
   and [I-D.ietf-6tisch-dtsecurity-secure-join].  This is the case for
   the RPL root to do careful filtering: it occurs only when the Join
   Coordinator is not co-located inside the RPL root.

   With the above precautions, an attack using IPv6-in-IPv6 tunnels will
   be by a node within the LLN on another node within the LLN.  Such an
   attack could, of course, be done directly.  An attack of this kind is
   meaningful only if the source addresses are either fake or if the
   point is to amplify return traffic.  Such an attack, could also be
   done without the use of IPv6-in-IPv6 headers using forged source
   addresses.  If the attack requires bi-directional communication, then
   IPv6-in-IPv6 provides no advantages.

   [RFC2473] suggests that tunnel entry and exit points can be secured,
   via the "Use IPsec".  The suggested solution has all the problems
   that [RFC5406] goes into.  In an LLN such a solution would degenerate
   into every node having a tunnel with every other node.  It would
   provide a small amount of origin address authentication at a very
   high cost; doing BCP38 at every node (linking layer-3 addresses to
   layer-2 addresses, and to already present layer-2 cryptographic
   mechanisms) would be cheaper should RPL be run in an environment
   where hostile nodes are likely to be a part of the LLN.




Robles, et al.            Expires July 27, 2019                [Page 47]


Internet-Draft               RPL-data-plane                 January 2019


   The RH3 header usage described here can be abused in equivalent ways
   with an IPv6-in-IPv6 header to add the needed RH3 header.  As such,
   the attacker's RH3 header will not be seen by the network until it
   reaches the end host, which will decapsulate it.  An end-host SHOULD
   be suspicious about a RH3 header which has additional hops which have
   not yet been processed, and SHOULD ignore such a second RH3 header.

   In addition, the LLN will likely use [RFC8138] to compress the IPv6-
   in-IPv6 and RH3 headers.  As such, the compressor at the RPL-root
   will see the second RH3 header and MAY choose to discard the packet
   if the RH3 header has not been completely consumed.  A consumed
   (inert) RH3 header could be present in a packet that flows from one
   LLN, crosses the Internet, and enters another LLN.  As per the
   discussion in this document, such headers do not need to be removed.
   However, there is no case described in this document where an RH3 is
   inserted in a non-storing network on traffic that is leaving the LLN,
   but this document should not preclude such a future innovation.  It
   should just be noted that an incoming RH3 must be fully consumed, or
   very carefully inspected.

   The RPI header, if permitted to enter the LLN, could be used by an
   attacker to change the priority of a packet by selecting a different
   RPLInstanceID, perhaps one with a higher energy cost, for instance.
   It could also be that not all nodes are reachable in an LLN using the
   default instanceID, but a change of instanceID would permit an
   attacker to bypass such filtering.  Like the RH3, a RPI header is to
   be inserted by the RPL root on traffic entering the LLN by first
   inserting an IPv6-in-IPv6 header.  The attacker's RPI header
   therefore will not be seen by the network.  Upon reaching the
   destination node the RPI header has no further meaning and is just
   skipped; the presence of a second RPI header will have no meaning to
   the end node as the packet has already been identified as being at
   it's final destination.

   The RH3 and RPI headers could be abused by an attacker inside of the
   network to route packets on non-obvious ways, perhaps eluding
   observation.  This usage is in fact part of [RFC6997] and can not be
   restricted at all.  This is a feature, not a bug.

   [RFC7416] deals with many other threats to LLNs not directly related
   to the use of IPv6-in-IPv6 headers, and this document does not change
   that analysis.

   Nodes within the LLN can use the IPv6-in-IPv6 mechanism to mount an
   attack on another part of the LLN, while disguising the origin of the
   attack.  The mechanism can even be abused to make it appear that the
   attack is coming from outside the LLN, and unless countered, this
   could be used to mount a Distributed Denial Of Service attack upon



Robles, et al.            Expires July 27, 2019                [Page 48]


Internet-Draft               RPL-data-plane                 January 2019


   nodes elsewhere in the Internet.  See [DDOS-KREBS] for an example of
   such attacks already seen in the real world.

   Nodes outside of the LLN will need to pass IPv6-in-IPv6 traffic
   through the RPL root to perform this attack.  To counter, the RPL
   root SHOULD either restrict ingress of IPv6-in-IPv6 packets (the
   simpler solution), or it SHOULD do a deep packet inspection wherein
   it walks the IP header extension chain until it can inspect the
   upper-layer-payload as described in [RFC7045].  In particular, the
   RPL root SHOULD do BCP38 ([RFC2827]) processing on the source
   addresses of all IP headers that it examines in both directions.

   Note: there are some situations where a prefix will spread across
   multiple LLNs via mechanisms such as the one described in
   [I-D.ietf-6lo-backbone-router].  In this case the BCP38 filtering
   needs to take this into account, either by exchanging detailed
   routing information on each LLN, or by moving the BCP38 filtering
   further towards the Internet, so that the details of the multiple
   LLNs do not matter.

12.  Acknowledgments

   We are very thankful to the grant by the Finnish Foundation for
   Technology Promotion (Tekniikan Edistaemissaeaetioen - TES), and the
   grant by the FP7 Marie Curie Initial Training Network (ITN) METRICS
   project (grant agreement No. 607728)

   A special BIG thanks to C.  M.  Heard for the help with the
   Section 3.  Much of the redaction in that section is based on his
   comments.

   Additionally, the authors would like to acknowledge the review,
   feedback, and comments of (alphabetical order): Robert Cragie, Simon
   Duquennoy, Ralph Droms, Cenk Guendogan, Rahul Jadhav, Matthias
   Kovatsch, Peter van der Stok, Xavier Vilajosana and Thomas Watteyne.

13.  References

13.1.  Normative References

   [I-D.thubert-roll-unaware-leaves]
              Thubert, P., "Routing for RPL Leaves", draft-thubert-roll-
              unaware-leaves-06 (work in progress), November 2018.

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



Robles, et al.            Expires July 27, 2019                [Page 49]


Internet-Draft               RPL-data-plane                 January 2019


   [RFC2827]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
              May 2000, <https://www.rfc-editor.org/info/rfc2827>.

   [RFC6550]  Winter, T., Ed., Thubert, P., Ed., 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,
              DOI 10.17487/RFC6550, March 2012,
              <https://www.rfc-editor.org/info/rfc6550>.

   [RFC6553]  Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
              Power and Lossy Networks (RPL) Option for Carrying RPL
              Information in Data-Plane Datagrams", RFC 6553,
              DOI 10.17487/RFC6553, March 2012,
              <https://www.rfc-editor.org/info/rfc6553>.

   [RFC6554]  Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
              Routing Header for Source Routes with the Routing Protocol
              for Low-Power and Lossy Networks (RPL)", RFC 6554,
              DOI 10.17487/RFC6554, March 2012,
              <https://www.rfc-editor.org/info/rfc6554>.

   [RFC7045]  Carpenter, B. and S. Jiang, "Transmission and Processing
              of IPv6 Extension Headers", RFC 7045,
              DOI 10.17487/RFC7045, December 2013,
              <https://www.rfc-editor.org/info/rfc7045>.

   [RFC8138]  Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,
              "IPv6 over Low-Power Wireless Personal Area Network
              (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,
              April 2017, <https://www.rfc-editor.org/info/rfc8138>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

13.2.  Informative References







Robles, et al.            Expires July 27, 2019                [Page 50]


Internet-Draft               RPL-data-plane                 January 2019


   [DDOS-KREBS]
              Goodin, D., "Record-breaking DDoS reportedly delivered by
              >145k hacked cameras", September 2016,
              <http://arstechnica.com/security/2016/09/botnet-of-145k-
              cameras-reportedly-deliver-internets-biggest-ddos-ever/>.

   [I-D.ietf-6lo-backbone-router]
              Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6
              Backbone Router", draft-ietf-6lo-backbone-router-10 (work
              in progress), January 2019.

   [I-D.ietf-6tisch-dtsecurity-secure-join]
              Richardson, M., "6tisch Secure Join protocol", draft-ietf-
              6tisch-dtsecurity-secure-join-01 (work in progress),
              February 2017.

   [I-D.ietf-anima-autonomic-control-plane]
              Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
              Control Plane (ACP)", draft-ietf-anima-autonomic-control-
              plane-18 (work in progress), August 2018.

   [I-D.ietf-anima-bootstrapping-keyinfra]
              Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
              S., and K. Watsen, "Bootstrapping Remote Secure Key
              Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
              keyinfra-18 (work in progress), January 2019.

   [RFC2473]  Conta, A. and S. Deering, "Generic Packet Tunneling in
              IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
              December 1998, <https://www.rfc-editor.org/info/rfc2473>.

   [RFC4192]  Baker, F., Lear, E., and R. Droms, "Procedures for
              Renumbering an IPv6 Network without a Flag Day", RFC 4192,
              DOI 10.17487/RFC4192, September 2005,
              <https://www.rfc-editor.org/info/rfc4192>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/info/rfc4443>.

   [RFC5406]  Bellovin, S., "Guidelines for Specifying the Use of IPsec
              Version 2", BCP 146, RFC 5406, DOI 10.17487/RFC5406,
              February 2009, <https://www.rfc-editor.org/info/rfc5406>.






Robles, et al.            Expires July 27, 2019                [Page 51]


Internet-Draft               RPL-data-plane                 January 2019


   [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,
              <https://www.rfc-editor.org/info/rfc6775>.

   [RFC6997]  Goyal, M., Ed., Baccelli, E., Philipp, M., Brandt, A., and
              J. Martocci, "Reactive Discovery of Point-to-Point Routes
              in Low-Power and Lossy Networks", RFC 6997,
              DOI 10.17487/RFC6997, August 2013,
              <https://www.rfc-editor.org/info/rfc6997>.

   [RFC7102]  Vasseur, JP., "Terms Used in Routing for Low-Power and
              Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
              2014, <https://www.rfc-editor.org/info/rfc7102>.

   [RFC7416]  Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,
              and M. Richardson, Ed., "A Security Threat Analysis for
              the Routing Protocol for Low-Power and Lossy Networks
              (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,
              <https://www.rfc-editor.org/info/rfc7416>.

   [RFC8180]  Vilajosana, X., Ed., Pister, K., and T. Watteyne, "Minimal
              IPv6 over the TSCH Mode of IEEE 802.15.4e (6TiSCH)
              Configuration", BCP 210, RFC 8180, DOI 10.17487/RFC8180,
              May 2017, <https://www.rfc-editor.org/info/rfc8180>.

Authors' Addresses

   Maria Ines Robles
   Aalto University
   Innopoli
   Espoo  02150
   Finland

   Email: mariainesrobles@gmail.com


   Michael C. Richardson
   Sandelman Software Works
   470 Dawson Avenue
   Ottawa, ON  K1Z 5V7
   CA

   Email: mcr+ietf@sandelman.ca
   URI:   http://www.sandelman.ca/mcr/





Robles, et al.            Expires July 27, 2019                [Page 52]


Internet-Draft               RPL-data-plane                 January 2019


   Pascal Thubert
   Cisco Systems, Inc
   Village d'Entreprises Green Side 400, Avenue de Roumanille
   Batiment T3, Biot - Sophia Antipolis    06410
   France

   Email: pthubert@cisco.com












































Robles, et al.            Expires July 27, 2019                [Page 53]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/