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Versions: (draft-koutsiamanis-roll-nsa-extension) 00 01

ROLL                                                R. Koutsiamanis, Ed.
Internet-Draft                                           G. Papadopoulos
Intended status: Standards Track                            N. Montavont
Expires: September 12, 2019                               IMT Atlantique
                                                              P. Thubert
                                                                   Cisco
                                                          March 11, 2019


RPL DAG Metric Container Node State and Attribute object type extension
                    draft-ietf-roll-nsa-extension-01

Abstract

   Implementing Packet Replication and Elimination from / to the RPL
   root requires the ability to forward copies of packets over different
   paths via different RPL parents.  Selecting the appropriate parents
   to achieve ultra-low latency and jitter requires information about a
   node's parents.  This document details what information needs to be
   transmitted and how it is encoded within a packet to enable this
   functionality.

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 September 12, 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



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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Alternative Parent Selection  . . . . . . . . . . . . . . . .   4
     3.1.  Common Ancestor Strict  . . . . . . . . . . . . . . . . .   4
     3.2.  Common Ancestor Medium  . . . . . . . . . . . . . . . . .   5
     3.3.  Common Ancestor Relaxed . . . . . . . . . . . . . . . . .   5
     3.4.  Usage . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Node State and Attribute (NSA) object type extension  . . . .   6
     4.1.  Usage . . . . . . . . . . . . . . . . . . . . . . . . . .   8
       4.1.1.  DAG Metric Container fields . . . . . . . . . . . . .   9
       4.1.2.  Node State and Attribute fields . . . . . . . . . . .   9
     4.2.  Compression . . . . . . . . . . . . . . . . . . . . . . .   9
   5.  Controlling PRE . . . . . . . . . . . . . . . . . . . . . . .   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Informative references  . . . . . . . . . . . . . . . . .  10
     8.2.  Other Informative References  . . . . . . . . . . . . . .  11
   Appendix A.  Implementation Status  . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   Industrial network applications have stringent requirements on
   reliability and predictability, and typically leverage 1+1
   redundancy, aka Packet Replication and Elimination (PRE)
   [I-D.papadopoulos-6tisch-pre-reqs] to achieve their goal.  In order
   for wireless networks to be able to be used in such applications, the
   principles of Deterministic Networking [I-D.ietf-detnet-architecture]
   lead to designs that aim at maximizing packet delivery rate and
   minimizing latency and jitter.  Additionally, given that the network
   nodes often do not have an unlimited power supply, energy consumption
   needs to be minimized as well.

   As an example, to meet this goal, IEEE Std. 802.15.4
   [IEEE802154-2015] provides Time-Slotted Channel Hopping (TSCH), a
   mode of operation which uses a fixed communication schedule to allow
   deterministic medium access as well as channel hopping to work around
   radio interference.  However, since TSCH uses retransmissions in the




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   event of a failed transmission, end-to-end delay and jitter
   performance can deteriorate.

   Furthermore, the 6TiSCH working group, focusing on IPv6 over IEEE
   Std. 802.15.4-TSCH, has worked on the issues previously highlighted
   and produced the "6TiSCH Architecture" [I-D.ietf-6tisch-architecture]
   to address that case.  Building on this architecture, "Exploiting
   Packet Replication and Elimination in Complex Tracks in 6TiSCH LLNs"
   [I-D.papadopoulos-6tisch-pre-reqs] leverages PRE to improve the
   Packet Delivery Ratio (PDR), provide a hard bound to the end-to-end
   latency, and limit jitter.

   PRE is a general method of maximizing packet delivery rate and
   potentially minimizing latency and jitter, not limited to 6TiSCH.
   More specifically, PRE achieves a controlled redundancy by laying
   multiple forwarding paths through the network and using them in
   parallel for different copies of a same packet.  PRE can follow the
   Destination-Oriented Directed Acyclic Graph (DODAG) formed by RPL
   from a node to the root.  Building a multi-path DODAG can be achieved
   based on the RPL capability of having multiple parents for each node
   in a network, a subset of which is used to forward packets.  In order
   for this subset to be defined, a RPL parent subset selection
   mechanism, which falls within the remit of the RPL Objective Function
   (OF), needs to have specific path information.  The specification of
   the transmission of this information is the focus of this document.

   More concretely, this specification focuses on the extensions to the
   DAG Metric Container [RFC6551] required for providing the PRE
   mechanism a part of the information it needs to operate.  This
   information is the RPL [RFC6550] parent address set of a node and it
   must be sent to potential children nodes of the node.  The RPL DIO
   Control Message is the canonical way of broadcasting this kind of
   information and therefore its DAG Metric Container [RFC6551] field is
   used to append a Node State and Attribute (NSA) object.  The node's
   parent address set is stored as an optional TLV within the NSA
   object.  This specification defines the type value and structure for
   this TLV.

2.  Terminology

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

   The draft uses the following Terminology:

   Packet Replication and Elimination (PRE)  The sending of multiple
      copies of a packet using multi-path forwarding over a multi-hop



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      network and the consolidation of multiple received packet copies
      to control flooding.  See "Exploiting Packet Replication and
      Elimination in Complex Tracks in 6TiSCH LLNs"
      [I-D.papadopoulos-6tisch-pre-reqs] for more.

   Alternative Parent (AP) Selection  The problem of how to select the
      next hop target node for a packet copy to be forwarded to when
      performing packet replication.

3.  Alternative Parent Selection

   In the RPL protocol, each node maintains a list of potential parents.
   For PRE, the PP node is defined to be the same as the RPL DODAG
   Preferred Parent (PP) node.  Furthermore, to construct an alternative
   path toward the root, in addition to the PP node, each node in the
   network registers an AP node as well from its Parent Set (PS).  There
   are multiple alternative methods of selecting the AP node,
   functionality which is included in operation of the RPL Objective
   Function (OF).  A scheme which allows the two paths to remain
   correlated is detailed here.  More specifically, in this scheme a
   node will select an alternative parent node close to its PP node to
   allow the operation of overhearing between parents.  If multiple
   potential APs match this condition, the AP with the lowest rank will
   be registered.

   There are at least three methods of performing the alternative parent
   selection based on common ancestors (CA), named Common Ancestor
   Strict, Common Ancestor Medium, and Common Ancestor Relaxed,
   depending on how restrictive the selection process is.  A more
   restrictive method will limit flooding but might fail to select an
   appropriate alternative parent, while a less restrictive one will
   more often find an appropriate alterantive parent but might increase
   flooding.

3.1.  Common Ancestor Strict

   In CA Strict, the node will check if its Preferred Grand Parent
   (PGP), the PP of its PP, is the same as the PP of the potential AP.













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               (  R  ) root
                  .                      PS(S) = {A, B, C, D}
                  .                      PP(S) = C
                  .                      PP(PP(S)) = Y
                  .
                                         PS(A) = {W, X}
  ( W )    ( X )    ( Y )    ( Z )       PP(A) = X
    ^ ^   ^^ ^ ^    ^^^^ ^   ^ ^^
    |  \ //  |  \ //  ||  \ /  ||        PS(B) = {W, X, Y}
    |   //   |   //   ||   /   ||        PP(B) = Y
    |  // \  |  // \  ||  / \  ||
    | //   \ | //   \ || /   \ ||        PS(C) = {X, Y, Z}
  ( A )    ( B )    ( C )    ( D )       PP(C) = Y
      ^        ^      ^^     ^
       \        \     ||    /            PS(D) = {Y, Z}
         \       \    ||   /             PP(D) = Z
           \      \   ||  /
             \----\\  || /               || Preferred Parent
                  (   S   ) source       |  Potential Alternative Parent

   Figure 1: Example Common Ancestor Strict Alternative Parent Selection
                                  method

   For example, in Figure 1, the source node S must know its grandparent
   sets both through nodes A, B, C, and D.  The Parent Sets (PS) and the
   Preferred Parents (PS) of nodes A, B, C, and D are shown on the side
   of the figure.  The CA Strict parent selection method will select an
   AP for node S for which PP(PP(S)) = PP(AP).  Therefore, node S can
   decide to use node B as its AP node, since PP(PP(S)) = Y = PP(B).

3.2.  Common Ancestor Medium

   In CA Medium, the node will check if its Preferred Grand Parent
   (PGP), the PP of its PP, is contained in the PS of the potential AP.

   Using the same example, in Figure 1, the CA Medium parent selection
   method will select an AP for node S for which PP(PP(S)) in PS(AP).
   Therefore, node S can decide to use node B or D as its AP node, since
   given that PP(PP(S)) = Y, for node B PS(B) = {W, X, Y} and for node D
   PD(D) = {Y, Z}.

3.3.  Common Ancestor Relaxed

   In CA Relaxed, the node will check if its the Parent Set (PS) of its
   Preferred Parent (PP), has a common node with the PS of the potential
   AP.





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   Using the same example, in Figure 1, the CA Relaxed parent selection
   method will select an AP for node S for which PS(PP(S)) has a non-
   empty intersection with PS(AP).  Therefore, node S can decide to use
   node A, B or D as its AP node.  Given that PS(PP(S)) = {X, Y, Z} the
   alternative parent selection process evaluates the nodes:

   o  Node A: PS(A) = {W, X} and the common nodes are {X}

   o  Node B: PS(B) = {W, X, Y} and the common nodes are {X, Y}

   o  Node D: PS(D) = {Y, Z} and the common nodes are {Y, Z}

3.4.  Usage

   The PS information can be used by any of the described Alternative
   Parent selection methods or other ones not described here, depending
   on requirements.  This document does not suggest a specific AP
   selection method.  Additionally, it is OPTIONAL for all nodes to use
   the same AP selection method.  Different nodes MAY use different AP
   selection methods, since the selection method is local to each node.
   For example, using different methods can be used to vary the
   transmission reliability in each hop.

4.  Node State and Attribute (NSA) object type extension

   In order to select their AP node, nodes need to be aware of their
   grandparent node sets.  Within RPL [RFC6550], the nodes use the DODAG
   Information Object (DIO) Control Message to broadcast information
   about themselves to potential children.  However, RPL [RFC6550], does
   not define how to propagate parent set related information, which is
   what this document addresses.

   DIO messages can carry multiple options, out of which the DAG Metric
   Container option [RFC6551] is the most suitable structurally and
   semantically for the purpose of carrying the parent set.  The DAG
   Metric Container option itself can carry different nested objects,
   out of which the Node State and Attribute (NSA) [RFC6551] is
   appropriate for transferring generic node state data.  Within the
   Node State and Attribute it is possible to store optional TLVs
   representing various node characteristics.  As per the Node State and
   Attribute (NSA) [RFC6551] description, no TLV has been defined for
   use.  This document defines one TLV for the purpose of transmitting a
   node's parent set.








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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | RPLInstanceID |Version Number |             Rank              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |G|0| MOP | Prf |     DTSN      |     Flags     |   Reserved    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +                            DODAGID                            +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | DAGMC Type (2)| DAGMC Length  |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |                                                               |
   //                   DAG Metric Container data                 //
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     Figure 2: Example DIO Message with a DAG Metric Container option

   Figure 2 shows the structure of the DIO Control Message when a DAG
   Metric Container option is included.  The DAG Metric Container option
   type (DAGMC Type in Figure 2) has the value 0x02 as per the IANA
   registry for the RPL Control Message Options, and is defined in
   [RFC6550].  The DAG Metric Container option length (DAGMC Length in
   Figure 2) expresses the DAG Metric Container length in bytes.  DAG
   Metric Container data holds the actual data and is shown expanded in
   Figure 3.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |Routing-MC-Type|Res Flags|P|C|O|R| A   |  Prec | Length (bytes)| |MC
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |     Res       |  Flags    |A|O|    PS  type   |   PS  Length  | |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |NSA
  |   6LoRH type  | 6LoRH-compressed PS IPv6 address(es) ...        |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Figure 3: DAG Metric Container (MC) data with Node State and
                   Attribute (NSA) object body and a TLV




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   The structure of the DAG Metric Container data in the form of a Node
   State and Attribute (NSA) object with a TLV in the NSA Optional TLVs
   field is shown in Figure 3.  The first 32 bits comprise the DAG
   Metric Container header and all the following bits are part of the
   Node State and Attribute object body, as defined in [RFC6551].  This
   document defines a new TLV, which CAN be carried in the Node State
   and Attribute (NSA) object Optional TLVs field.  The TLV is named
   Parent Set and is abbreviated as PS in Figure 3.

   PS type:  The type of the Parent Set TLV.  The value is TBD1.

   PS Length:  The total length of the TLV value field (PS IPv6
         address(es)) in bytes.

   6LoRH type:  The type of 6LoRH compression applied to the PS IPv6
         addresses.https://tools.ietf.org/html/rfc8138#section-5.1 For
         detailed usage see Section 5.1 of [RFC8138].  As an overview,
         the compressed size of each IPv6 address in the "6LoRH-
         compressed PS IPv6 address(es)" field depending on the value of
         "6LoRH type" is shown in Figure 4.

                +-----------+----------------------+
                |   6LoRH   | Length of compressed |
                |   Type    | IPv6 address (bytes) |
                +-----------+----------------------+
                |    0      |       1              |
                |    1      |       2              |
                |    2      |       4              |
                |    3      |       8              |
                |    4      |      16              |
                +-----------+----------------------+


                       Figure 4: The SRH-6LoRH Types

   6LoRH-compressed PS IPv6 address(es):  A sequence of zero or more
         IPv6 addresses belonging to a node's parent set.  Each address
         requires 16 bytes.  The order of the parents in the parent set
         is in decreasing preference based on the Objective Function
         [RFC6550] used by the node.

4.1.  Usage

   The PS SHOULD be used in the process of parent selection, and
   especially in alternative parent selection, since it can help the
   alternative path from significantly deviating from the preferred
   path.  The Parent Set is information local to the node that
   broadcasts it.



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4.1.1.  DAG Metric Container fields

   Given the intended usage, when using the PS, the NSA object it is
   contained in MUST be used as a constraint in the DAG Metric
   Container.  More specifically, using the PS places the following
   requirements on the DAG Metric Container header fields:

   o  'P' flag: MUST be cleared, since PS is used only with constraints.

   o  'C' flag: MUST be set, since PS is used only with constraints.

   o  'O' flag: Used as per [RFC6550], to indicated optionality.

   o  'R' flag: MUST be cleared, since PS is used only with constraints.

   o  'A' Field: MUST be set to 0 and ignored, since PS is used only
      with constraints.

   o  'Prec' Field: Used as per [RFC6550].

4.1.2.  Node State and Attribute fields

   For clarity reasons, the usage of the PS places no additional
   restrictions on the NSA flags ('A' and 'O'), which can be used as
   normally defined in [RFC6550].

4.2.  Compression

   The PS IPv6 address(es) field in the Parent Set TLV add overhead due
   to their size.  Therefore, compression is highly desirable in order
   for this extension to be usable.  To meet this goal, a good
   compression method candidate is [RFC8138] 6LoWPAN Routing Header
   (6LoRH).  Furthermore, the PS IPv6 address(es) belong by definition
   to nodes in the same RPL DODAG and are stored in the form of a list
   of addresses.  This makes this field a good candidate for the use of
   the same compression as in Source Routing Header 6LoRH (SRH-6LoRH),
   achieving efficiency and implementation reuse.  Therefore, the PS
   IPv6 address(es) field SHOULD be compressed using the compression
   method for Source Routing Header 6LoRH (SRH-6LoRH) [RFC8138].

5.  Controlling PRE

   PRE is very helpful when the aim is to increase reliability for a
   certain path, however it's use creates additional traffic as part of
   the replication process.  It is conceivable that not all paths have
   stringent reliability requirements.  Therefore, a way to control
   whether PRE is applied to a path's packets SHOULD be implemented.
   For example, a traffic class label can be used to determine this



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   behaviour per flow type as described in Deterministic Networking
   Architecture [I-D.ietf-detnet-architecture].

6.  Security Considerations

   The structure of the DIO control message is extended, within the pre-
   defined DIO options.  Therefore, the security mechanisms defined in
   RPL [RFC6550] apply to this proposed extension.

7.  IANA Considerations

   This proposal requests the allocation of a new value TBD1 for the
   "Parent Set" TLV in the Routing Metric/Constraint TLVs sub-registry
   from IANA.

8.  References

8.1.  Informative references

   [I-D.ietf-6tisch-architecture]
              Thubert, P., "An Architecture for IPv6 over the TSCH mode
              of IEEE 802.15.4", draft-ietf-6tisch-architecture-20 (work
              in progress), March 2019.

   [I-D.ietf-detnet-architecture]
              Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", draft-ietf-
              detnet-architecture-12 (work in progress), March 2019.

   [I-D.papadopoulos-6tisch-pre-reqs]
              Papadopoulos, G., Montavont, N., and P. Thubert,
              "Exploiting Packet Replication and Elimination in Complex
              Tracks in 6TiSCH LLNs", draft-papadopoulos-6tisch-pre-
              reqs-02 (work in progress), July 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>.

   [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>.





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   [RFC6551]  Vasseur, JP., Ed., Kim, M., Ed., Pister, K., Dejean, N.,
              and D. Barthel, "Routing Metrics Used for Path Calculation
              in Low-Power and Lossy Networks", RFC 6551,
              DOI 10.17487/RFC6551, March 2012,
              <https://www.rfc-editor.org/info/rfc6551>.

   [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>.

8.2.  Other Informative References

   [IEEE802154-2015]
              IEEE standard for Information Technology, "IEEE Std
              802.15.4-2015 Standard for Low-Rate Wireless Personal Area
              Networks (WPANs)", December 2015.

8.3.  URIs

   [1] https://github.com/ariskou/contiki/tree/draft-koutsiamanis-roll-
       nsa-extension

   [2] https://code.wireshark.org/review/gitweb?p=wireshark.git;a=commit
       ;h=e2f6ba229f45d8ccae2a6405e0ef41f1e61da138

Appendix A.  Implementation Status

   A research-stage implementation of the PRE mechanism using the
   proposed extension as part of a 6TiSCH IOT use case was developed at
   IMT Atlantique, France by Tomas Lagos Jenschke and Remous-Aris
   Koutsiamanis.  It was implemented on the open-source Contiki OS and
   tested with the Cooja simulator.  The DIO DAGMC NSA extension is
   implemented with a configurable number of parents from the parent set
   of a node to be reported.
















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                    ( R )


   (11)   (12)   (13)   (14)   (15)   (16)


   (21)   (22)   (23)   (24)   (25)   (26)


   (31)   (32)   (33)   (34)   (35)   (36)


   (41)   (42)   (43)   (44)   (45)   (46)


   (51)   (52)   (53)   (54)   (55)   (56)


                    ( S )

                       Figure 5: Simulation Topology

   The simulation setup is:

   Topology:  32 nodes structured in regular grid as show in Figure 5.
      Node S (source) is the only data packet sender, and send data to
      node R (root).  The parent set of each node (except R) is all the
      nodes in the immediatelly higher row, the immediatelly above 6
      nodes.  For example, each node in {51, 52, 53, 54, 55, 56} is
      connected to all of {41, 42, 43, 44, 45, 46}.  Node 11, 12, 13,
      14, 15, 16 have a single upwards link to R.

   MAC:  TSCH with 1 retransmission

   Platform:  Cooja

   Schedule:  Static, 2 timeslots per link from each node to each parent
      in its parent set, 1 broadcast EB slot, 1 sender-based shared
      timeslot (for DIO and DIS) per node (total of 32).

   Simulation lifecycle:  Allow link formation for 100 seconds before
      starting to send data packets.  Afterwards, S sends data packets
      to R.  The simulation terminates when 1000 packets have been sent
      by S.

   Radio Links:  Links are reset uniformly randomly between 70% and 100%
      every 60 seconds.




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   Traffic Pattern:  CBR, S sends one non-fragmented UDP packet every 5
      seconds to R.

   PS extension size:  3 parents.

   Routing Methods:

      *  RPL: The default RPL non-PRE implementation in Contiki OS.

      *  2nd ETX: PRE with a parent selection method which picks as AP
         the 2nd best parent in the parent set based on ETX.

      *  CA Strict: As described in Section 3.1.

      *  CA Medium: As described in Section 3.2.

                            Simulation results:

   +----------+---------------+------------------+---------------------+
   | Routing  |       Average |          Average |             Average |
   | Method   |        Packet |        Traversed | Duplications/packet |
   |          | Delivery Rate | Nodes/packet (#) |                 (#) |
   |          |           (%) |                  |                     |
   +----------+---------------+------------------+---------------------+
   | RPL      |         82.70 |             5.56 |                7.02 |
   | 2nd ETX  |         99.38 |            14.43 |               31.29 |
   | CA       |         97.32 |             9.86 |               18.23 |
   | Strict   |               |                  |                     |
   | CA       |         99.66 |            13.75 |               28.86 |
   | Medium   |               |                  |                     |
   +----------+---------------+------------------+---------------------+

   Links:

   o  Contiki OS DIO DAGMC NSA extension (draft-koutsiamanis-roll-nsa-
      extension branch) [1]

   o  Wireshark dissectors (for the optional TLV, i.e., PS) - currently
      merged / in master [2]

Authors' Addresses










Koutsiamanis, et al.   Expires September 12, 2019              [Page 13]


Internet-Draft      RPL MC NSA object type extension          March 2019


   Remous-Aris Koutsiamanis (editor)
   IMT Atlantique
   Office B00 - 126A
   2 Rue de la Chataigneraie
   Cesson-Sevigne - Rennes  35510
   FRANCE

   Phone: +33 299 12 70 49
   Email: aris@ariskou.com


   Georgios Papadopoulos
   IMT Atlantique
   Office B00 - 114A
   2 Rue de la Chataigneraie
   Cesson-Sevigne - Rennes  35510
   FRANCE

   Phone: +33 299 12 70 04
   Email: georgios.papadopoulos@imt-atlantique.fr


   Nicolas Montavont
   IMT Atlantique
   Office B00 - 106A
   2 Rue de la Chataigneraie
   Cesson-Sevigne - Rennes  35510
   FRANCE

   Phone: +33 299 12 70 23
   Email: nicolas.montavont@imt-atlantique.fr


   Pascal Thubert
   Cisco Systems, Inc
   Building D
   45 Allee des Ormes - BP1200
   MOUGINS - Sophia Antipolis  06254
   FRANCE

   Phone: +33 497 23 26 34
   Email: pthubert@cisco.com









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