Subject: [Roll] Comments on [draft-richardson-6tisch-roll-enrollment-priority-00]

From: "Georgios Z. Papadopoulos" <[email-masked]>
Date: Tue, 20 Feb 2018 11:59:40 +0100

Hello Michael,

I have some (maybe minor) comments on draft-richardson-6tisch-roll-enrollment-priority-00 draft.

Best,
Georgios

————————————————————
Georgios Z. Papadopoulos, Ph.D.
Associate Professor, IMT Atlantique

web: 	 www.georgiospapadopoulos.com <http://www.georgiospapadopoulos.com/>
twitter: 	@gzpapadopoulos <https://twitter.com/gzpapadopoulos?ref_src=twsrc%5Etfw&ref_url=http://georgiospapadopoulos.com/>
——
Consider to submit @AdHoc-Now 2018 <http://conferences.imt-atlantique.fr/adhocnow2018/>
————————————————————

6lo Working Group                                          M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Informational                         February 02, 2018
Expires: August 6, 2018

           Enabling secure network enrollment in RPL networks
          draft-richardson-6tisch-roll-enrollment-priority-00

Abstract

   [I-D.richardson-6tisch-join-enhanced-beacon] defines a method by
   which a potential [I-D.ietf-6tisch-minimal-security] can announce
   itself as a available for new Pledges to Join a network.  The
   announcement includes a priority for join.  This document provides a
   mechanism by which a RPL DODAG root can disable join announcements,
   or adjust the base priority for join operation.

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
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   This Internet-Draft will expire on August 6, 2018.

Copyright Notice

   Copyright (c) 2018 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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   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Protocol Definition . . . . . . . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   4.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Change history . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [RFC7554] describes the use of the time-slotted channel hopping
   (TSCH) mode of [ieee802154].  [I-D.ietf-6tisch-minimal-security] and
   [I-D.ietf-6tisch-dtsecurity-secure-join] describe mechanisms by which
   a new node (the "pledge)" can use a friendly router as a Join Proxy.
   [I-D.richardson-6tisch-join-enhanced-beacon] describes an extension
   to the 802.15.4 Enhanced Beacon that is used by a Join Proxy to
   announce its existence such that Pledges can find them.

   It has become clear that not every routing member of the mesh ought
   to announce itself as a Join Proxy.  There are a variety of local
   reasons by which a 6LR might not want to provide the Join Proxy
   function.  They include available battery power, already committed
   network bandwidth, and also total available memory available for Join
   proxy neighbor cache slots.

   There are other situations where the operator of the network would
   like to selective enable or disable the join process in a particular
   DODAG.

   As the join process involves permitting unencrypted traffic into the
   best effort part of a (TSCH) network, it would be better to have the
   join process off when no new nodes are expected.

   A network operator might also be able to recognize when certain parts
   of the network are overloaded and can not accomodate additional join
   traffic, and it would like to adjust the join priority among all
   nodes in the subtree of a congested link.
[GP] It MUST be in a centralized manner by a network operator? A node itself can not decide if it is or not overloaded (in terms of available bandwidth) and, thus, we may have less additional control traffic in the network?

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   This document describes an RPL DIO option that can be used to
   announce a minimum join priority.

1.1.  Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
   [RFC2119] and indicate requirement levels for compliant STuPiD
   implementations.

   In addition, the terminology of [I-D.ietf-6tisch-terminology] and
   from [I-D.ietf-anima-voucher] are used.

2.  Protocol Definition

   The following option is defined to transmission in the DIO issued by
   the DODAG root.  It may also be added by a router on part of the sub-
   tree as a result of some (out of scope for this document) management
   function.
[GP] When such DIO Option will be issued? What would be the trigger?

   6LRs that see this DIO Option SHOULD increment the minimum priority
   if they observe congestion on the channel used for join traffic.
   (TODO: how much?  Do we need to standardize this?)
[GP] On the channel, I assume you mean the radio channel? 
[GP] Shouldn’t be the link congestion, instead of radio channel? I mean, a link between A and B can be congested, independently the radio channel.

   A 6LR which would otherwise be willing to act as a Join Proxy, will
   examine the minimum priority field, and to that number, add any
   additional local consideration (such as upstream congestion).  The
   resulting priority, if less than 0x7f should enable the Join Proxy
   function.

       0                   1                   2
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Type = TBD01|Opt Length = 1|R| min. priority  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   min.priority  a 7 bit field which provides a base value for the
      Enhanced Beacon Join priority.  A value of 0x7f (127) disables the
      Join Proxy function entirely.

   R  a reserved bit that SHOULD be set to 0 by senders, and MUST be
      ignored by receivers.  The reserved bit SHOULD be copied to
      options created.

[GP] I assume this is the DIO Option field, i.e., DAGMC type?

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3.  Security Considerations

   As per [RFC7416], RPL control frames either run over a secured layer
   2, or use the [RFC6550] Secure DIO methods.  This option can be
   placed into either a "clear" (layer-2 secured) DIO, or a layer-3
   Secure DIO.  As such this option will have both integrity and
   confidentiality mechanisms applied to it.

   A malicious node (that was part of the RPL control plane) could see
   these options and could, based upon the observed minimal join
   priority signal a confederate that it was a good time to send
   malicious join traffic.

   A malicious node (that was part of the RPL control plane) could also
   send DIOs with a different minimal join priority which would cause
   downstream mesh routers to change their Join Proxy behaviour.  Lower
   minimal priorities would cause downstream nodes to accept more
   pledges than the network was expecting, and higher minimal priorities
   cause the join process to stall.

   The use of layer-2 or layer-3 security for RPL control messages
   prevents the above two attacks.

4.  Privacy Considerations

   There are no new privacy issues caused by this extension.

5.  IANA Considerations

   Allocate a new number TBD01 from Registry RPL Control Message
   Options.  This entry should be called Minimum Join Priority.

6.  Acknowledgements

   none so far.

7.  References

7.1.  Normative References

   [I-D.ietf-6tisch-minimal-security]
              Vucinic, M., Simon, J., Pister, K., and M. Richardson,
              "Minimal Security Framework for 6TiSCH", draft-ietf-
              6tisch-minimal-security-04 (work in progress), October
              2017.

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   [I-D.richardson-6tisch-join-enhanced-beacon]
              Dujovne, D. and M. Richardson, "IEEE802.15.4 Informational
              Element encapsulation of 6tisch Join Information", draft-
              richardson-6tisch-join-enhanced-beacon-03 (work in
              progress), January 2018.

   [ieee802154]
              IEEE Standard, ., "802.15.4-2015 - IEEE Standard for Low-
              Rate Wireless Personal Area Networks (WPANs)", 2015,
              <http://standards.ieee.org/findstds/
              standard/802.15.4-2015.html>.

   [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>.

   [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>.

   [RFC7554]  Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
              IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
              Internet of Things (IoT): Problem Statement", RFC 7554,
              DOI 10.17487/RFC7554, May 2015,
              <https://www.rfc-editor.org/info/rfc7554>.

7.2.  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-13 (work
              in progress), November 2017.

   [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.

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   [I-D.ietf-6tisch-terminology]
              Palattella, M., Thubert, P., Watteyne, T., and Q. Wang,
              "Terminology in IPv6 over the TSCH mode of IEEE
              802.15.4e", draft-ietf-6tisch-terminology-09 (work in
              progress), June 2017.

   [I-D.ietf-anima-voucher]
              Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
              "Voucher Profile for Bootstrapping Protocols", draft-ietf-
              anima-voucher-07 (work in progress), January 2018.

   [RFC8137]  Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information
              Element for the IETF", RFC 8137, DOI 10.17487/RFC8137, May
              2017, <https://www.rfc-editor.org/info/rfc8137>.

Appendix A.  Change history

   version 00.

Author's Address

   Michael Richardson
   Sandelman Software Works

   Email: [email-masked]

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---

From: Michael Richardson <[email-masked]>
Date: Tue, 20 Feb 2018 07:45:11 -0500

Georgios Z. Papadopoulos <[email-masked]> wrote:
    > I have some (maybe minor) comments on
    > draft-richardson-6tisch-roll-enrollment-priority-00 draft.

It would be great if you has used Usenet > quoting, and just left the parts of
the document which you wanted to comment on.  I have reformatted for the
list, without answering anything yet.

    > nodes in the subtree of a congested link.
    
    GP> It MUST be in a centralized manner by a network operator? A node
    GP> itself can not decide if it is or not overloaded (in terms of
    GP> available bandwidth) and, thus, we may have less additional control
    GP> traffic in the network? 

    > tree as a result of some (out of scope for this document) management
    
    GP> When such DIO Option will be issued? What would be the trigger?

    > (TODO: how much?  Do we need to standardize this?)
    
    GP> On the channel, I assume you mean the radio channel? 
    GP> Shouldn’t be the link congestion, instead of radio channel? I mean, a
    GP> link between A and B can be congested, independently the radio
    GP> channel. 

    > ignored by receivers.  The reserved bit SHOULD be copied to

    GP> I assume this is the DIO Option field, i.e., DAGMC type?

-- 
Michael Richardson <[email-masked]>, Sandelman Software Works
 -= IPv6 IoT consulting =-