Re: [Roll] [6tisch] Thomas' remarks on draft-robles-roll-useofrplinfo-00

Robert Cragie <robert.cragie@gridmerge.com> Fri, 03 July 2015 16:55 UTC

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To: Thomas Watteyne <watteyne@eecs.berkeley.edu>
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Subject: Re: [Roll] [6tisch] Thomas' remarks on draft-robles-roll-useofrplinfo-00
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Hi all,

Happy to help out - I will take a closer look next week.

A couple of points on first cursory read:

1) The control plane and data plane concepts should be distinct. By all
means talk about control plane (i.e. RPL messages) and how they are
formatted but keep this distinct from the structure of data plane packets
used where RPL is used for routing. It is the data plane where IP-in-IP,
RPL HbH and source routing headers are used and where the focus of the
document should really be.
2) In the data plane, there are potentially two sorts of leaf node to
consider: a) RPL-aware and b) not RPL-aware. This is important as it
determines whether IP-in-IP is needed between nodes in a 6LoWPAN.

Robert

On 3 July 2015 at 14:52, Thomas Watteyne <watteyne@eecs.berkeley.edu> wrote:

> Ines, Michael,
> Please find my remarks about draft-robles-roll-useofrplinfo-00 below.
> Thomas
>
> ----
>
> TW> overall comments
> TW> - this is a super important informational draft, which
> TW>   clears up a lot of questions
> TW> - I think it would be very useful to have more example
> TW>   packets. We are building such information for the upcoming 6TiSCH
> TW>   plugtest, so I can help there.
> TW> - After this is done I would recommend to ask explicitly for
> TW>   reviewers. Robert Cragie should be
> TW>   on the list of people to ask; he has provided very useful info
> TW>   during our discussions.
>
>
> ROLL Working Group                                           M.I. Robles
> Internet-Draft                                                  Ericsson
> Intended status: Informational                             M. Richardson
> Expires: December 29, 2015                                           SSW
>                                                            June 27, 2015
>
>
>               When to use RFC 6553, 6554 and IPv6-in-IPv6
>                    draft-robles-roll-useofrplinfo-00
>
> Abstract
>
>    This document states different cases where RFC 6553, RFC 6554 and
>    IPv6-in-IPv6 encapsulation is required to set the bases to help
>    defining the compression of RPL routing information in LLN
>    environments.
>
> Status of This Memo
>
>    This Internet-Draft is submitted in full conformance with the
>    provisions of BCP 78 and BCP 79.
>
>    Internet-Drafts are working documents of the Internet Engineering
>    Task Force (IETF).  Note that other groups may also distribute
>    working documents as Internet-Drafts.  The list of current Internet-
>    Drafts is at http://datatracker.ietf.org/drafts/current/.
>
>    Internet-Drafts are draft documents valid for a maximum of six months
>    and may be updated, replaced, or obsoleted by other documents at any
>    time.  It is inappropriate to use Internet-Drafts as reference
>    material or to cite them other than as "work in progress."
>
>    This Internet-Draft will expire on December 29, 2015.
>
> Copyright Notice
>
>    Copyright (c) 2015 IETF Trust and the persons identified as the
>    document authors.  All rights reserved.
>
>    This document is subject to BCP 78 and the IETF Trust's Legal
>    Provisions Relating to IETF Documents
>    (http://trustee.ietf.org/license-info) in effect on the date of
>    publication of this document.  Please review these documents
>    carefully, as they describe your rights and restrictions with respect
>    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.
>
>
>
> Robles & Richardson    Expires December 29, 2015                [Page 1]
> Internet-Draft                 Useof6553                       June 2015
>
>
> Table of Contents
>
>    1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
>    2.  Terminology and Requirements Language . . . . . . . . . . . .   2
>    3.  Sample/reference topology . . . . . . . . . . . . . . . . . .   3
>    4.  Example flow from leaf to root  . . . . . . . . . . . . . . .   4
>      4.1.  Non-storing . . . . . . . . . . . . . . . . . . . . . . .   5
>      4.2.  Storing . . . . . . . . . . . . . . . . . . . . . . . . .   5
>    5.  Example flow from leaf to Internet  . . . . . . . . . . . . .   6
>      5.1.  Non-storing . . . . . . . . . . . . . . . . . . . . . . .   6
>      5.2.  Storing . . . . . . . . . . . . . . . . . . . . . . . . .   7
>    6.  Example flow from leaf to leaf  . . . . . . . . . . . . . . .   7
>      6.1.  Traditional storing . . . . . . . . . . . . . . . . . . .   7
>      6.2.  Traditional non-storing . . . . . . . . . . . . . . . . .   7
>      6.3.  P2P non-storing . . . . . . . . . . . . . . . . . . . . .   7
>    7.  Example flow from Internet to leaf  . . . . . . . . . . . . .   7
>      7.1.  Storing . . . . . . . . . . . . . . . . . . . . . . . . .   7
>      7.2.  Non-storing . . . . . . . . . . . . . . . . . . . . . . .   7
>    8.  Example flow from root to leaf  . . . . . . . . . . . . . . .   7
>      8.1.  Storing . . . . . . . . . . . . . . . . . . . . . . . . .   7
>      8.2.  Non-storing . . . . . . . . . . . . . . . . . . . . . . .   7
>    9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
>    10. Security Considerations . . . . . . . . . . . . . . . . . . .   8
>    11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
>    12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
>      12.1.  Normative References . . . . . . . . . . . . . . . . . .   8
>      12.2.  Informative References . . . . . . . . . . . . . . . . .   8
>    Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8
>
>
> 1.  Introduction
>
>    RPL [RFC6550] defines RPL Option to transmit routing information.
>    RFC 6553 [RFC6553] defines how to transmit in a Hop-By-Hop Option RPL
>    Information,such as information to avoid and detect loops.  RFC 6554
>    [RFC6554] defines the use of Extension header for Source Routing.
> TW> this is a bit confusing to me. AFAICT:
> TW> - RFC6550 defines the RPL routing protocol
> TW> - RFC6553 defines the "RPL option", carried within the IPv6 Hop-by-Hop
> TW>   header to  quickly identify inconsistencies in the routing topology
> TW> - RFC6554 defines the "RPL Source Route Header", an IPv6 Extension
>       Header to deliver datagrams within a RPL routing domain
>
>    Several discussions in
> TW> the
>    ROLL/6lo/6tisch
> TW> 6tisch -> 6TiSCH
>    Mailing Lists took place
>    focusing in the definition
> TW> of
>    how to compress RPL Information in
>    constrained environment.  ROLL Virtual Interim Meeting (02-2015)
>    concluded that there is a need to define how to use RFC 6553, RFC6554
> TW> you have to decide whether you use "RFC 123" or "RFC123". I would
> TW> recommend you replace this by a hyperlink
>    and tunneling (IP-in-IP)
> TW> I would say "and IP-in-IP encapsulation"
>    to be able to set the correct environment
>    for compression.
>
> 2.  Terminology and Requirements Language
>
> TW> you're actually not using any of this language in the draft.
> TW> if you keep it that way, and since the draft is informational
> TW> I would recommend to remove this section
>
>
>
>
> Robles & Richardson    Expires December 29, 2015                [Page 2]
> Internet-Draft                 Useof6553                       June 2015
>
>
>    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
>    "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
>    document are to be interpreted as described in RFC 2119 [RFC2119].
>
>    Terminology defined in [RFC7102]
>
> 3.  Sample/reference topology
>
>    In a typical topology we found
> TW> "we found" reads strange. What about "A RPL network is composed of
> TW> ...[6LR,6LBR]... logically organized in a DODAG structure".
>    6LBR (6LoWPAN Border Router), 6lR
> TW> 6LR
>    (6LoWPAN Router) and 6LN (6LoWPAN Node) as leaf connected in a DODAG
>    (Destination Oriented Directed Acyclic Graph).  Between these
>    entities messages such as DIS, DIO and DAO are transmitted.  RPL
>    defines the RPL Control message as an ICMPv6 information message with
>    a Type of 155.
> TW> RPL defines the RPL Control message, a new ICMPv6 message with
> TW> Type 155. DIS, DIO and DAO messages are all RPL Control messages
> TW> but with different Code values.
>    RPL supports two modes of Downward traffic: Storing,
>    it is fully stateful or Non-Storing it is fully source routed.  Any
>    given RPL Instance is either storing or non-storing.
> TW> please specify that a RPL Instance is either fully storing or fully
> TW> non-storing, i.e. a RPL Instance with a combination of storing and
> TW> non-storing nodes is not supported
>
>                              +--------------+
>                              | Upper Layers |
>                              |              |
>                              +--------------+
>                              |   RPL        |
>                              |              |
>                              +--------------+
>                              |   ICMPv6     |
>                              |              |
>                              +--------------+
>                              |   IPv6       |
>                              |              |
>                              +--------------+
>                              |   6LoWPAN    |
>                              |              |
>                              +--------------+
>                              |   PHY-MAC    |
>                              |              |
>                              +--------------+
>
>
>
>                             Figure 1: RPL Stack
>
>
>
>
>
>
>
>
>
>
>
> Robles & Richardson    Expires December 29, 2015                [Page 3]
> Internet-Draft                 Useof6553                       June 2015
>
>
>                                           +---------+
>                                       +---+Internet |
>                                       |   +---------+
>                                       |
>                                  +----+--+
>                                  |DODAG  |
>                        +---------+Root   +----------+
>                        |         |6LBR   |          |
>                        |         +----+--+          |
>                        |              |             |
>                        |              |             |
>                        |              |             |
>                  +-----+-+         +--+---+      +--+---+
>                  |6LR    |         |      |      |      |
>            +-----+       |         |      |      |      |
>            |     |       |         |      |      |      +------+
>            |     +-----+-+         +-+----+      +-+----+      |
>            |           |             |             |           |
>            |           |             |             |           |
>            |           |             |             |           |
>          +-+---+     +-+---+      +--+--+       +- --+     +---+-+
>          |Leaf |     |     |      |     |       |    |     |     |
>          |6LN  |     |     |      |     |       |    |     |     |
>          +-----+     +-----+      +-----+       +----+     +-----+
>
>
>                     Figure 2: A reference RPL Topology
> TW> I would add a "." at end of each caption
>
>    In different scenarios the use of RFC 6553, RFC 6554 and tunneling
>    can take place:
> TW> I would say that a combination of RFC6553, RFC6554 and IP-in-IP
> TW> encapsulation is used for the following traffic flows:
>
>    -Flow from leaf to root
> TW> remove newlines?
>    -Flow from leaf to Internet
>
>    -Flow from leaf to leaf
>
>    -Flow from Internet to leaf
>
>    -Flow from leaf to root
> TW> duplicate
>
> 4.  Example flow from leaf to root
>
>    A leaf node generates DAO and DIS messages and in general does not
>    accept them.
> TW> what do you mean by "accept"?
>    Additionally, this kind of nodes
> TW> node
>    accepts DIO messages,
>    but in general do
> TW> does
>    not generate them.  (In inconsistency A leaf node
>    generates DIO with infinite rank, to fix it).
> TW> A -> a
>
>
>
>
> Robles & Richardson    Expires December 29, 2015                [Page 4]
> Internet-Draft                 Useof6553                       June 2015
>
>
> 4.1.  Non-storing
>
>    In non-storing
> TW> mode
>    in this case
> TW> remove "in this case"
>    the leaf node uses Hop-By-Hop option (RFC
>    6553) to indicate the routing information to send messages to the
>    DODAG root, this message is going to be analyzed in each node until
>    arrive the DODAG root.
>
>    RFC 6554 was created to strictly send information between RPL routers
>    in the same RPL routing domain.  How it would be in 6554?
> TW> I assume a "TODO" missing before last sentence?
>
>    TBD: Tunneling is necessary in case that there is information to send
>    outside RPL Domain and other cases?
>
>                           +------+
>                           |      |
>                           | 6LBR |
>                           |      |
>                           +---+--+
>                               |
>                               |  LoWPAN_HC
>                               |  Route= 6LN-6LR-6LBR
>                        ^      |
>                        |  +---+-+
>                        |  |     |
>                        |  | 6LR |
>                        |  |     |
>                        |  +--+--+
>                        |     |   LoWPAN_HC
>                        |     |   Route= 6LN-6LR-6LBR
>                        |     |
>                        +     |
>                           +--+--+
>                           | 6LN |
>                           |     |
>                           |     |
>                           +-----+
>
>               Figure 3: From leaf to Root - Non-Storing Mode
>
> TW> I don't fully understand what message this figure conveys
> TW> I would use A B and C to name the nodes, and write their role
> TW> next to them
>
>
>
> 4.2.  Storing
>
>    IP6 6553{X,Y] ?ipip payload.
> TW> something's wrong
>    In storing mode is suitable the use of
>    RFC 6553 to send RPL Information through HBH field checking the
>    routing table to find out where to send the message.
> TW> I don't understand "checking the routing table to find out where
> TW> to send the message"
>    It may include
>    IP-in-IP encapsulation to transmit information not related with the
>    RPL domain.
> TW> I would expand this info
>
>
>
>
>
> Robles & Richardson    Expires December 29, 2015                [Page 5]
> Internet-Draft                 Useof6553                       June 2015
>
>
>                       +------+
>                       |      |
>                       | 6LBR |
>                       |      |
>                       +---+--+
>                           |
>                           |  LoWPAN_HC
>                           |  0x63|HBH Data
>                    ^      |
>                    |  +---+-+
>                    |  |     |
>                    |  | 6LR | 6LR check in routing table
>                    |  |     |
>                    |  +--+--+
>                    |     |   LoWPAN_HC
>                    |     |   0x63|HBH Data
>                    |     |
>                    +     |
>                       +--+--+
>                       | 6LN |
>                       |     |
>                       |     |
>                       +-----+
>
>                 Figure 4: From leaf to Root - Storing Mode
>
> 5.  Example flow from leaf to Internet
>
> 5.1.  Non-storing
>
>    In this case the IP-in-IP encapsulation should take place to send
>    information not related to the RPL domain inside of the RPL domain.
>
>    RPL information from RFC 6553 should not go out to Internet.  The
>    router sould
> TW> typo
>    take this information out before send the packet to
>    Internet.  The HBH Option is going to be analyzed in each node to the
>    root.
> TW> illustrate this with a fig?
>
>    Related to RFC 6554 the Source Header route is added and removed by
>    DODAG root.  However, RFC 6554 was created to strictly send
>    information between RPL routers in the same RPL routing domain.  How
>    it would be in 6554?
> TW> this paragraph relates to down traffic, right? The name of the section
> TW> is "from leaf to Internet"
>
>
>
>
>
>
>
>
>
> Robles & Richardson    Expires December 29, 2015                [Page 6]
> Internet-Draft                 Useof6553                       June 2015
>
>
> 5.2.  Storing
>
>    In storing the information of RFC 6553 should take away by DODAG root
>    before go to Internet.
> TW> but as well in non-storing, no?
>
> 6.  Example flow from leaf to leaf
>
>    can leafs insert appropriate headers, without ipip?  In [RFC6550] RPL
>    allows a simple one-hop P2P optimization for both storing and non-
>    storing networks.  A node may send a P2P packet destined to a one-hop
>    neighbor direclty
> TW> typo
>    to that node.  Section 9 in [RFC6550].
> TW> I would say that IP-in-IP is not needed in this case
>
> 6.1.  Traditional storing
> TW> why "Traditional"?
>    The route go through an ancestor that knows the route to the
>    destination, using HBH [RFC6553] to carry RPL Information.
>
> 6.2.  Traditional non-storing
>
>    The route go through the DODAG root, using source routing [RFC6554].
>
> 6.3.  P2P non-storing
>
>    (p2p storing?  TBD)
>
> 7.  Example flow from Internet to leaf
>
>    A DODAG root do not add routing extension to incoming packets, it
>    instead uses tunneling.
>
> 7.1.  Storing
>
>    DODAG root adds the HBH header [RFC6553] and send the packet downward
>    to the destination.
>
> 7.2.  Non-storing
>
>    DODAG root is going to add the source route header [RFC6554]
>
> 8.  Example flow from root to leaf
>
> 8.1.  Storing
>
>    DODAG root adds the HBH header [RFC6553] and send the packet downward
>    to the destination.
>
> 8.2.  Non-storing
>
>
>
>
> Robles & Richardson    Expires December 29, 2015                [Page 7]
> Internet-Draft                 Useof6553                       June 2015
>
>
>    DODAG root is going to add the source route header [RFC6554]
>
> 9.  IANA Considerations
>
>    There are no IANA considerations related to this document.
>
> 10.  Security Considerations
>
>    TBD.
> TW> I would replace TBD by TODO, per usual covention
>
> 11.  Acknowledgements
> TW> typo
>
>    This work is partially funded by the FP7 Marie Curie Initial Training
>    Network (ITN) METRICS project (grant agreement No.  607728)
>
> 12.  References
>
> 12.1.  Normative References
>
>    [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
>               Requirement Levels", BCP 14, RFC 2119, March 1997.
>
>    [RFC6550]  Winter, T., Thubert, P., Brandt, A., Hui, J., Kelsey, R.,
>               Levis, P., Pister, K., Struik, R., Vasseur, JP., and R.
>               Alexander, "RPL: IPv6 Routing Protocol for Low-Power and
>               Lossy Networks", RFC 6550, March 2012.
>
>    [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, March
>               2012.
>
>    [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, March
>               2012.
>
> 12.2.  Informative References
>
>    [RFC7102]  Vasseur, JP., "Terms Used in Routing for Low-Power and
>               Lossy Networks", RFC 7102, January 2014.
>
> Authors' Addresses
>
>
>
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> Robles & Richardson    Expires December 29, 2015                [Page 8]
> Internet-Draft                 Useof6553                       June 2015
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>    Maria Ines Robles
>    Ericsson
>    Hirsalantie 11
>    Jorvas  02420
>    Finland
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>    Email: maria.ines.robles@ericsson.com
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>    Michael C. Richardson
>    Sandelman Software Works
>    470 Dawson Avenue
>    Ottawa, ON  K1Z 5V7
>    CA
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>    Email: mcr+ietf@sandelman.ca
>    URI:   http://www.sandelman.ca/
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> Robles & Richardson    Expires December 29, 2015                [Page 9]
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