RPL Storing Root-ACK
draft-jadhav-roll-storing-rootack-01

Document Type Active Internet-Draft (individual)
Author Rahul Jadhav 
Last updated 2020-06-05
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ROLL                                                      R. Jadhav, Ed.
Internet-Draft                                                    Huawei
Intended status: Standards Track                            June 5, 2020
Expires: December 7, 2020

                          RPL Storing Root-ACK
                  draft-jadhav-roll-storing-rootack-01

Abstract

   This document explains problems with DAO-ACK handling in RPL Storing
   MOP and provides updates to RFC6550 to solve those problems.

Status of This Memo

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

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   This Internet-Draft will expire on December 7, 2020.

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Jadhav                  Expires December 7, 2020                [Page 1]
Internet-Draft              Storing Root-ACK                   June 2020

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language and Terminology . . . . . . . . . .   3
   2.  Problems with DAO-ACK in Storing MOP  . . . . . . . . . . . .   3
     2.1.  End to End Path Establishment Indication  . . . . . . . .   4
     2.2.  Target node is unaware if it needs to retry the DAO . . .   5
     2.3.  RPL node acting as router for RULs  . . . . . . . . . . .   6
   3.  Requirements for Root-ACK handling in Storing MOP . . . . . .   6
   4.  Root-ACK from Root  . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Transit Information Option update in DAO message  . . . .   6
     4.2.  Root sends Root-ACK addressed to Target . . . . . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   RPL [RFC6550] specifies a proactive distance-vector routing scheme
   designed for LLNs (Low Power and Lossy Networks).  RPL enables the
   network to be formed as a DODAG and supports storing mode and non-
   storing mode of operations.  Non-storing mode allows reduced memory
   resource usage on the nodes by allowing non-BR nodes to operate
   without managing a routing table and involves use of source routing
   by the Root to direct the traffic along a specific path.  In storing
   mode of operation the routing happens on hop-by-hop basis and
   intermediate routers need to maintain routing tables.

   DAO messaging helps to install downstream routing paths in the DODAG.
   DAOs are generated on hop-by-hop basis.  DAO may contain multiple RPL
   Control Options.  The Target Option identifies the address prefix for
   which the route has to be installed and the corresponding Transit
   Information Option identifies the parameters (such as lifetime,
   freshness-counter, etc) for the target.  The DAO base object contains
   the 'K' flag indicating that a DAO-ACK is sought by the sender.  The
   DAO, DAO-ACK progresses on hop-by-hop basis all the way till Root.
   In non-storing MOP, the DAO from the target node is directly
   addressed to the Root and the Root responds with a DAO-ACK indicating
   path establishment status.  However, in storing MOP, the DAO-ACK is
   immediately sent by the upstream parent.  Thus in case of storing
   MOP, the target node cannot rely on DAO-ACK as an indication that the
   end to end (from the target node to Root) path has been established.

Jadhav                  Expires December 7, 2020                [Page 2]
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