Root initiated routing state in RPL
draft-ietf-roll-dao-projection-00
ROLL P. Thubert, Ed.
Internet-Draft J. Pylakutty
Intended status: Standards Track Cisco
Expires: June 10, 2017 December 07, 2016
Root initiated routing state in RPL
draft-ietf-roll-dao-projection-00
Abstract
This document proposes a protocol extension to RPL that enables to
install a limited amount of centrally-computed routes in a RPL graph,
enabling loose source routing down a non-storing mode DODAG, or
transversal routes inside the DODAG. As opposed to the classical
route injection by DAO messages, this draft projects the routes from
the root of the DODAG.
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This Internet-Draft will expire on April 27, 2017.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. New RPL Control Message Options . . . . . . . . . . . . . . . 4
3.1. Via Information . . . . . . . . . . . . . . . . . . . . . 4
4. Loose Source Routing in Non-storing Mode . . . . . . . . . . 5
5. Centralized Computation of Optimized Peer-to-Peer Routes . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
The Routing Protocol for Low Power and Lossy Networks [RFC6550] (LLN)
(RPL) specification defines a generic Distance Vector protocol that
is designed for very low energy consumption and adapted to a variety
of LLNs. RPL forms Destination Oriented Directed Acyclic Graphs
(DODAGs) which root often acts as the Border Router to connect the
RPL domain to the Internet. The root is responsible to select the
RPL Instance that is used to forward a packet coming from the
Internet into the RPL domain and set the related RPL information in
the packets.
In the non-storing mode (NSM) of operation (MOP), the root also
computes routes down the DODAG towards the end device and leverages
source routing to get there, while the default route via the root is
used for routing upwards within the LLN and to the Internet at large.
NSM is the dominant MOP because because networks may get arbitrary
large and in Storing Mode, the amount of memory in nodes close to the
root may unexpectedly require memory beyond a node's capabilities.
But as a network gets deep, the size of the source routing header
that the root must add to all the downward packets may also become an
issue for far away target devices. In some use cases, a RPL network
forms long lines and a limited amount of well-targeted routing state
would allow to make the source routing operation loose as opposed to
strict, and save packet size. Limiting the packet size is directly
beneficial to the energy budget, but, mostly, it reduces the chances
of frame loss and/or packet fragmentation, which is highly
detrimental to the LLN operation. Because the capability to store a
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