From: The IESG <firstname.lastname@example.org>
To: IETF-Announce <email@example.com>
Cc: RFC Editor <firstname.lastname@example.org>,
roll mailing list <email@example.com>,
roll chair <firstname.lastname@example.org>
Subject: Protocol Action: 'The Minimum Rank with Hysteresis Objective Function' to Proposed Standard (draft-ietf-roll-minrank-hysteresis-of-11.txt)
The IESG has approved the following document:
- 'The Minimum Rank with Hysteresis Objective Function'
(draft-ietf-roll-minrank-hysteresis-of-11.txt) as Proposed Standard
This document is the product of the Routing Over Low power and Lossy
networks Working Group.
The IESG contact persons are Adrian Farrel and Stewart Bryant.
A URL of this Internet Draft is:
An objective function specifies how RPL [RFC6550] selects paths.
Objective functions can choose paths based on routing metrics or
constraints. For example, if an RPL instance uses an objective
function that minimizes hop-count, RPL will select paths with minimum
The nodes running RPL might use a number of metrics to describe a
link or a node [RFC6551] and make it available for route selection.
These metrics are advertised in RPL Destination Information Object
(DIO) messages using a Metric Container suboption. An objective
function can use these metrics to choose routes. The only exception
is the ETX metric, which is used without the metric container as
described in Section 3.5.
To decouple the details of an individual metric or objective function
from forwarding and routing, RPL describes routes through a value
called Rank. Rank, roughly speaking, corresponds to the distance
associated with a route. An objective function is responsible for
computing a node's advertised Rank value based on the Rank of its
potential parents, metrics, and other network properties.
This specification describes MRHOF, an objective function for RPL.
MRHOF uses hysteresis while selecting the path with the smallest
metric value. The metric that MRHOF uses is determined by the
metrics in the DIO Metric Container. For example, the use of MRHOF
with the latency metric allows RPL to find stable minimum-latency
paths from the nodes to a root in the DAG instance. The use of MRHOF
with the ETX metric allows RPL to find the stable minimum-ETX paths
from the nodes to a root in the DAG instance.
MRHOF can only be used with an additive metric that must be minimized
on the paths selected for routing.
Working Group Summary
A relatively quiet WG process with no discontent. There were several late-
breaking review comments that caused the document to be recycled
after WG last call, but this was not contentious.
There are several known implementations of this specification.
JP Vasseur (email@example.com) is the Document Shepherd.
Adrian Farrel (firstname.lastname@example.org) is the Responsible AD