--- 1/draft-ietf-roll-of0-18.txt	2011-08-26 15:16:09.000000000 +0200
+++ 2/draft-ietf-roll-of0-19.txt	2011-08-26 15:16:09.000000000 +0200
@@ -1,18 +1,18 @@
 
 ROLL                                                     P. Thubert, Ed.
 Internet-Draft                                             Cisco Systems
 Intended status: Standards Track                         August 26, 2011
 Expires: February 27, 2012
 
                       RPL Objective Function Zero
-                         draft-ietf-roll-of0-18
+                         draft-ietf-roll-of0-19
 
 Abstract
 
    The Routing Protocol for Low Power and Lossy Networks (RPL)
    specification defines a generic Distance Vector protocol that is
    adapted to a variety of networks types by the application of specific
    Objective Functions (OFs).  An OF states the outcome of the process
    used by a RPL node to select and optimize routes within a RPL
    Instance based on the information objects available; an OF is not an
    algorithm.
@@ -85,27 +85,27 @@
      11.2. Informative References . . . . . . . . . . . . . . . . . . 13
    Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14
 
 1.  Introduction
 
    The Routing Protocol for Low Power and Lossy Networks (RPL)
    [I-D.ietf-roll-rpl]specification defines a generic Distance Vector
    protocol that is adapted to a variety of Low Power and Lossy Networks
    (LLN) types by the application of specific Objective Functions (OFs).
 
-   An OF states the outcome of the process used by a RPL node to select
-   and optimize routes within a RPL Instance based on the information
-   objects available; an OF is not an algorithm.  For example, "shortest
-   path first" is an algorithm where the least cost path between two
-   points is derived as an outcome; there are a number of algorithms
-   that can be used to satisfy the OF, of which the well-known Dijkstra
-   algorithm is an example.
+   A RPL OF states the outcome of the process used by a RPL node to
+   select and optimize routes within a RPL Instance based on the
+   information objects available.  As a general concept, an OF is not an
+   algorithm.  For example outside RPL, "shortest path first" is an OF
+   where the least cost path between two points is derived as an
+   outcome; there are a number of algorithms that can be used to satisfy
+   the OF, of which the well-known Dijkstra algorithm is an example.
 
    The separation of OFs from the core protocol specification allows RPL
    to be adapted to meet the different optimization criteria required by
    the wide range of deployments, applications, and network designs.
 
    RPL forms Directed Acyclic Graphs (DAGs) as collections of
    Destination Oriented DAGs (DODAGs) within instances of the protocol.
    Each instance is associated with a specialized Objective Function.  A
    DODAG is periodically reconstructed as a new DODAG Version to enable
    a global reoptimization of the graph.
@@ -306,48 +306,53 @@
         node to re-parent and in particular the boundaries to augment
         its Rank within a DODAG Version.  A candidate that would not
         satisfy those rules MUST NOT be considered.
 
    2.   An implementation SHOULD validate a router prior to selecting it
         as preferred.In most cases, a router that does not succeed the
         validation process can not be further considered for selection
         as preferred parent.  In any case a router that succeeded that
         validation process SHOULD be preferred.
 
-   3.   If the administrative preference of the root is configured to
+   3.   When multiple interfaces are available, a policy might be
+        locally configured to order them and that policy applies first;
+        that is a router on a higher order interface in the policy is
+        preferable.
+
+   4.   If the administrative preference of the root is configured to
         supersede the goal to join a Grounded DODAG, a router that
         offers connectivity to a more preferable root SHOULD be
         preferred.
 
-   4.   A router that offers connectivity to a grounded DODAG Version
+   5.   A router that offers connectivity to a grounded DODAG Version
         SHOULD be preferred over one that does not.
 
-   5.   A router that offers connectivity to a more preferable root
+   6.   A router that offers connectivity to a more preferable root
         SHOULD be preferred.
 
-   6.   When comparing 2 parents that belong to the same DODAG, a router
+   7.   When comparing 2 parents that belong to the same DODAG, a router
         that offers connectivity to the most recent DODAG Version SHOULD
         be preferred.
 
-   7.   The parent that causes the lesser resulting Rank for this node,
+   8.   The parent that causes the lesser resulting Rank for this node,
         as specified in Section 4.1, SHOULD be preferred.
 
-   8.   A DODAG Version for which there is an alternate parent SHOULD be
+   9.   A DODAG Version for which there is an alternate parent SHOULD be
         preferred.  This check is OPTIONAL.  It is performed by
         computing the backup feasible successor while assuming that the
         router that is currently examined is finally selected as
         preferred parent.
 
-   9.   The preferred parent that was in use already SHOULD be
+   10.  The preferred parent that was in use already SHOULD be
         preferred.
 
-   10.  A router that has announced a DIO message more recently SHOULD
+   11.  A router that has announced a DIO message more recently SHOULD
         be preferred.
 
    These rules and their order MAY be varied by an implementation
    according to configured policy.
 
 4.2.2.  Selection Of The Backup Feasible Successor
 
    When selecting a backup feasible successor, the OF performs in order
    the following checks: