Subject: [Roll] [roll] #26: Establishing downward routes in RPL : storing / non-storing / mixed modes of operation

From: "roll issue tracker" <[email-masked]>
Date: Tue, 09 Mar 2010 15:49:04 -0000

#26: Establishing downward routes in RPL : storing / non-storing / mixed modes
of operation
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 Reporter:  jpv@…               |       Owner:  wintert@…      
     Type:  task                |      Status:  new            
 Priority:  major               |   Milestone:                 
Component:  rpl                 |     Version:                 
 Severity:  Active WG Document  |    Keywords:                 
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 In the RPL-07 proposal the DAO mechanism described in Section 6 attempts
 to support
 operation with a mix of storing nodes and non-storing nodes- where storing
 nodes may
 be provisioned with enough memory that they are capable to provision hop-
 by-hop
 downward routes learned from DAO messages, and non-storing nodes would
 rely on source
 routing for downward routes.  The present proposal describes operation in
 a mixed
 mode operation, with both storing and non-storing nodes, where each node
 may
 provision downward routing state as according to its capabilities and
 largely
 independent of its position in the LLN topology.

 It has been noted that operation in the case where all nodes (except
 possibly the
 root) are non-storing nodes allows for certain optimizations, and that the
 case where
 all nodes (except possibly leaves) are storing leads to other
 optimizations.  It has
 also been noted that in the mixed cases the ability to provide an optimal
 solution
 may break down.  In particular there are concerns about the complexity and
 correctness of mixed-mode operation as proposed by RPL-07.

 With this in mind, should RPL allow for operation in a mixture of storing
 /non-storing
 nodes?  Or should each RPL Instance be exclusively operating in either
 storing or
 non-storing mode (with the provision that operation as a leaf is always an
 option)?
 (The non-mixed case may imply some control flag or equivalent given in the
 DIO to
 signal the mode of operation).

 Tim Winter.

-- 
Ticket URL: <http://trac.tools.ietf.org/wg/roll/trac/ticket/26>
roll <http://tools.ietf.org/wg/roll/>