--- 1/draft-ietf-roll-efficient-npdao-03.txt 2018-07-19 20:13:10.389080938 -0700 +++ 2/draft-ietf-roll-efficient-npdao-04.txt 2018-07-19 20:13:10.425081805 -0700 @@ -1,22 +1,22 @@ ROLL R. Jadhav, Ed. Internet-Draft Huawei Intended status: Standards Track P. Thubert -Expires: September 30, 2018 Cisco +Expires: January 20, 2019 Cisco R. Sahoo Z. Cao Huawei - March 29, 2018 + July 19, 2018 Efficient Route Invalidation - draft-ietf-roll-efficient-npdao-03 + draft-ietf-roll-efficient-npdao-04 Abstract This document describes the problems associated with the use of No- Path DAO messaging in RPL and signaling changes to improve route invalidation efficiency. Status of This Memo This Internet-Draft is submitted in full conformance with the @@ -25,21 +25,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on September 30, 2018. + This Internet-Draft will expire on January 20, 2019. Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -59,39 +59,39 @@ 2. Problems with current No-Path DAO messaging . . . . . 5 2.1. Lost NPDAO due to link break to the previous parent . . . 5 2.2. Invalidate routes to dependent nodes of the switching node . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3. Route downtime caused by asynchronous operation of NPDAO and DAO . . . . . . . . . . . . . . . . . . . . . . 6 3. Requirements for the No-Path DAO Optimization . . . . . . . . 6 3.1. Req#1: Tolerant to link failures to the previous parents . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.2. Req#2: Dependent nodes route invalidation on parent - switching . . . . . . . . . . . . . . . . . . . . . . . . 6 + switching . . . . . . . . . . . . . . . . . . . . . . . . 7 3.3. Req#3: No impact on traffic while NPDAO operation in progress . . . . . . . . . . . . . . . . . . . . . . . . 7 4. Proposed changes to RPL signaling . . . . . . . . . . . . . . 7 4.1. Change in RPL route invalidation semantics . . . . . . . 7 - 4.2. DAO message format changes . . . . . . . . . . . . . . . 7 - 4.3. Destination Cleanup Object (DCO) . . . . . . . . . . . . 8 + 4.2. DAO message format changes . . . . . . . . . . . . . . . 8 + 4.3. Destination Cleanup Object (DCO) . . . . . . . . . . . . 9 4.3.1. Secure DCO . . . . . . . . . . . . . . . . . . . . . 10 4.3.2. DCO Options . . . . . . . . . . . . . . . . . . . . . 10 4.3.3. Path Sequence number in the DCO . . . . . . . . . . . 10 4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK) 10 4.3.5. Secure DCO-ACK . . . . . . . . . . . . . . . . . . . 11 - 4.4. Other considerations . . . . . . . . . . . . . . . . . . 11 - 4.4.1. Dependent Nodes invalidation . . . . . . . . . . . . 11 + 4.4. Other considerations . . . . . . . . . . . . . . . . . . 12 + 4.4.1. Dependent Nodes invalidation . . . . . . . . . . . . 12 4.4.2. NPDAO and DCO in the same network . . . . . . . . . . 12 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 - 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 8.1. Normative References . . . . . . . . . . . . . . . . . . 13 8.2. Informative References . . . . . . . . . . . . . . . . . 13 Appendix A. Example DCO Messaging . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 1. Introduction RPL [RFC6550] specifies a proactive distance-vector based routing scheme. The specification has an optional messaging in the form of DAO messages using which the 6LBR can learn route towards any of the @@ -260,24 +260,26 @@ the previous path via (B) may still be available (albeit at relatively bad metrics). An NPDAO sent from previous route may invalidate the existing route whereas there is no way to determine whether the new DAO has successfully updated the route entries on the new path. 3. Requirements for the No-Path DAO Optimization 3.1. Req#1: Tolerant to link failures to the previous parents - When the switching node send the NPDAO message to the previous + When the switching node sends the NPDAO message to the previous parent, it is normal that the link to the previous parent is prone to failure. Therefore, it is required that the NPDAO message MUST be - tolerant to the link failure during the switching. + tolerant to the link failure during the switching. The link referred + here represents the link between the node and its previous parent + (from whom the node is now disassociating). 3.2. Req#2: Dependent nodes route invalidation on parent switching While switching the parent node and sending NPDAO message, it is required that the routing entries to the dependent nodes of the switching node will be updated accordingly on the previous parents and other relevant upstream nodes. 3.3. Req#3: No impact on traffic while NPDAO operation in progress @@ -290,24 +292,23 @@ 4. Proposed changes to RPL signaling 4.1. Change in RPL route invalidation semantics As described in Section 1.2, the NPDAO originates at the node switching the parent and traverses upstream towards the root. In order to solve the problems as mentioned in Section 2, the draft adds new pro-active route invalidation message called as "Destination Cleanup Object" (DCO) that originates at a common ancestor node - between the new and old path. The trigger for the common ancestor - node to generate this DCO is the change in the next hop for the - target on reception of an update message in the form of regular DAO - for the target. + between the new and old path. The common ancestor node generates a + DCO in response to the change in the next-hop on receiving a regular + DAO for the target. In the Figure 1, when node D decides to switch the path from B to C, it sends a regular DAO to node C with reachability information containing target as address of D and a incremented path sequence number. Node C will update the routing table based on the reachability information in DAO and in turn generate another DAO with the same reachability information and forward it to H. Node H also follows the same procedure as Node C and forwards it to node A. When node A receives the regular DAO, it finds that it already has a routing table entry on behalf of the target address of node D. It @@ -517,22 +518,22 @@ Even with the changed semantics, the current NPDAO mechanism in [RFC6550] can still be used. There are certain scenarios where current NPDAO signalling may still be used, for example, when the route lifetime expiry of the target happens or when the node simply decides to gracefully terminate the RPL session on graceful node shutdown. Moreover a deployment can have a mix of nodes supporting the proposed DCO and the existing NPDAO mechanism. 5. Acknowledgements - We would like to thank Cenk Gundogan and Simon Duquennoy for their - review and comments. + Many thanks to Cenk Gundogan, Simon Duquennoy, and Georgios + Papadopoulous for their review and comments. 6. IANA Considerations IANA is requested to allocate new ICMPv6 RPL control codes in RPL [RFC6550] for DCO and DCO-ACK messages. +------+---------------------------------------------+--------------+ | Code | Description | Reference | +------+---------------------------------------------+--------------+ | 0x04 | Destination Cleanup Object | This | @@ -567,22 +568,22 @@ Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, JP., and R. Alexander, "RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks", RFC 6550, DOI 10.17487/RFC6550, March 2012, . 8.2. Informative References [I-D.ietf-6tisch-architecture] Thubert, P., "An Architecture for IPv6 over the TSCH mode - of IEEE 802.15.4", draft-ietf-6tisch-architecture-13 (work - in progress), November 2017. + of IEEE 802.15.4", draft-ietf-6tisch-architecture-14 (work + in progress), April 2018. Appendix A. Example DCO Messaging In Figure 1, node (D) switches its parent from (B) to (C). The sequence of actions is as follows: 1. Node D switches its parent from node B to node C 2. D sends a regular DAO(tgt=D,pathseq=x+1,I_flag=1) in the updated path to C 3. C checks for routing entry on behalf of D, since it cannot find