draft-ietf-roll-efficient-npdao-06.txt   draft-ietf-roll-efficient-npdao-07.txt 
ROLL R. Jadhav, Ed. ROLL R. Jadhav, Ed.
Internet-Draft Huawei Internet-Draft Huawei
Intended status: Standards Track P. Thubert Intended status: Standards Track P. Thubert
Expires: March 30, 2019 Cisco Expires: March 31, 2019 Cisco
R. Sahoo R. Sahoo
Z. Cao Z. Cao
Huawei Huawei
September 26, 2018 September 27, 2018
Efficient Route Invalidation Efficient Route Invalidation
draft-ietf-roll-efficient-npdao-06 draft-ietf-roll-efficient-npdao-07
Abstract Abstract
This document describes the problems associated with the use of NPDAO This document describes the problems associated with the use of NPDAO
messaging in RPL and signaling changes to improve route invalidation messaging in RPL and signaling changes to improve route invalidation
efficiency. efficiency.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on March 30, 2019. This Internet-Draft will expire on March 31, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language and Terminology . . . . . . . . . . 3 1.1. Requirements Language and Terminology . . . . . . . . . . 3
1.2. Current NPDAO messaging . . . . . . . . . . . . . . . . . 3 1.2. Current NPDAO messaging . . . . . . . . . . . . . . . . . 4
1.3. Why NPDAO is important? . . . . . . . . . . . . . . . . . 4 1.3. Why NPDAO is important? . . . . . . . . . . . . . . . . . 4
2. Problems with current NPDAO messaging . . . . . . . . 5 2. Problems with current NPDAO messaging . . . . . . . . 5
2.1. Lost NPDAO due to link break to the previous parent . . . 5 2.1. Lost NPDAO due to link break to the previous parent . . . 5
2.2. Invalidate routes to dependent nodes . . . . . . . . . . 5 2.2. Invalidate routes to dependent nodes . . . . . . . . . . 5
2.3. Possible route downtime caused by async operation of 2.3. Possible route downtime caused by async operation of
NPDAO and DAO . . . . . . . . . . . . . . . . . . . . . . 5 NPDAO and DAO . . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements for the NPDAO Optimization . . . . . . . . . . . 5 3. Requirements for the NPDAO Optimization . . . . . . . . . . . 5
3.1. Req#1: Tolerant to link failures to the previous 3.1. Req#1: Tolerant to link failures to the previous
parents . . . . . . . . . . . . . . . . . . . . . . . . . 5 parents . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Req#2: Dependent nodes route invalidation on parent 3.2. Req#2: Dependent nodes route invalidation on parent
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4.2. Transit Information Option changes . . . . . . . . . . . 7 4.2. Transit Information Option changes . . . . . . . . . . . 7
4.3. Destination Cleanup Object (DCO) . . . . . . . . . . . . 8 4.3. Destination Cleanup Object (DCO) . . . . . . . . . . . . 8
4.3.1. Secure DCO . . . . . . . . . . . . . . . . . . . . . 9 4.3.1. Secure DCO . . . . . . . . . . . . . . . . . . . . . 9
4.3.2. DCO Options . . . . . . . . . . . . . . . . . . . . . 9 4.3.2. DCO Options . . . . . . . . . . . . . . . . . . . . . 9
4.3.3. Path Sequence number in the DCO . . . . . . . . . . . 9 4.3.3. Path Sequence number in the DCO . . . . . . . . . . . 9
4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK) 9 4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK) 9
4.3.5. Secure DCO-ACK . . . . . . . . . . . . . . . . . . . 10 4.3.5. Secure DCO-ACK . . . . . . . . . . . . . . . . . . . 10
4.4. Other considerations . . . . . . . . . . . . . . . . . . 11 4.4. Other considerations . . . . . . . . . . . . . . . . . . 11
4.4.1. Dependent Nodes invalidation . . . . . . . . . . . . 11 4.4.1. Dependent Nodes invalidation . . . . . . . . . . . . 11
4.4.2. NPDAO and DCO in the same network . . . . . . . . . . 11 4.4.2. NPDAO and DCO in the same network . . . . . . . . . . 11
4.4.3. DCO with multiple preferred parents . . . . . . . . . 11
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. Normative References . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. Example DCO Messaging . . . . . . . . . . . . . . . 12 Appendix A. Example DCO Messaging . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
RPL [RFC6550] specifies a proactive distance-vector based routing RPL [RFC6550] specifies a proactive distance-vector based routing
scheme. RPL has an optional messaging in the form of DAO messages scheme. RPL has an optional messaging in the form of DAO
using which the 6LBR can learn route towards the nodes. In storing (Destination Advertisement Object) messages using which the 6LBR can
mode, DAO messages would result in routing entries been created on learn route towards the nodes. In storing mode, DAO messages would
all intermediate hops from the node's parent all the way towards the result in routing entries been created on all intermediate hops from
6LBR. the node's parent all the way towards the 6LBR.
RPL allows use of No-Path DAO (NPDAO) messaging to invalidate a RPL allows use of No-Path DAO (NPDAO) messaging to invalidate a
routing path corresponding to the given target, thus releasing routing path corresponding to the given target, thus releasing
resources utilized on that path. A NPDAO is a DAO message with route resources utilized on that path. A NPDAO is a DAO message with route
lifetime of zero, originates at the target node and always flows lifetime of zero, originates at the target node and always flows
upstream towards the 6LBR. This document explains the problems upstream towards the 6LBR. This document explains the problems
associated with the current use of NPDAO messaging and also discusses associated with the current use of NPDAO messaging and also discusses
the requirements for an optimized route invalidation messaging the requirements for an optimized route invalidation messaging
scheme. Further a new pro-active route invalidation message called scheme. Further a new pro-active route invalidation message called
as "Destination Cleanup Object (DCO)" is specified which fulfills as "Destination Cleanup Object (DCO)" is specified which fulfills
requirements of an optimized route invalidation messaging. requirements of an optimized route invalidation messaging.
The document only caters to the RPL's storing mode of operation
(MOP). The non-storing MOP does not require use of NPDAO for route
invalidation since routing entries are not maintained on 6LRs.
1.1. Requirements Language and Terminology 1.1. Requirements Language and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
The document only caters to the RPL's storing mode of operation DAO: Destination Advertisement Object
(MOP). The non-storing MOP does not require use of NPDAO for route
invalidation since routing entries are not maintained on 6LRs. DIO: DODAG Information Object
Common Ancestor node: 6LR node which is the first common node on the Common Ancestor node: 6LR node which is the first common node on the
old and new path for the child node. old and new path for the child node.
NPDAO: No-Path DAO. A DAO message which has target with lifetime 0. NPDAO: No-Path DAO. A DAO message which has target with lifetime 0.
DCO: Destination Cleanup Object, A new RPL control message type DCO: Destination Cleanup Object, A new RPL control message type
defined by this draft. defined by this draft.
Regular DAO: A DAO message with non-zero lifetime. Regular DAO: A DAO message with non-zero lifetime.
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to (C). An NPDAO sent from previous route may invalidate the to (C). An NPDAO sent from previous route may invalidate the
existing route whereas there is no way to determine whether the new existing route whereas there is no way to determine whether the new
DAO has successfully updated the route entries on the new path. DAO has successfully updated the route entries on the new path.
3. Requirements for the NPDAO Optimization 3. Requirements for the NPDAO Optimization
3.1. Req#1: Tolerant to link failures to the previous parents 3.1. Req#1: Tolerant to link failures to the previous parents
When the switching node sends 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 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 failure. Therefore, it is required that the route invalidation does
tolerant to the link failure. The link referred here represents the not depend on the previous link which is prone to failure. The
link between the node and its previous parent (from whom the node is previous link referred here represents the link between the node and
now disassociating). its previous parent (from whom the node is now disassociating).
3.2. Req#2: Dependent nodes route invalidation on parent switching 3.2. Req#2: Dependent nodes route invalidation on parent switching
It should be possible to do route invalidation for dependent nodes It should be possible to do route invalidation for dependent nodes
rooted at the switching node. rooted at the switching node.
3.3. Req#3: Route invalidation should not impact data traffic 3.3. Req#3: Route invalidation should not impact data traffic
While sending the NPDAO and DAO messages, it is possible that the While sending the NPDAO and DAO messages, it is possible that the
NPDAO successfully invalidates the previous path, while the newly NPDAO successfully invalidates the previous path, while the newly
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are appended to add message/use-case specific attributes. As an are appended to add message/use-case specific attributes. As an
example, a DAO message may be attributed by one or more "RPL Target" example, a DAO message may be attributed by one or more "RPL Target"
options which specifies the reachability information for the given options which specifies the reachability information for the given
targets. Similarly, a Transit Information option may be associated targets. Similarly, a Transit Information option may be associated
with a set of RPL Target options. with a set of RPL Target options.
The draft proposes a change in Transit Information option to contain The draft proposes a change in Transit Information option to contain
"Invalidate previous route" (I) bit. This I-bit signals the common "Invalidate previous route" (I) bit. This I-bit signals the common
ancestor node to generate a DCO on behalf of the target node. The ancestor node to generate a DCO on behalf of the target node. The
I-bit is carried in the transit information option which augments the I-bit is carried in the transit information option which augments the
reachability information for a given set of RPL Target(s). reachability information for a given set of RPL Target(s). Transit
information option should be carried in the DAO message with I-bit
set in case route invalidation is sought for the correspondig
target(s).
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x06 | Option Length |E|I| Flags | Path Control | | Type = 0x06 | Option Length |E|I| Flags | Path Control |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Sequence | Path Lifetime | | | Path Sequence | Path Lifetime | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
+ + + +
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The DCO carries a Target option and an associated Transit Information The DCO carries a Target option and an associated Transit Information
option with a lifetime of 0x00000000 to indicate a loss of option with a lifetime of 0x00000000 to indicate a loss of
reachability to that Target. reachability to that Target.
4.3.3. Path Sequence number in the DCO 4.3.3. Path Sequence number in the DCO
A DCO message may contain a Path Sequence in the transit information A DCO message may contain a Path Sequence in the transit information
option to identify the freshness of the DCO message. The Path option to identify the freshness of the DCO message. The Path
Sequence in the DCO MUST use the same Path Sequence number present in Sequence in the DCO MUST use the same Path Sequence number present in
the regular DAO message when the DCO is generated in response to DAO the regular DAO message when the DCO is generated in response to DAO
message. message. The DAO and DCO path sequence are picked from the same
sequence number set. Thus if a DCO is received by a 6LR and
subsequently a DAO is received with old seqeunce number, then the DAO
should be ignored.
4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK) 4.3.4. Destination Cleanup Option Acknowledgement (DCO-ACK)
The DCO-ACK message may be sent as a unicast packet by a DCO The DCO-ACK message may be sent as a unicast packet by a DCO
recipient in response to a unicast DCO message. recipient in response to a unicast DCO message.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RPLInstanceID |D| Reserved | DCOSequence | Status | | RPLInstanceID |D| Reserved | DCOSequence | Status |
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nodes invalidation. Dependent nodes will generate their respective nodes invalidation. Dependent nodes will generate their respective
DAOs to update their paths, and the previous route invalidation for DAOs to update their paths, and the previous route invalidation for
those nodes should work in the similar manner described for switching those nodes should work in the similar manner described for switching
node. The dependent node may set the I-bit in the transit node. The dependent node may set the I-bit in the transit
information option as part of regular DAO so as to request information option as part of regular DAO so as to request
invalidation of previous route from the common ancestor node. invalidation of previous route from the common ancestor node.
4.4.2. NPDAO and DCO in the same network 4.4.2. NPDAO and DCO in the same network
Even with the changed semantics, the current NPDAO mechanism in Even with the changed semantics, the current NPDAO mechanism in
[RFC6550] can still be used. There are certain scenarios where [RFC6550] can still be used, for example, when the route lifetime
current NPDAO signalling may still be used, for example, when the expiry of the target happens or when the node simply decides to
route lifetime expiry of the target happens or when the node simply gracefully terminate the RPL session on graceful node shutdown.
decides to gracefully terminate the RPL session on graceful node Moreover a deployment can have a mix of nodes supporting the proposed
shutdown. Moreover a deployment can have a mix of nodes supporting DCO and the existing NPDAO mechanism.
the proposed DCO and the existing NPDAO mechanism.
4.4.3. DCO with multiple preferred parents
[RFC6550] allows a node to select multiple preferred parents for
route establishment. DCO can be used for route invalidation in such
cases as well. There are no changes required in the DCO messaging to
support multiple preferred parents and DCO should work seemlessly in
such scenarios.
5. Acknowledgements 5. Acknowledgements
Many thanks to Cenk Gundogan, Simon Duquennoy, Georgios Many thanks to Cenk Gundogan, Simon Duquennoy, Georgios
Papadopoulous, Peter Van Der Stok for their review and comments. Papadopoulous, Peter Van Der Stok for their review and comments.
6. IANA Considerations 6. IANA Considerations
IANA is requested to allocate new ICMPv6 RPL control codes in RPL IANA is requested to allocate new ICMPv6 RPL control codes in RPL
[RFC6550] for DCO and DCO-ACK messages. [RFC6550] for DCO and DCO-ACK messages.
skipping to change at page 12, line 4 skipping to change at page 12, line 17
+------+---------------------------------------------+--------------+ +------+---------------------------------------------+--------------+
| 0x04 | Destination Cleanup Object | This | | 0x04 | Destination Cleanup Object | This |
| | | document | | | | document |
| 0x05 | Destination Cleanup Object Acknowledgement | This | | 0x05 | Destination Cleanup Object Acknowledgement | This |
| | | document | | | | document |
| 0x84 | Secure Destination Cleanup Object | This | | 0x84 | Secure Destination Cleanup Object | This |
| | | document | | | | document |
| 0x85 | Secure Destination Cleanup Object | This | | 0x85 | Secure Destination Cleanup Object | This |
| | Acknowledgement | document | | | Acknowledgement | document |
+------+---------------------------------------------+--------------+ +------+---------------------------------------------+--------------+
IANA is requested to allocate bit 18 in the Transit Information IANA is requested to allocate bit 18 in the Transit Information
Option defined in RPL [RFC6550] section 6.7.8 for Invalidate route Option defined in RPL [RFC6550] section 6.7.8 for Invalidate route
'I' flag. 'I' flag.
7. Security Considerations 7. Security Considerations
This document handles security considerations inline to base RPL. The document adds new messages (DCO, DCO-ACK) which are similar to
Secure versions of DCO and DCO-ACK are added similar to other RPL existing RPL messages such as DAO, DAO-ACK. Secure versions of DCO
messages. For general RPL security considerations, see [RFC6550]. and DCO-ACK are added similar to other RPL messages (such as DAO,
DAO-ACK). For general RPL security considerations, see [RFC6550].
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
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