draft-ietf-homenet-dncp-00.txt   draft-ietf-homenet-dncp-01.txt 
Homenet Working Group M. Stenberg Homenet Working Group M. Stenberg
Internet-Draft Internet-Draft
Intended status: Standards Track S. Barth Intended status: Standards Track S. Barth
Expires: July 9, 2015 Expires: September 6, 2015
January 5, 2015 March 5, 2015
Distributed Node Consensus Protocol Distributed Node Consensus Protocol
draft-ietf-homenet-dncp-00 draft-ietf-homenet-dncp-01
Abstract Abstract
This document describes the Distributed Node Consensus Protocol This document describes the Distributed Node Consensus Protocol
(DNCP), a generic state synchronization protocol which uses Trickle (DNCP), a generic state synchronization protocol which uses Trickle
and Merkle trees. DNCP is transport agnostic and leaves some of the and Merkle trees. DNCP is transport agnostic and leaves some of the
details to be specified in profiles, which define actual details to be specified in profiles, which define actual
implementable DNCP based protocols. implementable DNCP based protocols.
Status of This Memo Status of This Memo
skipping to change at page 1, line 35 skipping to change at page 1, line 35
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 9, 2015. This Internet-Draft will expire on September 6, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Trickle-Driven Status Update Messages . . . . . . . . . . 6 5.1. Trickle-Driven Status Update Messages . . . . . . . . . . 6
5.2. Processing of Received Messages . . . . . . . . . . . . . 7 5.2. Processing of Received Messages . . . . . . . . . . . . . 7
5.3. Adding and Removing Peers . . . . . . . . . . . . . . . . 8 5.3. Adding and Removing Peers . . . . . . . . . . . . . . . . 8
5.4. Purging Unreachable Nodes . . . . . . . . . . . . . . . . 8 5.4. Purging Unreachable Nodes . . . . . . . . . . . . . . . . 9
6. Keep-Alive Extension . . . . . . . . . . . . . . . . . . . . 9 6. Keep-Alive Extension . . . . . . . . . . . . . . . . . . . . 9
6.1. Data Model Additions . . . . . . . . . . . . . . . . . . 9 6.1. Data Model Additions . . . . . . . . . . . . . . . . . . 10
6.2. Periodic Keep-Alive Messages . . . . . . . . . . . . . . 9 6.2. Per-Connection Periodic Keep-Alive Messages . . . . . . . 10
6.3. Received Message Processing Additions . . . . . . . . . . 10 6.3. Per-Peer Periodic Keep-Alive Messages . . . . . . . . . . 10
6.4. Neighbor Removal . . . . . . . . . . . . . . . . . . . . 10 6.4. Received Message Processing Additions . . . . . . . . . . 10
7. Protocol Messages . . . . . . . . . . . . . . . . . . . . . . 10 6.5. Neighbor Removal . . . . . . . . . . . . . . . . . . . . 11
7.1. Short Network State Update Message . . . . . . . . . . . 11 7. Support For Dense Broadcast Links . . . . . . . . . . . . . . 11
7.2. Long Network State Update Message . . . . . . . . . . . . 11 8. Protocol Messages . . . . . . . . . . . . . . . . . . . . . . 11
7.3. Network State Request Message . . . . . . . . . . . . . . 11 8.1. Short Network State Update Message . . . . . . . . . . . 12
7.4. Node Data Request Message . . . . . . . . . . . . . . . . 12 8.2. Long Network State Update Message . . . . . . . . . . . . 12
7.5. Node Data Reply Message . . . . . . . . . . . . . . . . . 12 8.3. Network State Request Message . . . . . . . . . . . . . . 13
8. Type-Length-Value Objects . . . . . . . . . . . . . . . . . . 12 8.4. Node Data Request Message . . . . . . . . . . . . . . . . 13
8.1. Request TLVs . . . . . . . . . . . . . . . . . . . . . . 13 8.5. Node Data Reply Message . . . . . . . . . . . . . . . . . 13
8.1.1. Request Network State TLV . . . . . . . . . . . . . . 13 9. Type-Length-Value Objects . . . . . . . . . . . . . . . . . . 13
8.1.2. Request Node Data TLV . . . . . . . . . . . . . . . . 13 9.1. Request TLVs . . . . . . . . . . . . . . . . . . . . . . 14
8.2. Data TLVs . . . . . . . . . . . . . . . . . . . . . . . . 14 9.1.1. Request Network State TLV . . . . . . . . . . . . . . 14
8.2.1. Node Connection TLV . . . . . . . . . . . . . . . . . 14 9.1.2. Request Node Data TLV . . . . . . . . . . . . . . . . 14
8.2.2. Network State TLV . . . . . . . . . . . . . . . . . . 14 9.2. Data TLVs . . . . . . . . . . . . . . . . . . . . . . . . 15
8.2.3. Node State TLV . . . . . . . . . . . . . . . . . . . 14 9.2.1. Node Connection TLV . . . . . . . . . . . . . . . . . 15
8.2.4. Node Data TLV . . . . . . . . . . . . . . . . . . . . 15 9.2.2. Network State TLV . . . . . . . . . . . . . . . . . . 15
8.2.5. Neighbor TLV (within Node Data TLV) . . . . . . . . . 16 9.2.3. Node State TLV . . . . . . . . . . . . . . . . . . . 15
8.2.6. Keep-Alive Interval TLV (within Node Data TLV) . . . 16 9.2.4. Node Data TLV . . . . . . . . . . . . . . . . . . . . 16
8.3. Custom TLV (within/without Node Data TLV) . . . . . . . . 17 9.2.5. Neighbor TLV (within Node Data TLV) . . . . . . . . . 17
9. Security and Trust Management . . . . . . . . . . . . . . . . 17 9.2.6. Keep-Alive Interval TLV (within Node Data TLV) . . . 17
9.1. Pre-Shared Key Based Trust Method . . . . . . . . . . . . 17 9.3. Custom TLV (within/without Node Data TLV) . . . . . . . . 18
9.2. PKI Based Trust Method . . . . . . . . . . . . . . . . . 17 10. Security and Trust Management . . . . . . . . . . . . . . . . 18
9.3. Certificate Based Trust Consensus Method . . . . . . . . 18 10.1. Pre-Shared Key Based Trust Method . . . . . . . . . . . 18
9.3.1. Trust Verdicts . . . . . . . . . . . . . . . . . . . 18 10.2. PKI Based Trust Method . . . . . . . . . . . . . . . . . 18
9.3.2. Trust Cache . . . . . . . . . . . . . . . . . . . . . 19 10.3. Certificate Based Trust Consensus Method . . . . . . . . 19
9.3.3. Announcement of Verdicts . . . . . . . . . . . . . . 19 10.3.1. Trust Verdicts . . . . . . . . . . . . . . . . . . . 19
9.3.4. Bootstrap Ceremonies . . . . . . . . . . . . . . . . 20 10.3.2. Trust Cache . . . . . . . . . . . . . . . . . . . . 20
10. DNCP Profile-Specific Definitions . . . . . . . . . . . . . . 21 10.3.3. Announcement of Verdicts . . . . . . . . . . . . . . 20
11. Security Considerations . . . . . . . . . . . . . . . . . . . 23 10.3.4. Bootstrap Ceremonies . . . . . . . . . . . . . . . . 21
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 11. DNCP Profile-Specific Definitions . . . . . . . . . . . . . . 22
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 12. Security Considerations . . . . . . . . . . . . . . . . . . . 24
13.1. Normative references . . . . . . . . . . . . . . . . . . 24 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
13.2. Informative references . . . . . . . . . . . . . . . . . 24 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
14.1. Normative references . . . . . . . . . . . . . . . . . . 25
14.2. Informative references . . . . . . . . . . . . . . . . . 25
Appendix A. Some Outstanding Issues . . . . . . . . . . . . . . 25 Appendix A. Some Outstanding Issues . . . . . . . . . . . . . . 25
Appendix B. Some Obvious Questions and Answers . . . . . . . . . 25 Appendix B. Some Obvious Questions and Answers . . . . . . . . . 26
Appendix C. Changelog . . . . . . . . . . . . . . . . . . . . . 25 Appendix C. Changelog . . . . . . . . . . . . . . . . . . . . . 26
Appendix D. Draft Source . . . . . . . . . . . . . . . . . . . . 26 Appendix D. Draft Source . . . . . . . . . . . . . . . . . . . . 27
Appendix E. Acknowledgements . . . . . . . . . . . . . . . . . . 26 Appendix E. Acknowledgements . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction 1. Introduction
DNCP is designed to provide a way for nodes to publish data DNCP is designed to provide a way for nodes to publish data
consisting of an ordered set of TLV (Type-Length-Value) tuples, and consisting of an ordered set of TLV (Type-Length-Value) tuples and to
to receive the data published by all other reachable DNCP nodes. receive the data published by all other reachable DNCP nodes.
DNCP validates the set of data within it by ensuring that it is
reachable via nodes that are currently accounted for; therefore,
unlike Time-To-Live (TTL) based solutions, it does not require
periodic re-publishing of the data by the nodes. On the other hand,
it does require the topology to be visible to every node that wants
to be able to identify unreachable nodes and therefore remove old,
stale data. Another notable feature is the use of Trickle to send
status updates as it makes the DNCP network very thrifty when there
are no updates. DNCP is most suitable for data that changes only
gradually to gain the maximum benefit from using Trickle, and if more
rapid state exchanges are needed, something point-to-point is
recommended and just e.g. publishing of addresses of the services
within DNCP.
DNCP has relatively few requirements for the underlying transport; it DNCP has relatively few requirements for the underlying transport; it
requires some way of transmitting either unicast datagram or stream requires some way of transmitting either unicast datagram or stream
data to a DNCP peer, and if used in multicast mode, a way of sending data to a DNCP peer and, if used in multicast mode, a way of sending
multicast datagrams. If security is desired and one of the built-in multicast datagrams. If security is desired and one of the built-in
security methods is to be used, support for some TLS-derived security methods is to be used, support for some TLS-derived
transport scheme, such as TLS [RFC5246] on top of TCP, or DTLS transport scheme - such as TLS [RFC5246] on top of TCP or DTLS
[RFC6347] on top of UDP, is also required. [RFC6347] on top of UDP - is also required.
2. Requirements Language 2. Requirements Language
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].
3. Terminology 3. Terminology
DNCP profile is a definition of a set of rules and values listed in A DNCP profile is a definition of a set of rules and values listed in
Section 10 specifying the behavior of a DNCP based protocol, such as Section 11 specifying the behavior of a DNCP based protocol, such as
the used transport method. For readability, any DNCP profile the used transport method. For readability, any DNCP profile
specific parameters with a profile-specific fixed value are prefixed specific parameters with a profile-specific fixed value are prefixed
with DNCP_. with DNCP_.
DNCP node is a single node which runs a protocol based on a DNCP A DNCP node is a single node which runs a protocol based on a DNCP
profile. profile.
DNCP network is a set of DNCP nodes running the same DNCP profile The DNCP network is a set of DNCP nodes running the same DNCP profile
that can reach each other, either via learned shared connections in that can reach each other, either via discovered connectivity in the
the underlying network, or using each other's addresses learned via underlying network, or using each other's addresses learned via other
other means. As DNCP exchanges are bidirectional, DNCP nodes means. As DNCP exchanges are bidirectional, DNCP nodes connected via
connected via only unidirectional links are not considered connected. only unidirectional links are not considered connected.
Node identifier is an opaque fixed-length identifier of The node identifier is an opaque fixed-length identifier consisting
DNCP_NODE_IDENTIFIER_LENGTH bytes which uniquely identifies a DNCP of DNCP_NODE_IDENTIFIER_LENGTH bytes which uniquely identifies a DNCP
node within a DNCP network. node within a DNCP network.
Link indicates a link-layer media over which directly connected nodes A link indicates a link-layer media over which directly connected
can communicate. nodes can communicate.
Interface indicates a port of a node that is connected to a An interface indicates a port of a node that is connected to a
particular link. particular link.
Connection denotes a locally configured use of DNCP on a DNCP node, A connection denotes a locally configured use of DNCP on a DNCP node,
that is attached either to an interface, to a specific remote unicast that is attached either to an interface, to a specific remote unicast
address to be contacted, or to a range of remote unicast addresses address to be contacted, or to a range of remote unicast addresses
that are allowed to contact. that are allowed to contact.
Connection identifier is a 32-bit opaque value, which identifies a The connection identifier is a 32-bit opaque value, which identifies
particular connection of that particular DNCP node. The value 0 is a particular connection of that particular DNCP node. The value 0 is
reserved for DNCP and sub-protocol purposes in the TLVs, and MUST NOT reserved for DNCP and sub-protocol purposes in the TLVs, and MUST NOT
be used to identify an actual connection. This definition is in sync be used to identify an actual connection. This definition is in sync
with [RFC3493], as the non-zero small positive integers should with [RFC3493], as the non-zero small positive integers should
comfortably fit within 32 bits. comfortably fit within 32 bits.
(DNCP) peer refers to another DNCP node with which a DNCP node A (DNCP) peer refers to another DNCP node with which a DNCP node
communicates directly on a particular connection. communicates directly on a particular connection.
Node data is a set of TLVs published by a node in the DNCP network. The node data is a set of TLVs published by a node in the DNCP
network. The whole node data is owned by the node that publishes it,
and it MUST be passed along as-is, including TLVs unknown to the
forwarder.
Node state is a set of metadata attributes for node data. It The node state is a set of metadata attributes for node data. It
includes a sequence number for versioning, a hash value for comparing includes a sequence number for versioning, a hash value for comparing
and a timestamp indicating the time passed since its last and a timestamp indicating the time passed since its last
publication. The hash function and the number of bits used are publication. The hash function and the number of bits used are
defined in the DNCP profile. defined in the DNCP profile.
Network state (hash) is a hash value which represents the current The network state (hash) is a hash value which represents the current
state of the network. The hash function and the number of bits used state of the network. The hash function and the number of bits used
are defined in the DNCP profile. Whenever any node is added, removed are defined in the DNCP profile. Whenever any node is added, removed
or changes its published node data this hash value changes as well. or changes its published node data this hash value changes as well.
It is calculated over the hash values of each reachable nodes' node It is calculated over the hash values of each reachable nodes' node
data in ascending order of the respective node identifier. data in ascending order of the respective node identifier.
Effective (trust) verdict for a certificate is defined as the verdict The effective (trust) verdict for a certificate is defined as the
with the highest priority within the set of verdicts announced for verdict with the highest priority within the set of verdicts
the certificate in the DNCP network. announced for the certificate in the DNCP network.
The neighbor graph is the undirected graph of DNCP nodes produced by
retaining only bidirectional peer relationships between nodes.
4. Data Model 4. Data Model
A DNCP node has: A DNCP node has:
o A timestamp indicating the most recent neighbor graph traversal o A timestamp indicating the most recent neighbor graph traversal
described in Section 5.4. described in Section 5.4.
A DNCP node has for every DNCP node in the DNCP network: A DNCP node has for every DNCP node in the DNCP network:
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o The connection identifier of the DNCP peer. o The connection identifier of the DNCP peer.
o The most recent address used by the DNCP peer (in an authenticated o The most recent address used by the DNCP peer (in an authenticated
message, if security is enabled). message, if security is enabled).
5. Operation 5. Operation
The DNCP protocol consists of Trickle [RFC6206] driven unicast or The DNCP protocol consists of Trickle [RFC6206] driven unicast or
multicast status messages which indicate the current status of shared multicast status messages which indicate the current status of shared
TLV data, and additional unicast message exchanges which ensure DNCP TLV data and additional unicast message exchanges which ensure DNCP
peer reachability and synchronize the data when necessary. peer reachability and synchronize the data when necessary.
If DNCP is to be used on a multicast-capable interface, as opposed to If DNCP is to be used on a multicast-capable interface, as opposed to
only point-to-point using unicast, a datagram-based transport which only point-to-point using unicast, a datagram-based transport which
supports multicast SHOULD be defined in the DNCP profile to be used supports multicast SHOULD be defined in the DNCP profile to be used
for the messages to be sent to the whole link. As this is used only for the messages to be sent to the whole link. As this is used only
to identify potential new DNCP nodes, and to notify that an unicast to identify potential new DNCP nodes and to notify that an unicast
exchange should be triggered, the multicast transport does not have exchange should be triggered, the multicast transport does not have
to be particularly secure. to be particularly secure.
5.1. Trickle-Driven Status Update Messages 5.1. Trickle-Driven Status Update Messages
Each node MUST send either a Long Network State Update message Each node MUST send either a Long Network State Update message
(Section 7.2) or a Short Network State Update message (Section 7.1) (Section 8.2) or a Short Network State Update message (Section 8.1)
every time the connection-specific Trickle algorithm [RFC6206] every time the connection-specific Trickle algorithm [RFC6206]
instance indicates that an update should be sent. The destination instance indicates that an update should be sent. The destination
address of the message should be multicast in case of an interface address of the message should be multicast in case of an interface
which is multicast-capable, or the unicast address of the remote which is multicast-capable, or the unicast address of the remote
party in case of a point-to-point connection. By default, Long party in case of a point-to-point connection. By default, Long
Network State Update messages SHOULD be used, but if it is defined as Network State Update messages SHOULD be used, but if it is defined as
undesirable for some case by the DNCP profile, Short Network State undesirable for some case by the DNCP profile, Short Network State
Update message MUST be sent instead. This may be useful to avoid Update message MUST be sent instead. This may be useful to avoid
fragmenting packets to multicast destinations, or for security fragmenting packets to multicast destinations, or for security
reasons. reasons.
A Trickle state MUST be maintained separately for each connection. A Trickle state MUST be maintained separately for each connection.
The Trickle state for all connections is considered inconsistent and The Trickle state for all connections is considered inconsistent and
reset if and only if the locally calculated network state hash reset if and only if the locally calculated network state hash
changes. This occurs either due to a change in the local node's own changes. This occurs either due to a change in the local node's own
node data, or due to receipt of more recent data from another node. node data, or due to receipt of more recent data from another node.
The Trickle algorithm has 3 parameters; Imin, Imax and k. Imin and The Trickle algorithm has 3 parameters: Imin, Imax and k. Imin and
Imax represent the minimum and maximum values for I, which is the Imax represent the minimum and maximum values for I, which is the
time interval during which at least k Trickle updates must be seen on time interval during which at least k Trickle updates must be seen on
a connection to prevent local state transmission. The actual a connection to prevent local state transmission. The actual
suggested Trickle algorithm parameters are DNCP profile specific, as suggested Trickle algorithm parameters are DNCP profile specific, as
described in Section 10. described in Section 11.
5.2. Processing of Received Messages 5.2. Processing of Received Messages
This section describes how received messages are processed. The DNCP This section describes how received messages are processed. The DNCP
profile may specify criteria based on which received messages are profile may specify criteria based on which received messages are
ignored. Any 'reply' mentioned in the steps below denotes sending of ignored. Any 'reply' mentioned in the steps below denotes sending of
the specified message via unicast to the originator of the message the specified message via unicast to the originator of the message
being processed. If the reply was caused by a multicast message and being processed. If the reply was caused by a multicast message and
sent to a link with shared bandwidth it SHOULD be delayed by a random sent to a link with shared bandwidth it SHOULD be delayed by a random
timespan in [0, Imin/2]. timespan in [0, Imin/2]. Sending of replies SHOULD be rate-limited
by the implementation, and in case of excess load (or some other
reason), a reply MAY be omitted altogether.
Upon receipt of: Upon receipt of:
Short Network State Update (Section 7.1): If the network state Short Network State Update (Section 8.1): If the network state
hash within the message differs from the locally calculated hash within the message differs from the locally calculated
network state hash, the receiver MUST reply with a Network State network state hash, the receiver MUST reply with a Network State
Request message (Section 7.3). Request message (Section 8.3).
Long Network State Update (Section 7.2): Long Network State Update (Section 8.2):
* If the network state hash within the message matches the * If the network state hash within the message matches the
locally calculated network state hash, stop processing. locally calculated network state hash, stop processing.
* Otherwise the receiver MUST identify nodes for which local * Otherwise the receiver MUST identify all nodes for which local
information is outdated (local update sequence number is lower information is outdated (local update sequence number is lower
than that within the message), potentially incorrect (local than that within the message), potentially incorrect (local
update sequence number matches but the hash of the node data update sequence number matches but the hash of the node data
TLV differs) or missing. TLV differs) or missing.
* If any such nodes are identified, the receiver MUST reply with * If any such nodes are identified, the receiver MUST reply with
one or more Node Data Request message(s) (Section 7.4) one or more Node Data Request message(s) (Section 8.4)
containing Request Node Data TLV(s) (Section 8.1.2) for the containing Request Node Data TLV(s) (Section 9.1.2) for the
corresponding nodes. corresponding nodes.
Network State Request (Section 7.3): the receiver MUST reply with Network State Request (Section 8.3): the receiver MUST reply with
a Long Network State Update (Section 7.2). a Long Network State Update (Section 8.2).
Node Data Request (Section 7.4): the receiver MUST reply with the Node Data Request (Section 8.4): the receiver MUST reply with the
requested data in a Node Data Reply message (Section 7.5). requested data in a Node Data Reply message (Section 8.5).
Optionally - if specified by the DNCP profile - multiple replies Optionally - if specified by the DNCP profile - multiple replies
MAY be sent in order to e.g. keep size of each datagram within the MAY be sent in order to e.g. keep size of each datagram within the
PMTU to the destination. However these replies must be valid PMTU to the destination. However these replies must be valid
stand-alone Node Data Reply messages, with the full state for the stand-alone Node Data Reply messages, with the full state for the
particular nodes. particular nodes.
Node Data Reply (Section 7.5): If the message contains Node State Node Data Reply (Section 8.5): If the message contains Node State
TLVs that are more recent than the local state (the received TLV TLVs that are more recent than the local state (the received TLV
has a higher update sequence number, the node data TLV hash has a higher update sequence number, the node data TLV hash
differs from the local one, or local data is missing altogether), differs from the local one, or local data is missing altogether)
and if the message also contains corresponding Node Data TLVs, the and if the message also contains corresponding Node Data TLVs, the
receiver MUST update its locally stored state. receiver MUST update its locally stored state.
If a message containing Node State TLVs (Section 8.2.3) is received If a message containing Node State TLVs (Section 9.2.3) is received
with the node identifier matching the local node identifier and a with the node identifier matching the local node identifier and a
higher update sequence number than its current local value, or the higher update sequence number than its current local value, or the
same update sequence number and a different hash, the node SHOULD re- same update sequence number and a different hash, the node SHOULD re-
publish its own node data with an update sequence number 1000 higher publish its own node data with an update sequence number 1000 higher
than the received one. This may occur normally once due to the local than the received one. This may occur normally once due to the local
node restarting, and not storing the most recently used update node restarting and not storing the most recently used update
sequence number. If this occurs more than once, the DNCP profile sequence number. If this occurs more than once, the DNCP profile
should provide guidance on how to handle these situations as it should provide guidance on how to handle these situations as it
indicates the existence of a second active node on the network with indicates the existence of another active node with the same node
the same node identifier. identifier.
5.3. Adding and Removing Peers 5.3. Adding and Removing Peers
When receiving a message on a connection from an unknown peer: When receiving a message on a connection from an unknown peer:
If it is a unicast message, the remote node MUST be added as a If it is a unicast message, and the message contains a Node
peer on the connection and a Neighbor TLV (Section 8.2.5) MUST be Connection TLV (Section 9.2.1), the remote node MUST be added as a
peer on the connection and a Neighbor TLV (Section 9.2.5) MUST be
created for it. created for it.
If it is a multicast message, the remote node SHOULD be sent a If it is a multicast message, and the message contains a Node
Connection TLV (Section 9.2.1), the remote node SHOULD be sent a
(possibly rate-limited) unicast Network State Request Message (possibly rate-limited) unicast Network State Request Message
(Section 7.3). (Section 8.3).
If keep-alives are NOT sent by the peer (either DNCP profile does not If keep-alives are NOT sent by the peer (either the DNCP profile does
specify the use of keep-alives, or the particular peer chooses not to not specify the use of keep-alives or the particular peer chooses not
send keep-alive messages), some other means MUST be employed to to send keep-alive messages), some other means MUST be employed to
ensure a DNCP peer is present, and when the peer is no longer ensure a DNCP peer is present. When the peer is no longer present,
present, the Neighbor TLV and the local DNCP peer state MUST be the Neighbor TLV and the local DNCP peer state MUST be removed.
removed.
5.4. Purging Unreachable Nodes 5.4. Purging Unreachable Nodes
When a Neighbor TLV or a whole node is added or removed, the neighbor When a Neighbor TLV or a whole node is added or removed, the neighbor
graph SHOULD be traversed for each node following the bidirectional graph SHOULD be traversed, starting from the local node. The edges
neighbor relationships. These are identified by looking for Neighbor to be traversed are identified by looking for Neighbor TLVs on both
TLVs on both nodes, that have the other node's identifier in the nodes, that have the other node's identifier in the neighbor node
neighbor node identifier, and local and neighbor connection identifier, and local and neighbor connection identifiers swapped.
identifiers swapped. Each node reached should be marked currently Each node reached should be marked currently reachable.
reachable.
DNCP nodes MUST be either purged immediately when not marked DNCP nodes MUST be either purged immediately when not marked
reachable in a particular graph traversal, or eventually after they reachable in a particular graph traversal, or eventually after they
have not been marked reachable within DNCP_GRACE_INTERVAL. During have not been marked reachable within DNCP_GRACE_INTERVAL. During
the grace period, the nodes that were not marked reachable in the the grace period, the nodes that were not marked reachable in the
most recent graph traversal MUST NOT be used for calculation of the most recent graph traversal MUST NOT be used for calculation of the
network state hash, be provided to any applications that need to use network state hash, be provided to any applications that need to use
the whole TLV graph, or be provided to remote nodes. the whole TLV graph, or be provided to remote nodes.
6. Keep-Alive Extension 6. Keep-Alive Extension
skipping to change at page 9, line 20 skipping to change at page 9, line 45
The Trickle-driven messages provide a mechanism for handling of new The Trickle-driven messages provide a mechanism for handling of new
peer detection (if applicable) on a connection, as well as state peer detection (if applicable) on a connection, as well as state
change notifications. Another mechanism may be needed to get rid of change notifications. Another mechanism may be needed to get rid of
old, no longer valid DNCP peers if the transport or lower layers do old, no longer valid DNCP peers if the transport or lower layers do
not provide one. not provide one.
If keep-alives are not specified in the DNCP profile, the rest of If keep-alives are not specified in the DNCP profile, the rest of
this section MUST be ignored. this section MUST be ignored.
A DNCP profile MAY specify either per-connection or per-peer keep- A DNCP profile MAY specify either per-connection or per-peer keep-
alive support. This document specifies only per-connection keep- alive support.
alive, thus if per-peer support is required either a lower layer
mechanism or a definition within the profile is required. For every connection that a keep-alive is specified for in the DNCP
profile, the connection-specific keep-alive interval MUST be
maintained. By default, it is DNCP_KEEPALIVE_INTERVAL. If there is
a local value that is preferred for that for any reason
(configuration, energy conservation, media type, ..), it should be
substituted instead. If a non-default keep-alive interval is used on
any connection, a DNCP node MUST publish appropriate Keep-Alive
Interval TLV(s) (Section 9.2.6).
6.1. Data Model Additions 6.1. Data Model Additions
The following additions to the Data Model (Section 4) are needed to The following additions to the Data Model (Section 4) are needed to
support keep-alive: support keep-alive:
Each node MUST have a timestamp which indicates the last time a Each node MUST have a timestamp which indicates the last time a
Network State TLV (Section 8.2.2) was sent for each connection, i.e. Network State TLV (Section 9.2.2) was sent for each connection, i.e.
on an interface or to the point-to-point peer(s). on an interface or to the point-to-point peer(s).
Each node MUST have for each peer: Each node MUST have for each peer:
o Last consistent state timestamp: a timestamp which indicates the o Last consistent state timestamp: a timestamp which indicates the
last time a consistent Network State TLV (Section 8.2.2) was last time a consistent Network State TLV (Section 9.2.2) was
received from the peer. When adding a new peer, it should be received from the peer. When adding a new peer, it should be
initialized to the current time. initialized to the current time.
6.2. Periodic Keep-Alive Messages 6.2. Per-Connection Periodic Keep-Alive Messages
For every connection that a keep-alive is specified for in the DNCP If per-connection keep-alives are enabled on connection with a
profile, the connection-specific keep-alive interval MUST be multicast-enabled link, and if no traffic containing a Network State
maintained. By default, it is DNCP_KEEPALIVE_INTERVAL. If there is TLV (Section 9.2.2) has been sent to a particular connection within
a local value that is preferred for that for any reason the connection-specific keep-alive interval, a Long Network State
(configuration, energy conservation, media type, ..), it should be Update message (Section 8.2) or a Short Network State Update message
substituted instead. If non-default keep-alive interval is used on (Section 8.1) MUST be sent on that connection. The type of message
any connection, a DNCP node MUST publish appropriate Keep-Alive should be chosen based on the considerations in Section 5.1. The
Interval TLV(s) (Section 8.2.6). actual sending time SHOULD be further delayed by a random timespan in
[0, Imin/2]. When such a message is sent, a new Trickle transmission
time 't' in [I/2, I] MUST be randomly chosen.
If no traffic containing a Network State TLV (Section 8.2.2) has been 6.3. Per-Peer Periodic Keep-Alive Messages
sent to a particular connection within the connection-specific keep-
alive interval, a Long Network State Update message (Section 7.2) or If per-peer keep-alives are enabled on a unicast-only connection, and
a Short Network State Update message (Section 7.1) MUST be sent on if no traffic containing a Network State TLV (Section 9.2.2) has been
that connection. The type of message should be chosen based on the sent to a particular peer within the connection-specific keep-alive
interval, a Long Network State Update message (Section 8.2) or a
Short Network State Update message (Section 8.1) MUST be sent to the
peer. The type of message should be chosen based on the
considerations in Section 5.1. When such a message is sent, a new considerations in Section 5.1. When such a message is sent, a new
Trickle transmission time 't' in [I/2, I] MUST be randomly chosen. Trickle transmission time 't' in [I/2, I] MUST be randomly chosen.
6.3. Received Message Processing Additions 6.4. Received Message Processing Additions
If the received message contains a Network State TLV (Section 8.2.2) If a message is received via unicast from the peer, the Last
which is consistent with the locally calculated network state hash, consistent state timestamp for the peer MUST be updated.
the Last consistent state timestamp for the peer MUST be updated.
6.4. Neighbor Removal If the received multicast message contains a Network State TLV
(Section 9.2.2) which is consistent with the locally calculated
network state hash, the Last consistent state timestamp for the peer
MUST be updated. If the TLV is inconsistent, and would not cause any
unicast exchange, Network State Request (Section 8.3) SHOULD be sent
via unicast.
6.5. Neighbor Removal
For every peer on every connection, the connection-specific keep- For every peer on every connection, the connection-specific keep-
alive interval must be calculated by looking for Keep-Alive Interval alive interval must be calculated by looking for Keep-Alive Interval
TLVs (Section 8.2.6) published by the node, and if none exist, using TLVs (Section 9.2.6) published by the node, and if none exist, using
the default value of DNCP_KEEPALIVE_INTERVAL. If the peer's last the default value of DNCP_KEEPALIVE_INTERVAL. If the peer's last
consistent state timestamp has not been updated for at least consistent state timestamp has not been updated for at least
DNCP_KEEPALIVE_MULTIPLIER times the peer's connection-specific keep- DNCP_KEEPALIVE_MULTIPLIER times the peer's connection-specific keep-
alive interval, the Neighbor TLV for that peer and the local DNCP alive interval, the Neighbor TLV for that peer and the local DNCP
peer state MUST be removed. peer state MUST be removed.
7. Protocol Messages 7. Support For Dense Broadcast Links
The DNCP profile or a user configuration should limit the number of
neighbors that are allowed for a (particular type of) link that a
connection runs on. If that limit is exceeded, nodes without the
highest Node Identifier on the link SHOULD treat the connection as an
unicast connection connected to the node that has the highest Node
Identifier detected on the link. The nodes MUST also keep listening
to multicast traffic to both detect the presence of that node, and to
react to nodes with a higher Node Identifier appearing. If the
highest Node Identifier present on the link changes, the connection
endpoint MUST be changed. If the Node Identifier of the local node
is the highest one, the node MUST keep the connection in normal
multicast mode, and the node MUST allow others to peer with it over
the link.
8. Protocol Messages
For point-to-point exchanges, DNCP can run across datagram-based or For point-to-point exchanges, DNCP can run across datagram-based or
reliable ordered stream-based transports. If a stream-based reliable ordered stream-based transports. If a stream-based
transport is used, a 32-bit length-value in network byte order is transport is used, a 32-bit length-value in network byte order is
sent before each message to indicate the number of bytes the sent before each message to indicate the number of bytes the
following message consists of. following message consists of.
DNCP messages are encoded as a concatenated sequence of Type-Length- DNCP messages are encoded as a concatenated sequence of Type-Length-
Value objects (Section 8). In order to facilitate fast comparing of Value objects (Section 9). In order to facilitate fast comparing of
local state with that in a received message update, all TLVs in every local state with that in a received message update, all TLVs in every
encoding scope (either within the message itself, or within a encoding scope (either within the message itself, or within a
container TLV) MUST be placed in ascending order based on the binary container TLV) MUST be placed in ascending order based on the binary
comparison of both TLV header and value. By design, the TLVs which comparison of both TLV header and value. By design, the TLVs which
MUST be present have the lowest available type values, ensuring they MUST be present have the lowest available type values, ensuring they
will naturally occur at the start of the Protocol Message, resembling will naturally occur at the start of the Protocol Message, resembling
a fixed format header. a fixed format header.
DNCP profiles MAY add additional TLVs to the message specified here, DNCP profiles MAY add additional TLVs to the message specified here,
or even define additional messages as needed. or even define additional messages as needed. TLVs not recognized by
the receiver MUST be ignored.
7.1. Short Network State Update Message 8.1. Short Network State Update Message
The Short Network State Update Message is used to announce the The Short Network State Update Message is used to announce the
sender's view of the network state using multicast. sender's view of the network state using multicast.
The following TLVs MUST be present: The following TLVs MUST be present:
o One Node Connection TLV (Section 8.2.1) identifying the o One Node Connection TLV (Section 9.2.1) identifying the
originating node and connection. originating node and connection.
o One Network State TLV (Section 8.2.2) containing the network state o One Network State TLV (Section 9.2.2) containing the network state
hash as calculated by the sender. hash as calculated by the sender.
The Short Network Status update message MUST NOT contain any Node The Short Network Status update message MUST NOT contain any Node
State TLV(s) (Section 8.2.3). State TLV(s) (Section 9.2.3).
7.2. Long Network State Update Message 8.2. Long Network State Update Message
The Long Network State Update Message is used to announce the The Long Network State Update Message is used to announce the
sender's view of the network state and all node states using sender's view of the network state and all node states using
multicast or unicast. multicast or unicast.
The following TLVs MUST be present: The following TLVs MUST be present:
o One Node Connection TLV (Section 8.2.1) identifying the o One Node Connection TLV (Section 9.2.1) identifying the
originating node and connection. originating node and connection.
o One Network State TLV (Section 8.2.2) containing the network state o One Network State TLV (Section 9.2.2) containing the network state
hash as calculated by the sender. hash as calculated by the sender.
o One or more Node State TLVs (Section 8.2.3) containing the node o One or more Node State TLVs (Section 9.2.3) containing the node
state of DNCP nodes as currently known to the sender. state of DNCP nodes as currently known to the sender.
The Long Network State Update message MUST include the corresponding The Long Network State Update message MUST include the corresponding
Node State TLV (Section 8.2.3) for each Node Data TLV used to Node State TLV (Section 9.2.3) for each Node Data TLV used to
calculate the network state hash. calculate the network state hash.
7.3. Network State Request Message 8.3. Network State Request Message
The Network State Request message is used to request the recipient's The Network State Request message is used to request the recipient's
view of the network state and all node states currently known to it. view of the network state and all node states currently known to it.
The following TLVs MUST be present: The following TLVs MUST be present:
o One Node Connection TLV (Section 8.2.1) identifying the o One Request Network State TLV (Section 9.1.1) indicating the type
originating node and connection.
o One Request Network State TLV (Section 8.1.1) indicating the type
of request. of request.
7.4. Node Data Request Message 8.4. Node Data Request Message
The Node Data Request message is used to request the node state and The Node Data Request message is used to request the node state and
data of one or more DNCP nodes in the network. data of one or more DNCP nodes in the network.
The following TLVs MUST be present: The following TLVs MUST be present:
o One Node Connection TLV (Section 8.2.1) identifying the o One or more Request Node Data TLVs (Section 9.1.2) indicating the
originating node and connection.
o One or more Request Node Data TLVs (Section 8.1.2) indicating the
nodes for which state and data is requested. nodes for which state and data is requested.
7.5. Node Data Reply Message 8.5. Node Data Reply Message
The Node Data Request message is used to provide the node data of one The Node Data Request message is used to provide the node data of one
or more DNCP nodes in the network. or more DNCP nodes in the network.
The following TLVs MUST be present: The following TLVs MUST be present:
o One Node Connection TLV (Section 8.2.1) identifying the o One Node Connection TLV (Section 9.2.1) identifying the
originating node and connection. originating node and connection.
o One or more Node State TLV (Section 8.2.3) and Node Data TLV o One or more Node State TLV (Section 9.2.3) and Node Data TLV
(Section 8.2.4) pairs with matching node identifiers for each node (Section 9.2.4) pairs with matching node identifiers for each node
previously requested in a Node Data Request message (Section 7.4). previously requested in a Node Data Request message (Section 8.4).
8. Type-Length-Value Objects 9. Type-Length-Value Objects
Each TLV is encoded as a 2 byte type field, followed by a 2 byte Each TLV is encoded as a 2 byte type field, followed by a 2 byte
length field (of the value, excluding header; 0 means no value) length field (of the value, excluding header; 0 means no value)
followed by the value itself (if any). Both type and length fields followed by the value itself (if any). Both type and length fields
in the header as well as all integer fields inside the value - unless in the header as well as all integer fields inside the value - unless
explicitly stated otherwise - are represented in network byte order. explicitly stated otherwise - are represented in network byte order.
Zero padding bytes MUST be added up to the next 4 byte boundary if Zero padding bytes MUST be added up to the next 4 byte boundary if
the length is not divisible by 4. These padding bytes MUST NOT be the length is not divisible by 4. These padding bytes MUST NOT be
included in the length field. included in the length field.
skipping to change at page 13, line 23 skipping to change at page 14, line 23
For example, type=123 (0x7b) TLV with value 'x' (120 = 0x78) is For example, type=123 (0x7b) TLV with value 'x' (120 = 0x78) is
encoded as: 007B 0001 7800 0000. encoded as: 007B 0001 7800 0000.
Notation: Notation:
.. = octet string concatenation operation. .. = octet string concatenation operation.
H(x) = non-cryptographic hash function specified by DNCP profile. H(x) = non-cryptographic hash function specified by DNCP profile.
8.1. Request TLVs 9.1. Request TLVs
8.1.1. Request Network State TLV 9.1.1. Request Network State TLV
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: REQ-NETWORK-STATE (2) | Length: 0 | | Type: REQ-NETWORK-STATE (2) | Length: 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This TLV is used to identify a Network State Request message This TLV is used to identify a Network State Request message
(Section 7.3). (Section 8.3).
8.1.2. Request Node Data TLV 9.1.2. Request Node Data TLV
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: REQ-NODE-DATA (3) | Length: >0 | | Type: REQ-NODE-DATA (3) | Length: >0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node Identifier | | Node Identifier |
| (length fixed in DNCP profile) | | (length fixed in DNCP profile) |
... ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This TLV is used within a Node Data Request message (Section 7.4) to This TLV is used within a Node Data Request message (Section 8.4) to
request node state and node data for the node with matching node request node state and node data for the node with matching node
identifier, if any, to be included in a subsequent Node Data Reply identifier, if any, to be included in a subsequent Node Data Reply
message (Section 7.5). message (Section 8.5).
8.2. Data TLVs 9.2. Data TLVs
8.2.1. Node Connection TLV 9.2.1. Node Connection TLV
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: NODE-CONNECTION (1) | Length: > 4 | | Type: NODE-CONNECTION (1) | Length: > 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node Identifier | | Node Identifier |
| (length fixed in DNCP profile) | | (length fixed in DNCP profile) |
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Connection Identifier | | Connection Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This TLV identifies both the local node's node identifier, as well as This TLV identifies both the local node's node identifier, as well as
the particular connection identifier. It MUST be sent in all the particular connection identifier. It MUST be sent in all
messages. messages if bidirectional peer relationship is desired with remote
nodes. Bidirectional peer relationship is not necessary for read-
only access to the DNCP state, but it is required to be able to
publish something.
8.2.2. Network State TLV 9.2.2. Network State TLV
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: NETWORK-STATE (10) | Length: > 0 | | Type: NETWORK-STATE (10) | Length: > 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| H(H(node data TLV 1) .. [...] .. H(node data TLV N)) | | H(H(node data TLV 1) .. [...] .. H(node data TLV N)) |
| (length fixed in DNCP profile) | | (length fixed in DNCP profile) |
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This TLV contains the current locally calculated network state hash. This TLV contains the current locally calculated network state hash.
The network state hash is derived by calculating the hash value for The network state hash is derived by calculating the hash value for
each currently reachable node's Node Data TLV, concatenating said each currently reachable node's Node Data TLV, concatenating said
hash values based on the ascending order of their corresponding node hash values based on the ascending order of their corresponding node
identifiers, and hashing the resulting concatenated hash values. identifiers, and hashing the resulting concatenated hash values.
8.2.3. Node State TLV 9.2.3. Node State TLV
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: NODE-STATE (11) | Length: > 8 | | Type: NODE-STATE (11) | Length: > 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node Identifier | | Node Identifier |
| (length fixed in DNCP profile) | | (length fixed in DNCP profile) |
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Update Sequence Number | | Update Sequence Number |
skipping to change at page 15, line 34 skipping to change at page 16, line 34
field in the TLV. field in the TLV.
The whole network should have roughly same idea about the time since The whole network should have roughly same idea about the time since
origination of any particular published state. Therefore every node, origination of any particular published state. Therefore every node,
including the originating one, MUST increment the time whenever it including the originating one, MUST increment the time whenever it
needs to send a Node State TLV for an already published Node Data needs to send a Node State TLV for an already published Node Data
TLV. This age value is not included within the Node Data TLV, TLV. This age value is not included within the Node Data TLV,
however, as that is immutable and used to detect changes in the however, as that is immutable and used to detect changes in the
network state. network state.
8.2.4. Node Data TLV 9.2.4. Node Data TLV
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: NODE-DATA (12) | Length: > 4 | | Type: NODE-DATA (12) | Length: > 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| node identifier | | node identifier |
| (length fixed in DNCP profile) | | (length fixed in DNCP profile) |
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Update Sequence Number | | Update Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nested TLVs containing node information | | Nested TLVs containing node information |
8.2.5. Neighbor TLV (within Node Data TLV) 9.2.5. Neighbor TLV (within Node Data TLV)
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: NEIGHBOR (13) | Length: > 8 | | Type: NEIGHBOR (13) | Length: > 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| neighbor node identifier | | neighbor node identifier |
| (length fixed in DNCP profile) | | (length fixed in DNCP profile) |
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 16, line 28 skipping to change at page 17, line 28
| Local Connection Identifier | | Local Connection Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This TLV indicates that the node in question vouches that the This TLV indicates that the node in question vouches that the
specified neighbor is reachable by it on the specified local specified neighbor is reachable by it on the specified local
connection. The presence of this TLV at least guarantees that the connection. The presence of this TLV at least guarantees that the
node publishing it has received traffic from the neighbor recently. node publishing it has received traffic from the neighbor recently.
For guaranteed up-to-date bidirectional reachability, the existence For guaranteed up-to-date bidirectional reachability, the existence
of both nodes' matching Neighbor TLVs should be checked. of both nodes' matching Neighbor TLVs should be checked.
8.2.6. Keep-Alive Interval TLV (within Node Data TLV) 9.2.6. Keep-Alive Interval TLV (within Node Data TLV)
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: KEEP-ALIVE-INTERVAL (14)| Length: 8 | | Type: KEEP-ALIVE-INTERVAL (14)| Length: 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Connection Identifier | | Connection Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interval | | Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Connection identifier is used to identify the particular connection Connection identifier is used to identify the particular connection
for which the interval applies. If 0, it applies for ALL connections for which the interval applies. If 0, it applies for ALL connections
for which no specific TLV exists. for which no specific TLV exists.
Interval specifies the interval in milliseconds at which the node Interval specifies the interval in milliseconds at which the node
sends keep-alives. A value of zero means no keep-alives are sent at sends keep-alives. A value of zero means no keep-alives are sent at
all; in that case, some lower layer mechanism that ensures presence all; in that case, some lower layer mechanism that ensures presence
of nodes MUST be available and used. of nodes MUST be available and used.
8.3. Custom TLV (within/without Node Data TLV) 9.3. Custom TLV (within/without Node Data TLV)
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: CUSTOM-DATA (15) | Length: > 0 | | Type: CUSTOM-DATA (15) | Length: > 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| H(URI) | | H(URI) |
| (length fixed in DNCP profile) | | (length fixed in DNCP profile) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque Data | | Opaque Data |
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This TLV can be used to contain anything; the URI used should be This TLV can be used to contain anything; the URI used should be
under control of the author of that specification. For example: under control of the author of that specification. For example:
V = H('http://example.com/author/json-for-dncp') .. '{"cool": "json V = H('http://example.com/author/json-for-dncp') .. '{"cool": "json
extension!"}' extension!"}'
or or
V = H('mailto:author@example.com') .. '{"cool": "json extension!"}' V = H('mailto:author@example.com') .. '{"cool": "json extension!"}'
9. Security and Trust Management 10. Security and Trust Management
If specified in the DNCP profile, either DTLS [RFC6347] or TLS If specified in the DNCP profile, either DTLS [RFC6347] or TLS
[RFC5246] may be used to authenticate and encrypt either some (if [RFC5246] may be used to authenticate and encrypt either some (if
specified optional in the profile), or all unicast traffic. The specified optional in the profile), or all unicast traffic. The
following methods for establishing trust are defined, but it is up to following methods for establishing trust are defined, but it is up to
the DNCP profile to specify which ones may, should or must be the DNCP profile to specify which ones may, should or must be
supported. supported.
9.1. Pre-Shared Key Based Trust Method 10.1. Pre-Shared Key Based Trust Method
A PSK-based trust model is a simple security management mechanism A PSK-based trust model is a simple security management mechanism
that allows an administrator to deploy devices to an existing network that allows an administrator to deploy devices to an existing network
by configuring them with a pre-defined key, similar to the by configuring them with a pre-defined key, similar to the
configuration of an administrator password or WPA-key. Although configuration of an administrator password or WPA-key. Although
limited in nature it is useful to provide a user-friendly security limited in nature it is useful to provide a user-friendly security
mechanism for smaller networks. mechanism for smaller networks.
9.2. PKI Based Trust Method 10.2. PKI Based Trust Method
A PKI-based trust-model enables more advanced management capabilities A PKI-based trust-model enables more advanced management capabilities
at the cost of increased complexity and bootstrapping effort. It at the cost of increased complexity and bootstrapping effort. It
however allows trust to be managed in a centralized manner and is however allows trust to be managed in a centralized manner and is
therefore useful for larger networks with a need for an authoritative therefore useful for larger networks with a need for an authoritative
trust management. trust management.
9.3. Certificate Based Trust Consensus Method 10.3. Certificate Based Trust Consensus Method
The certificate-based consensus model is designed to be a compromise The certificate-based consensus model is designed to be a compromise
between trust management effort and flexibility. It is based on between trust management effort and flexibility. It is based on
X.509-certificates and allows each DNCP node to provide a verdict on X.509-certificates and allows each DNCP node to provide a verdict on
any other certificate and a consensus is found to determine whether a any other certificate and a consensus is found to determine whether a
node using this certificate or any certificate signed by it is to be node using this certificate or any certificate signed by it is to be
trusted. trusted.
The current effective trust verdict for any certificate is defined as The current effective trust verdict for any certificate is defined as
the one with the highest priority from all verdicts announced for the one with the highest priority from all verdicts announced for
said certificate at the time. said certificate at the time.
9.3.1. Trust Verdicts 10.3.1. Trust Verdicts
Trust Verdicts are statements of DNCP nodes about the trustworthiness Trust Verdicts are statements of DNCP nodes about the trustworthiness
of X.509-certificates. There are 5 possible verdicts in order of of X.509-certificates. There are 5 possible verdicts in order of
ascending priority: ascending priority:
0 Neutral : no verdict exists but the DNCP network should determine 0 Neutral : no verdict exists but the DNCP network should determine
one. one.
1 Cached Trust : the last known effective verdict was Configured or 1 Cached Trust : the last known effective verdict was Configured or
Cached Trust. Cached Trust.
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trusted for participating in the DNCP network if and only if the trusted for participating in the DNCP network if and only if the
current effective verdict for its own certificate or any one in its current effective verdict for its own certificate or any one in its
certificate hierarchy is (Cached or Configured) Trust and none of the certificate hierarchy is (Cached or Configured) Trust and none of the
certificates in its hierarchy have an effective verdict of (Cached or certificates in its hierarchy have an effective verdict of (Cached or
Configured) Distrust. In case a node has a configured verdict, which Configured) Distrust. In case a node has a configured verdict, which
is different from the current effective verdict for a certificate, is different from the current effective verdict for a certificate,
the current effective verdict takes precedence in deciding the current effective verdict takes precedence in deciding
trustworthiness. Despite that, the node still retains and announces trustworthiness. Despite that, the node still retains and announces
its configured verdict. its configured verdict.
9.3.2. Trust Cache 10.3.2. Trust Cache
Each node SHOULD maintain a trust cache containing the current Each node SHOULD maintain a trust cache containing the current
effective trust verdicts for all certificates currently announced in effective trust verdicts for all certificates currently announced in
the DNCP network. This cache is used as a backup of the last known the DNCP network. This cache is used as a backup of the last known
state in case there is no node announcing a configured verdict for a state in case there is no node announcing a configured verdict for a
known certificate. It SHOULD be saved to a non-volatile memory at known certificate. It SHOULD be saved to a non-volatile memory at
reasonable time intervals to survive a reboot or power outage. reasonable time intervals to survive a reboot or power outage.
Every time a node (re)joins the network or detects the change of an Every time a node (re)joins the network or detects the change of an
effective trust verdict for any certificate, it will synchronize its effective trust verdict for any certificate, it will synchronize its
cache, i.e. store new effective verdicts overwriting any previously cache, i.e. store new effective verdicts overwriting any previously
cached verdicts. Configured verdicts are stored in the cache as cached verdicts. Configured verdicts are stored in the cache as
their respective cached counterparts. Neutral verdicts are never their respective cached counterparts. Neutral verdicts are never
stored and do not override existing cached verdicts. stored and do not override existing cached verdicts.
9.3.3. Announcement of Verdicts 10.3.3. Announcement of Verdicts
A node SHOULD always announce any configured trust verdicts it has A node SHOULD always announce any configured trust verdicts it has
established by itself, and it MUST do so if announcing the configured established by itself, and it MUST do so if announcing the configured
trust verdict leads to a change in the current effective verdict for trust verdict leads to a change in the current effective verdict for
the respective certificate. In absence of configured verdicts, it the respective certificate. In absence of configured verdicts, it
MUST announce cached trust verdicts it has stored in its trust cache, MUST announce cached trust verdicts it has stored in its trust cache,
if one of the following conditions applies: if one of the following conditions applies:
o The stored verdict is Cached Trust and the current effective o The stored verdict is Cached Trust and the current effective
verdict for the certificate is Neutral or does not exist. verdict for the certificate is Neutral or does not exist.
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(reserved) is reserved for future additions and MUST be set to 0 (reserved) is reserved for future additions and MUST be set to 0
when creating TLVs and ignored when parsing them. when creating TLVs and ignored when parsing them.
SHA-256 Fingerprint contains the SHA-256 [RFC6234] hash value of SHA-256 Fingerprint contains the SHA-256 [RFC6234] hash value of
the certificate in DER-format. the certificate in DER-format.
Common Name contains the variable-length (1-64 bytes) common name Common Name contains the variable-length (1-64 bytes) common name
of the certificate. Final byte MUST have value of 0. of the certificate. Final byte MUST have value of 0.
9.3.4. Bootstrap Ceremonies 10.3.4. Bootstrap Ceremonies
The following non-exhaustive list of methods describes possible ways The following non-exhaustive list of methods describes possible ways
to establish trust relationships between DNCP nodes and node to establish trust relationships between DNCP nodes and node
certificates. Trust establishment is a two-way process in which the certificates. Trust establishment is a two-way process in which the
existing network must trust the newly added node and the newly added existing network must trust the newly added node and the newly added
node must trust at least one of its neighboring nodes. It is node must trust at least one of its neighboring nodes. It is
therefore necessary that both the newly added node and an already therefore necessary that both the newly added node and an already
trusted node perform such a ceremony to successfully introduce a node trusted node perform such a ceremony to successfully introduce a node
into the DNCP network. In all cases an administrator MUST be into the DNCP network. In all cases an administrator MUST be
provided with external means to identify the node belonging to a provided with external means to identify the node belonging to a
certificate based on its fingerprint and a meaningful common name. certificate based on its fingerprint and a meaningful common name.
9.3.4.1. Trust by Identification 10.3.4.1. Trust by Identification
A node implementing certificate-based trust MUST provide an interface A node implementing certificate-based trust MUST provide an interface
to retrieve the current set of effective trust verdicts, fingerprints to retrieve the current set of effective trust verdicts, fingerprints
and names of all certificates currently known and set configured and names of all certificates currently known and set configured
trust verdicts to be announced. Alternatively it MAY provide a trust verdicts to be announced. Alternatively it MAY provide a
companion DNCP node or application with these capabilities with which companion DNCP node or application with these capabilities with which
it has a pre-established trust relationship. it has a pre-established trust relationship.
9.3.4.2. Preconfigured Trust 10.3.4.2. Preconfigured Trust
A node MAY be preconfigured to trust a certain set of node or CA A node MAY be preconfigured to trust a certain set of node or CA
certificates. However such trust relationships MUST NOT result in certificates. However such trust relationships MUST NOT result in
unwanted or unrelated trust for nodes not intended to be run inside unwanted or unrelated trust for nodes not intended to be run inside
the same network (e.g. all other devices by the same manufacturer). the same network (e.g. all other devices by the same manufacturer).
9.3.4.3. Trust on Button Press 10.3.4.3. Trust on Button Press
A node MAY provide a physical or virtual interface to put one or more A node MAY provide a physical or virtual interface to put one or more
of its internal network interfaces temporarily into a mode in which of its internal network interfaces temporarily into a mode in which
it trusts the certificate of the first DNCP node it can successfully it trusts the certificate of the first DNCP node it can successfully
establish a connection with. establish a connection with.
9.3.4.4. Trust on First Use 10.3.4.4. Trust on First Use
A node which is not associated with any other DNCP node MAY trust the A node which is not associated with any other DNCP node MAY trust the
certificate of the first DNCP node it can successfully establish a certificate of the first DNCP node it can successfully establish a
connection with. This method MUST NOT be used when the node has connection with. This method MUST NOT be used when the node has
already associated with any other DNCP node. already associated with any other DNCP node.
10. DNCP Profile-Specific Definitions 11. DNCP Profile-Specific Definitions
Each DNCP profile MUST define following: Each DNCP profile MUST define following:
o How the messages are secured: o How the messages are secured: Not at all, optionally or always
with the TLS scheme defined here using one or more of the methods,
* Not at all, or with something else. If the links with DNCP nodes can be
sufficiently secured or isolated, it is possible to run DNCP in a
* optionally or always with the TLS scheme defined here using one secure manner without using any form of authentication or
or more of the methods, or encryption.
* with something else.
Given that links with DNCP nodes can be sufficiently secured or
isolated it is possible to run DNCP in a secure manner without
using any form of authentication or encryption.
o Unicast and optionally multicast transport protocol(s) to be used. o Unicast and optionally multicast transport protocol(s) to be used.
If TLS scheme within this document is to be used security, TLS or If TLS scheme within this document is to be used security, TLS or
DTLS support for at least the unicast transport protocol is DTLS support for at least the unicast transport protocol is
mandatory. mandatory.
o Transport protocols' parameters such as port numbers to be used, o Transport protocols' parameters such as port numbers to be used,
or multicast address to be used. Unicast, multicast, and secure or multicast address to be used. Unicast, multicast, and secure
unicast may each require different parameters, if applicable. unicast may each require different parameters, if applicable.
o When receiving messages, what sort of messages are dropped, as o When receiving messages, what sort of messages are dropped, as
specified in Section 5.2. specified in Section 5.2.
o What is the criteria for sending Trickle-based Long Network State o What is the criteria for sending Trickle-based Long Network State
Update message (Section 7.2) on an interface or to a DNCP peer. Update message (Section 8.2) on an interface or to a DNCP peer.
o How to deal with node identifier collision as described in o How to deal with node identifier collision as described in
Section 5.2. Main options are either for one or both nodes to Section 5.2. Main options are either for one or both nodes to
assign new node identifiers to themselves, or to notify someone assign new node identifiers to themselves, or to notify someone
about a fatal error condition in the DNCP network. about a fatal error condition in the DNCP network.
o Imin, Imax and k ranges to be suggested for implementations to be o Imin, Imax and k ranges to be suggested for implementations to be
used in the Trickle algorithm. The Trickle algorithm does not used in the Trickle algorithm. The Trickle algorithm does not
require these to be same across all implementations for it to require these to be same across all implementations for it to
work, but similar orders of magnitude helps implementations of a work, but similar orders of magnitude helps implementations of a
skipping to change at page 23, line 13 skipping to change at page 24, line 5
also associated parameters: also associated parameters:
* DNCP_KEEPALIVE_INTERVAL: How often keep-alive messages are to * DNCP_KEEPALIVE_INTERVAL: How often keep-alive messages are to
be sent by default (if enabled). be sent by default (if enabled).
* DNCP_KEEPALIVE_MULTIPLIER: How many times the * DNCP_KEEPALIVE_MULTIPLIER: How many times the
DNCP_KEEPALIVE_INTERVAL (or peer-supplied keep-alive interval DNCP_KEEPALIVE_INTERVAL (or peer-supplied keep-alive interval
value) a node may not be heard from to be considered still value) a node may not be heard from to be considered still
valid. valid.
11. Security Considerations 12. Security Considerations
DNCP profiles may use multicast to indicate DNCP state changes and DNCP profiles may use multicast to indicate DNCP state changes and
for keep-alive purposes. However, no actual data TLVs will be sent for keep-alive purposes. However, no actual data TLVs will be sent
across that channel. Therefore an attacker may only learn hash across that channel. Therefore an attacker may only learn hash
values of the state within DNCP and may be able to trigger unicast values of the state within DNCP and may be able to trigger unicast
synchronization attempts between nodes on a local link this way. A synchronization attempts between nodes on a local link this way. A
DNCP node should therefore rate-limit its reactions to multicast DNCP node should therefore rate-limit its reactions to multicast
packets. packets.
When using DNCP to bootstrap a network, PKI based solutions may have When using DNCP to bootstrap a network, PKI based solutions may have
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accurate time, or due to inability to use the network to either check accurate time, or due to inability to use the network to either check
Certifcate Revocation Lists or perform on-line validation. Certifcate Revocation Lists or perform on-line validation.
The Certificate-based trust consensus mechanism defined in this The Certificate-based trust consensus mechanism defined in this
document allows for a consenting revocation, however in case of a document allows for a consenting revocation, however in case of a
compromised device the trust cache may be poisoned before the actual compromised device the trust cache may be poisoned before the actual
revocation happens allowing the distrusted device to rejoin the revocation happens allowing the distrusted device to rejoin the
network using a different identity. Stopping such an attack might network using a different identity. Stopping such an attack might
require physical intervention and flushing of the trust caches. require physical intervention and flushing of the trust caches.
12. IANA Considerations 13. IANA Considerations
IANA should set up a registry for DNCP TLV types, with the following IANA should set up a registry for DNCP TLV types, with the following
initial contents: initial contents:
0: Reserved (should not happen on wire) 0: Reserved (should not happen on wire)
1: Node connection 1: Node connection
2: Request network state 2: Request network state
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17-31: Reserved for future DNCP versions. 17-31: Reserved for future DNCP versions.
192-255: Reserved for per-implementation experimentation. The nodes 192-255: Reserved for per-implementation experimentation. The nodes
using TLV types in this range SHOULD use e.g. Custom TLV to identify using TLV types in this range SHOULD use e.g. Custom TLV to identify
each other and therefore eliminate potential conflict caused by each other and therefore eliminate potential conflict caused by
potential different use of same TLV numbers. potential different use of same TLV numbers.
For the rest of the values (32-191, 256-65535), policy of 'standards For the rest of the values (32-191, 256-65535), policy of 'standards
action' should be used. action' should be used.
13. References 14. References
13.1. Normative references 14.1. 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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6206] Levis, P., Clausen, T., Hui, J., Gnawali, O., and J. Ko, [RFC6206] Levis, P., Clausen, T., Hui, J., Gnawali, O., and J. Ko,
"The Trickle Algorithm", RFC 6206, March 2011. "The Trickle Algorithm", RFC 6206, March 2011.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012. Security Version 1.2", RFC 6347, January 2012.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
13.2. Informative references 14.2. Informative references
[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
Stevens, "Basic Socket Interface Extensions for IPv6", RFC Stevens, "Basic Socket Interface Extensions for IPv6", RFC
3493, February 2003. 3493, February 2003.
[RFC6234] Eastlake, D. and T. Hansen, "US Secure Hash Algorithms [RFC6234] Eastlake, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234, May 2011. (SHA and SHA-based HMAC and HKDF)", RFC 6234, May 2011.
Appendix A. Some Outstanding Issues Appendix A. Some Outstanding Issues
Should per-peer keep-alives be specified here? They are essentially Should better forms of combined messages be defined? e.g. allow
constant unicast keep-alives, as opposed to unicast OR multicast per- sending both request-network-state, and currently set of known local
connection ones are. state at same time in one message.
Should some sort of fragmentation scheme be defined for the data?
Currently, DNCP uses Merkle tree of depth 2 (node data -> node hash
-> network hash). However, it essentially treats all TLVs published
by a single node as a single chunk on the protocol level. Is that a
scalability problem? Adding one more level to the tree might address
this.
Appendix B. Some Obvious Questions and Answers Appendix B. Some Obvious Questions and Answers
Q: Should there be nested container syntax that is actually self- Q: Should there be nested container syntax that is actually self-
describing? (i.e. type flag that indicates container, no body except describing? (i.e. type flag that indicates container, no body except
sub-TLVs?) sub-TLVs?)
A: Not for now, but perhaps valid design.. TBD. A: Not for now, but perhaps valid design.. TBD.
Q: Add third case for multicast - 'medium' network state, which is Q: Add third case for multicast - 'medium' network state, which is
'long' one, but partial? 'long' one, but partial?
A: Drops typical convergence on large networks 5->3 packets, at A: Drops typical convergence on large networks 5->3 packets, at
expense of some specification/implementation complexity. However, as expense of some specification/implementation complexity. However, as
anything else than short network state leaks information via anything else than short network state leaks information via
multicast, it does not seem worth it as secure protocols probably multicast, it does not seem worth it as secure protocols probably
want to prevent multicast sending of anything else than short network want to prevent multicast sending of anything else than short network
state in any case. state in any case. Additionally, the long network state being
complete set of nodes actually facilitates light-weight nodes that do
not want to do graph-based pruning. So all in all, perhaps not worth
it.
Q: 32-bit connection id? Q: 32-bit connection id?
A: Here, it would save 32 bits per neighbor if it was 16 bits (and A: Here, it would save 32 bits per neighbor if it was 16 bits (and
less is not realistic). However, TLVs defined elsewhere would not less is not realistic). However, TLVs defined elsewhere would not
seem to even gain that much on average. 32 bits is also used for seem to even gain that much on average. 32 bits is also used for
ifindex in various operating systems, making for simpler ifindex in various operating systems, making for simpler
implementation. implementation.
Q: Why not doing (performance thing X, Y or Z)? Q: Why have topology information at all?
A: This is designed mostly to be minimal (only timers Trickle ones; A: It is an alternative to the more traditional seq#/TTL-based
everything triggered by Trickle-driven messages or local state flooding schemes. In steady state, there is no need to e.g. re-
changes). However, feel free to suggest better (even more minimal) publish every now and then.
design which works.
Appendix C. Changelog Appendix C. Changelog
draft-stenberg-homenet-dncp-00: Split from pre-version of draft-ietf- draft-ietf-homenet-dncp-01:
o Fixed keep-alive semantics to consider unicast requests also
updates of most recently consistent, and added proactive unicast
request to ensure even inconsistent keep-alive messages eventually
triggering consistency timestamp update.
o Facilitated (simple) read-only clients by making Node Connection
TLV optional if just using DNCP for read-only purposes.
o Added text describing how to deal with "dense" networks, but left
actual numbers and mechanics up to DNCP profiles and (local)
configurations.
draft-ietf-homenet-dncp-00: Split from pre-version of draft-ietf-
homenet-hncp-03 generic parts. Changes that affect implementations: homenet-hncp-03 generic parts. Changes that affect implementations:
o TLVs were renumbered. o TLVs were renumbered.
o TLV length does not include header (=-4). This facilitates e.g. o TLV length does not include header (=-4). This facilitates e.g.
use of DHCPv6 option parsing libraries (same encoding), and use of DHCPv6 option parsing libraries (same encoding), and
reduces complexity (no need to handle error values of length less reduces complexity (no need to handle error values of length less
than 4). than 4).
o Trickle is reset only when locally calculated network state hash o Trickle is reset only when locally calculated network state hash
 End of changes. 116 change blocks. 
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