draft-ietf-6tisch-enrollment-enhanced-beacon-05.txt   draft-ietf-6tisch-enrollment-enhanced-beacon-06.txt 
6lo Working Group D. Dujovne 6lo Working Group D. Dujovne
Internet-Draft Universidad Diego Portales Internet-Draft Universidad Diego Portales
Intended status: Standards Track M. Richardson Intended status: Standards Track M. Richardson
Expires: March 19, 2020 Sandelman Software Works Expires: May 7, 2020 Sandelman Software Works
September 16, 2019 November 04, 2019
IEEE802.15.4 Informational Element encapsulation of 6tisch Join and IEEE 802.15.4 Information Element encapsulation of 6TiSCH Join and
Enrollment Information Enrollment Information
draft-ietf-6tisch-enrollment-enhanced-beacon-05 draft-ietf-6tisch-enrollment-enhanced-beacon-06
Abstract Abstract
In TSCH mode of IEEE STD 802.15.4 opportunities for broadcasts are In TSCH mode of IEEE STD 802.15.4, opportunities for broadcasts are
limited to specific times and specific channels. Nodes in a TSCH limited to specific times and specific channels. Nodes in a TSCH
network typically frequently send Enhanced Beacon (EB) frames to network typically frequently send Enhanced Beacon (EB) frames to
announce the presence of the network. This document provides a announce the presence of the network. This document provides a
mechanism by which small details critical for new nodes (pledges) and mechanism by which small details critical for new nodes (pledges) and
long sleeping nodes may be carried within the Enhanced Beacon. long sleeping nodes may be carried within the Enhanced Beacon.
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
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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 March 19, 2020. This Internet-Draft will expire on May 7, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Use of BCP 14 Terminology . . . . . . . . . . . . . . . . 2 1.1. Use of BCP 14 Terminology . . . . . . . . . . . . . . . . 2
1.2. Layer-2 Synchronization . . . . . . . . . . . . . . . . . 2 1.2. Layer-2 Synchronization . . . . . . . . . . . . . . . . . 2
1.3. Layer-3 synchronization IPv6 Router solicitations and 1.3. Layer-3 synchronization: IPv6 Router Solicitations and
advertisements . . . . . . . . . . . . . . . . . . . . . 3 Advertisements . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol Definition . . . . . . . . . . . . . . . . . . . . . 3 2. Protocol Definition . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5 4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6 7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
[RFC7554] describes the use of the time-slotted channel hopping [RFC7554] describes the use of the time-slotted channel hopping
(TSCH) mode of [ieee802154]. As further details in [RFC8180], an (TSCH) mode of [ieee802154]. As further detailed in [RFC8180], an
Enhanced Beacon is transmitted during a slot designated a broadcast Enhanced Beacon (EB) is transmitted during a slot designated a
slot. broadcast slot.
1.1. Use of BCP 14 Terminology 1.1. Use of BCP 14 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", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[BCP14] [RFC2119] when, and only when, they appear in all capitals, [BCP14] [RFC2119] when, and only when, they appear in all capitals,
as shown here. as shown here.
Other terminology can be found in [I-D.ietf-6tisch-architecture] in Other terminology can be found in [I-D.ietf-6tisch-architecture] in
section 2.1. section 2.1.
1.2. Layer-2 Synchronization 1.2. Layer-2 Synchronization
As explained in section 6 of [RFC8180], the Enhanced Beacon has a As explained in section 6 of [RFC8180], the Enhanced Beacon (EB) has
number of purposes: synchronization of ASN and Join Metric, timeslot a number of purposes: synchronization of ASN and Join Metric,
template identifier, the channel hopping sequence identifier, TSCH carrying timeslot template identifier, carrying the channel hopping
SlotFrame and Link IE. sequence identifier, and indicating the TSCH SlotFrame.
The Enhanced Beacon (EB) is used by nodes already part of a TSCH The EB is used by nodes already part of a TSCH network to annouce its
network to annouce its existance. Receiving an EB allows a Joining existence. Receiving an EB allows a Joining Node (pledge) to learn
Node (pledge) to learn about the network and synchronize to it. The about the network and synchronize to it. The EB may also be used as
EB may also be used as a means for a node already part of the network a means for a node already part of the network to re-synchronize
to re-synchronize [RFC7554]. [RFC7554].
There are a limited number of timeslots designated as a broadcast There is a limited number of timeslots designated as a broadcast slot
slot by each router. These slots are rare, and with 10ms slots, with by each router in the network. These slots are rare, and with 10ms
a slot-frame length of 100, there may be only 1 slot/s for the slots, with a slot-frame length of 100, there may be only 1 slot/s
beacon. for the beacon.
1.3. Layer-3 synchronization IPv6 Router solicitations and 1.3. Layer-3 synchronization: IPv6 Router Solicitations and
advertisements Advertisements
At layer 3, [RFC4861] defines a mechanism by which nodes learn about At layer 3, [RFC4861] defines a mechanism by which nodes learn about
routers by listening for multicasted Router Advertisements (RA). If routers by listening for multicasted Router Advertisements (RA). If
no RA is heard within a set time, then a Router Solicitation (RS) may no RA is heard within a set time, then a Router Solicitation (RS) may
be multicast, to which an RA will be received, usually unicast. be multicast, to which an RA will be received, usually unicast.
Although [RFC6775] reduces the amount of multicast necessary to do Although [RFC6775] reduces the amount of multicast necessary to do
address resolution via Neighbor Solicitation messages, it still address resolution via Neighbor Solicitation (NS) messages, it still
requires multicast of either RAs or RS. This is an expensive requires multicast of either RAs or RS. This is an expensive
operation for two reasons: there are few multicast timeslots for operation for two reasons: First, there are few multicast timeslots
unsolicited RAs; if a pledge node does not hear an RA, and decides to for unsolicited RAs; and second, if a pledge node does not hear an
send a RS (consuming a broadcast aloha slot with unencrypted RA, and decides to send a RS, a broadcast aloha slot is consumed with
traffic), unicast RS may be sent in response. unencrypted traffic. In this case, a unicast RS may be sent in
response.
This is a particularly acute issue for the join process for the This is a particularly acute issue for the join process for the
following reasons: following reasons:
1. use of a multicast slot by even a non-malicious unauthenticated 1. use of a multicast slot by even a non-malicious unauthenticated
node for a Router Solicitation may overwhelm that time slot. node for a Router Solicitation (RS) may overwhelm that time slot.
2. it may require many seconds of on-time before a new pledge hears 2. it may require many seconds of on-time before a new pledge hears
a Router Soliciation that it can use. a Router Advertisement (RA) that it can use.
3. a new pledge may listen to many Enhanced Beacons before it can 3. a new pledge may listen to many Enhanced Beacons (EB) before it
pick an appropriate network and/or closest Join Assistant to can pick an appropriate network and/or closest Join Assistant to
attach to. If it must listen for a RS as well as find the attach to. If it must listen for a RA as well as find the
Enhanced Beacon, then the process may take a very long time. Enhanced Beacon (EB), then the process may take a very long time.
This document defines a new IETF IE subtype to provide join and
enrollment information to prospective pledges in a more efficient
way.
2. Protocol Definition 2. Protocol Definition
[RFC8137] creates a registry for new IETF IE subtypes. This document [RFC8137] creates a registry for new IETF IE subtypes. This document
allocates a new subtype. allocates a new subtype.
The new IE subtype structure is as follows. As explained in The new IE subtype structure is as follows. As explained in
[RFC8137] the length of the Sub-Type Content can be calculated from [RFC8137] the length of the Sub-Type Content can be calculated from
the container, so no length information is necessary. the container, so no length information is necessary.
1 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD-XXX |R|P| res | proxy prio | rank priority | | TBD-XXX |R|P| res | proxy prio | rank priority |
+-+-+-+-+-+-+-+-+-+-------------+-------------+-----------------+ +-+-+-+-+-+-+-+-+-+-------------+-------------+-----------------+
| pan priority | | | pan priority | |
+---------------+ + +---------------+ +
| Join Proxy lower-64 | | Join Proxy lower-64 |
+ (present if P=1) + + (present if P=1) +
| | | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | | | |
+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+ +
| network ID | | network ID |
+ variable length, up to 16 bytes + + variable length, up to 16 bytes +
~ ~ ~ ~
+ + + +
| | | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
proxy priority this field indicates the willingness to act as join Figure 1: IE subtype structure
proxy. Lower value indicates willing to act as a Join Proxy as
described in [I-D.ietf-6tisch-minimal-security]. Values range 0
(most willing) to 0x7e (least willing). A priority of 0x7f
indicates that the announcer should never be considered as a
viable enrollment proxy. Only unenrolled pledges look at this
value.
pan priority the pan priority is a value set by the DODAG root to R the Router Advertisement R-flag is set if the sending node will
indicate the relative priority of this LLN compared to those with act as a Router for host-only nodes that need addressing via
different PANIDs. This value may be used as part of the unicast Router Solicitation messages.
enrollment priority, but typically is used by devices which have
already enrolled, and need to determine which PAN to pick. P if the Proxy Address P-flag is set, then the lower 64-bits of the
Unenrolled pledges MAY consider this value when selecting a PAN to Join Proxy's link-local address follows the network ID. If the
join. Enrolled devices MAY consider this value when looking for Proxy Address bit is not set, then the Link Layer address of the
an eligible parent device. Join Proxy is identical to the Layer-2 8-byte address used to
originate this enhanced beacon. In either case, the destination
layer-2 address of this beacon may use the layer-2 address which
was used to originate the beacon.
proxy priority this field indicates the willingness fo the sender to
act as join proxy. Lower value indicates greater willingness to
act as a Join Proxy as described in
[I-D.ietf-6tisch-minimal-security]. Values range 0x00 (most
willing) to 0x7e (least willing). A priority of 0x7f indicates
that the announcer should never be considered as a viable
enrollment proxy. Only unenrolled pledges look at this value.
rank priority the rank "priority" is set by the 6LR which sent the rank priority the rank "priority" is set by the 6LR which sent the
beacon and is an indication of how willing this 6LR is to serve as beacon and is an indication of how willing this 6LR is to serve as
an RPL parent within a particular network ID. This is a local an RPL parent within a particular network ID. This is a local
value to be determined in other work. It might be calculated from value to be determined in other work. It might be calculated from
RPL rank, and it may include some modifications based upon current RPL rank, and it may include some modifications based upon current
number of children, or number of neighbor cache entries available. number of children, or number of neighbor cache entries available.
This value MUST be ignored by pledges, it is for enrolled devices This value MUST be ignored by pledges, it is for enrolled devices
only. only.
R the Router Advertisement R-flag is set if the sending node will pan priority the pan priority is a value set by the DODAG root to
act as a Router for host-only nodes that need addressing via indicate the relative priority of this LLN compared to those with
unicast Router Solicitation messages. different PANIDs. This value may be used as part of the
enrollment priority, but typically is used by devices which have
P if the Proxy Address P-flag is set, then the lower 64-bits of the already enrolled, and need to determine which PAN to pick.
Join Proxy's Link Layer address follows the network ID. If the Unenrolled pledges MAY consider this value when selecting a PAN to
Proxy Address bit is not set, then the Link Layer address of the join. Enrolled devices MAY consider this value when looking for
Join Proxy is identical to the Layer-2 8-byte address used to an eligible parent device.
originate this enhanced beacon. In either case, the layer-2
address of any IPv6 traffic to the originator of this beacon may
use the layer-2 address which was used to originate the beacon.
join-proxy interface ID if the P bit is set, then 64 bits (8 bytes) Join Proxy lower-64 if the P bit is set, then 64 bits (8 bytes) of
of address are present. This field provides the suffix of the address are present. This field provides the suffix of the Link-
Link-Local address of the Join Proxy. The associated prefix is Local address of the Join Proxy. The associated prefix is well-
well-known as fe80::/64. known as fe80::/64.
network ID this is an variable length field, up to 16-bytes in size network ID this is a variable length field, up to 16-bytes in size
that uniquely identifies this network, potentially among many that uniquely identifies this network, potentially among many
networks that are operating in the same frequencies in overlapping networks that are operating in the same frequencies in overlapping
physical space. The length of this field can be calculated as physical space. The length of this field can be calculated as
being whatever is left in the Information Element. being whatever is left in the Information Element.
In a 6tisch network, where RPL [RFC6550] is used as the mesh routing In a 6tisch network, where RPL [RFC6550] is used as the mesh routing
protocol, the network ID can be constructed from a SHA256 hash of the protocol, the network ID can be constructed from a SHA256 hash of the
prefix (/64) of the network. That is just a suggestion for a default prefix (/64) of the network. That is just a suggestion for a default
value. In some LLNs where multiple PANIDs may lead to the same value. In some LLNs where multiple PANIDs may lead to the same
management device (the JRC), then a common value that is the same management device (the JRC), then a common value that is the same
skipping to change at page 6, line 12 skipping to change at page 6, line 26
The use of a SHA256 hash of the DODAGID, rather than using the The use of a SHA256 hash of the DODAGID, rather than using the
DODAGID directly provides some cover the addresses used within the DODAGID directly provides some cover the addresses used within the
network. The DODAGID is usually the IPv6 address of the root of the network. The DODAGID is usually the IPv6 address of the root of the
RPL mesh. RPL mesh.
An interloper with a radio sniffer would be able to use the network An interloper with a radio sniffer would be able to use the network
ID to map out the extend of the mesh network. ID to map out the extend of the mesh network.
5. IANA Considerations 5. IANA Considerations
Allocate a new number TBD-XXX from Registry IETF IE Sub-type ID. Allocate a new number TBD-XXX from Registry IETF IE Sub-type ID, as
This entry should be called 6tisch-Join-Info, and should refer to defined by [RFC8137]. This entry should be called 6tisch-Join-Info,
this document. and should refer to this document.
6. Acknowledgements 6. Acknowledgements
Thomas Watteyne provided extensive editorial comments on the Thomas Watteyne provided extensive editorial comments on the
document. document. Carles Gomez Montenegro generated a detailed review of the
document at WGLC.
7. References 7. References
7.1. Normative References 7.1. Normative References
[BCP14] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [BCP14] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[I-D.ietf-6tisch-minimal-security] [I-D.ietf-6tisch-minimal-security]
Vucinic, M., Simon, J., Pister, K., and M. Richardson, Vucinic, M., Simon, J., Pister, K., and M. Richardson,
"Minimal Security Framework for 6TiSCH", draft-ietf- "Minimal Security Framework for 6TiSCH", draft-ietf-
6tisch-minimal-security-12 (work in progress), July 2019. 6tisch-minimal-security-13 (work in progress), October
2019.
[ieee802154] [ieee802154]
IEEE standard for Information Technology, ., "IEEE Std. IEEE standard for Information Technology, ., "IEEE Std.
802.15.4, Part. 15.4: Wireless Medium Access Control (MAC) 802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)
and Physical Layer (PHY) Specifications for Low-Rate and Physical Layer (PHY) Specifications for Low-Rate
Wireless Personal Area Networks", n.d., Wireless Personal Area Networks", n.d.,
<http://standards.ieee.org/findstds/ <http://standards.ieee.org/findstds/
standard/802.15.4-2015.html>. standard/802.15.4-2015.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
skipping to change at page 7, line 19 skipping to change at page 7, line 37
<https://www.rfc-editor.org/info/rfc6775>. <https://www.rfc-editor.org/info/rfc6775>.
[RFC8137] Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information [RFC8137] Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information
Element for the IETF", RFC 8137, DOI 10.17487/RFC8137, May Element for the IETF", RFC 8137, DOI 10.17487/RFC8137, May
2017, <https://www.rfc-editor.org/info/rfc8137>. 2017, <https://www.rfc-editor.org/info/rfc8137>.
7.2. Informative References 7.2. Informative References
[I-D.ietf-6tisch-architecture] [I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-26 (work of IEEE 802.15.4", draft-ietf-6tisch-architecture-28 (work
in progress), August 2019. in progress), October 2019.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550, Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012, DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>. <https://www.rfc-editor.org/info/rfc6550>.
[RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using [RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
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