draft-ietf-6tisch-enrollment-enhanced-beacon-13.txt   draft-ietf-6tisch-enrollment-enhanced-beacon-14.txt 
6tisch Working Group D. Dujovne 6tisch 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: 20 August 2020 Sandelman Software Works Expires: 24 August 2020 Sandelman Software Works
17 February 2020 21 February 2020
IEEE 802.15.4 Information 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-13 draft-ietf-6tisch-enrollment-enhanced-beacon-14
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. Routers in a Time- limited to specific times and specific channels. Routers in a Time-
Slotted Channel Hopping (TSCH) network transmit Enhanced Beacon (EB) Slotted Channel Hopping (TSCH) network transmit Enhanced Beacon (EB)
frames to announce the presence of the network. This document frames to announce the presence of the network. This document
provides a mechanism by which additional information critical for new provides a mechanism by which additional information critical for new
nodes (pledges) and long sleeping nodes may be carried within the nodes (pledges) and long sleeping nodes may be carried within the
Enhanced Beacon in order to conserve use of broadcast opportunities. Enhanced Beacon in order to conserve use of broadcast opportunities.
skipping to change at page 1, line 38 skipping to change at page 1, line 38
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-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
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 20 August 2020. This Internet-Draft will expire on 24 August 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 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 (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License. provided without warranty as 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 . . . . . . . . . . . . . . . . . 3
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 . . . . . . . . . . . . . . . . . . . . . 4 1.4. Layer-2 Selection . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 7 2. Protocol Definition . . . . . . . . . . . . . . . . . . . . . 5
4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 8 3. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 9
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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 detailed in [RFC8180], an (TSCH) mode of [ieee802154].
Enhanced Beacon (EB) is transmitted during a slot designated as a
broadcast slot. In TSCH mode of IEEE STD 802.15.4, opportunities for broadcasts are
limited to specific times and specific channels. Routers in a Time-
Slotted Channel Hopping (TSCH) network transmit Enhanced Beacon (EB)
frames during broadcast slots in order to announce the time and
channel schedule.
This document defines a new IETF Information Element (IE) subtype to
place into the Enhanced Beacon (EB) to provide join and enrollment
information to prospective pledges in a more efficient way.
The following sub-sections explain the problem being solved, which
justify carrying the join and enrollement information in the EB.
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
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, 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 (EB) has As explained in section 6 of [RFC8180], the Enhanced Beacon (EB) has
a number of purposes: synchronization of Absolute Slot Number (ASN) a number of purposes: synchronization of the Absolute Slot Number
and Join Metric, carrying timeslot template identifier, carrying the (ASN) and Join Metric, carrying the timeslot template identifier,
channel hopping sequence identifier, and indicating the TSCH carrying the channel hopping sequence identifier, and indicating the
SlotFrame. TSCH SlotFrame.
An EB announces the existence of a TSCH network, and of the nodes An EB announces the existence of a TSCH network, and of the nodes
already joined to that network. Receiving an EB allows a Joining already joined to that network. Receiving an EB allows a Joining
Node (pledge) to learn about the network and synchronize to it. Node (pledge) to learn about the network and synchronize to it.
The EB may also be used as a means for a node already part of the The EB may also be used as a means for a node already part of the
network to re-synchronize [RFC7554]. network to re-synchronize [RFC7554].
There are a limited number of timeslots designated as broadcast slots There are a limited number of timeslots designated as broadcast slots
by each router in the network. Considering 10ms slots and a slot- by each router in the network. Considering 10ms slots and a slot-
frame length of 100, these slots are rare and could result in only 1 frame length of 100, these slots are rare and could result in only 1
slot per second for broadcasts, which needs to be used for the slot per second for broadcasts, which needs to be used for the
beacon. Additional broadcasts for Router Advertisements (RS), or beacon. Additional broadcasts for Router Advertisements (RA), or
Neighbor Discovery (ND) could even more scarce. Neighbor Discovery (ND) could even more scarce.
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 receiving multicast Router Advertisements (RA). If no RA routers by receiving multicast Router Advertisements (RA). If no RA
is received within a set time, then a Router Solicitation (RS) may be is received within a set time, then a Router Solicitation (RS) may be
transmitted as a multicast, to which an RA will be received, usually transmitted as a multicast, to which an RA will be received, usually
unicast. unicast.
Although However, even in this case, a unicast RS may be transmitted Although [RFC6775] reduces the amount of multicast necessary to do
in response[RFC6775] reduces the amount of multicast necessary to do
address resolution via Neighbor Solicitation (NS) 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 RSes. This is an expensive
operation for two reasons: there are few multicast timeslots for operation for two reasons: there are few multicast timeslots for
unsolicited RAs; and if a pledge node does not receive an RA, and unsolicited RAs; and if a pledge node does not receive an RA, and
decides to transmit an RS, a broadcast aloha slot (see {?RFC7554} decides to transmit an RS, a broadcast aloha slot (see [RFC7554]
section A.5) is consumed with unencrypted traffic. section A.5) is consumed with unencrypted traffic. [RFC6775] already
allows for a unicast reply to such an RS.
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 (RS) 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 2. It may require many seconds of on-time before a new pledge
receives a Router Advertisement (RA) that it can use. receives a Router Advertisement (RA) that it can use.
3. A new pledge may have to receive many Enhanced Beacons (EB) 3. A new pledge may have to receive many Enhanced Beacons (EB)
before it can pick an appropriate network and/or closest Join before it can pick an appropriate network and/or closest Join
Assistant to attach to. If it must remain in the receive state Assistant to attach to. If it must remain in the receive state
for an RA as well as find the Enhanced Beacon (EB), then the for an RA as well as find the Enhanced Beacon (EB), then the
process may take a very long time. process may take dozens of seconds, even minutes for each
enrollment attempt that it needs to make.
This document defines a new IETF Information Element (IE) subtype to 1.4. Layer-2 Selection
place into the Enhanced Beacon (EB) to provide join and enrollment
information to prospective pledges in a more efficient way. In a complex Low-power and Lossy Networks (LLN), multiple LLNs may be
connected together by backbone routers ( technology such as
[I-D.ietf-6lo-backbone-router]), resulting in an area that is
serviced by multiple distinct Layer-2 instances. These are called
Personal Area Networks (PAN). Each instance will have a separate
Layer-2 security profile, and will be distinguished by a different
PANID. The PANID is part of the [ieee802154] layer-2 header: it is a
16-bit value which is chosen to be unique, and it contributes context
to the layer-2 security mechanisms. The PANID provides a context
similar to the ESSID does in 802.11 networking, and can be conceived
of in a similar fashion as the 802.3 ethernet VLAN tag in that it
provides context for all layer-2 addresses.
A device which is already enrolled in a network may find after a long
sleep that it needs to resynchronize to the Layer 2 network. The
enrollment keys that it has will be specific to a PANID, but it may
have more than one set of keys. Such a device may wish to connect to
a PAN that is experiencing less congestion, or which has a shalower
([RFC6550]) Routing Protocol for LLNs (RPL) tree. It may even
observe PANs for which it does not have keys, but which is believes
it may have credentials that would allow it to join.
In order to identify which PANs are part of the same backbone
network, the network ID is introduced in this extension. PANs that
are part of the same backbone will be configured to use the same
network ID. For [RFC6550] RPL networks, configuration of the network
ID can be done with an configuration option, which is the subject of
future work.
In order to provide some input to the choice of which PAN to use, the
PAN priority field has been added. This lists the relative priority
for the PAN among different PANs. Every Enhanced Beacon from a given
PAN will likely have the same PAN priority. Determination of the the
PAN priority is the subject of future work; but it is expected that
it will be calculated by an algorithm in the 6LBR, possibly involving
communication between 6LBRs over the backbone network.
The [RFC6550] parent selection process can only operate within a
single PAN, because it depends upon receiving RPL DIO messages from
all available parents. As part of the PAN selection process, the
device may wish to know how deep in the LLN mesh it will be if it
joins a particular PAN, and the rank priority field provides an
estimation of what the rank of each announcer is. Once the device
synchronizes to a particular PAN's TSCH schedule then it may receive
DIOs that are richer in their diversity than this value. How this
value will be used in practice is the subject of future research, and
the interpretation of this value of the structure is considered
experimental.
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.
skipping to change at page 4, line 42 skipping to change at page 5, line 50
+ variable length, up to 16 bytes + + variable length, up to 16 bytes +
~ ~ ~ ~
+ + + +
| | | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 1: IE subtype structure Figure 1: IE subtype structure
res: reserved bits MUST be ignored upon receipt, and SHOULD be set
to 0 when sending.
R: The Router Advertisement R-flag is set if the sending node will R: The Router Advertisement R-flag is set if the sending node will
act as a Router for host-only nodes that need addressing via act as a Router for host-only nodes relying on stateless address
unicast Router Solicitation messages. auto-configuration (SLAAC) to get their global IPv6 address.
Those hosts MUST send a unicast Router Solicitation message in
order to receive a RA with the Prefix Information Option.
In most cases, every node sending a beacon will set this flag, and In most cases, every node sending a beacon will set this flag, and
in a typical mesh, this will be every single node. When this bit in a typical mesh, this will be every single node. When this bit
is not set, it indicates that this node may be under provisioned, is not set, it might indicate that this node may be under
or may have no additional slots for additional nodes. This could provisioned, or may have no additional slots for additional nodes.
make this node more interesting to an attacker. This could make this node more interesting to an attacker.
P: If the Proxy Address P-flag is set, then the Join Proxy Interface P: If the Proxy Address P-flag is set, then the Join Proxy Interface
ID bit field is present. Otherwise, it is not provided. ID bit field is present. Otherwise, it is not provided.
This bit only indicates if another part of the structure is This bit only indicates if another part of the structure is
present, and has little security or privacy impact. present, and has little security or privacy impact.
proxy priority (proxy prio): This field indicates the willingness of proxy priority (proxy prio): This field indicates the willingness of
the sender to act as join proxy. Lower value indicates greater the sender to act as join proxy. Lower value indicates greater
willingness to act as a Join Proxy as described in willingness to act as a Join Proxy as described in
[I-D.ietf-6tisch-minimal-security]. Values range 0x00 (most [I-D.ietf-6tisch-minimal-security]. Values range from 0x00 (most
willing) to 0x7e (least willing). A priority of 0x7f indicates willing) to 0x7e (least willing). A priority of 0x7f indicates
that the announcer should never be considered as a viable that the announcer should never be considered as a viable
enrollment proxy. enrollment proxy. Only unenrolled pledges look at this value.
Only unenrolled pledges look at this value.
Lower values in this field indicate that the transmitter may have Lower values in this field indicate that the transmitter may have
more capacity to handle unencrypted traffic. more capacity to handle unencrypted traffic. A higher value may
indicate that the transmitter is low on neighbor cache entries, or
A higher value may indicate that the transmitter is low on other resources. Ongoing work such as
neighbor cache entries, or other resources. [I-D.ietf-roll-enrollment-priority] documents one way to set this
field.
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
an RPL {?RFC6550} parent within a particular network ID.
Lower values indicate more willing, and higher values indicate
less willing. This value is calculated by each 6LR according to
algorithms specific to the routing metrics used by the RPL
({?RFC6550}).
The exact process is a subject of significant research work.
It will typically be calculated from the RPL rank, and it may
include some modifications based upon current number of children,
or number of neighbor cache entries available.
This value MUST be ignored by pledges, it is to help enrolled rank priority: The rank "priority" is set by the IPv6 LLN Router
devices only to compare different connection points. (6LR) which sent the beacon and is an indication of how willing
this 6LR is to serve as an RPL [RFC6550] parent within a
particular network ID. Lower values indicate more willingness,
and higher values indicate less willingness. This value is
calculated by each 6LR according to algorithms specific to the
routing metrics used by the RPL ([RFC6550]). The exact process is
a subject of significant research work. It will typically be
calculated from the RPL rank, and it may include some
modifications based upon current number of children, or number of
neighbor cache entries available. Pledges MUST ignore this value.
It helps enrolled devices only to compare connection points.
An attacker can use this value to determine which nodes are An attacker can use this value to determine which nodes are
potentially more interesting. Nodes which are less willing to be potentially more interesting. Nodes which are less willingness to
parents likely have more traffic, and an attacker could use this be parents likely have more traffic, and an attacker could use
information to determine which nodes would be more interesting to this information to determine which nodes would be more
attack or disrupt. interesting to attack or disrupt.
pan priority: The pan priority is a value set by the Destination- pan priority: The pan priority is a value set by the Destination-
Oriented Directed Acycling Graph (DODAG) root (see {?RFC6550}, Oriented Directed Acyclic Graph (DODAG) root (see [RFC6550],
typically, the 6LBR) to indicate the relative priority of this LLN typically, the 6LBR) to indicate the relative priority of this LLN
compared to those with different PANIDs that the operator might compared to those with different PANIDs that the operator might
control. control. This value may be used as part of the enrollment
priority, but typically is used by devices which have already
This value may be used as part of the enrollment priority, but enrolled, and need to determine which PAN to pick when resuming
typically is used by devices which have already enrolled, and need from a long sleep. Unenrolled pledges MAY consider this value
to determine which PAN to pick when resuming from a long sleep. when selecting a PAN to join. Enrolled devices MAY consider this
Unenrolled pledges MAY consider this value when selecting a PAN to value when looking for an eligible parent device. Lower values
join. Enrolled devices MAY consider this value when looking for indicate a higher willingness to accept new nodes.
an eligible parent device. Lower values indicate a higher
willingness to accept new nodes.
An attacker can use this value, along with the observed PANID in An attacker can use this value, along with the observed PANID in
the Beacon to determine which PANIDs have more network resources, the Beacon to determine which PANIDs have more network resources,
and may have more interesting traffic. and may have more interesting traffic.
Join Proxy Interface ID: If the P bit is set, then 64 bits (8 bytes) Join Proxy Interface ID: If the P bit is set, then 64 bits (8 bytes)
of address are present. This field provides the Interface ID of address are present. This field provides the Interface ID
(IID) of the Link-Local address of the Join Proxy. The associated (IID) of the Link-Local address of the Join Proxy. The associated
prefix is well-known as fe80::/64. If this field is not present, prefix is well-known as fe80::/64. If this field is not present,
then IID is derived from the layer-2 address of the sender as per then IID is derived from the layer-2 address of the sender as per
SLAAC ({?RFC4662}). SLAAC ([RFC4662]).
This field communicates an Interface ID bits that should be used This field communicates the Interface ID bits that should be used
for this nodes' layer-3 address, if it should not be derived from for this node's layer-3 address, if it should not be derived from
the layer-2 address. Communication with the Join Proxy occurs in the layer-2 address. Communication with the Join Proxy occurs in
the clear, this field avoids the need for an additional service the clear. This field avoids the need for an additional service-
discovery process for the case where the L3 address is not derived discovery process for the case where the L3 address is not derived
from the L2 address. An attacker will see both L2 and L3 from the L2 address. An attacker will see both L2 and L3
addresses, so this field provides no new information. addresses, so this field provides no new information.
network ID: This is a 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 In a 6tisch network, where RPL [RFC6550] is used as the mesh
routing protocol, the network ID can be constructed from a routing protocol, the network ID can be constructed from a
truncated SHA256 hash of the prefix (/64) of the network. This truncated SHA256 hash of the prefix (/64) of the network. This
will be done by the RPL DODAG root and communicated by the RPL will be done by the RPL DODAG root and communicated by the RPL
Configuration Option payloads, so it is not calculated more than Configuration Option payloads, so it is not calculated more than
once. That is just a suggestion for a default algorithm: it may once. This is just a suggestion for a default algorithm: it may
be set in any convenience way that results in a non-identifing be set in any convenience way that results in a non-identifing
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 Join Registrar/Coordinator - JRC), then a
across all PANs MUST be configured so that pledges that attempt to common value that is the same across all the PANs MUST be
enroll do not waste time attempting multiple times with the same configured. Pledges that see the same networkID will not waste
network that has multiple attachment points. time attempting to enroll multiple times with the same network
that when the network has multiple attachment points.
If the network ID is derived as suggested, then it will an opaque, If the network ID is derived as suggested, then it will be an
seemingly random value, and will reveal nothing in of itself. An opaque, seemingly random value, and will not directly reveal any
attacker can match this value across many transmissions to map the information about the network. An attacker can match this value
extent of a network beyond what the PANID might already provide. across many transmissions to map the extent of a network beyond
what the PANID might already provide.
3. Security Considerations 3. Security Considerations
All of the contents of this Information Element are transmitted in All of the contents of this Information Element are transmitted in
the clear. The content of the Enhanced Beacon is not encrypted. the clear. The content of the Enhanced Beacon is not encrypted.
This is a restriction in the cryptographic architecture of the This is a restriction in the cryptographic architecture of the
802.15.4 mechanism. In order to decrypt or do integrity checking of 802.15.4 mechanism. In order to decrypt or do integrity checking of
layer-2 frames in TSCH, the TSCH Absolute Slot Number (ASN) is layer-2 frames in TSCH, the TSCH Absolute Slot Number (ASN) is
needed. The Enhanced Beacon provides the ASN to new (and long- needed. The Enhanced Beacon provides the ASN to new (and long-
sleeping) nodes. sleeping) nodes.
The sensitivity of each field is describe within the description of The sensitivity of each field is described within the description of
each field. each field.
The Enhanced Beacon is authenticated at the layer-2 level using The Enhanced Beacon is authenticated at the layer-2 level using
802.15.4 mechanisms using the network-wide keying material. Nodes 802.15.4 mechanisms using the network-wide keying material. Nodes
which are enrolled will have the network-wide keying material and can which are enrolled will have the network-wide keying material and can
validate the beacon. validate the beacon.
Pledges which have not yet enrolled are unable to authenticate the Pledges which have not yet enrolled are unable to authenticate the
beacons, and will be forced to temporarily take the contents on beacons, and will be forced to temporarily take the contents on
faith. After enrollment, a newly enrolled node will be able to faith. After enrollment, a newly enrolled node will be able to
skipping to change at page 8, line 8 skipping to change at page 9, line 8
can provide an attacker with a list of channels and frequencies on can provide an attacker with a list of channels and frequencies on
which communication will occur. Knowledge of this can help an which communication will occur. Knowledge of this can help an
attacker to more efficiently jam communications, although there is attacker to more efficiently jam communications, although there is
future work being considered to make some of the schedule less future work being considered to make some of the schedule less
visible. Encrypting the schedule does not prevent an attacker from visible. Encrypting the schedule does not prevent an attacker from
jamming, but rather increases the energy cost of doing that jamming. jamming, but rather increases the energy cost of doing that jamming.
4. Privacy Considerations 4. Privacy Considerations
The use of a network ID may reveal information about the network. The use of a network ID may reveal information about the network.
The use of a SHA256 hash of the DODAGID, rather than using the The use of a SHA256 hash of the DODAGID (see [RFC6550]), rather than
DODAGID (which is usually derived from the LLN prefix) directly using the DODAGID itself directly provides some privacy for the the
provides some privacy for the the addresses used within the network, addresses used within the network, as the DODAGID is usually the IPv6
as the DODAGID is usually the IPv6 address of the root of the RPL address of the root of the RPL mesh.
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 extent of the mesh network. ID to map out the extent of the mesh network.
5. IANA Considerations 5. IANA Considerations
IANA is asked to assign a new number TBD-XXX from Registry "IEEE Std IANA is asked to assign a new number TBD-XXX from Registry "IEEE Std
802.15.4 IETF IE Subtype IDs" as defined by [RFC8137]. 802.15.4 IETF IE Subtype IDs" as defined by [RFC8137].
This entry should be called 6tisch-Join-Info, and should refer to This entry should be called 6tisch-Join-Info, and should refer to
skipping to change at page 9, line 39 skipping to change at page 10, line 37
[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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] 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>.
7.2. Informative References 7.2. Informative References
[I-D.ietf-6lo-backbone-router]
Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6
Backbone Router", Work in Progress, Internet-Draft, draft-
ietf-6lo-backbone-router-17, 20 February 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-6lo-
backbone-router-17.txt>.
[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", Work in Progress, Internet-Draft, of IEEE 802.15.4", Work in Progress, Internet-Draft,
draft-ietf-6tisch-architecture-28, 29 October 2019, draft-ietf-6tisch-architecture-28, 29 October 2019,
<http://www.ietf.org/internet-drafts/draft-ietf-6tisch- <http://www.ietf.org/internet-drafts/draft-ietf-6tisch-
architecture-28.txt>. architecture-28.txt>.
[I-D.ietf-roll-enrollment-priority]
Richardson, M., "Enabling secure network enrollment in RPL
networks", Work in Progress, Internet-Draft, draft-ietf-
roll-enrollment-priority-00, 16 September 2019,
<http://www.ietf.org/internet-drafts/draft-ietf-roll-
enrollment-priority-00.txt>.
[RFC4662] Roach, A. B., Campbell, B., and J. Rosenberg, "A Session
Initiation Protocol (SIP) Event Notification Extension for
Resource Lists", RFC 4662, DOI 10.17487/RFC4662, August
2006, <https://www.rfc-editor.org/info/rfc4662>.
[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
Internet of Things (IoT): Problem Statement", RFC 7554, Internet of Things (IoT): Problem Statement", RFC 7554,
 End of changes. 33 change blocks. 
94 lines changed or deleted 171 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/