Internet DRAFT - draft-ietf-6tisch-6top-protocol
draft-ietf-6tisch-6top-protocol
6TiSCH Q. Wang, Ed.
Internet-Draft Univ. of Sci. and Tech. Beijing
Intended status: Standards Track X. Vilajosana
Expires: December 22, 2018 Universitat Oberta de Catalunya
T. Watteyne
Analog Devices
June 20, 2018
6TiSCH Operation Sublayer Protocol (6P)
draft-ietf-6tisch-6top-protocol-12
Abstract
This document defines the IPv6 over the TSCH mode of IEEE 802.15.4e
(6TiSCH) Operation Sublayer (6top) Protocol (6P), which enables
distributed scheduling in 6TiSCH networks. 6P allows neighbor nodes
to add/delete TSCH cells to one another. 6P is part of the 6TiSCH
Operation Sublayer (6top), the next higher layer to the IEEE Std
802.15.4 TSCH medium access control layer. The 6top layer terminates
the 6top Protocol defined in this document, and runs one or more 6top
Scheduling Function(s). A 6top Scheduling Function (SF) decides when
to add/delete cells, and triggers 6P Transactions. This document
lists the requirements for an SF, but leaves the definition of SFs
out of scope.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on December 22, 2018.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. 6TiSCH Operation Sublayer (6top) . . . . . . . . . . . . . . 4
2.1. Hard/Soft Cells . . . . . . . . . . . . . . . . . . . . . 5
2.2. Using 6P with the Minimal 6TiSCH Configuration . . . . . 5
3. 6top Protocol (6P) . . . . . . . . . . . . . . . . . . . . . 6
3.1. 6P Transactions . . . . . . . . . . . . . . . . . . . . . 6
3.1.1. 2-step 6P Transaction . . . . . . . . . . . . . . . . 7
3.1.2. 3-step 6P Transaction . . . . . . . . . . . . . . . . 9
3.2. Message Format . . . . . . . . . . . . . . . . . . . . . 11
3.2.1. 6top Information Element (IE) . . . . . . . . . . . . 11
3.2.2. Generic 6P Message Format . . . . . . . . . . . . . . 11
3.2.3. 6P CellOptions . . . . . . . . . . . . . . . . . . . 12
3.2.4. 6P CellList . . . . . . . . . . . . . . . . . . . . . 15
3.3. 6P Commands and Operations . . . . . . . . . . . . . . . 16
3.3.1. Adding Cells . . . . . . . . . . . . . . . . . . . . 16
3.3.2. Deleting Cells . . . . . . . . . . . . . . . . . . . 18
3.3.3. Relocating Cells . . . . . . . . . . . . . . . . . . 19
3.3.4. Counting Cells . . . . . . . . . . . . . . . . . . . 25
3.3.5. Listing Cells . . . . . . . . . . . . . . . . . . . . 26
3.3.6. Clearing the Schedule . . . . . . . . . . . . . . . . 28
3.3.7. Generic Signaling Between SFs . . . . . . . . . . . . 29
3.4. Protocol Functional Details . . . . . . . . . . . . . . . 29
3.4.1. Version Checking . . . . . . . . . . . . . . . . . . 29
3.4.2. SFID Checking . . . . . . . . . . . . . . . . . . . . 30
3.4.3. Concurrent 6P Transactions . . . . . . . . . . . . . 30
3.4.4. 6P Timeout . . . . . . . . . . . . . . . . . . . . . 31
3.4.5. Aborting a 6P Transaction . . . . . . . . . . . . . . 31
3.4.6. SeqNum Management . . . . . . . . . . . . . . . . . . 31
3.4.7. Handling Error Responses . . . . . . . . . . . . . . 38
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3.5. Security . . . . . . . . . . . . . . . . . . . . . . . . 38
4. Requirements for 6top Scheduling Functions (SF) Specification 38
4.1. SF Identifier (SFID) . . . . . . . . . . . . . . . . . . 38
4.2. Requirements for an SF specification . . . . . . . . . . 38
5. Security Considerations . . . . . . . . . . . . . . . . . . . 39
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
6.1. IETF IE Subtype '6P' . . . . . . . . . . . . . . . . . . 40
6.2. 6TiSCH parameters sub-registries . . . . . . . . . . . . 40
6.2.1. 6P Version Numbers . . . . . . . . . . . . . . . . . 40
6.2.2. 6P Message Types . . . . . . . . . . . . . . . . . . 41
6.2.3. 6P Command Identifiers . . . . . . . . . . . . . . . 41
6.2.4. 6P Return Codes . . . . . . . . . . . . . . . . . . . 42
6.2.5. 6P Scheduling Function Identifiers . . . . . . . . . 43
6.2.6. 6P CellOptions bitmap . . . . . . . . . . . . . . . . 44
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.1. Normative References . . . . . . . . . . . . . . . . . . 45
7.2. Informative References . . . . . . . . . . . . . . . . . 45
Appendix A. Recommended Structure of an SF Specification . . . . 46
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46
1. Introduction
All communication in a IPv6 over the TSCH mode of IEEE 802.15.4e
(6TiSCH) network is orchestrated by a schedule [RFC7554]. The
schedule is composed of cells, each identified by a
[slotOffset,channelOffset]. This specification defines the 6TiSCH
Operation Sublayer (6top) Protocol (6P), terminated by the 6TiSCH
Operation sublayer (6top). 6P allows a node to communicate with a
neighbor node to add/delete TSCH cells to one another. This results
in distributed schedule management in a 6TiSCH network. The 6top
layer terminates the 6top Protocol, and runs one or more 6top
Scheduling Functions (SFs) that decide when to add/delete cells and
trigger 6P Transactions. The SF is out of scope of this document but
this document defines the requirements for an SF.
(R)
/ \
/ \
(B)-----(C)
| |
| |
(A) (D)
Figure 1: A simple 6TiSCH network.
The example network depicted in Figure 1 is used to describe the
interaction between nodes. We consider the canonical case where node
"A" issues 6P requests to node "B". We keep this example throughout
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this document. Throughout the document, node A always represents the
node that issues a 6P request; node B the node that receives this
request.
We consider that node A monitors the communication cells it has in
its schedule to node B:
o If node A determines that the number of link-layer frames it is
sending to node B per unit of time exceeds the capacity offered by
the TSCH cells it has scheduled to node B, it triggers a 6P
Transaction with node B to add one or more cells to the TSCH
schedule of both nodes.
o If the traffic is lower than the capacity, node A triggers a 6P
Transaction with node B to delete one or more cells in the TSCH
schedule of both nodes.
o Node A MAY also monitor statistics to determine whether collisions
are happening on a particular cell to node B. If this feature is
enabled, node A communicates with node B to "relocate" the cell
which undergoes collisions to a different
[slotOffset,channelOffset] location in the TSCH schedule.
This results in distributed schedule management in a 6TiSCH network.
The 6top Scheduling Function (SF) defines when to add/delete a cell
to a neighbor. Different applications require different SFs, so the
SF is left out of scope of this document. Different SFs are expected
to be defined in future companion specifications. A node MAY
implement multiple SFs and run them at the same time. At least one
SF MUST be running. The SFID field contained in all 6P messages
allows a node to invoke the appropriate SF on a per-6P Transaction
basis.
Section 2 describes the 6TiSCH Operation Sublayer (6top). Section 3
defines the 6top Protocol (6P). Section 4 provides guidelines on how
to define an SF.
2. 6TiSCH Operation Sublayer (6top)
As depicted in Figure 2, the 6TiSCH Operation Sublayer (6top) is the
next higher layer to the IEEE Std 802.15.4 TSCH medium access control
(MAC) layer [IEEE802154]. We use "802.15.4" as a short version of
"IEEE Std 802.15.4" in this document.
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.
| . |
| higher layers |
+------------------------------------------+
| 6top |
+------------------------------------------+
| IEEE Std 802.15.4 TSCH |
| . |
.
Figure 2: The 6top sublayer in the protocol stack.
The roles of the 6top sublayer are to:
o Terminate the 6top Protocol (6P), which allows neighbor nodes to
communicate to add/delete cells to one another.
o Run one or multiple 6top Scheduling Functions (SFs), which define
the rules that decide when to add/delete cells.
2.1. Hard/Soft Cells
Each cell in the schedule is either "hard" or "soft":
o a soft cell can be read, added, deleted or updated by 6top.
o a hard cell is read-only for 6top.
In the context of this specification, all the cells used by 6top are
soft cells. Hard cells can be used for example when "hard-coding" a
schedule [RFC8180].
2.2. Using 6P with the Minimal 6TiSCH Configuration
6P MAY be used alongside the Minimal 6TiSCH Configuration [RFC8180].
In this case, it is RECOMMENDED to use 2 slotframes, as depicted in
Figure 3:
o Slotframe 0 is used for traffic defined in the Minimal 6TiSCH
Configuration. In Figure 3, Slotframe 0 is 5 slots long, but it
can be shorter or longer.
o 6P allocates cells from Slotframe 1. In Figure 3, Slotframe 1 is
10 slots long, but it can be shorter or longer.
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| 0 1 2 3 4 | 0 1 2 3 4 |
+------------------------+------------------------+
Slotframe 0 | | | | | | | | | | |
5 slots long | EB | | | | | EB | | | | |
(Minimal 6TiSCH) | | | | | | | | | | |
+-------------------------------------------------+
| 0 1 2 3 4 5 6 7 8 9 |
+-------------------------------------------------+
Slotframe 1 | | | | | | | | | | |
10 slots long | |A->B| | | | | | |B->A| |
(6P) | | | | | | | | | | |
+-------------------------------------------------+
Figure 3: 2-slotframe structure when using 6P alongside the Minimal
6TiSCH Configuration.
The Minimal 6TiSCH Configuration cell SHOULD be allocated from a
slotframe of higher priority than the slotframe used by 6P for
dynamic cell allocation. This way, dynamically allocated cells
cannot "mask" the cells used by the Minimal 6TiSCH Configuration.
6top MAY support additional slotframes; how to use additional
slotframes is out of scope for this document.
3. 6top Protocol (6P)
The 6top Protocol (6P) enables two neighbor nodes to add/delete/
relocate cells in their TSCH schedule. Conceptually, two neighbor
nodes "negotiate" the location of the cells to add, delete, or
relocate in their TSCH schedule.
3.1. 6P Transactions
We call "6P Transaction" a complete negotiation between two neighbor
nodes. A particular 6P Transaction is executed between two nodes as
a result of an action triggered by one SF. For a 6P Transaction to
succeed, both nodes must use the same SF to handle the particular
transaction. A 6P Transaction starts when a node wishes to
add/delete/relocate one or more cells with one of its neighbors. A
6P Transaction ends when the cell(s) have been added/deleted/
relocated in the schedule of both nodes, or when the 6P Transaction
has failed.
6P messages exchanged between nodes A and B during a 6P Transaction
SHOULD be exchanged on non-shared unicast cells ("dedicated" cells)
between A and B. If no dedicated cells are scheduled between nodes A
and B, shared cells MAY be used.
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Keeping consistency between the schedules of the two neighbor nodes
is important. A loss of consistency can cause loss of connectivity.
One example is when node A has a transmit cell to node B, but node B
does not have the corresponding reception cell. To verify
consistency, neighbor nodes maintain a Sequence Number (SeqNum).
Neighbor nodes exchange the SeqNum as part of each 6P Transaction to
detect a possible inconsistency. This mechanism is explained in
Section 3.4.6.2.
An implementation MUST include a mechanism to associate each
scheduled cell with the SF that scheduled it. This mechanism is
implementation-specific and out of scope of this document.
A 6P Transaction can consist of 2 or 3 steps. A 2-step transaction
is used when node A selects the cells to be allocated. A 3-step
transaction is used when node B selects the cells to be allocated.
An SF MUST specify whether to use 2-step transactions, 3-step
transactions, or both.
We illustrate 2-step and 3-step transactions using the topology in
Figure 1.
3.1.1. 2-step 6P Transaction
Figure 4 shows an example 2-step 6P Transaction. In a 2-step
transaction, node A selects the candidate cells. Several elements
are left out to simplify understanding.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
| |
| 6P ADD Request |
| Type = REQUEST |
| Code = ADD |
| SeqNum = 123 |
cells | NumCells = 2 |
locked | CellList = [(1,2),(2,2),(3,5)] |
+-- |-------------------------------------->|
| | L2 ACK |
| 6P Timeout |<- - - - - - - - - - - - - - - - - - - |
| | | |
| | | 6P Response |
| | | Type = RESPONSE |
| | | Code = RC_SUCCESS |
| | | SeqNum = 123 | cells
| | | CellList = [(2,2),(3,5)] | locked
+-> X |<--------------------------------------| --+
| L2 ACK | |
| - - - - - - - - - - - - - - - - - - ->| <-+
| |
Figure 4: An example 2-step 6P Transaction.
In this example, the 2-step transaction occurs as follows:
1. The SF running on node A determines that 2 extra cells need to be
scheduled to node B.
2. The SF running on node A selects candidate cells for node B to
choose from. Node A MUST select at least as many candidate cells
as the number of cells to add. Here, node A selects 3 candidate
cells. Node A locks those candidate cells in its schedule until
it receives a 6P response.
3. Node A sends a 6P ADD Request to node B, indicating it wishes to
add 2 cells (the "NumCells" value), and specifying the list of 3
candidate cells (the "CellList" value). Each cell in the
CellList is a [slotOffset,channelOffset] tuple. This 6P ADD
Request is link-layer acknowledged by node B (labeled "L2 ACK" in
Figure 4).
4. After having successfully sent the 6P ADD Request (i.e. receiving
the link-layer acknowledgment), node A starts a 6P Timeout to
abort the 6P Transaction in case no response is received from
node B.
5. The SF running on node B selects 2 out of the 3 cells from the
CellList of the 6P ADD Request. Node B locks those cells in its
schedule until the transmission is successful (i.e. node B
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receives a link-layer ACK from node A). Node B sends back a 6P
Response to node A, indicating the cells it has selected. The
response is link-layer acknowledged by node A.
6. Upon completion of this 6P Transaction, 2 cells from A to B have
been added to the TSCH schedule of both nodes A and B.
7. An inconsistency in the schedule can happen if the 6P Timeout
expires when the 6P Response is in the air, if the last link-
layer ACK for the 6P Response is lost, or if one of the nodes is
power cycled during the transaction. 6P provides an
inconsistency detection mechanism described in Section 3.4.6.1 to
cope with such situations.
3.1.2. 3-step 6P Transaction
Figure 5 shows an example 3-step 6P Transaction. In a 3-step
transaction, node B selects the candidate cells. Several elements
are left out to simplify understanding.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
| |
| 6P ADD Request |
| Type = REQUEST |
| Code = ADD |
| SeqNum = 178 |
| NumCells = 2 |
| CellList = [] |
|-------------------------------------->|
| L2 ACK |
6P Timeout |<- - - - - - - - - - - - - - - - - - - |
| | |
| | 6P Response |
| | Type = RESPONSE |
| | Code = RC_SUCCESS |
| | SeqNum = 178 | cells
| | CellList = [(1,2),(2,2),(3,5)] | locked
X |<--------------------------------------| --+
| L2 ACK | |
| - - - - - - - - - - - - - - - - - - ->| 6P Timeout |
| | | |
| 6P Confirmation | | |
| Type = CONFIRMATION | | |
| Code = RC_SUCCESS | | |
cells | SeqNum = 178 | | |
locked | CellList = [(2,2),(3,5)] | | |
+-- |-------------------------------------->| X <--+
| | L2 ACK |
+-> |<- - - - - - - - - - - - - - - - - - - |
| |
Figure 5: An example 3-step 6P Transaction.
In this example, the 3-step transaction occurs as follows:
1. The SF running on node A determines that 2 extra cells need to be
scheduled to node B. The SF uses a 3-step transaction, so it
does not select candidate cells.
2. Node A sends a 6P ADD Request to node B, indicating it wishes to
add 2 cells (the "NumCells" value), with an empty "CellList".
This 6P ADD Request is link-layer acknowledged by node B.
3. After having successfully sent the 6P ADD Request, node A starts
a 6P Timeout to abort the transaction in case no 6P Response is
received from node B.
4. The SF running on node B selects 3 candidate cells, and locks
them. Node B sends back a 6P Response to node A, indicating the
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3 cells it has selected. The response is link-layer acknowledged
by node A.
5. After having successfully sent the 6P Response, node B starts a
6P Timeout to abort the transaction in case no 6P Confirmation is
received from node A.
6. The SF running on node A selects 2 cells from the CellList field
in the 6P Response, and locks those. Node A sends back a 6P
Confirmation to node B, indicating the cells it selected. The
confirmation is link-layer acknowledged by node B.
7. Upon completion of the 6P Transaction, 2 cells from A to B have
been added to the TSCH schedule of both nodes A and B.
8. An inconsistency in the schedule can happen if the 6P Timeout
expires when the 6P Confirmation is in the air, if the last link-
layer ACK for the 6P Confirmation is lost, or if one of the nodes
is power cycled during the transaction. 6P provides an
inconsistency detection mechanism described in Section 3.4.6.1 to
cope with such situations.
3.2. Message Format
3.2.1. 6top Information Element (IE)
6P messages travel over a single hop. 6P messages are carried as
payload of an 802.15.4 Payload Information Element (IE) [IEEE802154].
The messages are encapsulated within the Payload IE Header. The
Group ID is set to the IETF IE value defined in [RFC8137]. The
content is encapsulated by a SubType ID, as defined in [RFC8137].
Since 6P messages are carried in IEs, IEEE bit/byte ordering applies.
Bits within each field in the 6top IE are numbered from 0 (leftmost
and least significant) to k-1 (rightmost and most significant), where
the length of the field is k bits. Fields that are longer than a
single octet are copied to the packet in the order from the octet
containing the lowest numbered bits to the octet containing the
highest numbered bits (little endian).
This document defines the "6top IE", a SubType of the IETF IE defined
in [RFC8137], with subtype ID IANA_6TOP_SUBIE_ID. The SubType
Content of the "6top IE" is defined in Section 3.2.2. The length of
the "6top IE" content is variable.
3.2.2. Generic 6P Message Format
All 6P messages follow the generic format shown in Figure 6.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Other Fields...
+-+-+-+-+-+-+-+-+-
Figure 6: Generic 6P Message Format.
6P Version (Version): The version of the 6P protocol. Only version
0 is defined in this document. Future specifications may
define further versions of the 6P protocol.
Type (T): Type of message. The message types are defined in
Section 6.2.2.
Reserved (R): Reserved bits. These two bits SHOULD be set to zero
when sending the message, and MUST be ignored upon reception.
Code: The Code field contains a 6P Command Identifier when the 6P
message is of Type REQUEST. Section 6.2.3 lists the 6P command
identifiers. The Code field contains a 6P return code when the
6P message is of Type RESPONSE or CONFIRMATION. Section 6.2.4
lists the 6P return codes. The same return codes are used in
both 6P Response and 6P Confirmation messages.
6top Scheduling Function Identifier (SFID): The identifier of the SF
to use to handle this message. The SFID is defined in
Section 4.1.
SeqNum: Sequence number associated with the 6P Transaction, used to
match the 6P Request, 6P Response and 6P Confirmation of the
same 6P Transaction. The value of SeqNum MUST be different at
each new 6P Request issued to the same neighbor and using the
same SF. The SeqNum is also used to ensure consistency between
the schedules of the two neighbors. Section 3.4.6 details how
the SeqNum is managed.
Other Fields: The list of other fields and how they are used is
detailed in Section 3.3.
6P Requests, 6P Response and 6P Confirmation messages for a same
transaction MUST share the same Version, SFID and SeqNum values.
Future versions of the 6P Message SHOULD maintain the format of the
6P Version, Type and Code fields for backward compatibility.
3.2.3. 6P CellOptions
An 8-bit 6P CellOptions bitmap is present in the following 6P
requests: ADD, DELETE, COUNT, LIST, RELOCATE. The format and meaning
of this field MAY be redefined by the SF; the routine that parses
this field is therefore associated with a specific SF.
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o In the 6P ADD request, the 6P CellOptions bitmap is used to
specify what type of cell to add.
o In the 6P DELETE request, the 6P CellOptions bitmap is used to
specify what type of cell to delete.
o In the 6P RELOCATE request, the 6P CellOptions bitmap is used to
specify what type of cell to relocate.
o In the 6P COUNT and the 6P LIST requests, the 6P CellOptions
bitmap is used as a selector of a particular type of cells.
The content of the 6P CellOptions bitmap applies to all elements in
the CellList field. The possible values of the 6P CellOptions are:
TX = 1 (resp. 0) refers to macTxType = TRUE (resp. FALSE) in the
macLinkTable of 802.15.4 [IEEE802154]. RX = 1 (resp. 0) refers to
macRxType = TRUE (resp. FALSE) in the macLinkTable of 802.15.4. S =
1 (resp. 0) refers to macSharedType = TRUE (resp. FALSE) in the
macLinkTable of 802.15.4. Section 6.2.6 contains the format of the
6P CellOptions bitmap, unless redefined by the SF. Figure 7 contains
the meaning of the 6P CellOptions bitmap for the 6P ADD, DELETE,
RELOCATE requests, unless redefined by the SF. Figure 8 contains the
meaning of the 6P CellOptions bitmap for the 6P COUNT, LIST requests,
unless redefined by the SF.
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Note: assuming node A issues the 6P command to node B.
+-------------+-----------------------------------------------------+
| CellOptions | The type of cells B adds/deletes/relocates to its |
| Value | schedule when receiving a 6P ADD/DELETE/RELOCATE |
| | Request from A. |
+-------------+-----------------------------------------------------+
|TX=0,RX=0,S=0| Invalid combination. RC_ERR is returned. |
+-------------+-----------------------------------------------------+
|TX=1,RX=0,S=0| add/delete/relocate RX cells at B (TX cells at A) |
+-------------+-----------------------------------------------------+
|TX=0,RX=1,S=0| add/delete/relocate TX cells at B (RX cells at A) |
+-------------+-----------------------------------------------------+
|TX=1,RX=1,S=0| add/delete/relocate TX|RX cells at B (and at A) |
+-------------+-----------------------------------------------------+
|TX=0,RX=0,S=1| Invalid combination. RC_ERR is returned. |
+-------------+-----------------------------------------------------+
|TX=1,RX=0,S=1| add/delete/relocate RX|SHARED cells at B |
| | (TX|SHARED cells at A) |
+-------------+-----------------------------------------------------+
|TX=0,RX=1,S=1| add/delete/relocate TX|SHARED cells at B |
| | (RX|SHARED cells at A) |
+-------------+-----------------------------------------------------+
|TX=1,RX=1,S=1| add/delete/relocate TX|RX|SHARED cells at B |
| | (and at A) |
+-------------+-----------------------------------------------------+
Figure 7: Meaning of the 6P CellOptions bitmap for the 6P ADD,
DELETE, RELOCATE requests.
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Note: assuming node A issues the 6P command to node B.
+-------------+-----------------------------------------------------+
| CellOptions | The type of cells B selects from its schedule when |
| Value | receiving a 6P COUNT or LIST Request from A, |
| | from all the cells B has scheduled with A |
+-------------+-----------------------------------------------------+
|TX=0,RX=0,S=0| all cells |
+-------------+-----------------------------------------------------+
|TX=1,RX=0,S=0| all cells marked as RX only |
+-------------+-----------------------------------------------------+
|TX=0,RX=1,S=0| all cells marked as TX only |
+-------------+-----------------------------------------------------+
|TX=1,RX=1,S=0| all cells marked as TX and RX only |
+-------------+-----------------------------------------------------+
|TX=0,RX=0,S=1| all cells marked as SHARED (regardless of TX, RX) |
+-------------+-----------------------------------------------------+
|TX=1,RX=0,S=1| all cells marked as RX and SHARED only |
+-------------+-----------------------------------------------------+
|TX=0,RX=1,S=1| all cells marked as TX and SHARED only |
+-------------+-----------------------------------------------------+
|TX=1,RX=1,S=1| all cells marked as TX and RX and SHARED |
+-------------+-----------------------------------------------------+
Figure 8: Meaning of the 6P CellOptions bitmap for the 6P COUNT, LIST
requests.
The CellOptions is an opaque set of bits, sent unmodified to the SF.
The SF MAY redefine the format and meaning of the CellOptions field.
3.2.4. 6P CellList
A CellList field MAY be present in a 6P ADD Request, a 6P DELETE
Request, a 6P RELOCATE Request, a 6P Response, or a 6P Confirmation.
It is composed of a concatenation of zero, one or more 6P Cells as
defined in Figure 9. The content of the CellOptions field specifies
the options associated with all cells in the CellList. This
necessarily means that the same options are associated with all cells
in the CellList.
A 6P Cell is a 4-byte field, its default format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| slotOffset | channelOffset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: 6P Cell Format.
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slotOffset: The slot offset of the cell.
channelOffset: The channel offset of the cell.
The CellList is an opaque set of bytes, sent unmodified to the SF.
The length of the CellList field is implicit, and determined by the
IE Length field of the Payload IE header as defined in 802.15.4. The
SF MAY redefine the format of the CellList field; the routine that
parses this field is therefore associated with a specific SF.
3.3. 6P Commands and Operations
3.3.1. Adding Cells
Cells are added by using the 6P ADD command. The Type field (T) is
set to REQUEST. The Code field is set to ADD. Figure 10 defines the
format of a 6P ADD Request.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata | CellOptions | NumCells |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CellList ...
+-+-+-+-+-+-+-+-+-
Figure 10: 6P ADD Request Format.
Metadata: Used as extra signaling to the SF. The contents of the
Metadata field is an opaque set of bytes passed unmodified to
the SF. The meaning of this field depends on the SF, and is
out of scope of this document. For example, Metadata can
specify in which slotframe to add the cells.
CellOptions: Indicates the options to associate with the cells to be
added. If more than one cell is added (NumCells>1), the same
options are associated with each one. This necessarily means
that, if node A needs to add multiple cells with different
options, it needs to initiate multiple 6P ADD Transactions.
NumCells: The number of additional cells node A wants to schedule to
node B.
CellList: A list of 0 or multiple candidate cells. Its length is
implicit and determined by the Length field of the Payload IE
header.
Figure 11 defines the format of a 6P ADD Response and Confirmation.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CellList ...
+-+-+-+-+-+-+-+-+-
Figure 11: 6P ADD Response and Confirmation Formats.
CellList: A list of 0 or more 6P Cells.
Consider the topology in Figure 1 where the SF on node A decides to
add NumCells cells to node B.
Node A's SF selects NumCandidate cells from its schedule. These are
cells that are candidates to be scheduled with node B. The
CellOptions field specifies the type of these cells. NumCandidate
MUST be larger or equal to NumCells. How many cells node A selects
(NumCandidate) and how that selection is done is specified in the SF
and out of scope of this document. Node A sends a 6P ADD Request to
node B which contains the CellOptions, the value of NumCells, and a
selection of NumCandidate cells in the CellList. In case the
NumCandidate cells do not fit in a single packet, this operation MUST
be split into multiple independent 6P ADD Requests, each for a subset
of the number of cells that eventually need to be added. In case of
a 3-step transaction, the SF is responsible for ensuring that the
returned candidate CellList fits into the 6P Response.
Upon receiving the request, node B checks whether the cellOptions are
set to a valid value as noted by Figure 7. If this is not the case,
a Response with code RC_ERR is returned. If the cells in the
received CellList in node B is smaller than NumCells, Node B MUST
return a 6P Response with RC_ERR_CELLLIST code. Otherwise, node B's
SF verifies which of the cells in the CellList it can install in node
B's schedule, following the specified CellOptions field. How that
selection is done is specified in the SF and out of scope of this
document. The verification can succeed (NumCells cells from the
CellList can be used), fail (none of the cells from the CellList can
be used), or partially succeed (fewer than NumCells cells from the
CellList can be used). In all cases, node B MUST send a 6P Response
with return code set to RC_SUCCESS, and which specifies the list of
cells that were scheduled following the CellOptions field. That can
contain NumCells elements (succeed), 0 elements (fail), or between 0
and NumCells elements (partially succeed).
Upon receiving the response, node A adds the cells specified in the
CellList according to the CellOptions field.
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3.3.2. Deleting Cells
Cells are deleted by using the 6P DELETE command. The Type field (T)
is set to REQUEST. The Code field is set to DELETE. Figure 12
defines the format of a 6P DELETE Request.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata | CellOptions | NumCells |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CellList ...
+-+-+-+-+-+-+-+-+-
Figure 12: 6P DELETE Request Format.
Metadata: Same usage as for the 6P ADD command, see Section 3.3.1.
Its format is the same as that in the 6P ADD command, but its
content could be different.
CellOptions: Indicates the options that need to be associated to the
cells to delete. Only cells matching the CellOptions can are
deleted.
NumCells: The number of cells from the specified CellList the sender
wants to delete from the schedule of both sender and receiver.
CellList: A list of 0 or more 6P Cells. Its length is determined by
the Length field of the Payload IE header.
Figure 13 defines the format of a 6P DELETE Response and
Confirmation.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CellList ...
+-+-+-+-+-+-+-+-+-
Figure 13: 6P DELETE Response and Confirmation Formats.
CellList: A list of 0 or more 6P Cells.
The behavior for deleting cells is equivalent to that of adding cells
except that:
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o The nodes delete the cells they agree upon rather than adding
them.
o All cells in the CellList MUST already be scheduled between the
two nodes and MUST match the CellOptions field. If node A puts
cells in its CellList that are not already scheduled between the
two nodes and match the CellOptions field, node B MUST reply with
a RC_ERR_CELLLIST return code.
o The CellList in a 6P Request (2-step transaction) or 6P Response
(3-step transaction) MUST either be empty, contain exactly
NumCells cells, or more than NumCells cells. The case where the
CellList is not empty but contains fewer than NumCells cells is
not supported. RC_ERR_CELLLIST code MUST be returned when the
CellList contains fewer than NumCells cells. If the CellList is
empty, the SF on the receiving node SHOULD choose NumCells cells
with the sender from its schedule, which match the CellOption
field, and delete them. If the CellList contains more than
NumCells cells, the SF on the receiving node chooses exactly
NumCells cells from the CellList to delete.
3.3.3. Relocating Cells
Cell relocation consists in moving a cell to a different
[slotOffset,channelOffset] location in the schedule. The Type field
(T) is set to REQUEST. The Code is set to RELOCATE. Figure 14
defines the format of a 6P RELOCATE Request.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata | CellOptions | NumCells |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Relocation CellList ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Candidate CellList ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 14: 6P RELOCATE Request Format.
Metadata: Same usage as for the 6P ADD command, see Section 3.3.1.
CellOptions: Indicates the options that need to be associated with
cells to be relocated.
NumCells: The number of cells to relocate, which MUST be equal or
greater than 1.
Relocation CellList: The list of NumCells 6P Cells to relocate.
Candidate CellList: A list of NumCandidate candidate cells for node
B to pick from. NumCandidate MUST be 0, equal to NumCells, or
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greater than NumCells. Its length is determined by the Length
field of the Payload IE header.
In a 2-step 6P RELOCATE Transaction, node A specifies both the cells
it needs to relocate, and the list of candidate cells to relocate to.
The Relocation CellList MUST contain exactly NumCells entries. The
Candidate CellList MUST contain at least NumCells entries
(NumCandidate>=NumCells).
In a 3-step 6P RELOCATE Transaction, node A specifies only the cells
it needs to relocate, but not the list of candidate cells to relocate
to. The Candidate CellList MUST therefore be empty.
Figure 15 defines the format of a 6P RELOCATE Response and
Confirmation.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CellList ...
+-+-+-+-+-+-+-+-+-
Figure 15: 6P RELOCATE Response and Confirmation Formats.
CellList: A list of 0 or more 6P Cells.
Node A's SF wants to relocate NumCells cells. Node A creates a 6P
RELOCATE Request, and indicates the cells it wants to relocate in the
Relocation CellList. It also selects NumCandidate cells from its
schedule as candidate cells to relocate the cells to, and puts those
in the Candidate CellList. The CellOptions field specifies the type
of the cell(s) to relocate. NumCandidate MUST be larger or equal to
NumCells. How many cells it selects (NumCandidate) and how that
selection is done is specified in the SF and out of scope of this
document. Node A sends the 6P RELOCATE Request to node B.
Upon receiving the request, Node B checks if the length of the
Candidate CellList is larger or equal to NumCells. Node B's SF
verifies that all the cells in the Relocation CellList are scheduled
with node A, and are associate the options specified in the
CellOptions field. If either check fails, node B MUST send a 6P
Response to node A with return code RC_ERR_CELLLIST. If both checks
pass, node B's SF verifies which of the cells in the Candidate
CellList it can install in its schedule. How that selection is done
is specified in the SF and out of scope of this document. That
verification on Candidate CellList can succeed (NumCells cells from
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the Candidate CellList can be used), fail (none of the cells from the
Candidate CellList can be used) or partially succeed (fewer than
NumCells cells from the Candidate CellList can be used). In all
cases, node B MUST send a 6P Response with return code set to
RC_SUCCESS, and which specifies the list of cells that will be re-
scheduled following the CellOptions field. That can contain NumCells
elements (succeed), 0 elements (fail), between 0 and NumCells
elements (partially succeed). If N < NumCells cells appear in the
CellList, this means the first N cells in the Relocation CellList
have been relocated, the remainder have not.
Upon receiving the response with Code RC_SUCCESS, node A relocates
the cells specified in Relocation CellList of its RELOCATE Request to
the new locations specified in the CellList of the 6P Response, in
the same order. In case the received return code is RC_ERR_CELLLIST,
the transaction is aborted and no cell is relocated. In case of a
2-step transaction, Node B relocates the selected cells upon
receiving the link-layer ACK for the 6P Response. In case of a
3-step transaction, Node B relocates the selected cells upon
receiving the 6P Confirmation.
The SF SHOULD NOT relocate all cells between two nodes at the same
time, which might result in the schedules of both nodes diverging
significantly.
Figure 16 shows an example of a successful 2-step 6P RELOCATION
Transaction.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
| |
| 6P RELOCATE Request |
| Type = REQUEST |
| Code = RELOCATE |
| SeqNum = 11 |
| NumCells = 2 |
| R.CellList = [(1,2),(2,2)] |
| C.CellList = [(3,3),(4,3),(5,3)] |
|-------------------------------------->| B prepares
| L2 ACK | to relocate
|<- - - - - - - - - - - - - - - - - - - | (1,2)->(5,3)
| | and
| | (2,2)->(3,3)
| 6P Response |
| Code = RC_SUCCESS |
| SeqNum = 11 |
| CellList = [(5,3),(3,3)] |
A relocates|<--------------------------------------|
(1,2)->(5,3)| L2 ACK |
and | - - - - - - - - - - - - - - - - - - ->|B relocates
(2,2)->(3,3)| |(1,2)->(5,3)
| |and
| |(2,2)->(3,3)
Figure 16: Example of a successful 2-step 6P RELOCATION Transaction.
Figure 17 shows an example of a partially successful 2-step 6P
RELOCATION Transaction.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
| |
| 6P RELOCATE Request |
| Type = REQUEST |
| Code = RELOCATE |
| SeqNum = 199 |
| NumCells = 2 |
| R.CellList = [(1,2),(2,2)] |
| C.CellList = [(3,3),(4,3),(5,3)] |B prepares
|-------------------------------------->|to relocate
| L2 ACK |(1,2)->(4,3)
|<- - - - - - - - - - - - - - - - - - - |but cannot
| |relocate (2,2)
| 6P Response |
| Type = RESPONSE |
| Code = RC_SUCCESS |
| SeqNum = 199 |
| CellList = [(4,3)] |
A relocates |<--------------------------------------|
(1,2)->(4,3)| L2 ACK |
| - - - - - - - - - - - - - - - - - - ->|B relocates
| |(1,2)->(4,3)
| |
| |
Figure 17: Example of a partially successful 2-step 6P RELOCATION
Transaction.
Figure 18 shows an example of a failed 2-step 6P RELOCATION
Transaction.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
| |
| 6P RELOCATE Request |
| Type = REQUEST |
| Code = RELOCATE |
| SeqNum = 53 |
| NumCells = 2 |
| R.CellList = [(1,2),(2,2)] |
| C.CellList = [(3,3),(4,3),(5,3)] |
|-------------------------------------->| B cannot
| L2 ACK | relocate
|<- - - - - - - - - - - - - - - - - - - | (1,2)
| | nor (2,2)
| 6P Response |
| Type = RESPONSE |
| Code = RC_SUCCESS |
| SeqNum = 53 |
| CellList = [] |
|<--------------------------------------| B does not
| L2 ACK | relocate
A does not | - - - - - - - - - - - - - - - - - - ->|
relocate | |
| |
Figure 18: Failed 2-step 6P RELOCATION Transaction Example.
Figure 19 shows an example of a successful 3-step 6P RELOCATION
Transaction.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
| |
| 6P RELOCATE Request |
| Type = REQUEST |
| Code = RELOCATE |
| SeqNum = 11 |
| NumCells = 2 |
| R.CellList = [(1,2),(2,2)] |
| C.CellList = [] |
|-------------------------------------->|
| L2 ACK |
|<- - - - - - - - - - - - - - - - - - - | B identifies
| | candidate
| | cells
| 6P Response | (3,3),
| Code = RC_SUCCESS | (4,3) and
| SeqNum = 11 | (5,3)
| CellList = [(3,3),(4,3),(5,3)] |
A prepares |<--------------------------------------|
to relocate | L2 ACK |
(1,2)->(5,3) | - - - - - - - - - - - - - - - - - - ->|
and | |
(2,2)->(3,3) | 6P Confirmation |
| Code = RC_SUCCESS |
| SeqNum = 11 |
| CellList = [(5,3),(3,3)] |
|-------------------------------------->| B relocates
| L2 ACK | (1,2)->(5,3)
A relocates |<- - - - - - - - - - - - - - - - - - - | and
(1,2)->(5,3)| | (2,2)->(3,3)
and | |
(2,2)->(3,3)| |
| |
Figure 19: Example of a successful 3-step 6P RELOCATION Transaction.
3.3.4. Counting Cells
To retrieve the number of scheduled cells node A has with B, node A
issues a 6P COUNT command. The Type field (T) is set to REQUEST.
The Code field is set to COUNT. Figure 20 defines the format of a 6P
COUNT Request.
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1 2
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata | CellOptions |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 20: 6P COUNT Request Format.
Metadata: Same usage as for the 6P ADD command, see Section 3.3.1.
Its format is the same as that in the 6P ADD command, but its
content could be different.
CellOptions: Specifies which type of cell to be counted.
Figure 21 defines the format of a 6P COUNT Response.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NumCells |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: 6P COUNT Response Format.
NumCells: The number of cells which correspond to the fields of the
request.
Node A issues a COUNT command to node B, specifying some cell
options. Upon receiving the 6P COUNT request, node B goes through
its schedule and counts the number of cells scheduled with node A in
its own schedule which match the cell options in the CellOptions
field of the request. Section 3.2.3 details the use of the
CellOptions field.
Node B issues a 6P response to node A with return code set to
RC_SUCCESS, and with NumCells containing the number of cells that
match the request.
3.3.5. Listing Cells
To retrieve a list of scheduled cells node A has with node B, node A
issues a 6P LIST command. The Type field (T) is set to REQUEST. The
Code field is set to LIST. Figure 22 defines the format of a 6P LIST
Request.
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1 2
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata | CellOptions | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset | MaxNumCells |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 22: 6P LIST Request Format.
Metadata: Same usage as for the 6P ADD command, see Section 3.3.1.
Its format is the same as that in the 6P ADD command, but its
content could be different.
CellOptions: Specifies which type of cell to be listed.
Reserved: Reserved bits. These bits SHOULD be set to zero when
sending the message, and MUST be ignored upon reception.
Offset: The Offset of the first scheduled cell that is requested.
The mechanism assumes cells are ordered according to a rule
defined in the SF. The rule MUST always order the cells in the
same way.
MaxNumCells: The maximum number of cells to be listed. Node B MAY
return fewer than MaxNumCells cells, for example if MaxNumCells
cells do not fit in the frame.
Figure 23 defines the format of a 6P LIST Response.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CellList ...
+-+-+-+-+-+-+-+-+-
Figure 23: 6P LIST Response Format.
CellList: A list of 0 or more 6P Cells.
When receiving a LIST command, node B returns the cells scheduled
with A in its schedule that match the CellOptions field as specified
in Section 3.2.3.
When node B receives a LIST request, the returned CellList in the 6P
Response contains between 0 and MaxNumCells cells, starting from the
specified offset. Node B SHOULD include as many cells as fit in the
frame. If the response contains the last cell, Node B MUST set the
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Code field in the response to RC_EOL ("End of List", as per
Figure 38), indicating to Node A that there no more cells that match
the request. Node B MUST return at least one cell, unless the
specified Offset is beyond the end of B's cell list in its schedule.
If node B has fewer than Offset cells that match the request, node B
returns an empty CellList and a Code field set to RC_EOL.
3.3.6. Clearing the Schedule
To clear the schedule between nodes A and B (for example after a
schedule inconsistency is detected), node A issues a CLEAR command.
The Type field (T) is set to 6P Request. The Code field is set to
CLEAR. Figure 24 defines the format of a 6P CLEAR Request.
1 2
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 24: 6P CLEAR Request Format.
Metadata: Same usage as for the 6P ADD command, see Section 3.3.1.
Its format is the same as that in the 6P ADD command, but its
content could be different.
Figure 25 defines the format of a 6P CLEAR Response.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 25: 6P CLEAR Response Format.
When a 6P CLEAR command is issued from node A to node B, both nodes A
and B MUST remove all the cells scheduled between them. That is,
node A MUST remove all the cells scheduled with node B, and node B
MUST remove all the cells scheduled with node A. In a 6P CLEAR
command, the SeqNum MUST NOT be checked. In particular, even if the
request contains a SeqNum value that would normally cause node B to
detect a schedule inconsistency, the transaction MUST NOT be aborted.
Upon 6P CLEAR completion, the value of SeqNum MUST be reset to 0.
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The return code to a 6P CLEAR command SHOULD be RC_SUCCESS unless the
operation cannot be executed. When the CLEAR operation cannot be
executed, the return code MUST be set to RC_RESET.
3.3.7. Generic Signaling Between SFs
The 6P SIGNAL message allows the SF implementations on two neighbor
nodes to exchange generic commands. The payload in a received SIGNAL
message is an opaque set of bytes passed unmodified to the SF. The
length of the payload is determined through the length field of the
Payload IE Header. How the generic SIGNAL command is used is
specified by the SF, and outside the scope of this document. The
Type field (T) is set to REQUEST. The Code field is set to SIGNAL.
Figure 26 defines the format of a 6P SIGNAL Request.
1 2
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata | payload ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 26: 6P SIGNAL Request Format.
Metadata: Same usage as for the 6P ADD command, see Section 3.3.1.
Its format is the same as that in the 6P ADD command, but its
content could be different.
Figure 27 defines the format of a 6P SIGNAL Response.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| T | R | Code | SFID | SeqNum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| payload ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 27: 6P SIGNAL Response Format.
3.4. Protocol Functional Details
3.4.1. Version Checking
All messages contain a Version field. If multiple Versions of the 6P
protocol have been defined (in future specifications for Version
values different from 0), a node MAY implement multiple protocol
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versions at the same time. When a node receives a 6P message with a
Version number it does not implement, the node MUST reply with a 6P
Response with a return code field set to RC_ERR_VERSION. The format
of this 6P Response message MUST be compliant with Version 0 and MUST
be supported by all future versions of the protocol. This ensures
that, when node B sends a 6P Response to node A indicating it does
not implement the 6P version in the 6P Request, node A can
successfully parse that response.
When a node supports a version number received in a 6P Request
message, the Version field in the 6P Response MUST be the same as the
Version field in the corresponding 6P Request. Similarly, in a
3-step transaction, the Version field in the 6P Confirmation MUST
match that of the 6P Request and 6P Response of the same transaction.
3.4.2. SFID Checking
All messages contain an SFID field. A node MAY support multiple SFs
at the same time. When receiving a 6P message with an unsupported
SFID, a node MUST reply with a 6P Response with return code of
RC_ERR_SFID. The SFID field in the 6P Response MUST be the same as
the SFID field in the corresponding 6P Request. In a 3-step
transaction, the SFID field in the 6P Confirmation MUST match that of
the 6P Request and the 6P Response of the same transaction.
3.4.3. Concurrent 6P Transactions
Only a single 6P Transaction between two neighbors, in a given
direction, can take place at the same time. That is, a node MUST NOT
issue a new 6P Request to a given neighbor before the previous 6P
Transaction it initiated has finished (possibly timed out). If a
node receives a 6P Request from a given neighbor before having sent
the 6P Response to the previous 6P Request from that neighbor, it
MUST send back a 6P Response with a return code of RC_RESET (as per
Figure 38) and discard this ongoing second transaction. A node
receiving a RC_RESET code MUST abort the second transaction and
consider it never happened (i.e. reverting changes to the schedule or
SeqNum done by this transaction).
Nodes A and B MAY support having two transactions going on at the
same time, one in each direction. Similarly, a node MAY support
concurrent 6P Transactions with different neighbors. In this case,
the cells involved in an ongoing 6P Transaction MUST be "locked"
until the transaction finishes. For example, in Figure 1, node C can
have a different ongoing 6P Transaction with nodes B and R. In case
a node does not have enough resources to handle concurrent 6P
Transactions from different neighbors it MUST reply with a 6P
Response with return code RC_ERR_BUSY (as per Figure 38). In case
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the requested cells are locked, it MUST reply to that request with a
6P Response with return code RC_ERR_LOCKED (as per Figure 38). The
node receiving RC_ERR_BUSY or a RC_ERR_LOCKED MAY implement a retry
mechanism, defined by the SF.
3.4.4. 6P Timeout
A timeout occurs when the node that successfully sent a 6P Request
does not receive the corresponding 6P Response within an amount of
time specified by the SF. In a 3-step transaction, a timeout also
occurs when a node sending the 6P Response does not receive a 6P
Confirmation. When a timeout occurs, the transaction MUST be
canceled at the node where the timeout occurs. The value of the 6P
Timeout should be larger than the longest possible time it takes to
receive the 6P Response or Confirmation. The value of the 6P Timeout
hence depends on the number of cells scheduled between the neighbor
nodes, the maximum number of link-layer retransmissions, etc. The SF
MUST determine the value of the timeout. The value of the timeout is
out of scope of this document.
3.4.5. Aborting a 6P Transaction
In case the receiver of a 6P Request fails during a 6P Transaction
and is unable to complete it, it SHOULD reply to that Request with a
6P Response with return code RC_RESET. Upon receiving this 6P
Response, the initiator of the 6P Transaction MUST consider the 6P
Transaction as failed.
Similarly, in the case of 3-step transaction, when the receiver of a
6P Response fails during the 6P Transaction and is unable to complete
it, it MUST reply to that 6P Response with a 6P Confirmation with
return code RC_RESET. Upon receiving this 6P Confirmation, the
sender of the 6P Response MUST consider the 6P Transaction as failed.
3.4.6. SeqNum Management
The SeqNum is the field in the 6top IE header used to match Request,
Response and Confirmation. The SeqNum is used to detect and handle
duplicate commands (Section 3.4.6.1) and schedule inconsistencies
(Section 3.4.6.2). Each node remembers the last used SeqNum for each
neighbor. That is, a node stores as many SeqNum values as it has
neighbors. In case of supporting multiple SFs at a time, a SeqNum
value is maintained per SF and per neighbor. In the remainder of
this section, we describe the use of SeqNum between two neighbors;
the same happens for each other neighbor, independently.
When a node resets or after a CLEAR transaction, it MUST reset SeqNum
to 0. The 6P Response and 6P Confirmation for a transaction MUST use
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the same SeqNum value as that in the Request. After every
transaction, the SeqNum MUST be incremented by exactly 1.
Specifically, if node A receives the link-layer acknowledgment for
its 6P Request, it commits to incrementing the SeqNum by exactly 1
after the 6P Transaction ends. This ensure that, at the next 6P
Transaction where it sends a 6P Request, 6P Request will have a
different SeqNum.
Similarly, a node B increments the SeqNum by exactly 1 after having
received the link-layer acknowledgment for the 6P Response (2-step 6P
Transaction), or after having sent the link-layer acknowledgment for
the 6P Confirmation (3-step 6P Transaction) .
When a node B receives a 6P Request from node A with SeqNum equal to
0, it checks the stored SeqNum for A. If A is a new neighbor, the
stored SeqNum in B will be 0. The transaction can continue. If the
stored SeqNum for A in B is different than 0, a potential
inconsistency is detected. In this case, B MUST return RC_ERR_SEQNUM
with SeqNum=0. The SF of node A MAY decide what to do next, as
described in Section 3.4.6.2.
The SeqNum MUST be implemented as a lollipop counter: it rolls over
from 0xFF to 0x01 (not to 0x00). This is used to detect a neighbor
reset. Figure 28 lists the possible values of the SeqNum.
+-----------+-----------------------------+
| Value | Meaning |
+-----------+-----------------------------+
| 0x00 | Clear or After device Reset |
| 0x01-0xFF | Lollipop Counter values |
+-----------+-----------------------------+
Figure 28: Possible values of the SeqNum.
3.4.6.1. Detecting and Handling Duplicate 6P Messages
All 6P commands are link-layer acknowledged. A duplicate message
means that a node receives a second 6P Request, Response or
Confirmation. This happens when the link-layer acknowledgment is not
received, and a link-layer retransmission happens. Duplicate
messages are normal and unavoidable.
Figure 29 shows an example 2-step transaction in which Node A
receives a duplicate 6P Response.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
| |
| 6P Request (SeqNum=456) |
|-------------------------------------->|
| L2 ACK |
|<- - - - - - - - - - - - - - - - - - - |
| |
| 6P Response (SeqNum=456) |
|<--------------------------------------|
| L2 ACK |
| - - - - - - - - - - -X | No ACK:
| | link-layer
| 6P Response (SeqNum=456) | retransmit
duplicate |<--------------------------------------|
6P Response | L2 ACK |
received | - - - - - - - - - - - - - - - - - - ->|
| |
Figure 29: Example duplicate 6P message.
Figure 30 shows example 3-step transaction in which Node A receives a
out-of-order duplicate 6P Response after having sent a 6P
Confirmation.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
| |
| 6P Request (SeqNum=123) |
|-------------------------------------->|
| L2 ACK |
|<- - - - - - - - - - - - - - - - - - - |
| |
| 6P Response (SeqNum=123) |
|<--------------------------------------|
| L2 ACK |
| - - - - - - - - - - -X | No ACK:
| | link-layer
| 6P Confirmation (SeqNum=123) | retransmit
|-------------------------------------->| |
| L2 ACK | |
|<- - - - - - - - - - - - - - - - - - - | frame
| | queued
| 6P Response (SeqNum=123) | |
duplicate |<--------------------------------------| <--+
out-of-order | L2 ACK |
6P Response | - - - - - - - - - - - - - - - - - - ->|
received | |
Figure 30: Example out-of-order duplicate 6P message.
A node detects a duplicate 6P message when it has the same SeqNum and
type as the last frame received from the same neighbor. When
receiving a duplicate 6P message, a node MUST send a link-layer
acknowledgment, but MUST silently ignore the 6P message at the 6top
sublayer.
3.4.6.2. Detecting and Handling a Schedule Inconsistency
A schedule inconsistency happens when the schedules of nodes A and B
are inconsistent. For example, when node A has a transmit cell to
node B, but node B does not have the corresponding receive cell, and
therefore isn't listening to node A on that cell. A schedule
inconsistency results in loss of connectivity.
The SeqNum field, which is present in each 6P message, is used to
detect an inconsistency. The SeqNum field increments by 1 at each
message, as detailed in Section 3.4.6. A node computes the expected
SeqNum field for the next 6P Transaction. If a node receives a 6P
Request with a SeqNum value that is not the expected one, it has
detected an inconsistency.
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There are at least 2 cases in which a schedule inconsistency happens.
The first case is when a node loses state, for example when it is
power cycled (turned off, then on). In that case, its SeqNum value
is reset to 0. Since the SeqNum is a lollipop counter, its neighbor
detects an inconsistency at the next 6P transaction. This is
illustrated in Figure 31 and Figure 32.
+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
SeqNum=87 | | SeqNum=87
| |
| 6P Request (SeqNum=87) |
|-------------------------------------->|
| L2 ACK |
|<- - - - - - - - - - - - - - - - - - - |
| |
| 6P Response (SeqNum=87) |
|<--------------------------------------|
| L2 ACK |
| - - - - - - - - - - - - - - - - - - ->|
| ==== power-cycle
| |
SeqNum=88 | | SeqNum=0
| |
| 6P Request (SeqNum=88) |
|-------------------------------------->| Inconsistency
| L2 ACK | Detected
|<- - - - - - - - - - - - - - - - - - - |
| |
| 6P Response (SeqNum=0, RC_ERR_SEQNUM) |
|<--------------------------------------|
| L2 ACK |
| - - - - - - - - - - - - - - - - - - ->|
Figure 31: Example of inconsistency because of node B reset.
Detected by node B
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
SeqNum=97 | | SeqNum=97
| |
| 6P Request (SeqNum=97) |
|-------------------------------------->|
| L2 ACK |
|<- - - - - - - - - - - - - - - - - - - |
| |
| 6P Response (SeqNum=97) |
|<--------------------------------------|
| L2 ACK |
| - - - - - - - - - - - - - - - - - - ->|
| ==== power-cycle
| |
SeqNum=98 | | SeqNum=0
| |
| 6P Request (SeqNum=0) |
Inconsistency|<--------------------------------------|
Detected | L2 ACK |
|- - - - - - - - - - - - - - - - - - - >|
| |
| 6P Response (SeqNum=0, RC_ERR_SEQNUM) |
|-------------------------------------->|
| L2 ACK |
|<- - - - - - - - - - - - - - - - - - - |
Figure 32: Example of inconsistency because node B resets. Detected
by node A
The second case is when the maximum number of link-layer
retransmissions is reached on the 6P Response of a 2-step transaction
(or equivalently on a 6P Confirmation of a 3-step transaction). This
is illustrated in Figure 33.
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+----------+ +----------+
| Node A | | Node B |
+----+-----+ +-----+----+
SeqNum=87 | | SeqNum=87
| |
| 6P Request (SeqNum=87) |
|-------------------------------------->|
| L2 ACK |
|<- - - - - - - - - - - - - - - - - - - |
| |
| 6P Response (SeqNum=87) |
|<--------------------------------------|
| L2 ACK |
| - - - - - - - - X |
SeqNum=88 | | no ACK:
| 6P Response (SeqNum=87) | retrans. 1
(duplicate) |<--------------------------------------|
| L2 ACK |
| - - - - - - - - X |
| | no ACK:
| 6P Response (SeqNum=87) | retrans. 2
(duplicate) |<--------------------------------------|
| L2 ACK |
| - - - - - - - - X |
| | max retrans.:
| | Inconsistency
| | Detected
Figure 33: Example inconsistency because of maximum link-layer
retransmissions (here 2).
In both cases, node B detects the inconsistency.
If the inconsistency is detected during a 6P Transaction (Figure 31),
the node that has detected it MUST send back a 6P Response or 6P
Confirmation with an error code of RC_ERR_SEQNUM. In this 6P
Response or 6P Confirmation, the SeqNum field MUST be set to the
value of the sender of the message (0 in the example in Figure 31).
The SF of the node which has detected the inconsistency MUST define
how to handle the inconsistency. A first possibility is to issue a
6P CLEAR request to clear the schedule, and rebuild. A second
possibility is to issue a 6P LIST request to retrieve the schedule.
A third possibility is to internally "roll-back" the schedule. How
to handle an inconsistency is out of scope of this document. The SF
defines how to handle an inconsistency.
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3.4.7. Handling Error Responses
A return code marked as Yes in the "Is Error" column in Figure 38
indicates an error. When a node receives a 6P Response or 6P
Confirmation with an error, it MUST consider the 6P Transaction as
failed. In particular, if this was a response to a 6P ADD, DELETE or
RELOCATE Request, the node MUST NOT add, delete or relocate any of
the cells involved in this 6P Transaction. Similarly, a node sending
a 6P Response or a 6P Confirmation with an error code MUST NOT add,
delete, relocate any cells as part of that 6P Transaction. If a node
receives an unrecognized return code the 6P Transaction MUST be
considered as failed. In particular, in a 3 step 6P Transaction, a
6P Response with an unrecognized return code MUST be responded with a
6P Confirmation with return code RC_ERR and consider the transaction
as failed. Defining what to do after an error has occurred is out of
scope of this document. The SF defines what to do after an error has
occurred.
3.5. Security
6P messages MUST be secured through link-layer security. This is
possible because 6P messages are carried as Payload IEs.
4. Requirements for 6top Scheduling Functions (SF) Specification
4.1. SF Identifier (SFID)
Each SF has a 1-byte identifier. Section 6.2.5 defines the rules for
applying for an SFID.
4.2. Requirements for an SF specification
The specification for an SF
o MUST specify an identifier for that SF.
o MUST specify the rule for a node to decide when to add/delete one
or more cells to a neighbor.
o MUST specify the rule for a Transaction source to select cells to
add to the CellList field in the 6P ADD Request.
o MUST specify the rule for a Transaction destination to select
cells from CellList to add to its schedule.
o MUST specify a value for the 6P Timeout, or a rule/equation to
calculate it.
o MUST specify the rule for ordering cells.
o MUST specify a meaning for the "Metadata" field in the 6P ADD
Request.
o MUST specify the SF behavior of a node when it boots.
o MUST specify how to handle a schedule inconsistency.
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o MUST specify what to do after an error has occurred (either the
node sent a 6P Response with an error code, or received one).
o MUST specify the list of statistics to gather. Example statistics
include the number of transmitted frames to each neighbor. In
case the SF requires no statistics to be gathered, the specific of
the SF MUST explicitly state so.
o SHOULD clearly state the application domain the SF is created for.
o SHOULD contain examples which highlight normal and error
scenarios.
o SHOULD contain a list of current implementations, at least during
the I-D state of the document, per [RFC6982].
o SHOULD contain a performance evaluation of the scheme, possibly
through references to external documents.
o SHOULD define the format of the SIGNAL command payload and its
use.
o MAY redefine the format of the CellList field.
o MAY redefine the format of the CellOptions field.
o MAY redefine the meaning of the CellOptions field.
5. Security Considerations
6P messages are carried inside 802.15.4 Payload Information Elements
(IEs). Those Payload IEs are encrypted and authenticated at the link
layer through CCM* [CCM-Star]. 6P benefits from the same level of
security as any other Payload IE. The 6P protocol does not define
its own security mechanisms. In particular, although a key
management solution is out of scope of this document, the 6P protocol
will benefit for the key management solution used in the network.
This is relevant as security attacks such as forgery and
misattribution attacks become more damaging when a single key is
shared amongst a group of more than 2 participants.
The 6P protocol does not provide protection against DOS attacks.
Example attacks include, not sending confirmation messages in 3-step
transaction, and sending wrongly formatted requests. These cases
SHOULD be handled by an appropriate policy, such as rate-limiting or
time-limited blacklisting the attacker after several attempts. The
effect on the overall network is mostly localized to those two nodes,
as communication happens in dedicated cells.
6. IANA Considerations
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6.1. IETF IE Subtype '6P'
This document adds the following number to the "IEEE Std 802.15.4
IETF IE subtype IDs" registry defined by [RFC8137]:
+--------+------------+-----------+
| Value | Subtype ID | Reference |
+--------+------------+-----------+
| <TBD> | SUBID_6TOP | RFCXXXX |
+---------------------+-----------+
Figure 34: IETF IE Subtype SUBID_6TOP.
6.2. 6TiSCH parameters sub-registries
This section defines sub-registries within the "IPv6 over the TSCH
mode of IEEE 802.15.4e (6TiSCH) parameters" registry, hereafter
referred to as the "6TiSCH parameters" registry. Each sub-registry
is described in a subsection.
6.2.1. 6P Version Numbers
The name of the sub-registry is "6P Version Numbers".
A Note included in this registry should say: "In the 6top Protocol
(6P) [RFCXXXX] there is a field to identify the version of the
protocol. This field is 4 bits in size."
Each entry in the sub-registry must include the Version in the range
0-15, and a reference to the 6P version's documentation.
The initial entry in this sub-registry is as follows:
+---------+-----------+
| Version | Reference |
+---------+-----------+
| 0 | RFCXXXX |
+---------+-----------+
Figure 35: 6P Version Numbers.
All other Version Numbers are Unassigned.
The IANA policy for future additions to this sub-registry is "IETF
Review or IESG Approval" as described in [RFC8126].
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6.2.2. 6P Message Types
The name of the sub-registry is "6P Message Types".
A note included in this registry should say: "In the 6top Protocol
(6P) version 0 [RFCXXXX], there is a field to identify the type of
message. This field is 2 bits in size."
Each entry in the sub-registry must include the Type in range
b00-b11, the corresponding Name, and a reference to the 6P message
type's documentation.
Initial entries in this sub-registry are as follows:
+------+--------------+-----------+
| Type | Name | Reference |
+------+--------------+-----------+
| b00 | REQUEST | RFCXXXX |
| b01 | RESPONSE | RFCXXXX |
| b10 | CONFIRMATION | RFCXXXX |
+------+--------------+-----------+
Figure 36: 6P Message Types.
All other Message Types are Reserved.
The IANA policy for future additions to this sub-registry is "IETF
Review or IESG Approval" as described in [RFC8126].
6.2.3. 6P Command Identifiers
The name of the sub-registry is "6P Command Identifiers".
A Note included in this registry should say: "In the 6top Protocol
(6P) version 0 [RFCXXXX], there is a Code field which is 8 bits in
size. In a 6P Request, the value of this Code field is used to
identify the command."
Each entry in the sub-registry must include an Identifier in the
range 0-255, the corresponding Name, and a reference to the 6P
command identifier's documentation.
Initial entries in this sub-registry are as follows:
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+------------+------------+-----------+
| Identifier | Name | Reference |
+------------+------------+-----------+
| 0 | Reserved | |
| 1 | ADD | RFCXXXX |
| 2 | DELETE | RFCXXXX |
| 3 | RELOCATE | RFCXXXX |
| 4 | COUNT | RFCXXXX |
| 5 | LIST | RFCXXXX |
| 6 | SIGNAL | RFCXXXX |
| 7 | CLEAR | RFCXXXX |
| 8-254 | Unassigned | |
| 255 | Reserved | |
+------------+------------+-----------+
Figure 37: 6P Command Identifiers.
The IANA policy for future additions to this sub-registry is "IETF
Review or IESG Approval" as described in [RFC8126].
6.2.4. 6P Return Codes
The name of the sub-registry is "6P Return Codes".
A Note included in this registry should say: "In the 6top Protocol
(6P) version 0 [RFCXXXX], there is a Code field which is 8 bits in
size. In a 6P Response or 6P Confirmation, the value of this Code
field is used to identify the return code."
Each entry in the sub-registry must include a Code in the range
0-255, the corresponding Name, the corresponding Description, and a
reference to the 6P return code's documentation.
Initial entries in this sub-registry are as follows:
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+------+-----------------+---------------------------+-----------+
| Code | Name | Description | Is Error? |
+------+-----------------+---------------------------+-----------+
| 0 | RC_SUCCESS | operation succeeded | No |
| 1 | RC_EOL | end of list | No |
| 2 | RC_ERR | generic error | Yes |
| 3 | RC_RESET | critical error, reset | Yes |
| 4 | RC_ERR_VERSION | unsupported 6P version | Yes |
| 5 | RC_ERR_SFID | unsupported SFID | Yes |
| 6 | RC_ERR_SEQNUM | schedule inconsistency | Yes |
| 7 | RC_ERR_CELLLIST | cellList error | Yes |
| 8 | RC_ERR_BUSY | busy | Yes |
| 9 | RC_ERR_LOCKED | cells are locked | Yes |
+------+-----------------+---------------------------+-----------+
Figure 38: 6P Return Codes.
All other Message Types are Unassigned.
The IANA policy for future additions to this sub-registry is "IETF
Review or IESG Approval" as described in [RFC8126].
6.2.5. 6P Scheduling Function Identifiers
6P Scheduling Function Identifiers.
A Note included in this registry should say: "In the 6top Protocol
(6P) version 0 [RFCXXXX], there is a field to identify the scheduling
function to handle the message. This field is 8 bits in size."
Each entry in the sub-registry must include an SFID in the range
0-255, the corresponding Name, and a reference to the 6P Scheduling
Function's documentation.
Initial entries in this sub-registry are as follows:
+----+---------------------------------+----------------------------+
|SFID| Name | Reference |
+----+---------------------------------+----------------------------+
| 0 | Minimal Scheduling Function | draft-chang-6tisch-msf |
| | (MSF) | |
+----+---------------------------------+----------------------------+
Figure 39: SF Identifiers (SFID).
All other Message Types are Unassigned.
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The IANA policy for future additions to this sub-registry depends on
the value of the SFID, as defined in Figure 40. These specifications
must follow the guidelines of Section 4.
+-----------+------------------------------+
| Range | Registration Procedures |
+-----------+------------------------------+
| 0-127 | IETF Review or IESG Approval |
| 128-255 | Expert Review |
+-----------+------------------------------+
Figure 40: SF Identifier (SFID): Registration Procedure.
6.2.6. 6P CellOptions bitmap
The name of the sub-registry is "6P CellOptions bitmap".
A Note included in this registry should say: "In the 6top Protocol
(6P) version 0 [RFCXXXX], there is an optional CellOptions field
which is 8 bits in size."
Each entry in the sub-registry must include a bit position in the
range 0-7, the corresponding Name, and a reference to the bit's
documentation.
Initial entries in this sub-registry are as follows:
+-----+---------------+-----------+
| bit | Name | Reference |
+-----+---------------+-----------+
| 0 | TX (Transmit) | RFCXXXX |
| 1 | RX (Receive) | RFCXXXX |
| 2 | SHARED | RFCXXXX |
| 3-7 | Reserved | |
+-----+---------------+-----------+
Figure 41: 6P CellOptions bitmap.
All other Message Types are Reserved.
The IANA policy for future additions to this sub-registry is "IETF
Review or IESG Approval" as described in [RFC8126].
7. References
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7.1. Normative References
[IEEE802154]
IEEE standard for Information Technology, "IEEE Std
802.15.4-2015 - IEEE Standard for Low-Rate Wireless
Personal Area Networks (WPANs)", October 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8137] Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information
Element for the IETF", RFC 8137, DOI 10.17487/RFC8137, May
2017, <https://www.rfc-editor.org/info/rfc8137>.
7.2. Informative References
[CCM-Star]
Struik, R., "Formal Specification of the CCM* Mode of
Operation, IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs).", September 2005.
[OpenWSN] Watteyne, T., Vilajosana, X., Kerkez, B., Chraim, F.,
Weekly, K., Wang, Q., Glaser, S., and K. Pister, "OpenWSN:
a Standards-Based Low-Power Wireless Development
Environment", Transactions on Emerging Telecommunications
Technologies , August 2012.
[RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", RFC 6982,
DOI 10.17487/RFC6982, July 2013,
<https://www.rfc-editor.org/info/rfc6982>.
[RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
Internet of Things (IoT): Problem Statement", RFC 7554,
DOI 10.17487/RFC7554, May 2015,
<https://www.rfc-editor.org/info/rfc7554>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
Wang, et al. Expires December 22, 2018 [Page 45]
Internet-Draft 6tisch-6top-protocol June 2018
[RFC8180] Vilajosana, X., Ed., Pister, K., and T. Watteyne, "Minimal
IPv6 over the TSCH Mode of IEEE 802.15.4e (6TiSCH)
Configuration", BCP 210, RFC 8180, DOI 10.17487/RFC8180,
May 2017, <https://www.rfc-editor.org/info/rfc8180>.
Appendix A. Recommended Structure of an SF Specification
The following section structure for a SF document is RECOMMENDED:
o Introduction
o Scheduling Function Identifier
o Rules for Adding/Deleting Cells
o Rules for CellList
o 6P Timeout Value
o Rule for Ordering Cells
o Meaning of the Metadata Field
o Node Behavior at Boot
o Schedule Inconsistency Handling
o 6P Error Handling
o Examples
o Implementation Status
o Security Considerations
o IANA Considerations
Authors' Addresses
Qin Wang (editor)
Univ. of Sci. and Tech. Beijing
30 Xueyuan Road
Beijing, Hebei 100083
China
Email: wangqin@ies.ustb.edu.cn
Xavier Vilajosana
Universitat Oberta de Catalunya
156 Rambla Poblenou
Barcelona, Catalonia 08018
Spain
Email: xvilajosana@uoc.edu
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Thomas Watteyne
Analog Devices
32990 Alvarado-Niles Road, Suite 910
Union City, CA 94587
USA
Email: thomas.watteyne@analog.com
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