draft-ietf-6lo-deadline-time-02.txt   draft-ietf-6lo-deadline-time-03.txt 
6lo Lijo Thomas 6lo Lijo Thomas
Internet-Draft C-DAC Internet-Draft C-DAC
Intended status: Standards Track S. Anamalamudi Intended status: Standards Track S. Anamalamudi
Expires: March 4, 2019 SRM University-AP Expires: April 18, 2019 SRM University-AP
S.V.R.Anand S.V.R.Anand
Malati Hegde Malati Hegde
Indian Institute of Science Indian Institute of Science
C. Perkins C. Perkins
Futurewei Futurewei
August 31, 2018 October 15, 2018
Packet Delivery Deadline time in 6LoWPAN Routing Header Packet Delivery Deadline time in 6LoWPAN Routing Header
draft-ietf-6lo-deadline-time-02 draft-ietf-6lo-deadline-time-03
Abstract Abstract
This document specifies a new type for the 6LoWPAN routing header This document specifies a new type for the 6LoWPAN routing header
containing the delivery deadline time for data packets. The deadline containing the delivery deadline time for data packets. The deadline
time enables forwarding and scheduling decisions for time critical time enables forwarding and scheduling decisions for time critical
IoT M2M applications that need deterministic delay guarantees over IoT M2M applications that need deterministic delay guarantees over
constrained networks and operate within time-synchronized networks. constrained networks and operate within time-synchronized networks.
Status of This Memo Status of This Memo
skipping to change at page 1, line 40 skipping to change at page 1, line 40
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 March 4, 2019. This Internet-Draft will expire on April 18, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Deadline-6LoRHE . . . . . . . . . . . . . . . . . . . . . . . 3 3. 6LoRHE Generic Format . . . . . . . . . . . . . . . . . . . . 3
4. Deadline-6LoRHE Format . . . . . . . . . . . . . . . . . . . 5 4. Deadline-6LoRHE . . . . . . . . . . . . . . . . . . . . . . . 4
5. Deadline-6LoRHE in Three Network Scenarios . . . . . . . . . 7 5. Deadline-6LoRHE Format . . . . . . . . . . . . . . . . . . . 6
5.1. Scenario 1: Endpoints in the same DODAG (N1) . . . . . . 7 6. Deadline-6LoRHE in Three Network Scenarios . . . . . . . . . 7
5.2. Scenario 2: Endpoints in Networks with Dissimilar L2 6.1. Scenario 1: Endpoints in the same DODAG (N1) . . . . . . 8
Technologies. . . . . . . . . . . . . . . . . . . . . . . 8 6.2. Scenario 2: Endpoints in Networks with Dissimilar L2
5.3. Scenario 3: Packet transmission across different DODAGs Technologies. . . . . . . . . . . . . . . . . . . . . . . 9
(N1 to N2). . . . . . . . . . . . . . . . . . . . . . . . 9 6.3. Scenario 3: Packet transmission across different DODAGs
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 (N1 to N2). . . . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 11 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 12 10.1. Normative References . . . . . . . . . . . . . . . . . . 12
Appendix A. Changes after draft-ietf-6lo-deadline-time-01 . . . 13 10.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix B. Changes between earlier versions . . . . . . . . . . 13 Appendix A. Changes from revision 02 to revision 03 . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 Appendix B. Changes from revision 01 to revision 02 . . . . . . 15
Appendix C. Changes between earlier versions . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
Low Power and Lossy Networks (LLNs) are likely to be deployed for Low Power and Lossy Networks (LLNs) are likely to be deployed for
real time industrial applications requiring end-to-end delay real time industrial applications requiring end-to-end delay
guarantees [I-D.ietf-detnet-use-cases]. A Deterministic Network guarantees [I-D.ietf-detnet-use-cases]. A Deterministic Network
("detnet") typically requires some data packets to reach their ("detnet") typically requires some data packets to reach their
receivers within strict time bounds. Intermediate nodes use the receivers within strict time bounds. Intermediate nodes use the
deadline information to make appropriate packet forwarding and deadline information to make appropriate packet forwarding and
scheduling decisions to meet the time bounds. scheduling decisions to meet the time bounds.
skipping to change at page 3, line 14 skipping to change at page 3, line 16
clocks. Time synchronization techniques need not be mandated by this clocks. Time synchronization techniques need not be mandated by this
specificiation. There are a number of standards available for this specificiation. There are a number of standards available for this
purpose, including IEEE 1588 [ieee-1588], IEEE 802.1AS [dot1AS-2011], purpose, including IEEE 1588 [ieee-1588], IEEE 802.1AS [dot1AS-2011],
IEEE 802.15.4-2015 TSCH [dot15-tsch], and more. IEEE 802.15.4-2015 TSCH [dot15-tsch], and more.
The Deadline-6LoRHE can be used in any time synchronized 6Lo network. The Deadline-6LoRHE can be used in any time synchronized 6Lo network.
A 6TiSCH network has been used to describe the implementation of the A 6TiSCH network has been used to describe the implementation of the
Deadline-6LoRHE, but this does not preclude its use in scenarios Deadline-6LoRHE, but this does not preclude its use in scenarios
other than 6TiSCH. For instance, there is a growing interest in other than 6TiSCH. For instance, there is a growing interest in
using 6lo over a BLE mesh network [I-D.ietf-6lo-blemesh] in using 6lo over a BLE mesh network [I-D.ietf-6lo-blemesh] in
industrial IoT. BLE mesh time synchronization is also being recently industrial IoT [dotBLEMesh]. BLE mesh time synchronization is also
explored by the Bluetooth community. There are also cases under being recently explored by the Bluetooth community. There are also
consideration in Wi-SUN. cases under consideration in Wi-SUN [Wi-SUN_PHY], [dotWi-SUN].
2. Terminology 2. 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
[RFC2119]. [RFC2119] [RFC8174].
This document uses terminology consistent with the terminology used This document uses terminology consistent with the terminology used
in [RFC6550] and [I-D.ietf-6tisch-terminology]. Also, in this in [RFC6550] and [I-D.ietf-6tisch-terminology]. Also, in this
document, the terms "expiration time", "delivery deadline time", and document, the terms "expiration time", "delivery deadline time", and
"deadline" are used interchangeably with the same meaning. "deadline" are used interchangeably with the same meaning.
3. Deadline-6LoRHE 3. 6LoRHE Generic Format
The Deadline-6LoRHE (see Figure 2) is an elective 6LoRH (i.e., a Note: this section is not normative and is included for convenience.
The generic header format of the 6LoRHE is specified in
[I-D.ietf-roll-routing-dispatch]. Figure 1 illustrates the 6LoRHE
generic format.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+
|1|0|1| Length | Type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+
<-- length -->
Figure 1: 6LoRHE format
o Length: Length of the 6LoRHE expressed in bytes, excluding the
first 2 bytes. This enables a node to skip a 6LoRHE if the Type
is not recognized/supported.
o Type: Type of the 6LoRHE.
o length: variable
4. Deadline-6LoRHE
The Deadline-6LoRHE (see Figure 3) is an elective 6LoRH (i.e., a
6LoRHE [RFC8138]) that provides the Deadline Time (DT) for an IPv6 6LoRHE [RFC8138]) that provides the Deadline Time (DT) for an IPv6
datagram in a compressed form. Along with the deadline, the header datagram in a compressed form. Along with the deadline, the header
can include the packet Origination Time (OT), to enable a close can include the packet Origination Time (OT), the time at which the
estimate of the total delay incurred by a packet. The OT field is packet is enqueued for transmission, to enable a close estimate of
initialized by the sender using the current time at the outgoing the total delay incurred by a packet. The OT field is initialized by
network interface through which the packet is forwarded. the sender using the current time at the outgoing network interface
through which the packet is forwarded.
The deadline field contains the value of the delivery deadline time The deadline field contains the value of the delivery deadline time
for the packet. The packet SHOULD be delivered to the Receiver for the packet. The packet SHOULD be delivered to the Receiver
before this time. before this time.
packet_deadline_time = packet_origination_time + max_delay packet_deadline_time = packet_origination_time + max_delay
All nodes within the network SHOULD process the Deadline-6LoRHE in All nodes within the network SHOULD process the Deadline-6LoRHE in
order to support delay-sensitive deterministic applications. The order to support delay-sensitive deterministic applications. The
packet deadline time (DT) and origination time (OT) are represented packet deadline time (DT) and origination time (OT) are represented
skipping to change at page 4, line 27 skipping to change at page 5, line 7
Origination Time in new network = current_time_in_new_network - Origination Time in new network = current_time_in_new_network -
delay_already_experienced_in_previous_network(s) delay_already_experienced_in_previous_network(s)
The following example illustrates the origination time calculation The following example illustrates the origination time calculation
when a packet travels between three networks, each in a different when a packet travels between three networks, each in a different
time zone. 'x' can be 1,2 or 3. time zone. 'x' can be 1,2 or 3.
TxA : Time of arrival of packet in the network 'x' TxA : Time of arrival of packet in the network 'x'
TxD : Departure time of packet in the network 'x' TxD : Departure time of packet from the network 'x'
Dx : Delay experienced by the packet in the previous network(s) Dx : Delay experienced by the packet in the previous network(s)
TZx : Indicates the time zone of network 'x' TZx : Indicates the time zone of network 'x'
As an illustration, we consider a packet traversing through three As an illustration, we consider a packet traversing through three
time synchronized networks along with numerical values as shown in time synchronized networks along with numerical values as shown in
Figure 1. Figure 1.
TZ1 TZ2 TZ3 TZ1 TZ2 TZ3
T1A=0| | | T1A=0| | |
|---- D1=100 | | |---- D1=100 | |
| \ | | | \ | |
| \ | | | \ | |
| \ T1D=100 |T2A=1000 | | \ T1D=100 |T2A=1000 |
| -------->|----- D2=400 | | -------->|----- D2=400 |
| | \ | | | \ |
| | \ | | | \ |
| | \ T2D=1400 | T3A=5000 | | \ T2D=1400 | T3A=5000
| | ------------------->| | | ------------------->|
| | | | | |
v v v v v v
D = 0 D = T1D-OT D = T2D-OT D = 0 D = T1D-OT D = T2D-OT
= 100-0 = 1400 - 900 = 100-0 = 1400 - 900
= 100 = 500 i.e. (D1 + D2) = 100 = 500 [= (D1 + D2)]
OT = T1A-D OT = T2A-D OT = T3A-D OT = T1A-D OT = T2A-D OT = T3A-D
= 0 = 1000-100 = 5000 - 500 = 0 = 1000-100 = 5000 - 500
= 900 = 4500 = 900 = 4500
Figure 1: Origination Time update example Figure 2: Origination Time update example
There are multiple ways that a packet can be delayed, including There are multiple ways that a packet can be delayed, including
propagation delay and queuing delays. Sometimes there are processing queuing delay, MAC layer contention delay, serialization delay, and
delays as well. For the purpose of determining whether or not the propagation delays. Sometimes there are processing delays as well.
deadline has already passed, these various delays are not For the purpose of determining whether or not the deadline has
distinguished. already passed, these various delays are not distinguished.
4. Deadline-6LoRHE Format 5. Deadline-6LoRHE Format
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0|1| Length | 6LoRH Type |O|D| DTL | OTL | TU| EXP | Rsv | |1|0|1| Length | 6LoRH Type |O|D| DTL | OTL | TU| EXP | Rsv |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DT (variable length) | OT(variable length)(optional) | | DT (variable length) | OT(variable length)(optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Deadline-6LoRHE format Figure 3: Deadline-6LoRHE format
Length (5 bits): Length represents the total length of the Deadline- Length (5 bits): Length represents the total length of the Deadline-
6LoRHE type measured in octets. 6LoRHE type measured in octets.
6LoRH Type: TBD 6LoRH Type: TBD
O flag (1bit): Indicates the presence of Origination Time field. '1' O flag (1bit): Indicates the presence of Origination Time field. '1'
means the OT field is present, and '0' means it is absent. means the OT field is present, and '0' means it is absent.
D flag (1 bit): The 'D' flag, set by the Sender, indicates the action D flag (1 bit): The 'D' flag, set by the Sender, indicates the action
to be taken when a 6LR detects that the deadline time has elapsed. to be taken when a 6LR detects that the deadline time has elapsed.
If 'D' bit is 1, then the 6LR MUST drop the packet if the deadline If 'D' bit is 1, then the 6LR MUST drop the packet if the deadline
time is elapsed. If 'D' bit is 0, then the 6LR MAY ignore the time is elapsed.
deadline time and forward the packet.
DTL (3 bits): Length of DT field. If 'D' bit is 0, implies the packet MAY be forwarded on an exception
basis, if the forwarding node is NOT in a situation of constrained
resource, and if there are reasons to suspect that downstream nodes
might find it useful (delay measurements, interpolations, etc.).
OTL (3 bits) : Length of OT field. DTL (3 bits): Length of DT field as an unsigned 3-bit integer,
encoding the length of the field in octets, minus one.
OTL (3 bits) : Length of OT field as an unsigned 3-bit integer,
encoding the length of the field in octets, minus one.
For example, DTL = 000 means the deadline time in the 6LoRHE is 1 For example, DTL = 000 means the deadline time in the 6LoRHE is 1
octet (8 bits) long. Similarly, OTL = 111 means the origination octet (8 bits) long. Similarly, OTL = 111 means the origination
time is 8 octets (64 bits) long. time is 8 octets (64 bits) long.
TU (2 bits) : Indicates the time units for DT and OT fields TU (2 bits) : Indicates the time units for DT and OT fields
00 : Time represented in microseconds 00 : Time represented in microseconds
01 : Time represented in seconds 01 : Time represented in seconds
10 : Network ASN 10 : Network ASN
11 : Reserved 11 : Reserved
EXP (3 bits) : Multiplication factor expressed as exponent of 10. EXP (3 bits) : Multiplication factor expressed as exponent of 10.
The value of the DT field is multiplied by 10 to this power, to The value of the DT field is multiplied by 10 to this power, to
get the actual deadline time in the units represented by TU. The get the actual deadline time in the units represented by TU. The
default value of EXP is 000, so that the DT field is unaffected. default value of EXP is 000, so that the DT field is unaffected.
Rsv (3 bits) : Reserved Rsv (3 bits) : Reserved, sent as zero and ignored on receipt
DT Value (8..64-bit) : Deadline Time value DT Value (8..64-bit) : An unsigned integer of DTL octets giving the
Deadline Time value
OT Value (8..64-bit) : Origination Time value OT Value (8..64-bit) : An unsigned integer of OTL octets giving the
Origination Time value
Whenever a sender initiates the IP datagram, it includes the Whenever a sender initiates the IP datagram, it includes the
Deadline-6LoRHE along with other 6LoRH information. Deadline-6LoRHE along with other 6LoRH information.
Example: Consider a 6TiSCH network with time-slot length of 10ms. Example: Consider a 6TiSCH network with time-slot length of 10ms.
Let the current ASN when the packet is originated be 54400, and the Let the current ASN when the packet is originated be 54400, and the
maximum allowable delay (max_delay) for the packet delivery is 1 maximum allowable delay (max_delay) for the packet delivery is 1
second from the packet origination, then: second from the packet origination, then:
deadline_time = packet_origination_time + max_delay deadline_time = packet_origination_time + max_delay
= 55400 + 100 (in Network ASNs) = 55400 + 100 (in Network ASNs)
= 55500(Network ASNs) = 55500(Network ASNs)
Deadline-6LoRHE encoding with 'O' flag and 'D' flag set to 1: Deadline-6LoRHE encoding with 'O' flag and 'D' flag set to 1:
DTL = 001, OTL = 001, TU = '10', EXP = 2, DT = 0x22B, OT = 0x22A DTL = 001, OTL = 001, TU = '10', EXP = 2, DT = 0x22B, OT = 0x22A
5. Deadline-6LoRHE in Three Network Scenarios 6. Deadline-6LoRHE in Three Network Scenarios
In this section, Deadline-6LoRHE operation is described for 3 network In this section, Deadline-6LoRHE operation is described for 3 network
scenarios. Figure 3 depicts a constrained time-synchronized LLN that scenarios. Figure 4 depicts a constrained time-synchronized LLN that
has two subnets N1 and N2, connected through LBRs has two subnets N1 and N2, connected through LBRs
[I-D.ietf-6lo-backbone-router] with different reference clock times [I-D.ietf-6lo-backbone-router] with different reference clock times
T1 and T2. T1 and T2.
+-------------------+ +-------------------+
| Time Synchronized | | Time Synchronized |
| Network | | Network |
+---------+---------+ +---------+---------+
| |
| |
skipping to change at page 7, line 36 skipping to change at page 8, line 24
+-----+ +-----+ +-----+ +-----+
| | Backbone | | Backbone | | Backbone | | Backbone
o | | router | | router o | | router | | router
+-----+ +-----+ +-----+ +-----+
o o o o o o
o o o o o o o o o o o o o o o o o o
o LLN o o LLN o o o LLN o o LLN o o
o o o o o o o o o o o o o o o o o o
6LoWPAN Network (subnet N1) 6LoWPAN Network (subnet N2) 6LoWPAN Network (subnet N1) 6LoWPAN Network (subnet N2)
Figure 3: Intra-network Timezone Scenario Figure 4: Intra-network Timezone Scenario
5.1. Scenario 1: Endpoints in the same DODAG (N1) 6.1. Scenario 1: Endpoints in the same DODAG (N1)
In scenario 1, shown in Figure 4, the Sender 'S' has an IP datagram In scenario 1, shown in Figure 5, the Sender 'S' has an IP datagram
to be routed to a Receiver 'R' within the same DODAG. For the route to be routed to a Receiver 'R' within the same DODAG. For the route
segment from Sender to 6LBR, the Sender includes a Deadline-6LoRHE by segment from Sender to 6LBR, the Sender includes a Deadline-6LoRHE by
encoding the deadline time contained in the packet. Subsequently, encoding the deadline time contained in the packet. Subsequently,
each 6LR will perform hop-by-hop routing to forward the packet each 6LR will perform hop-by-hop routing to forward the packet
towards the 6LBR. Once 6LBR receives the IP datagram, it sends the towards the 6LBR. Once 6LBR receives the IP datagram, it sends the
packet downstream towards 'R'. packet downstream towards 'R'.
In case of a network running RPL non-storing mode, the 6LBR generates In case of a network running RPL non-storing mode, the 6LBR generates
a IPv6-in-IPv6 encapsulated packet when sending the packet downwards a IPv6-in-IPv6 encapsulated packet when sending the packet downwards
to the Receiver [I-D.ietf-roll-useofrplinfo]. The 6LBR copies the to the Receiver [I-D.ietf-roll-useofrplinfo]. The 6LBR copies the
Deadline-6LoRHE from the Sender originated IP header to the outer IP Deadline-6LoRHE from the Sender originated IP header to the outer IP
header. The Deadline-6LoRHE contained in the inner IP header is header. The Deadline-6LoRHE contained in the inner IP header is
elided. removed.
+-------+ +-------+
^ | 6LBR | | ^ | 6LBR | |
| | | | | | | |
| +-------+ | | +-------+ |
Upward | (F)/ /| \ | Downward Upward | (F)/ /| \ | Downward
routing | / \ / | \ | routing routing | / \ / | \ | routing
| / \ (C) | (D) | | / \ (C) | (D) |
| (A) (B) / | / |\ | | (A) (B) / | / |\ |
| /|\ |\: (E) : R | | /|\ |\: (E) : R |
S : : : / \ v S : : : / \ v
Figure 4: End points within same DODAG (subnet N1) Figure 5: End points within same DODAG (subnet N1)
At the tunnel endpoint of the IPv6-in-IPv6 encapsulation, the At the tunnel endpoint of the IPv6-in-IPv6 encapsulation, the
Deadline-6LoRHE is copied back from the outer header to inner header, Deadline-6LoRHE is copied back from the outer header to inner header,
and the inner IP packet is delivered to 'R'. and the inner IP packet is delivered to 'R'.
5.2. Scenario 2: Endpoints in Networks with Dissimilar L2 Technologies. 6.2. Scenario 2: Endpoints in Networks with Dissimilar L2 Technologies.
In scenario 2, shown in Figure 5, the Sender 'S' (belonging to DODAG In scenario 2, shown in Figure 6, the Sender 'S' (belonging to DODAG
1) has IP datagram to be routed to a Receiver 'R' over a time- 1) has IP datagram to be routed to a Receiver 'R' over a time-
synchronized IPv6 network. For the route segment from 'S' to 6LBR, synchronized IPv6 network. For the route segment from 'S' to 6LBR,
'S' includes a Deadline-6LoRHE. Subsequently, each 6LR will perform 'S' includes a Deadline-6LoRHE. Subsequently, each 6LR will perform
hop-by-hop routing to forward the packet towards the 6LBR. Once the hop-by-hop routing to forward the packet towards the 6LBR. Once the
Deadline Time information reaches the border router, the packet will Deadline Time information reaches the border router, the packet will
be encoded as per the mechanism prescribed in the new time be encoded according to the mechanism prescribed in the other time-
synchronized network. The specific data encapsulation mechanisms synchronized network depicted as "Time Synchronized Network" in the
followed in the new network are beyond the scope of this document. figure 6. The specific data encapsulation mechanisms followed in the
new network are beyond the scope of this document.
+----------------+ +----------------+
| Time | | Time |
| Synchronized |------R | Synchronized |------R
| Network | | Network |
+----------------+ +----------------+
| |
| |
----------+----------- ----------+-----------
^ | ^ |
skipping to change at page 9, line 26 skipping to change at page 10, line 26
Upward | | | Upward | | |
routing | +------++ routing | +------++
| (F)/ /| \ | (F)/ /| \
| / \ / | \ | / \ / | \
| / \ (C) | (D) | / \ (C) | (D)
: (A) (B) / | / |\ : (A) (B) / | / |\
/|\ |\: (E) :: /|\ |\: (E) ::
S : : : / \ S : : : / \
: : : :
Figure 5: Packet transmission in Dissimilar L2 Technologies or Figure 6: Packet transmission in Dissimilar L2 Technologies or
Internet Internet
For instance, the IP datagram could be routed to another time For instance, the IP datagram could be routed to another time
synchronized deterministic network using the mechanism specified in synchronized deterministic network using the mechanism specified in
the In-band OAM [I-D.ietf-ippm-ioam-data], and then the deadline time the In-band OAM [I-D.ietf-ippm-ioam-data], and then the deadline time
would be updated according to the measurement of the current time in would be updated according to the measurement of the current time in
the new network. the new network.
5.3. Scenario 3: Packet transmission across different DODAGs (N1 to 6.3. Scenario 3: Packet transmission across different DODAGs (N1 to
N2). N2).
Consider the scenario depicted in Figure 6, in which the Sender 'S' Consider the scenario depicted in Figure 7, in which the Sender 'S'
(belonging to DODAG 1) has an IP datagram to be sent to Receiver 'R' (belonging to DODAG 1) has an IP datagram to be sent to Receiver 'R'
belonging to another DODAG (DODAG 2). The operation of this scenario belonging to another DODAG (DODAG 2). The operation of this scenario
can be decomposed into combination of case 1 and case 2 scenarios. can be decomposed into combination of case 1 and case 2 scenarios.
For the route segment from 'S' to 6LBR, 'S' includes the Deadline- For the route segment from 'S' to 6LBR1, 'S' includes the Deadline-
6LoRHE. Subsequently, each 6LR will perform hop-by-hop operation to 6LoRHE. Subsequently, each 6LR will perform hop-by-hop operation to
forward the packet towards the 6LBR. Once the IP datagram reaches forward the packet towards the 6LBR1. Once the IP datagram reaches
6LBR1 of DODAG1, it applies the same rule as described in Case 2 6LBR1 of DODAG1, it applies the same rule as described in Case 2
while routing the packet to 6LBR2 over a (likely) time synchronized while routing the packet to 6LBR2 over a (likely) time synchronized
wired backhaul. The wired side of 6LBR2 can be mapped to receiver of wired backhaul. The wired side of 6LBR2 can be mapped to receiver of
Case 2. Once the packet reaches 6LBR2, it updates the Deadline- Case 2. Once the packet reaches 6LBR2, it updates the Deadline-
6LoRHE by adding or subtracting the difference of time of DODAG2 and 6LoRHE by adding or subtracting the difference of time of DODAG2 and
sends the packet downstream towards 'R'. sends the packet downstream towards 'R'.
Time Synchronized Network Time Synchronized Network
-+---------------------------+- -+---------------------------+-
| | | |
skipping to change at page 10, line 21 skipping to change at page 11, line 21
+-------+ +-------+ +-------+ +-------+
(F)/ /| \ (F)/ /| \ (F)/ /| \ (F)/ /| \
/ \ / | \ / \ / | \ / \ / | \ / \ / | \
/ \ (C) | (D) / \ (C) | (D) / \ (C) | (D) / \ (C) | (D)
(A) (B) / | / |\ (A) (B) / | / |\ (A) (B) / | / |\ (A) (B) / | / |\
/|\ |\: (E) : : /|\ |\: (E) : : /|\ |\: (E) : : /|\ |\: (E) : :
S : : : / \ : : : : / \ S : : : / \ : : : : / \
: : : R : : : R
Network N1, time zone T1 Network N2, time zone T2 Network N1, time zone T1 Network N2, time zone T2
Figure 6: Packet transmission in different DODAGs(N1 to N2) Figure 7: Packet transmission in different DODAGs(N1 to N2)
Consider an example of a 6TiSCH network in which S in DODAG1 Consider an example of a 6TiSCH network in which S in DODAG1
generates the packet at ASN 20000 to R in DODAG2. Let the maximum generates the packet at ASN 20000 to R in DODAG2. Let the maximum
allowable delay be 1 second. The time-slot length in DODAG1 and allowable delay be 1 second. The time-slot length in DODAG1 and
DODAG2 is assumed to be 10ms. Once the deadline time is encoded in DODAG2 is assumed to be 10ms. Once the deadline time is encoded in
Deadline-6LoRHE, the packet is forwarded to 6LBR of DODAG1. Suppose Deadline-6LoRHE, the packet is forwarded to 6LBR of DODAG1. Suppose
the packet reaches 6LBR of DODAG1 at ASN 20030. the packet reaches 6LBR of DODAG1 at ASN 20030.
current_time = ASN at LBR * slot_length_value current_time = ASN at LBR * slot_length_value
remaining_time = deadline_time - current_time remaining_time = deadline_time - current_time
= ((packet_origination_time + max_delay) - current time) = ((packet_origination_time + max_delay) - current time)
= (20000 + 100) - 20030 = (20000 + 100) - 20030
= 30 (in Network ASNs) = 30 (in Network ASNs)
= 30 * 10^3 milliseconds. = 30 * 10^3 milliseconds.
Once the Deadline Time information reaches the border router, the Once the Deadline Time information reaches the border router, the
packet will be encoded as per the mechanism prescribed in the new packet will be encoded accoding to the mechanism prescribed in the
time synchronized network other time-synchronized network.
6. IANA Considerations 7. IANA Considerations
This document defines a new 6LoWPAN Timestamp Header Type, and This document defines a new Elective 6LoWPAN Routing Header Type, and
assigns a value (TBD) from the 6LoWPAN Dispatch Page1 number space. IANA is requested to assign a value (TBD) from the 6LoWPAN Dispatch
Page1 number space for this purpose.
6LoRH Type Value Elective 6LoRH Type Value
+------------------+--------+ +----------------------+--------+
| Deadline-6LoRHE | TBD | | Deadline-6LoRHE | TBD |
+------------------+--------+ +----------------------+--------+
Figure 7: Deadline-6LoRHE type Figure 8: Deadline-6LoRHE type
7. Security Considerations 8. Security Considerations
The security considerations of [RFC4944], [RFC6282] and [RFC6553] The security considerations of [RFC4944], [RFC6282] and [RFC6553]
apply. Using a compressed format as opposed to the full in-line apply. Using a compressed format as opposed to the full in-line
format is logically equivalent and does not create an opening for a format is logically equivalent and does not create an opening for a
new threat when compared to [RFC6550], [RFC6553] and [RFC6554]. new threat when compared to [RFC6550], [RFC6553] and [RFC6554].
8. Acknowledgements 9. Acknowledgements
The authors thank Pascal Thubert for suggesting the idea and The authors thank Pascal Thubert for suggesting the idea and
encouraging the work. Thanks to Shwetha Bhandari's suggestions which encouraging the work. Thanks to Shwetha Bhandari's suggestions which
were instrumental in extending the timing information to were instrumental in extending the timing information to
heterogeneous networks. The authors acknowledge the 6TiSCH WG heterogeneous networks. The authors acknowledge the 6TiSCH WG
members for their inputs on the mailing list. Special thanks to members for their inputs on the mailing list. Special thanks to
Jerry Daniel, Seema Kumar, Avinash Mohan, Shalu Rajendran and Anita Jerry Daniel, Seema Kumar, Avinash Mohan, Shalu Rajendran and Anita
Varghese for their support and valuable feedback. Varghese for their support and valuable feedback.
9. References 10. References
9.1. Normative References 10.1. Normative References
[I-D.ietf-6tisch-terminology] [I-D.ietf-6tisch-terminology]
Palattella, M., Thubert, P., Watteyne, T., and Q. Wang, Palattella, M., Thubert, P., Watteyne, T., and Q. Wang,
"Terms Used in IPv6 over the TSCH mode of IEEE 802.15.4e", "Terms Used in IPv6 over the TSCH mode of IEEE 802.15.4e",
draft-ietf-6tisch-terminology-10 (work in progress), March draft-ietf-6tisch-terminology-10 (work in progress), March
2018. 2018.
[I-D.ietf-roll-routing-dispatch] [I-D.ietf-roll-routing-dispatch]
Thubert, P., Bormann, C., Toutain, L., and R. Cragie, Thubert, P., Bormann, C., Toutain, L., and R. Cragie,
"6LoWPAN Routing Header", draft-ietf-roll-routing- "6LoWPAN Routing Header", draft-ietf-roll-routing-
skipping to change at page 12, line 29 skipping to change at page 13, line 34
Routing Header for Source Routes with the Routing Protocol Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554, for Low-Power and Lossy Networks (RPL)", RFC 6554,
DOI 10.17487/RFC6554, March 2012, DOI 10.17487/RFC6554, March 2012,
<https://www.rfc-editor.org/info/rfc6554>. <https://www.rfc-editor.org/info/rfc6554>.
[RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie, [RFC8138] Thubert, P., Ed., Bormann, C., Toutain, L., and R. Cragie,
"IPv6 over Low-Power Wireless Personal Area Network "IPv6 over Low-Power Wireless Personal Area Network
(6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138, (6LoWPAN) Routing Header", RFC 8138, DOI 10.17487/RFC8138,
April 2017, <https://www.rfc-editor.org/info/rfc8138>. April 2017, <https://www.rfc-editor.org/info/rfc8138>.
9.2. Informative References [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative References
[dot15-tsch] [dot15-tsch]
P802.11, "IEEE Standard for Low-Rate Wireless Networks, P802.11, "IEEE Standard for Low-Rate Wireless Networks,
Part 15.4, IEEE Std 802.15.4-2015", April 2016. Part 15.4, IEEE Std 802.15.4-2015", April 2016.
[dot1AS-2011] [dot1AS-2011]
IEEE 802.1AS Working Group, "IEEE Standard for Local and IEEE 802.1AS Working Group, "IEEE Standard for Local and
Metropolitan Area Networks - Timing and Synchronization Metropolitan Area Networks - Timing and Synchronization
for Time-Sensitive Applications in Bridged Local Area for Time-Sensitive Applications in Bridged Local Area
Networks", March 2011. Networks", March 2011.
[dotBLEMesh]
Luca Leonardi, Gaetano Pattim, and Lucia Lo Bello, "Multi-
Hop Real-Time Communications Over Bluetooth Low Energy
Industrial Wireless Mesh Networks", IEEE Access Vol 6,
26505-26519, May 2018.
[dotWi-SUN]
Hiroshi Harada, Keiichi Mizutani, Jun Fujiwara, Kentaro
Mochizuki, Kentaro Obata, and Okumura, Ryota, "IEEE
802.15.4g Based Wi-SUN Communication Systems", IEICE
Transactions on Communications volume E100.B, Jan 2017.
[I-D.ietf-6lo-backbone-router] [I-D.ietf-6lo-backbone-router]
Thubert, P., "IPv6 Backbone Router", draft-ietf-6lo- Thubert, P. and C. Perkins, "IPv6 Backbone Router", draft-
backbone-router-06 (work in progress), February 2018. ietf-6lo-backbone-router-07 (work in progress), September
2018.
[I-D.ietf-6lo-blemesh] [I-D.ietf-6lo-blemesh]
Gomez, C., Darroudi, S., Savolainen, T., and M. Spoerk, Gomez, C., Darroudi, S., Savolainen, T., and M. Spoerk,
"IPv6 Mesh over BLUETOOTH(R) Low Energy using IPSP", "IPv6 Mesh over BLUETOOTH(R) Low Energy using IPSP",
draft-ietf-6lo-blemesh-03 (work in progress), July 2018. draft-ietf-6lo-blemesh-03 (work in progress), July 2018.
[I-D.ietf-detnet-use-cases] [I-D.ietf-detnet-use-cases]
Grossman, E., "Deterministic Networking Use Cases", draft- Grossman, E., "Deterministic Networking Use Cases", draft-
ietf-detnet-use-cases-17 (work in progress), June 2018. ietf-detnet-use-cases-19 (work in progress), October 2018.
[I-D.ietf-ippm-ioam-data] [I-D.ietf-ippm-ioam-data]
Brockners, F., Bhandari, S., Pignataro, C., Gredler, H., Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov, Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
P., Chang, R., daniel.bernier@bell.ca, d., and J. Lemon, P., Chang, R., daniel.bernier@bell.ca, d., and J. Lemon,
"Data Fields for In-situ OAM", draft-ietf-ippm-ioam- "Data Fields for In-situ OAM", draft-ietf-ippm-ioam-
data-03 (work in progress), June 2018. data-03 (work in progress), June 2018.
[I-D.ietf-roll-useofrplinfo] [I-D.ietf-roll-useofrplinfo]
Robles, I., Richardson, M., and P. Thubert, "When to use Robles, I., Richardson, M., and P. Thubert, "When to use
RFC 6553, 6554 and IPv6-in-IPv6", draft-ietf-roll- RFC 6553, 6554 and IPv6-in-IPv6", draft-ietf-roll-
useofrplinfo-23 (work in progress), May 2018. useofrplinfo-23 (work in progress), May 2018.
[ieee-1588] [ieee-1588]
Precise Time and Time Interval Working Group, "IEEE Std Precise Time and Time Interval Working Group, "IEEE Std
1588-2008 Standard for a Precision Clock Synchronization 1588-2008 Standard for a Precision Clock Synchronization
Protocol for Networked Measurement and Control Systems", Protocol for Networked Measurement and Control Systems",
July 2008. July 2008.
Appendix A. Changes after draft-ietf-6lo-deadline-time-01 [Wi-SUN_PHY]
Wi-SUN Alliance, "Wi-SUN PHY Specification V1.0", March
2016.
Appendix A. Changes from revision 02 to revision 03
This section lists the changes between draft-ietf-6lo-deadline-time
revisions ...-02.txt and ...-03.txt.
o Added non-normative 6LoRHE description, citing RFC 8138.
o Specified that the Origination Time (OT) is the time that packet
is enqueued for transmission.
o Mentioned more sources of packet delay.
o Clarified reasons that packet MAY be forwarded if 'D' bit is 0.
o Clarified that DT, OT, DTL and OTL are unsigned integers.
o Updated bibliographic citations, including BLEmesh and Wi-SUN.
Appendix B. Changes from revision 01 to revision 02
This section lists the changes between draft-ietf-6lo-deadline-time This section lists the changes between draft-ietf-6lo-deadline-time
revisions ...-01.txt and ...-02.txt. revisions ...-01.txt and ...-02.txt.
o Replaced 6LoRHE description by reference to RFC 8138. o Replaced 6LoRHE description by reference to RFC 8138.
o Added figure to illustrate change to Origination Time when a o Added figure to illustrate change to Origination Time when a
packet crosses timezone boundaries. packet crosses timezone boundaries.
o Clarified that use of 6tisch networks is descriptive, not o Clarified that use of 6tisch networks is descriptive, not
normative. normative.
o Clarified that In-Band OAM is used as an example and is not o Clarified that In-Band OAM is used as an example and is not
normative. normative.
o Updated bibliographic citations. o Updated bibliographic citations.
o Alphabetized contributor names. o Alphabetized contributor names.
Appendix B. Changes between earlier versions Appendix C. Changes between earlier versions
This section lists the changes between draft-ietf-6lo-deadline-time This section lists the changes between draft-ietf-6lo-deadline-time
revisions ...-00.txt and ...-01.txt. revisions ...-00.txt and ...-01.txt.
o Changed "SHOULD drop" to "MUST drop" a packet if the deadline is o Changed "SHOULD drop" to "MUST drop" a packet if the deadline is
passed (see Section 4). passed (see Section 5).
o Added explanatory text about how packet delays might arise. (see o Added explanatory text about how packet delays might arise. (see
Section 3). Section 4).
o Mentioned availability of time-synchronization protocols (see o Mentioned availability of time-synchronization protocols (see
Section 1). . Section 1).
o Updated bibliographic citations. o Updated bibliographic citations.
o Alphabetized contributor names. o Alphabetized contributor names.
o Added this section. o Added this section.
Authors' Addresses Authors' Addresses
Lijo Thomas Lijo Thomas
C-DAC C-DAC
Centre for Development of Advanced Computing (C-DAC), Vellayambalam
Trivandrum 695033 Trivandrum 695033
India India
Email: lijo@cdac.in Email: lijo@cdac.in
Satish Anamalamudi Satish Anamalamudi
SRM University-AP SRM University-AP
Amaravati Campus Amaravati Campus
Amaravati, Andhra Pradesh 522 502 Amaravati, Andhra Pradesh 522 502
India India
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