Internet DRAFT - draft-peng-6man-deadline-option
draft-peng-6man-deadline-option
Network Shaofu. Peng
Internet-Draft Bin. Tan
Intended status: Standards Track ZTE Corporation
Expires: January 12, 2023 Peng. Liu
China Mobile
July 11, 2022
Deadline Option
draft-peng-6man-deadline-option-01
Abstract
This document introduces new IPv6 options for Hop-by-Hop Options
header, to carry deadline related information for deterministic
flows.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 12, 2023.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Deadline Option . . . . . . . . . . . . . . . . . . . . . . . 3
3. Encapsulation of Deadline Options On Ingress Node . . . . . . 4
4. Operations of Deadline Options On Transit Node . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC8655] describes the architecture of deterministic network and
defines the QoS goals of deterministic forwarding: Minimum and
maximum end-to-end latency from source to destination, timely
delivery, and bounded jitter (packet delay variation); packet loss
ratio under various assumptions as to the operational states of the
nodes and links; an upper bound on out-of-order packet delivery. In
order to achieve these goals, deterministic networks use resource
reservation, explicit routing, service protection and other means.
In general, a deterministic path is a strictly explicit path
calculated by a centralized controller, and resources are reserved on
the nodes along the path to meet the SLA requirements of
deterministic services.
[I-D.peng-detnet-deadline-based-forwarding] describes a deadline
based forwarding mechanism to get bounded latency and jitter. A
single or multiple planned deadline offset time, as well as dynamic
delay budget adjustment, are used to control the packets scheduling
of all nodes along the path. The offset time is based on the time
when the packet enters the node and represents the maximum time
allowed for the packet to stay inside the node.
This document introduces new IPv6 options for Hop-by-Hop Options
header, to carry deadline related information for deterministic
flows.
1.1. 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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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2. Deadline Option
[I-D.peng-detnet-deadline-based-forwarding] describes the following
deadline related informatin that can be carried in packets.
Planned deadline.
Existing accumulated planned deadline
Existing accumulated actual residence time
Existing accumulated deadline deviation
The planned deadline of the packet is an offset time, i.e., a delay
budget allowed for the packet to stay inside the local node.
The existing accumulated planned deadline of the packet refers to the
sum of the planned deadline of all upstream nodes before the packet
is transmitted to this node.
The existing accumulated actual residence time of the packet, refers
to the sum of the actual residence time of all upstream nodes before
the packet is transmitted to this node.
The existing accumulated deadline deviation equals existing
accumulated planned deadline minus existing accumulated actual
residence time. This value can be positive or negative.
The deadline option has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |M|D| Planned Deadline |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Accumulated Planned Deadline / Accumulated Deadline Deviation |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Accumulated Actual Residence Time / Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Deadline Option Format
Option Type: 8-bit identifier of the type of option. Value TBD by
IANA; the highest-order 3 bits of thie field is 001 to skip over this
option and continue processing the header if the processing IPv6 node
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does not recognize the Option Type and to permit the Option Data to
be changed en route to the packet's final destination.
Opt Data Len: 8-bit unsigned integer. Length of the Option Data
field of this option, in octets. It is set to 12.
Flags: 8-bit flags. Currently two flags are defined.
D-Flag: if D-flag is 0, the "Accumulated Planned Deadline /
Accumulated Deadline Deviation" field contains Accumulated Planned
Deadline information, and "Accumulated Actual Residence Time /
Reserved" contains Accumulated Actual Residence Time information,
otherwise these fields contain Accumulated Deadline Deviation and
Reserved, respectively.
M-Flag: if M-flag is 0, the packet will apply in-time mode,
otherwise apply on-time mode. For more description of the
forwarding mode, please refer to
[I-D.peng-detnet-deadline-based-forwarding].
Planned Deadline: 24-bit unsigned integer, represents the delay
budget allowed for the packet to stay inside the received node. A
single planned deadline is used for each node along the path. For
multiple planned deadlines case, it is defined in future.
Accumulated Planned Deadline: 32-bit unsigned integer, represents the
sum of the planned deadline of all upstream nodes before the packet
is transmitted to the received node.
Accumulated Deadline Deviation: 32-bit signed integer, represents the
sum of the deviation between delay budget and actual residence time
of all upstream nodes before the packet is transmitted to the
received node.
Accumulated Actual Residence Time: 32-bit unsigned integer,
represents the sum of the actual residence time of all upstream nodes
before the packet is transmitted to the received node.
Reserved: 32-bit unused.
3. Encapsulation of Deadline Options On Ingress Node
The ingress PE node, when encapsulating the deterministic service
flow, can explicitly insert the deadline option into the packet
according to SLA.
For a deterministic delay path based on deadline queue scheduling,
the path it passes through has deterministic end-to-end delay
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requirements. It includes two parts, one is the accumulated node
delay and the other is the accumulated link propagation delay. The
end-to-end delay requirement is subtracted from the accumulated link
propagation delay to obtain the accumulated node delay. A simple
method is that the accumulated node delay is shared equally by each
intermediate node along the path to obtain the planning deadline of
each node.
Suppose that the planned deadline is D, the actual residence time is
R, then the packet sent by the ingress PE may have one of the
following deadline option information:
D-flag is set to 0; Planned Deadline is set to D; Accumulated
Planned Deadline is set to D; Accumulated Actual Residence Time is
set to R.
D-flag is set to 1; Planned Deadline is set to D; Accumulated
Deadline Deviation is set to D minus R;
For in-time service, the M-flag is set to 0, and for on-time service,
the M-flag is set to 1.
4. Operations of Deadline Options On Transit Node
The intermediate node, after receiving the packet, can obtain the
planned deadline from the packet as the delay budget of this node.
It need get the existing accumulated deadline deviation, and then add
it to the planned deadline of this node, to obtain the deadline
adjustment value, and then on the basis of the deadline adjustment
value, deducting the forwarding delay of the packet in the node, the
allowable queuing delay value is obtained, and then the packet will
be put to the deadline queue with TTL as the above allowable queuing
delay value for sending. If M-flag is 0, the packet will be put to
in-time queue, otherwise, it is put to on-time queue. See
[I-D.peng-detnet-deadline-based-forwarding] for more details.
If D-flag of the received packet is set to 0, the existing
accumulated deadline deviation is the value of the Accumulated
Planned Deadline field minus the value of the Accumulated Actual
Residence Time field.
If D-flag of the received packet is set to 1, the existing
accumulated deadline deviation is directly get from the Accumulated
Deadline Deviation field.
When the intermediate node continues to send the packet to the
downstream node, it need update the Accumulated Planned Deadline
field and the Accumulated Actual Residence Time field, or the
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Accumulated Deadline Deviation field. Note that field Planned
Deadline remains unchanged.
For the update of field Accumulated Planned Deadline, it can add the
planned deadline of this node to this field.
For the update of field Accumulated Actual Residence Time, it can add
the actual residence time of this node to this field. A possible
method to get the actual residence time in the node is that, the
receiving and sending time of the packet can be recorded in the
auxiliary data structure (note that is not packet itself) of the
packet, then the actual residence time of the packet in the node can
be calculated according to these two times.
For the update of field Accumulated Deadline Deviation, it can add
the difference of the planned deadline and the actual residence time
to this field.
5. IANA Considerations
This document updates the "Destination Options and Hop-by-Hop
Options" under the "Internet Protocol Version 6 (IPv6) Parameters"
registry:
+---------+-----+-----+------+-------------------+-------------+
|Hex Value| act | chg | rest | Description | Reference |
+---------+-----+-----+------+-------------------+-------------+
| TBD | 00 | 1 |00000 | Deadline Option |This document|
+---------+-----+-----+------+-------------------+-------------+
6. Security Considerations
TBD
7. Acknowledgements
TBD
8. Normative References
[I-D.peng-detnet-deadline-based-forwarding]
Peng, S., Tan, B., and P. Liu, "Deadline Based
Deterministic Forwarding", draft-peng-detnet-deadline-
based-forwarding-02 (work in progress), July 2022.
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[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>.
[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>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>.
Authors' Addresses
Shaofu Peng
ZTE Corporation
China
Email: peng.shaofu@zte.com.cn
Bin Tan
ZTE Corporation
China
Email: tan.bin@zte.com.cn
Peng Liu
China Mobile
China
Email: liupengyjy@chinamobile.com
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