Network Shaofu. Peng
Internet-Draft ZTE Corporation
Intended status: Standards Track 27 January 2026
Expires: 31 July 2026
Delay Options
draft-peng-6man-delay-options-01
Abstract
This document introduces new IPv6 options for HBH or DOH Options
header, to carry delay related information for deterministic
forwarding.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Path Latency Deviation Option . . . . . . . . . . . . . . . . 3
3. endpoint damping delay Option . . . . . . . . . . . . . . . . 4
4. Process of Path Latency Deviation Option . . . . . . . . . . 5
5. Process of Endpoint Damping Delay Option . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
9. Normative References . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
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 provide deterministic forwarding service, the scheduling
mechanisms applied in the network generally require application flows
to comply with predefine constraints, such as a token bucket
specification consisting of a "token rate" r and a "bucket size" b.
This can be achieved by configuring regulators with parameter (r, b)
and states per flow on each node, however, the cost is too high.
Another more feasible way is to carry the states in the packet, and
the scheduling mechanism automatically regulate and sorts the packet
based on the states read from the packet.
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There are some common states that are used by multiple scheduling
mechanisms. For example, the latency deviation (E) defined in EDF
[I-D.ietf-detnet-deadline-based-forwarding] or TQF
[I-D.ietf-detnet-packet-timeslot-mechanism], and the damping delay
defind in gLBF [I-D.ietf-detnet-glbf], are actually the same thing
and can be considered as the latency compensation used for the
forwarded path. Another example is that the endpoint damping delay
defined in [I-D.peng-detnet-policing-jitter-control] that can be
combined with any on-time scheduling mechanisms to further avoid
jitter caused by policing.
This document introduces new IPv6 options for HBH or DOH Options
header, to carry common scheduling parameters for deterministic
forwarding. Note that the motivation of the common scheduling
parameters defined in this document is to be shared and used by
multiple scheduling mechanisms, rather than a container that includes
some different parameters.
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.
2. Path Latency Deviation Option
The path latency deviation is used to characterize the deviation
between the delay budget (such as a planned residence time or
estimated worst-case delay) and the actual delay of a packet at each
hop. Each hop along the path can use this information to shape or
sort arrived packets, to ensure that the flow conforms to predefined
constraints. Examples include the latency deviation (E) defined in
EDF or TQF mechanism, and damping delay defined in gLBF mechanism.
Strictly speaking, the path latency deviation should be a cumulative
value, that is, it accumulates the latency deviation of all upstream
nodes. However, if the scheduling mechanism used in the network can
ensure that the path latency deviation is cleared and reset at each
hop, then this cumulative value actually only includes the latency
deviation generated by a single hop and updated again on the next
hop.
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The scope of use of the path latency deviation is the forwarded path.
It is generally included in HBH to eliminate jitter at each hop (such
as each transit node in EDF or gLBF technology domain). It may also
be included in DOH, eliminating jitter only at the last hop (such as
the egress node in TQF technology domain).
The path latency deviation 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Latency Deviation |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Path Latency Deviation Option
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
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 4.
Path Latency Deviation: 32-bit signed integer, represents the the
deviation between delay budget and actual delay on each hop (such as
EDF, gLBF), or the deviation between the ideal arrival/departure time
and the actual arrival/departure time (such as TQF). It is the
holding time imposed on the downstream node before the packet is
further scheduled.
3. endpoint damping delay Option
The endpoint damping delay is used to characterize the necessary
holding time of the packet on the endpoint of the path, i.e., the
final destination, to avoid jitter caused by policing delay. Please
refer to [I-D.peng-detnet-policing-jitter-control] for more details.
The scope of use of the endpoint damping delay is the final
destination of the egress domain. It is recommoned to be included in
DOH.
The endpoint damping delay option has the following format:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| endpoint damping delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: endpoint damping delay Option
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
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 4.
endpoint damping delay: 32-bit signed integer, represents the the
holding time imposed on the endpoint before the packet is delivered
to the application destination. Note that the holding time may also
be imposed on the downstream node.
4. Process of Path Latency Deviation Option
For a specific queueing technology domain that guarantee low jitter,
the ingress node of the domain will encapsulte outer IPv6 header for
the application flow. There are metadata related with the queueing
technology contained in the outer IPv6 header. The ingress node may
check the latency deviation between the delay budget and the actual
delay expierenced at this node, and put a path latency deviation
optioin in HBH or DOH within the outer IPv6 header. For those
mechanisms that use the path latency deviation to eliminate jitter at
transit nodes, the option is included in HBH. For mechanisms that do
not require path latency deviation to eliminate jitter at transit
nodes, the option is included in DOH.
For a transit node that received an IPv6 packet with HBH and the path
latency deviation option, it should firstly impose the corresponding
holding time for that packet. If the packet has undergone the
holding time, the path latency deviation option is reset to zero;
otherwise, the path latency deviation option remains unchanged. Then
the packet continue to be shceduled at this node. The transit node
will also check the latency deviation between the delay budget and
the actual delay expierenced at this node, and adds this latency
deviation to the path latency deviation optioin in HBH and then sends
to the next hop.
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For the egress node of the domain that received an IPv6 packet with
HBH or DOH and the path latency deviation option, it should firstly
impose the corresponding holding time for that packet. If the packet
has undergone the holding time, the path latency deviation option is
reset to zero; otherwise, the path latency deviation option remains
unchanged. Then the packet continue to be shceduled at this node.
The egress node will also check the latency deviation between the
delay budget and the actual delay expierenced at this node, and adds
this latency deviation to the path latency deviation optioin in HBH
or DOH. The outer IPv6 header is removed and the remaining latency
devication may be informed to the next hop.
5. Process of Endpoint Damping Delay Option
The ingress node of the ingress domain that received an application
packet may calculate the the endpoint damping delay for the packet,
that equals to edge-to-edge policing delay budget minus the headend
runtime policing delay. An outer IPv6 header corresponding to end-
to-end path is encapsulted and contains DOH with endpoint damping
delay option. Note that the DOH is closed to the upper-layer header.
The egress node of the egress domain that received an IPv6 packet
with DOH and the endpoint damping delay option, should impose the
corresponding holding time for that packet. This may be happened
after the packet is shceduled at this node, or the remaining damping
delay may be informed to the next hop.
6. 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 |
+---------+-----+-----+------+-----------------------+-------------+
| TBD1 | 00 | 1 | 00000| Path Latency Deviation|This document|
+---------+-----+-----+------+-----------------------+-------------+
| TBD2 | 00 | 1 | 00000| Endpoint Damping Delay|This document|
+---------+-----+-----+------+-----------------------+-------------+
7. Security Considerations
TBD
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8. Acknowledgements
TBD
9. Normative References
[I-D.ietf-detnet-deadline-based-forwarding]
Peng, S., Du, Z., Basu, K., cheng, C., Yang, D., and C.
Liu, "Deadline Based Deterministic Forwarding", Work in
Progress, Internet-Draft, draft-ietf-detnet-deadline-
based-forwarding-00, 16 January 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
deadline-based-forwarding-00>.
[I-D.ietf-detnet-glbf]
Eckert, T. T., Clemm, A., Bryant, S., and S. Hommes,
"Deterministic Networking (DetNet) Data Plane - guaranteed
Latency Based Forwarding (gLBF) for bounded latency with
low jitter and asynchronous forwarding in Deterministic
Networks", Work in Progress, Internet-Draft, draft-ietf-
detnet-glbf-00, 16 January 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
glbf-00>.
[I-D.ietf-detnet-packet-timeslot-mechanism]
Peng, S., Liu, P., Basu, K., Liu, A., Yang, D., Peng, G.,
and J. Zhao, "Timeslot Queueing and Forwarding Mechanism",
Work in Progress, Internet-Draft, draft-ietf-detnet-
packet-timeslot-mechanism-00, 16 January 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
packet-timeslot-mechanism-00>.
[I-D.peng-detnet-policing-jitter-control]
Peng, S., Liu, P., and K. Basu, "Mechanism to control
jitter caused by policing in Detnet", Work in Progress,
Internet-Draft, draft-peng-detnet-policing-jitter-control-
01, 8 October 2024,
<https://datatracker.ietf.org/doc/html/draft-peng-detnet-
policing-jitter-control-01>.
[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>.
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[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>.
Author's Address
Shaofu Peng
ZTE Corporation
China
Email: peng.shaofu@zte.com.cn
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