Mechanism to Control Jitter Caused by Ingress Shaping
draft-peng-detnet-policing-jitter-control-03
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Shaofu Peng , Peng Liu , Kashinath Basu | ||
| Last updated | 2026-07-03 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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| IESG | IESG state | I-D Exists | |
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draft-peng-detnet-policing-jitter-control-03
DetNet Shaofu. Peng
Internet-Draft ZTE
Intended status: Standards Track Peng. Liu
Expires: 5 January 2027 China Mobile
Kashinath. Basu
Oxford Brookes University
4 July 2026
Mechanism to Control Jitter Caused by Ingress Shaping
draft-peng-detnet-policing-jitter-control-03
Abstract
This document presents a noble mechanism to eliminate jitter caused
by shaping delay on the network entrance node. It needs to be used
in combination with a queueing mechanism that provides low jitter for
the DetNet path, and ultimately provides a low jitter guarantee for
the DetNet flow.
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 5 January 2027.
Copyright Notice
Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Overview of the Solution . . . . . . . . . . . . . . . . . . 3
4. Set Shaping Delay Budget . . . . . . . . . . . . . . . . . . 5
5. Multi-domain Considerations . . . . . . . . . . . . . . . . . 5
5.1. Separate Shaping for Each Domain . . . . . . . . . . . . 5
5.2. Single Shaping for All Domains . . . . . . . . . . . . . 6
6. Encoding Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Policing (as defined in[RFC2216]) is the set of actions triggered
when a flow's actual data traffic characteristics exceed the expected
values given in the flow's traffic specification. Services which
require policing functions to operate correctly must specify both the
action to be taken when such discrepancies occur and the locations in
the network where discrepancies are to be detected. Examples of such
actions might include relegating the packet to best effort service,
dropping packets, reshaping the traffic, or marking non-conforming
traffic in some fashion. Shaping (as defined in[RFC2475]) is the
process of delaying packets within a traffic stream to cause it to
conform to some defined traffic profile.
DetNet [RFC8655] flows are assumed to be rate limited and DetNet is
designed to provide sufficient allocated resources. Rate limiting
and shaping functions at the ingress of the DetNet domain must be
applied. This is needed for meeting the requirements of DetNet flows
as well as for protecting non-DetNet traffic from potentially
misbehaving DetNet traffic sources.
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[RFC9016] defines the traffic specification of the DetNet flow,
including Interval, MinPayloadSize, MaxPayloadSize,
MinPacketsPerInterval, and MaxPacketsPerInterval. Flows exceeding
the traffic specification (i.e., having more traffic than defined by
the maximum attributes) must be shaped at the network entrance.
Assuming that there is enough buffer space to store nonconforming
packets, then that is important for application flows that expect
zero packet loss. A conforming packet may experience zero shaping
delay, while a nonconforming packet may experience non-zero shaping
delay. After shaping at the network entrance, each packet of the
application flow will be guaranteed the path delay and jitter bound
by the applied queueing mechanisms in the DetNet domain. Generally,
the applied queueing mechanism is only responsible for the delay
performance of the DetNet path, but not the runtime shaping delay at
the network entrance.
This document describes a mechanism to eliminate jitter caused by the
ingress shaping delay. It needs to be used in combination with a
queueing mechanism that provides low jitter for the DetNet path, and
ultimately provides a low jitter guarantee for the application flow.
2. 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.
3. Overview of the Solution
The end-to-end delay experienced by the application flow can be
considered to consist of two parts: ingress shaping delay, and DetNet
path delay. According to flow's end-to-end delay requirement and
shaping delay budget, a DetNet path delay requirement (i.e., end-to-
end delay requirement minus shaping delay budget) can be calculated.
An appropriate shaping delay budget can be configured for the
application flow according to its TSpec and actual possible arrival
pattern, and generally be the maximum shaping delay that may be
possibly experienced at the network entrance.
The shaping delay budget is consumed by the ingress and egress of the
DetNet path.
shaping delay budget = ingress shaping delay + egress damping
delay
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The ingress shaping delay is the runtime shaping delay experienced at
the network entrance. The egress damping delay is obtained by
subtracting the ingress shaping delay from the shaping delay budget.
Figure 1 shows that the relationship between these delay components.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(~ ~)
(~ ~)
+------+ +-------+ DetNet Path +--------+ +------+
|AppSrc|---|Headend|---------------------------|Endpoint|---|AppDst|
+------+ +-------+ +--------+ +------+
(~ ~)
(~ DetNet Domain ~)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|<---------- E2E Delay Reuirement ---------->|
| |
| |<--------- Path Delay ----------->| |
|<-->| |<-->|
ingress egress
shaping damping
delay delay
Figure 1: Relationship Between Delay Elements
When the headend of the DetNet path receives the packet from the
application source, it may carry the egress damping delay value in
the encoded packet sent to the endpoint, and the egress damping delay
will be used as the holding time imposed on the endpoint before the
packet is delivered to the application destination. The endpoint can
also distribute this value to downstream device for damping.
Note that some queueing mechanisms, such as
[I-D.ietf-detnet-deadline-based-forwarding] and
[I-D.ietf-detnet-packet-timeslot-mechanism], also provide the latency
deviation (E) information of the DetNet path. Depending on the
implementation, the endpoint can use different buffers to firstly
implement jitter control based on path latency deviation (E) and
secondly jitter control based on egress damping delay, or use the
same buffer to uniformly implement jitter control based on the sum of
path latency deviation (E) and egress damping delay. However, it
must use separate fields in the packet to carry these two values.
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Therefore, a flow with possible nonconforming packets will be
regulated and changed to be conforming at the network entrance, then
get the DetNet service within the network, and finally reverted to
the nonconforming pattern at the network exit, and then delivered to
the application destination.
4. Set Shaping Delay Budget
The shaping delay budget can be configured for the application flow
according to its TSpec and actual possible arrival pattern.
For example, an applicaiton flow has service burst interval (SBI) 100
us, and three packets P1, P2, P3 per SBI. Assuming the maximum
packet size is 1000 bits. In the ideal case, a conforming pattern of
this application flow is that the three packets arrive evenly at the
network entrance, i.e., with packet interval 33 us. However, an
extremely case of nonconforming pattern may be that P1, P2, P3
arrived back-to-back. After leaky bucket based regulation, P1, P2
and P3 will get different shaping delays, of which P3 has the largest
shaping delay, which may be 2/3 of SBI and can be used as the shaping
delay budget.
There may be other ways to set the shaping delay budget, such as
sampling the most likely arrival pattern of flow to set a smaller
shaping delay budget.
The network entrance node should maintain the shaping delay budget
for each application flow, and when it receives a packet from the
application source, it identifies the flow and applies the
corresponding shaping delay budget. If the shaping delay budget is
M, and the ingress shaping delay of the packet is S, then the egress
damping delay for that packet equals to M - S.
5. Multi-domain Considerations
In the case of multi-domain, all domains may apply the same or
different queueing machanisms. For each transit domain and egress
domain, the input traffic should be conforming and then get the
DetNet services. The output traffic from the upstream domain must be
conforming, that can be achieved based on path latency deviation (E).
There are two options to implement shaping jitter control.
5.1. Separate Shaping for Each Domain
This option is to implement shaping jitter control at the entrance
and exit of each domain independently. It is only applicable to
scenarios where transit domains maintain flow states.
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At each domain entrance, it maintain the shaping delay budget for the
application flow, regulate the nonconforming arrived packets, and
calculate the egress damping delay for each packet. Then, at each
domain exit, packets are held based on the egress damping delay. In
this option, each domain contribute a separate shaping delay budget
to the end-to-end delay.
When the packet leaves the upstream domain, the scheduling metadata
related to the queueing mechanism of the upstream domain and the
egress damping delay information are removed, and the application
header is exposed. The current domain entrance will re-encapsulate
the scheduling metadata related to the queueing mechanism of the
current domain and the endpoint damping delay information.
The limitation of this option is the states per flow maintained at
each domain entrance.
5.2. Single Shaping for All Domains
This option is to implement shaping jitter control only at the
ingress domain entrance and the egress domain exit. It is applicable
to scenarios where transit domains do not maintain flow states.
At the ingress domain entrance, it maintain the shaping delay budget
for the application flow, regulate the nonconforming arrived packets,
and calculate the egress damping delay for each packet. Then, at the
egress domain exit, packets are held based on the egress damping
delay. In this option, only a single shaping delay budget is
contributed to the end-to-end delay.
When the packet leaves the upstream domain, the scheduling metadata
related to the queueing mechanism of the upstream domain is removed,
but the egress damping delay information remains unchanged. The
current domain entrance will re-encapsulate the scheduling metadata
related to the queueing mechanism of the current domain. However, if
all domains use the same queueing mechanism, they may optionally
share a single metadata to avoid removing and re-encapsulating.
This option has less cost than the first option, i.e., no states per
flow maintained on each domain entrance.
6. Encoding Considerations
A new IPv6 option for DOH Options header ([RFC8200]) to carry egress
damping delay is defined in [I-D.peng-6man-delay-options].
A new ancillary data for MPLS MNA header ([I-D.ietf-mpls-mna-hdr]) to
carry endpoint damping delay is for further definition.
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7. IANA Considerations
This document need not require IANA allocations.
8. Security Considerations
TBD.
9. Acknowledgements
TBD.
10. References
10.1. 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-01, 26 June 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
deadline-based-forwarding-01>.
[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-01, 27 June 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
packet-timeslot-mechanism-01>.
[I-D.ietf-mpls-mna-hdr]
Rajamanickam, J., Gandhi, R., Zigler, R., Song, H., and K.
Kompella, "MPLS Network Action (MNA) Sub-Stack
Specification including In-Stack Network Actions and
Data", Work in Progress, Internet-Draft, draft-ietf-mpls-
mna-hdr-21, 24 February 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-mpls-
mna-hdr-21>.
[I-D.peng-6man-delay-options]
Peng, S., "Delay Options", Work in Progress, Internet-
Draft, draft-peng-6man-delay-options-01, 26 January 2026,
<https://datatracker.ietf.org/doc/html/draft-peng-6man-
delay-options-01>.
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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>.
[RFC2216] Shenker, S. and J. Wroclawski, "Network Element Service
Specification Template", RFC 2216, DOI 10.17487/RFC2216,
September 1997, <https://www.rfc-editor.org/info/rfc2216>.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<https://www.rfc-editor.org/info/rfc2475>.
[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>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[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>.
[RFC9016] Varga, B., Farkas, J., Cummings, R., Jiang, Y., and D.
Fedyk, "Flow and Service Information Model for
Deterministic Networking (DetNet)", RFC 9016,
DOI 10.17487/RFC9016, March 2021,
<https://www.rfc-editor.org/info/rfc9016>.
Authors' Addresses
Shaofu Peng
ZTE
China
Email: peng.shaofu@zte.com.cn
Peng Liu
China Mobile
China
Email: liupengyjy@chinamobile.com
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Kashinath Basu
Oxford Brookes University
United Kingdom
Email: kbasu@brookes.ac.uk
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