



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.

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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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