IPv6 Option for Scaling Deterministic Networks

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.¶

Abbreviations and definitions used in this document:¶

SRH:

Segment Routing Header¶

SRv6:

Segment Routing for IPv6 forwarding plane¶

DL:

Deterministic Latency¶

CSQF:

Cycle Specified Queuing and Forwarding¶

TQF:

Timeslot Queuing and Forwarding¶

C-SCORE:

Work Conserving Stateless Core Fair Queuing¶

EDF:

Earliest Deadline First¶

TAS:

Time Aware Shaper¶

ATS:

Asynchronous Traffic Shaping¶

CQF:

Cyclic Queuing and Forwarding¶

FQ:

Fair Queuing¶

TSN:

Time-Sensitive Networking¶

ECQF:

Enhanced Cyclic Queuing and Forwarding¶

gLBF:

guaranteed Latency Based Forwarding¶

2.1. Flow Aggregation

As per [RFC8655], the DetNet data plane must support the aggregation of DetNet flows in order to support larger numbers of DetNet flows and improve scalability by reducing the per-hop states. And the flow aggregation may be necessary for scaling networks. As per [I-D.ietf-detnet-scaling-requirements], the deterministic services may demand different deterministic QoS requirements according to different levels of application requirements. For example, industrial applications may demand tight jitter, strict latency limit requirements. The video applications may demand relative loose latency requirements and so on. The flow identification with service-level aggregation and explicit aggregated flow identification should be supported.¶

The flow identification is required to be dynamic and simplified to ensure the aggregated flows have compatible DetNet flow-specific QoS characteristics. In DetNet MPLS, A-Label defined as per [RFC8964] can be added explicitly to the packets. But in other DetNet data plane, no aggregated flow specific information is available. The aggregation identification and service type should be defined as the DetNet-specific metadata. The DetNet nodes along the path can identify the aggregated flow to achieve the end-to-end QoS in scaling networks.¶

2.2. Deterministic Latency

As described in [RFC9320], the end-to-end bounded latency depends on the queuing delay bound and the queuing mechanisms. Multiple queuing mechanisms have been proposed such as TAS [IIEEE802.1Qbv], CBS [IEEE802.1Q-2014],ATS [IEEE802.1Qcr], CQF [IEEE802.1Qch] and so on.¶

In scaling networks which has large variation in latency among hops, great number of flows and multiple domains, [I-D.ietf-detnet-scaling-requirements] has described the technical requirements for enhanced data plane solutions. Many variations and extensions of queuing mechanisms have been proposed to resolve the scalability issues in DetNet. [I-D.ietf-detnet-dataplane-taxonomy] has described the classification criteria of the solutions. For instance, the CQF variations for cyclic-based scheduling includes the ECQF [IEEE 802.1Qdv], Multi-CQF [I-D.dang-queuing-with-multiple-cyclic-buffers], TCQF [I-D.eckert-detnet-tcqf] and CSQF [I-D.chen-detnet-sr-based-bounded-latency]. The TAS variations for timeslot-based scheduling includes TQF [I-D.peng-detnet-packet-timeslot-mechanism]. The FQ variations for rate-based scheduling includes C-SCORE [I-D.joung-detnet-stateless-fair-queuing] ATS [IEEE802.1Qcr] and gLBF [I-D.eckert-detnet-glbf]. The EDF variations for deadline-based scheduling includes EDF[I-D.peng-detnet-deadline-based-forwarding] and Local Deadline [I-D.stein-srtsn]. The Damper variations for damper-based scheduling includes Damper [I-D.mohammadpour-detnet-bounded-delay-variation] and gLBF [I-D.eckert-detnet-glbf].¶

And when queuing mechanisms used in large-scale networks, the per-flow states can not be maintained with scalability issues. Some queuing parameters should be carried for coordination between nodes so as to make appropriate packet forwarding and scheduling decisions to meet the time bounds. As per [I-D.ietf-detnet-scaling-requirements], the information used by functions ensuring deterministic latency should be supported as such queuing-based information. And queuing mechanisms and solutions require different information to help the functions of ensuring deterministic latency, including regulation, queue management. The deterministic latency metadata should be defined for forwarding nodes along the path which can apply the queuing mechanisms and get the related deterministic latency metadata in packet to achieve the end-to-end bounded latency.¶

3.1. Aggregation Option

The Aggregation Option helps to identify the aggregated flow and discriminate the different deterministic QoS requirements and specify the related parameters.¶

     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  |Option Data Len|  Service  Type|    Flag       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |               Aggregation ID                                  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |              End-to-end Delay Budget                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |              End-to-end Delay Variation Budget                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Service Type: 8-bit unsigned integer, indicates the service-level or class-based aggregation type of packet treatment ensuring the deterministic QoS as following shown. This type can also indicate the aggregated class.¶

        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        | Value |         Service Type                |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0000 |  Reserved                           |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0100 |  Bandwidth guarantee                |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0200 |  Jitter guarantee                   |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0300 |  Delay guarantee                    |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0400 |  Low delay and jitter guarantee     |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0500 |Ultra-low delay and jitter guarantee |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Flag: 8-bit flags field.¶

Aggregation ID: 32bits. It provides explicit and unique identifier for aggregated flow identification. DetNet nodes performing aggregation using aggregation ID.¶

End-to-end Delay Budget: 32bits. It provides the value of end-to-end delay budget for the aggregated flow.¶

End-to-end Delay Variation Budget: 32bits. It provides the value of end-to-end delay variation budget for the aggregated flow.¶

3.2. Deterministic Latency Option

The Deterministic Latency Option helps to discriminate the deterministic latency technologies and specify the related parameters.¶

   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  |Option Data Len|   DL Type     |     Flag      |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                                                               |
  ~      Deterministic Latency Data(variable)(optional)           ~
  |                                                               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Option Type: TBD1, 8-bit option type identifier indicates the Deterministic Latency Option.¶

Option Data Len: 8-bit unsigned integer. Length of this option, in octets, not including the first 2 octets.¶

DL (Deterministic Latency) Type: 8-bit unsigned integer, indicates the type of deterministic latency information and related queuing and scheduling metadata.¶

Flag: 8-bit flags field.¶

Deterministic Latency Data: Variable-length field and the data is specific to the type. The Deterministic Latency type and data should depend on and align with the classification of the data plane queuing and scheduling solutions as per [I-D.ietf-detnet-dataplane-taxonomy]. For instance, it may cover the information such as cycle, timeslot, deadline, rate, packet size, damper, timestamp information as shown in Figure 3.¶

        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        | Type   |Deterministic Latency Type and Information|
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0000  |  Unassigned                              |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0001  |  Cycle Information                       |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0002  |  Timeslot Information                    |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0003  |  Deadline Information                    |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0004  |  Ratio Information                       |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |0x0005  |  Damper Information                      |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.1. IPv6 Networks

The DetNet Options is intended to be placed in an IPv6 HbH EH since it must be processed by every DetNet forwarding node along the path. For the DetNet options, all DetNet forwarding nodes can use the queuing information to achieve the packet forwarding and scheduling. The format of DetNet options in IPv6 is as follows.¶

            +-----------------------------------+
            |         DetNet App-Flow           |
            |       (original IP) Packet        |
            +-----------------------------------+
            |            other EHs              |
            +-----------------------------------+
            |        IPv6 Hop-by-Hop Ex Hdr     |
            |         (DetNet Options)          |
            |                                   |
            +-----------------------------------+
            |            IPv6 Header            |
            +-----------------------------------+
            |             Data-Link             |
            +-----------------------------------+
            |             Physical              |
            +-----------------------------------+

4.2. SRv6 Networks

The DetNet Options is intended to be placed in an DOH EH before an SRH since it must be processed by the DetNet forwarding nodes of the SRv6 segment list. For the DetNet options, the DetNet forwarding nodes among SRv6 segment list can use the queuing-based information to achieve the packet forwarding and scheduling. The format of DetNet options in SRv6 is as follows.¶

            +-----------------------------------+
            |         DetNet App-Flow           |
            |       (original IP) Packet        |
            +-----------------------------------+
            |       Segment Routing Header      |
            +-----------------------------------+
            |        IPv6 Destination Ex Hdr    |
            |        (DetNet Options)           |
            |                                   |
            +-----------------------------------+
            |            IPv6 Header            |
            +-----------------------------------+
            |             Data-Link             |
            +-----------------------------------+
            |             Physical              |
            +-----------------------------------+

8.1. Normative References

[I-D.chen-detnet-sr-based-bounded-latency]

Chen, M., Geng, X., Li, Z., Joung, J., and J. Ryoo, "Segment Routing (SR) Based Bounded Latency", Work in Progress, Internet-Draft, draft-chen-detnet-sr-based-bounded-latency-03, 7 July 2023, <https://datatracker.ietf.org/doc/html/draft-chen-detnet-sr-based-bounded-latency-03>.

[I-D.dang-queuing-with-multiple-cyclic-buffers]

Liu, B. and J. Dang, "A Queuing Mechanism with Multiple Cyclic Buffers", Work in Progress, Internet-Draft, draft-dang-queuing-with-multiple-cyclic-buffers-00, 22 February 2021, <https://datatracker.ietf.org/doc/html/draft-dang-queuing-with-multiple-cyclic-buffers-00>.

[I-D.eckert-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-eckert-detnet-glbf-02, 5 January 2024, <https://datatracker.ietf.org/doc/html/draft-eckert-detnet-glbf-02>.

[I-D.eckert-detnet-tcqf]

Eckert, T. T., Li, Y., Bryant, S., Malis, A. G., Ryoo, J., Liu, P., Li, G., Ren, S., and F. Yang, "Deterministic Networking (DetNet) Data Plane - Tagged Cyclic Queuing and Forwarding (TCQF) for bounded latency with low jitter in large scale DetNets", Work in Progress, Internet-Draft, draft-eckert-detnet-tcqf-05, 5 January 2024, <https://datatracker.ietf.org/doc/html/draft-eckert-detnet-tcqf-05>.

[I-D.ietf-detnet-dataplane-taxonomy]

Joung, J., Geng, X., Peng, S., and T. T. Eckert, "Dataplane Enhancement Taxonomy", Work in Progress, Internet-Draft, draft-ietf-detnet-dataplane-taxonomy-00, 24 May 2024, <https://datatracker.ietf.org/doc/html/draft-ietf-detnet-dataplane-taxonomy-00>.

[I-D.ietf-detnet-scaling-requirements]

Liu, P., Li, Y., Eckert, T. T., Xiong, Q., Ryoo, J., zhushiyin, and X. Geng, "Requirements for Scaling Deterministic Networks", Work in Progress, Internet-Draft, draft-ietf-detnet-scaling-requirements-06, 22 May 2024, <https://datatracker.ietf.org/doc/html/draft-ietf-detnet-scaling-requirements-06>.

[I-D.joung-detnet-stateless-fair-queuing]

Joung, J., Ryoo, J., Cheung, T., Li, Y., and P. Liu, "Latency Guarantee with Stateless Fair Queuing", Work in Progress, Internet-Draft, draft-joung-detnet-stateless-fair-queuing-02, 29 February 2024, <https://datatracker.ietf.org/doc/html/draft-joung-detnet-stateless-fair-queuing-02>.

[I-D.mohammadpour-detnet-bounded-delay-variation]

Mohammadpour, E. and J. Le Boudec, "DetNet Bounded Packet-Delay-Variation", Work in Progress, Internet-Draft, draft-mohammadpour-detnet-bounded-delay-variation-00, 10 September 2021, <https://datatracker.ietf.org/doc/html/draft-mohammadpour-detnet-bounded-delay-variation-00>.

[I-D.peng-detnet-deadline-based-forwarding]

Peng, S., Du, Z., Basu, K., cheng, Yang, D., and C. Liu, "Deadline Based Deterministic Forwarding", Work in Progress, Internet-Draft, draft-peng-detnet-deadline-based-forwarding-10, 20 June 2024, <https://datatracker.ietf.org/doc/html/draft-peng-detnet-deadline-based-forwarding-10>.

[I-D.peng-detnet-packet-timeslot-mechanism]

Peng, S., Liu, P., Basu, K., Liu, A., Yang, D., and G. Peng, "Timeslot Queueing and Forwarding Mechanism", Work in Progress, Internet-Draft, draft-peng-detnet-packet-timeslot-mechanism-07, 20 June 2024, <https://datatracker.ietf.org/doc/html/draft-peng-detnet-packet-timeslot-mechanism-07>.

[I-D.stein-srtsn]

Stein, Y. J., "Segment Routed Time Sensitive Networking", Work in Progress, Internet-Draft, draft-stein-srtsn-01, 29 August 2021, <https://datatracker.ietf.org/doc/html/draft-stein-srtsn-01>.

[I-D.xiong-detnet-data-fields-edp]

Xiong, Q., Liu, A., Gandhi, R., and D. Yang, "Data Fields for DetNet Enhanced Data Plane", Work in Progress, Internet-Draft, draft-xiong-detnet-data-fields-edp-02, 1 July 2024, <https://datatracker.ietf.org/doc/html/draft-xiong-detnet-data-fields-edp-02>.

[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>.

[RFC4915]

Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, DOI 10.17487/RFC4915, June 2007, <https://www.rfc-editor.org/info/rfc4915>.

[RFC5120]

Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, DOI 10.17487/RFC5120, February 2008, <https://www.rfc-editor.org/info/rfc5120>.

[RFC5440]

Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, March 2009, <https://www.rfc-editor.org/info/rfc5440>.

[RFC7752]

Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and S. Ray, "North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP", RFC 7752, DOI 10.17487/RFC7752, March 2016, <https://www.rfc-editor.org/info/rfc7752>.

[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>.

[RFC8231]

Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path Computation Element Communication Protocol (PCEP) Extensions for Stateful PCE", RFC 8231, DOI 10.17487/RFC8231, September 2017, <https://www.rfc-editor.org/info/rfc8231>.

[RFC8250]

Elkins, N., Hamilton, R., and M. Ackermann, "IPv6 Performance and Diagnostic Metrics (PDM) Destination Option", RFC 8250, DOI 10.17487/RFC8250, September 2017, <https://www.rfc-editor.org/info/rfc8250>.

[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>.

[RFC8664]

Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., and J. Hardwick, "Path Computation Element Communication Protocol (PCEP) Extensions for Segment Routing", RFC 8664, DOI 10.17487/RFC8664, December 2019, <https://www.rfc-editor.org/info/rfc8664>.

[RFC8938]

Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S. Bryant, "Deterministic Networking (DetNet) Data Plane Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020, <https://www.rfc-editor.org/info/rfc8938>.

[RFC8939]

Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S. Bryant, "Deterministic Networking (DetNet) Data Plane: IP", RFC 8939, DOI 10.17487/RFC8939, November 2020, <https://www.rfc-editor.org/info/rfc8939>.

[RFC8964]

Varga, B., Ed., Farkas, J., Berger, L., Malis, A., Bryant, S., and J. Korhonen, "Deterministic Networking (DetNet) Data Plane: MPLS", RFC 8964, DOI 10.17487/RFC8964, January 2021, <https://www.rfc-editor.org/info/rfc8964>.

[RFC9055]

Grossman, E., Ed., Mizrahi, T., and A. Hacker, "Deterministic Networking (DetNet) Security Considerations", RFC 9055, DOI 10.17487/RFC9055, June 2021, <https://www.rfc-editor.org/info/rfc9055>.

[RFC9320]

Finn, N., Le Boudec, J.-Y., Mohammadpour, E., Zhang, J., and B. Varga, "Deterministic Networking (DetNet) Bounded Latency", RFC 9320, DOI 10.17487/RFC9320, November 2022, <https://www.rfc-editor.org/info/rfc9320>.

[RFC9357]

Xiong, Q., "Label Switched Path (LSP) Object Flag Extension for Stateful PCE", RFC 9357, DOI 10.17487/RFC9357, February 2023, <https://www.rfc-editor.org/info/rfc9357>.