RFC 9938: A Framework for the Deterministic Networking (DetNet) Controller Plane
- A. Malis,
- X. Geng, Ed.,
- M. Chen,
- B. Varga,
- CJ. Bernardos
Abstract
This document provides a framework overview for the Deterministic Networking (DetNet) Controller Plane. It discusses concepts and requirements for the DetNet Controller Plane, which could be the basis for a future solution specification.¶
Status of This Memo
This document is not an Internet Standards Track specification; it is published for informational purposes.¶
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are candidates for any level of Internet Standard; see Section 2 of RFC 7841.¶
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Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved.¶
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1. Introduction
Deterministic Networking (DetNet) provides the ability to carry specified unicast or multicast data flows for real-time applications with extremely low packet loss rates and assured maximum end-to-end delivery latency. A description of the general background and concepts of DetNet can be found in [RFC8655].¶
The DetNet data plane is defined in the DetNet data plane framework [RFC8938] (and is further explained in the associated DetNet MPLS [RFC8964], the DetNet IP [RFC8939], and other data plane specifications [RFC9023] [RFC9024] [RFC9025] [RFC9037] [RFC9056]).¶
Note that in the DetNet overall architecture, the controller plane includes what are more usually considered separate control and management planes (see Section 4.4.2 of [RFC8655]). The management plane is primarily involved with fault management, configuration management, and performance management (sometimes accounting management and security management are also considered in the management plane (Section 4.2 of [RFC6632]) but they are out of the scope of this document). At the same time, the control plane is primarily responsible for the instantiation and maintenance of flows, MPLS label allocation and distribution, and active in-band or out-of-band signaling to support DetNet functions. In the DetNet architecture, all of this functionality is combined into a single controller plane. See Section 4.4.2 of [RFC8655] and the aggregation of control and management planes in [RFC7426] for further details.¶
While the DetNet architecture and data plane documents are primarily concerned with data plane operations, they do contain some requirements and considerations for functions that would be required in order to automate DetNet service provisioning and monitoring via a DetNet Controller Plane (e.g., see Section 4 of [RFC8938]). The purpose of this document is to take these requirements and considerations into a single document and extend and discuss how various possible DetNet Controller Plane architectures could be used to satisfy these requirements, while not providing the protocol details for a DetNet Controller Plane solution. Such controller plane protocol solutions will be the subject of subsequent documents. Therefore, this document should be considered as the authoritative reference to be considered if/when protocol work on the DetNet Controller Plane starts.¶
2. DetNet Controller Plane Requirements
Other DetNet documents, including [RFC8655], [RFC8938], [RFC9551], and [RFC9055], among others, contain requirements for the controller plane. For convenience, these requirements have been compiled here. These requirements have been organized into three groups: 1) requirements primarily applicable to the control plane, 2) requirements primarily applicable to the management plane, and 3) requirements applicable to both planes. In addition, security requirements for the DetNet Controller Plane have been discussed in [RFC9055], and a summary of those requirements is provided in Section 2.3. For the sake of clarity, when applicable, the document in which the requirements originally appear is referenced.¶
2.1. DetNet Control Plane Requirements
The primary requirements for the DetNet Control Plane are as follows:¶
2.2. DetNet Management Plane Requirements
The primary requirements for the DetNet management plane are as follows:¶
2.3. Requirements for Both Planes
The following requirements apply to both the DetNet control and management planes:¶
In addition to the above, the DetNet Controller Plane should also satisfy security requirements derived from [RFC9055], which defines the security framework for DetNet. The following requirements are especially relevant:¶
3. DetNet Control Plane Architecture
As noted in the Introduction, the DetNet Control Plane is responsible for the instantiation and maintenance of flows, the allocation and distribution of flow-related information (e.g., MPLS label), and active in-band or out-of-band information distribution to support these functions.¶
The following sections define three types of DetNet Control Plane architectures: 1) a fully distributed control plane utilizing dynamic signaling protocols, 2) a fully centralized SDN-like control plane, and 3) a hybrid control plane containing both distributed protocols and centralized controlling. This document describes the various information exchanges between entities in the network for each type of these architectures and the corresponding advantages and disadvantages.¶
The examples in the following sections illustrate possible mechanisms that could be used in each type of the architectures. They are not meant to be exhaustive or to preclude any other possible mechanism that could be used in place of those used in the examples.¶
3.1. Distributed Control Plane and Signaling Protocols
In a fully distributed configuration model, the User-Network Interface (UNI) information is transmitted over a DetNet UNI protocol from the user side to the network side. Then, the UNI and network configuration information propagates in the network via distributed control plane signaling protocols. Such a DetNet UNI protocol is not necessary when the end systems are DetNet capable.¶
Taking an RSVP-TE [RFC3209] MPLS network as an example, where end systems are not part of the DetNet domain:¶
In this example, both the IGP and RSVP-TE may require extensions for DetNet.¶
3.2. Fully Centralized Control Plane
In the fully centralized configuration model (e.g., using an SDN controller), both flow and UNI information can be transmitted from a centralized user controller or from other applications, via an API or northbound interface, to a centralized controller. Network node configurations for DetNet flows are performed by the controller using a protocol such as NETCONF [RFC6241], YANG [RFC6020] [RFC7950], DetNet YANG [RFC9633], or a PCE-based central controller (PCE-CC) [RFC8283].¶
Take the following case as an example:¶
The protocols in the above example may require extensions for DetNet.¶
3.3. Hybrid Control Plane (Partly Centralized and Partly Distributed)
In the hybrid model, the controller and control plane protocols work together to provide DetNet services, and there are a number of possible combinations.¶
In the following case, the RSVP-TE and controller are used together:¶
There are many other variations that could be included in a hybrid control plane. The requested DetNet extensions for a protocol in each possible case is for future work.¶
4. DetNet Control Plane for DetNet Mechanisms
This section discusses the requested control plane features for DetNet mechanisms as defined in [RFC8655], including PREOF. Different DetNet services may implement any or all of these based on the requirements.¶
4.1. Explicit Paths
Explicit paths are required in DetNet to provide a stable forwarding service and guarantee that the DetNet service is not impacted when the network topology changes. The following features are necessary in the control plane to implement explicit paths in DetNet:¶
4.2. Resource Reservation
DetNet flows are supposed to be protected from congestion, so sufficient resource reservation for a DetNet service could protect a service from congestion. There are multiple types of resources in the network that could be allocated to DetNet flows, e.g., packet processing resources, buffer resources, and the bandwidth of the output port. The network resource requested by a specified DetNet service is determined by the SLA requirements and network capability.¶
4.3. PREOF Support
DetNet path redundancy is supported via Packet Replication,
Elimination, and Ordering Functions (PREOF). A DetNet
flow is replicated and forwarded by multiple networks paths to avoid
packet loss caused by device or link failures. In general, current
control plane mechanisms that can be used to establish an explicit
path, whether distributed or centralized, support point-to-point (P2P)
and point
4.4. Data-Plane-Specific Considerations
4.4.1. DetNet in an MPLS Domain
For the purposes of this document, "legacy MPLS" is defined as MPLS without the use of Segment Routing (see Section 4.4.3 for a discussion of MPLS with Segment Routing) or MPLS Transport Profile (MPLS-TP) [RFC5960].¶
In legacy MPLS domains, a dynamic control plane using distributed signaling protocols is typically used for the distribution of MPLS labels used for forwarding MPLS packets. The dynamic signaling protocols most commonly used for label distribution are LDP [RFC5036], RSVP-TE [RFC4875], and BGP [RFC8277] (which enables BGP-based MPLS Layer 3 VPNs [RFC4384], Layer 2 VPNs [RFC4664], and EVPNs [RFC7432]).¶
Any of these protocols could be used to distribute DetNet Service Labels (S-Labels) and Aggregation Labels (A-Labels) [RFC8964]. As discussed in [RFC8938], S-Labels are similar to other MPLS service labels, such as pseudowire and L3 VPN and L2 VPN labels, and could be distributed in a similar manner, such as through the use of targeted LDP or BGP. If these were to be used for DetNet, they would require extensions to support DetNet-specific features, such as PREOF, aggregation (A-Labels), node resource allocation, and queue placement.¶
4.4.2. DetNet in an IP Domain
For the purposes of this document, "legacy IP" is defined as IP without the use of Segment Routing (see Section 4.4.3 for a discussion of IP with Segment Routing). It should be noted that a DetNet IP data plane [RFC8939] is simpler than a DetNet MPLS data plane [RFC8964] and doesn't support PREOF, so only one path per flow or flow aggregate is required. Therefore, possible protocol extensions are expected to be limited, e.g., to existing IP routing protocols.¶
4.4.3. DetNet in a Segment Routing Domain
Segment Routing [RFC8402] is a scalable approach to building network domains that provides explicit routing via source routing encoded in packet headers, and it is combined with centralized network control to compute paths through the network. Forwarding paths are distributed with associated policies to network edge nodes for use in packet headers. Segment Routing reduces the amount of network signaling associated with distributed signaling protocols, such as RSVP-TE, and also reduces the amount of state in core nodes compared with that required for legacy MPLS and IP routing, as the state is now in the packets rather than in the routers. This could be useful for DetNet, where a very large number of flows through a network domain are expected, which would otherwise require the instantiation of state for each flow traversing each node in the network.¶
Note that the DetNet MPLS and IP data planes described in [RFC8964] and [RFC8939] were constructed to be compatible with both types of Segment Routing: Segment Routing over MPLS (SR-MPLS) [RFC8660] and Segment Routing over IPv6 (SRv6) [RFC8754] [RFC8986].¶
4.5. Encapsulation and Metadata Support
To effectively manage DetNet flows, the controller plane will need to have a clear understanding of the encapsulation and metadata capabilities of the underlying network nodes. This will require a control mechanism that can discover, configure, and manage these parameters for each flow.¶
The controller plane needs to understand and manage the encapsulation and metadata capabilities of the network nodes to provision DetNet flows effectively. This process might need a discovery phase in which the controller discovers which encapsulation types (e.g., MPLS, IP) and metadata schemes (e.g., sequencing, timestamping) that each node supports. After discovery, the controller might instruct nodes on the specific encapsulation and companion metadata to apply for a given flow. This ensures that DetNet packets are handled consistently across the network. For example, the controller might instruct a node to use an MPLS header and add a sequence number for a particular flow.¶
5. Management Plane Overview
The management plane includes the ability to statically provision network nodes and to use Operations, Administration, and Maintenance (OAM) to monitor DetNet performance and to detect outages or other issues at the DetNet layer.¶
5.1. DetNet Operations, Administration, and Maintenance (OAM)
This document covers the general considerations for OAM.¶
5.1.1. OAM for Performance Monitoring (PM)
5.1.1.1. Active PM
Active PM is performed by injecting OAM packets into the
network to estimate the performance of the network and by then measuring
the performance of those OAM packets. Adding extra traffic can
affect the delay and throughput performance of the network, and
for this reason, Active PM is not recommended for use in
operational DetNet domains. However, it is a useful test tool when
commissioning a new network or during troubleshooting
5.1.1.2. Passive PM
Passive PM, such as In Situ Operations, Administration, and Maintenance (IOAM) [RFC9197], monitors the actual service traffic in a network domain in order to measure its performance without having a detrimental effect on the network. As compared to Active PM, Passive PM is much preferred for use in DetNet domains.¶
6. Multi-Domain Aspects
When there are multiple domains involved, multiple Controller Plane
Functions (CPFs) would have to collaborate to implement the requests
received from the Flow Management Entity (FME) [RFC8655]
as per-flow, per-hop behaviors installed in the DetNet nodes for each
individual flow. Adding multi-domain support might require some support
at the CPF. For example, CPFs of different domains, e.g., PCEs, need to
discover each other and then authenticate and negotiate per-hop
behaviors. Furthermore, in the case of wireless domains,
per-domain functions specific to Reliable and Available Wireless (RAW) [RAW-ARCH], such as Point of Local Repairs (PLRs), have to also be
considered, e.g., in addition to the PCEs. Depending on the multi-domain
support provided by the application plane, the controller plane might be
relieved from some responsibilitie
7. IANA Considerations
This document has no IANA actions.¶
8. Security Considerations
This document provides a framework for the DetNet Controller Plane and does not include any protocol specifications. Any future specification that is defined to support the DetNet Controller Plane is expected to include the appropriate security considerations. For overall security considerations of DetNet, see [RFC8655] and [RFC9055].¶
9. References
9.1. Normative References
- [RFC8655]
-
Finn, N., Thubert, P., Varga, B., and J. Farkas, "Deterministic Networking Architecture", RFC 8655, DOI 10
.17487 , , <https:///RFC8655 www >..rfc -editor .org /info /rfc8655 - [RFC8938]
-
Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S. Bryant, "Deterministic Networking (DetNet) Data Plane Framework", RFC 8938, DOI 10
.17487 , , <https:///RFC8938 www >..rfc -editor .org /info /rfc8938 - [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 , , <https:///RFC9016 www >..rfc -editor .org /info /rfc9016 - [RFC9055]
-
Grossman, E., Ed., Mizrahi, T., and A. Hacker, "Deterministic Networking (DetNet) Security Considerations", RFC 9055, DOI 10
.17487 , , <https:///RFC9055 www >..rfc -editor .org /info /rfc9055 - [RFC9551]
-
Mirsky, G., Theoleyre, F., Papadopoulos, G., Bernardos, CJ., Varga, B., and J. Farkas, "Framework of Operations, Administration, and Maintenance (OAM) for Deterministic Networking (DetNet)", RFC 9551, DOI 10
.17487 , , <https:///RFC9551 www >..rfc -editor .org /info /rfc9551
9.2. Informative References
- [RAW-ARCH]
-
Thubert, P., Ed., "Reliable and Available Wireless Architecture", Work in Progress, Internet-Draft, draft
-ietf , , <https://-raw -architecture -30 datatracker >..ietf .org /doc /html /draft -ietf -raw -architecture -30 - [RFC3209]
-
Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, DOI 10
.17487 , , <https:///RFC3209 www >..rfc -editor .org /info /rfc3209 - [RFC4384]
-
Meyer, D., "BGP Communities for Data Collection", BCP 114, RFC 4384, DOI 10
.17487 , , <https:///RFC4384 www >..rfc -editor .org /info /rfc4384 - [RFC4664]
-
Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664, DOI 10
.17487 , , <https:///RFC4664 www >..rfc -editor .org /info /rfc4664 - [RFC4875]
-
Aggarwal, R., Ed., Papadimitriou, D., Ed., and S. Yasukawa, Ed., "Extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for Point
-to , RFC 4875, DOI 10-Multipoint TE Label Switched Paths (LSPs)" .17487 , , <https:///RFC4875 www >..rfc -editor .org /info /rfc4875 - [RFC5036]
-
Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., "LDP Specification", RFC 5036, DOI 10
.17487 , , <https:///RFC5036 www >..rfc -editor .org /info /rfc5036 - [RFC5960]
-
Frost, D., Ed., Bryant, S., Ed., and M. Bocci, Ed., "MPLS Transport Profile Data Plane Architecture", RFC 5960, DOI 10
.17487 , , <https:///RFC5960 www >..rfc -editor .org /info /rfc5960 - [RFC6020]
-
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10
.17487 , , <https:///RFC6020 www >..rfc -editor .org /info /rfc6020 - [RFC6241]
-
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10
.17487 , , <https:///RFC6241 www >..rfc -editor .org /info /rfc6241 - [RFC6632]
-
Ersue, M., Ed. and B. Claise, "An Overview of the IETF Network Management Standards", RFC 6632, DOI 10
.17487 , , <https:///RFC6632 www >..rfc -editor .org /info /rfc6632 - [RFC7426]
-
Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S., Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software
-Defined Networking (SDN): Layers and Architecture Terminology" , RFC 7426, DOI 10.17487 , , <https:///RFC7426 www >..rfc -editor .org /info /rfc7426 - [RFC7432]
-
Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet VPN", RFC 7432, DOI 10
.17487 , , <https:///RFC7432 www >..rfc -editor .org /info /rfc7432 - [RFC7950]
-
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10
.17487 , , <https:///RFC7950 www >..rfc -editor .org /info /rfc7950 - [RFC8277]
-
Rosen, E., "Using BGP to Bind MPLS Labels to Address Prefixes", RFC 8277, DOI 10
.17487 , , <https:///RFC8277 www >..rfc -editor .org /info /rfc8277 - [RFC8283]
-
Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An Architecture for Use of PCE and the PCE Communication Protocol (PCEP) in a Network with Central Control", RFC 8283, DOI 10
.17487 , , <https:///RFC8283 www >..rfc -editor .org /info /rfc8283 - [RFC8402]
-
Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10
.17487 , , <https:///RFC8402 www >..rfc -editor .org /info /rfc8402 - [RFC8660]
-
Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing with the MPLS Data Plane", RFC 8660, DOI 10
.17487 , , <https:///RFC8660 www >..rfc -editor .org /info /rfc8660 - [RFC8754]
-
Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header (SRH)", RFC 8754, DOI 10
.17487 , , <https:///RFC8754 www >..rfc -editor .org /info /rfc8754 - [RFC8939]
-
Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S. Bryant, "Deterministic Networking (DetNet) Data Plane: IP", RFC 8939, DOI 10
.17487 , , <https:///RFC8939 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 , , <https:///RFC8964 www >..rfc -editor .org /info /rfc8964 - [RFC8986]
-
Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer, D., Matsushima, S., and Z. Li, "Segment Routing over IPv6 (SRv6) Network Programming", RFC 8986, DOI 10
.17487 , , <https:///RFC8986 www >..rfc -editor .org /info /rfc8986 - [RFC9023]
-
Varga, B., Ed., Farkas, J., Malis, A., and S. Bryant, "Deterministic Networking (DetNet) Data Plane: IP over IEEE 802.1 Time-Sensitive Networking (TSN)", RFC 9023, DOI 10
.17487 , , <https:///RFC9023 www >..rfc -editor .org /info /rfc9023 - [RFC9024]
-
Varga, B., Ed., Farkas, J., Malis, A., Bryant, S., and D. Fedyk, "Deterministic Networking (DetNet) Data Plane: IEEE 802.1 Time-Sensitive Networking over MPLS", RFC 9024, DOI 10
.17487 , , <https:///RFC9024 www >..rfc -editor .org /info /rfc9024 - [RFC9025]
-
Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S. Bryant, "Deterministic Networking (DetNet) Data Plane: MPLS over UDP/IP", RFC 9025, DOI 10
.17487 , , <https:///RFC9025 www >..rfc -editor .org /info /rfc9025 - [RFC9037]
-
Varga, B., Ed., Farkas, J., Malis, A., and S. Bryant, "Deterministic Networking (DetNet) Data Plane: MPLS over IEEE 802.1 Time-Sensitive Networking (TSN)", RFC 9037, DOI 10
.17487 , , <https:///RFC9037 www >..rfc -editor .org /info /rfc9037 - [RFC9056]
-
Varga, B., Ed., Berger, L., Fedyk, D., Bryant, S., and J. Korhonen, "Deterministic Networking (DetNet) Data Plane: IP over MPLS", RFC 9056, DOI 10
.17487 , , <https:///RFC9056 www >..rfc -editor .org /info /rfc9056 - [RFC9197]
-
Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi, Ed., "Data Fields for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9197, DOI 10
.17487 , , <https:///RFC9197 www >..rfc -editor .org /info /rfc9197 - [RFC9320]
-
Finn, N., Le Boudec, J.-Y., Mohammadpour, E., Zhang, J., and B. Varga, "Deterministic Networking (DetNet) Bounded Latency", RFC 9320, DOI 10
.17487 , , <https:///RFC9320 www >..rfc -editor .org /info /rfc9320 - [RFC9546]
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Mirsky, G., Chen, M., and B. Varga, "Operations, Administration, and Maintenance (OAM) for Deterministic Networking (DetNet) with the MPLS Data Plane", RFC 9546, DOI 10
.17487 , , <https:///RFC9546 www >..rfc -editor .org /info /rfc9546 - [RFC9552]
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Talaulikar, K., Ed., "Distribution of Link-State and Traffic Engineering Information Using BGP", RFC 9552, DOI 10
.17487 , , <https:///RFC9552 www >..rfc -editor .org /info /rfc9552 - [RFC9633]
-
Geng, X., Ryoo, Y., Fedyk, D., Rahman, R., and Z. Li, "Deterministic Networking (DetNet) YANG Data Model", RFC 9633, DOI 10
.17487 , , <https:///RFC9633 www >..rfc -editor .org /info /rfc9633 - [RFC9634]
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Mirsky, G., Chen, M., and D. Black, "Operations, Administration, and Maintenance (OAM) for Deterministic Networking (DetNet) with the IP Data Plane", RFC 9634, DOI 10
.17487 , , <https:///RFC9634 www >..rfc -editor .org /info /rfc9634
Acknowledgments
Thanks to Jim Guichard, Donald Eastlake 3rd, and Stewart Bryant for their reviews and comments.¶
The authors would also like to thank Deb Cooley, Mike Bishop, Mohamed Boucadair, Gorry Fairhurst, and Dave Thaler for their comments during the different directorate and IESG reviews.¶