DetNet B. Varga, Ed. Internet-Draft J. Farkas Intended status: Standards Track Ericsson Expires: April 29, 2020 A. Malis Independent S. Bryant Futurewei Technologies D. Fedyk LabN Consulting, L.L.C. October 27, 2019 DetNet Data Plane: IEEE 802.1 Time Sensitive Networking over MPLS draft-ietf-detnet-tsn-vpn-over-mpls-01 Abstract This document specifies the Deterministic Networking data plane when TSN networks are interconnected over a DetNet MPLS Network. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 29, 2020. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. 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 and restrictions with respect to this document. Code Components extracted from this document must Varga, et al. Expires April 29, 2020 [Page 1] Internet-Draft TSN over DetNet MPLS October 2019 include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Terms Used in This Document . . . . . . . . . . . . . . . 3 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 2.3. Requirements Language . . . . . . . . . . . . . . . . . . 4 3. IEEE 802.1 TSN Over DetNet MPLS Data Plane Scenario . . . . . 4 4. DetNet MPLS Data Plane . . . . . . . . . . . . . . . . . . . 6 4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 6 4.2. TSN over DetNet MPLS Encapsulation . . . . . . . . . . . 7 5. TSN over MPLS Data Plane Procedures . . . . . . . . . . . . . 8 5.1. Edge Node TSN Procedures . . . . . . . . . . . . . . . . 8 5.2. Edge Node DetNet Service Proxy Procedures . . . . . . . . 9 5.3. Edge Node DetNet Service and Forwarding Sub-Layer Procedures . . . . . . . . . . . . . . . . . . . . . . . 9 6. Controller Plane (Management and Control) Considerations . . 10 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 10.1. Normative References . . . . . . . . . . . . . . . . . . 11 10.2. Informative References . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 1. Introduction The Time-Sensitive Networking Task Group (TSN TG) within IEEE 802.1 Working Group deals with deterministic services through IEEE 802 networks. Deterministic Networking (DetNet) defined by IETF is a service that can be offered by a L3 network to DetNet flows. General background and concepts of DetNet can be found in [I-D.ietf-detnet-architecture]. This document specifies the use of a DetNet MPLS network to interconnect TSN nodes/network segments. DetNet MPLS data plane is defined in [I-D.ietf-detnet-mpls]. Varga, et al. Expires April 29, 2020 [Page 2] Internet-Draft TSN over DetNet MPLS October 2019 2. Terminology 2.1. Terms Used in This Document This document uses the terminology and concepts established in the DetNet architecture [I-D.ietf-detnet-architecture] and [I-D.ietf-detnet-data-plane-framework], and [I-D.ietf-detnet-mpls]. The reader is assumed to be familiar with these documents and their terminology. 2.2. Abbreviations The following abbreviations are used in this document: AC Attachment Circuit. CE Customer Edge equipment. CoS Class of Service. CW Control Word. DetNet Deterministic Networking. DF DetNet Flow. FRER Frame Replication and Elimination for Redundancy (TSN function). L2 Layer 2. L2VPN Layer 2 Virtual Private Network. L3 Layer 3. LSR Label Switching Router. MPLS Multiprotocol Label Switching. MPLS-TE Multiprotocol Label Switching - Traffic Engineering. MPLS-TP Multiprotocol Label Switching - Transport Profile. MS-PW Multi-Segment PseudoWire (MS-PW). NSP Native Service Processing. OAM Operations, Administration, and Maintenance. Varga, et al. Expires April 29, 2020 [Page 3] Internet-Draft TSN over DetNet MPLS October 2019 PE Provider Edge. PEF Packet Elimination Function. PRF Packet Replication Function. PREOF Packet Replication, Elimination and Ordering Functions. POF Packet Ordering Function. PSN Packet Switched Network. PW PseudoWire. QoS Quality of Service. S-PE Switching Provider Edge. T-PE Terminating Provider Edge. TSN Time-Sensitive Network. 2.3. 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. IEEE 802.1 TSN Over DetNet MPLS Data Plane Scenario Figure 1 shows IEEE 802.1 TSN end stations operating over a TSN aware DetNet service running over an MPLS network. DetNet Edge Nodes sit at the boundary of a DetNet domain. They are responsible for mapping non-DetNet aware L2 traffic to DetNet services. They also support the imposition and disposition of the required DetNet encapsulation. These are functionally similar to pseudowire (PW) Terminating Provider Edge (T-PE) nodes which use MPLS-TE LSPs. In this example TSN Streams are simple applicaions over DetNet flows. The specific of this operation are discussed later in this document. Varga, et al. Expires April 29, 2020 [Page 4] Internet-Draft TSN over DetNet MPLS October 2019 TSN Edge Transit Edge TSN End System Node Node Node End System (T-PE) (LSR) (T-PE) +----------+ +----------+ | TSN | <---------End to End TSN Service----------> | TSN | | Applic. | | Applic. | +----------+ +.........+ +.........+ +----------+ | | | \S-Proxy: :S-Proxy/ | | | | TSN | | +.+---+<-- DetNet flow -->+---+ | | | TSN | | | |TSN| |Svc| |Svc| |TSN| | | +----------+ +---+ +---+ +----------+ +---+ +---+ +----------+ | L2 | | L2| |Fwd| |Forwarding| |Fwd| |L2 | | L2 | +------.---+ +-.-+ +-.-+ +---.----.-+ +--.+ +-.-+ +---.------+ : Link : / ,-----. \ : Link : / ,-----. \ +........+ +-[ Sub ]-+ +........+ +-[ TSN ]-+ [Network] [Network] `-----' `-----' |<------ DetNet MPLS ------>| |<---------------------- TSN --------------------->| Figure 1: A TSN over DetNet MPLS Enabled Network In this example, edge nodes provide a service proxy function that "associates" the DetNet flows and native flows (i.e., TSN Streams) at the edge of the DetNet domain. TSN streams are treated as App-flows for DetNet. The whole DetNet domain behaves as a TSN relay node for the TSN streams. The service proxy behaves as a port of that TSN relay node. Figure 2 illustrates how DetNet can provide services for IEEE 802.1 TSN end systems, CE1 and CE2, over a DetNet enabled MPLS network. Edge nodes, E1 and E2, insert and remove required DetNet data plane encapsulation. The 'X' in the edge nodes and relay node, R1, represent a potential DetNet compound flow packet replication and elimination point. This conceptually parallels L2VPN services, and could leverage existing related solutions as discussed below. Varga, et al. Expires April 29, 2020 [Page 5] Internet-Draft TSN over DetNet MPLS October 2019 TSN |<------- End to End DetNet Service ------>| TSN Service | Transit Transit | Service TSN (AC) | |<-Tnl->| |<-Tnl->| | (AC) TSN End | V V 1 V V 2 V V | End System | +--------+ +--------+ +--------+ | System +---+ | | E1 |=======| R1 |=======| E2 | | +---+ | |--|----|._X_....|..DF1..|.._ _...|..DF3..|...._X_.|---|---| | |CE1| | | \ | | X | | / | | |CE2| | | | \_.|..DF2..|._/ \_..|..DF4..|._/ | | | +---+ | |=======| |=======| | +---+ ^ +--------+ +--------+ +--------+ ^ | Edge Node Relay Node Edge Node | | (T-PE) (S-PE) (T-PE) | | | |<- TSN -> <------- TSN Over DetNet MPLS -------> <- TSN ->| | | |<-------- Time Sensitive Networking (TSN) Service ------->| X = Service protection DFx = DetNet member flow x over a TE LSP Figure 2: IEEE 802.1TSN Over DetNet 4. DetNet MPLS Data Plane 4.1. Overview The basic approach defined in [I-D.ietf-detnet-mpls] supports the DetNet service sub-layer based on existing pseudowire (PW) encapsulations and mechanisms, and supports the DetNet forwarding sub-layer based on existing MPLS Traffic Engineering encapsulations and mechanisms. A node operating on a DetNet flow in the Detnet service sub-layer, i.e. a node processing a DetNet packet which has the S-Label as top of stack uses the local context associated with that S-Label, for example a received F-Label, to determine what local DetNet operation(s) are applied to that packet. An S-Label may be unique when taken from the platform label space [RFC3031], which would enable correct DetNet flow identification regardless of which input interface or LSP the packet arrives on. The service sub-layer functions (i.e., PREOF) use a DetNet control word (d-CW). The DetNet MPLS data plane builds on MPLS Traffic Engineering encapsulations and mechanisms to provide a forwarding sub-layer that is responsible for providing resource allocation and explicit routes. Varga, et al. Expires April 29, 2020 [Page 6] Internet-Draft TSN over DetNet MPLS October 2019 The forwarding sub-layer is supported by one or more forwarding labels (F-Labels). DetNet edge/relay nodes are DetNet service sub-layer aware, understand the particular needs of DetNet flows and provide both DetNet service and forwarding sub-layer functions. They add, remove and process d-CWs, S-Labels and F-labels as needed. MPLS enabled DetNet nodes can enhance the reliability of delivery by enabling the replication of packets where multiple copies, possibly over multiple paths, are forwarded through the DetNet domain. They can also eliminate surplus previously replicated copies of DetNet packets. MPLS (DetNet) nodes also include DetNet forwarding sub-layer functions, support for notably explicit routes, and resources allocation to eliminate (or reduce) congestion loss and jitter. DetNet transit nodes reside wholly within a DetNet domain, and also provide DetNet forwarding sub-layer functions in accordance with the performance required by a DetNet flow carried over an LSP. Unlike other DetNet node types, transit nodes provide no service sub-layer processing. 4.2. TSN over DetNet MPLS Encapsulation The basic encapsulation approach is to treat a TSN Stream as an app- flow from the DetNet MPLS perspective. The corresponding example shown in Figure 3. /-> +------+ +------+ +------+ TSN ^ ^ | | X | | X | | X |<- Appli : : App-Flow <-+ +------+ +------+ +------+ cation : :(1) for MPLS | |TSN-L2| |TSN-L2| |TSN-L2| : v \-> +---+======+--+======+--+======+-----+ : | d-CW | | d-CW | | d-CW | : DetNet-MPLS +------+ +------+ +------+ :(2) |Labels| |Labels| |Labels| v +---+======+--+======+--+======+-----+ Link/Sub-Network | L2 | | TSN | | UDP | +------+ +------+ +------+ | IP | +------+ | L2 | +------+ (1) TSN Stream (2) DetNet MPLS Flow Figure 3: Example TSN over MPLS Encapsulation Formats Varga, et al. Expires April 29, 2020 [Page 7] Internet-Draft TSN over DetNet MPLS October 2019 In the figure, "Application" indicates the application payload carried by the TSN network. "MPLS App-Flow" indicates that the TSN Stream is the payload from the perspective of the DetNet MPLS data plane defined in [I-D.ietf-detnet-mpls]. A single DetNet MPLS flow can aggregate multiple TSN Streams. 5. TSN over MPLS Data Plane Procedures Description of Edge Nodes procedures and functions for TSN over DetNet MPLS scenario follows the concept of [RFC3985] and covers the Edge Nodes components shown on Figure 1. In this section the following procedures of DetNet Edge Nodes are described: o TSN related (Section 5.1) o DetNet Service Proxy (Section 5.2) o DetNet service and forwarding sub-layer (Section 5.3) 5.1. Edge Node TSN Procedures The Time-Sensitive Networking (TSN) Task Group of the IEEE 802.1 Working Group have defined (and are defining) a number of amendments to IEEE 802.1Q [IEEE8021Q] that provide zero congestion loss and bounded latency in bridged networks. IEEE 802.1CB [IEEE8021CB] defines packet replication and elimination functions for a TSN network. TSN specific functions are executed on the data received by the PE from the CE before presentation to the DetNet PW for transmission across the DetNet domain, or on the data received from a DetNet PW by a PE before it is output on the Attachment Circuit (AC). TSN specific function(s) of Edge Nodes (T-PE) are belonging to the native service processing (NSP) [RFC3985] block. This is similar to other functionalities being defined by standard bodies other than the IETF (for example in case of Ethernet: stripping, overwriting or adding VLAN tags, etc.). Depending on the TSN role of the Edge Node in the end-to-end TSN service selected TSN functions must be supported. Implementations of this document SHALL use management and control information to ensure TSN specific functions of the Edge Node according to the expectations of the connected TSN network. Varga, et al. Expires April 29, 2020 [Page 8] Internet-Draft TSN over DetNet MPLS October 2019 5.2. Edge Node DetNet Service Proxy Procedures The Service Proxy function maps between App-flows and DetNet flows. The DetNet Edge Node TSN function MUST support the TSN Stream identification functions and the related managed objects as defined in IEEE 802.1CB [IEEE8021CB] and IEEE P802.1CBdb [IEEEP8021CBdb] to recognize the App-flow related packets. The Service Proxy presents TSN Streams as an App-flow to a DetNet Flow. Implementations of this document SHALL use management and control information to map a TSN Stream to a DetNet flow. N:1 mapping (aggregating multiple TSN Streams in a single DetNet flow) SHALL be supported. The management or control function that provisions flow mapping SHALL ensure that adequate resources are allocated and configured to provide proper service requirements of the mapped flows. Due to the (intentional) similarities of the DetNet PREOF and TSN FRER functions service protection function interworking is possible between the TSN and the DetNet domains. Such service protection interworking scenarios MAY require to copy sequence number fields from TSN (L2) to PW (MPLS) encapsulation. However, such interworking is out-of-scope in this document and left for further study. A MPLS DetNet flow is configured to carry any number of TSN flows. The DetNet flow specific bandwidth profile SHOULD match the required bandwidth of the App-flow aggregate. 5.3. Edge Node DetNet Service and Forwarding Sub-Layer Procedures In the design of [I-D.ietf-detnet-mpls] an MPLS service label (the S-Label), similar to a pseudowire (PW) label [RFC3985], is used to identify both the DetNet flow identity and the payload MPLS payload type. The DetNet sequence number is carried in the DetNet Control word (d-CW) which carries the Data/OAM discriminator as well. In [I-D.ietf-detnet-mpls] two sequence number sizes are supported: a 16 bit sequence number and a 28 bit sequence number. PREOF functions and the provided service recovery is available only within the DetNet domain as the DetNet flow-ID and the DetNet sequence number are not valid outside the DetNet network. MPLS (DetNet) Edge node terminates all related information elements encoded in the MPLS labels. The LSP used to forward the DetNet packet may be of any type (MPLS- LDP, MPLS-TE, MPLS-TP [RFC5921], or MPLS-SR [I-D.ietf-spring-segment-routing-mpls]). The LSP (F-Label) label Varga, et al. Expires April 29, 2020 [Page 9] Internet-Draft TSN over DetNet MPLS October 2019 and/or the S-Label may be used to indicate the queue processing as well as the forwarding parameters. For further details see [I-D.ietf-detnet-mpls]. 6. Controller Plane (Management and Control) Considerations TSN Stream(s) to DetNet flow mapping related information are required only for the service proxy function of MPLS (DetNet) Edge nodes. From the Data Plane perspective there is no practical difference based on the origin of flow mapping related information (management plane or control plane). MPLS DetNet Edge nodes are member of both the DetNet domain and the connected TSN network. From the TSN network perspective the MPLS (DetNet) Edge node has a "TSN relay node" role, so TSN specific management and control plane functionalities must be implemented. There are many similarities in the management plane techniques used in DetNet and TSN, but that is not the case for the control plane protocols. For example, RSVP-TE and MSRP behaves differently. Therefore management and control plane design is an important aspect of scenarios, where mapping between DetNet and TSN is required. Note that, as the DetNet network is just a portion of the end to end TSN path (i.e., single hop from Ethernet perspective), some parameters (e.g., delay) may differ significantly. Since there is no interworking function the bandwidth of DetNet network is assumed to be set large enough to handle all TSN Flows it will support. At the egress of the Detnet Domain the MPLS headers are stripped and the TSN flow continues on as a normal TSN flow. In order to use a DetNet network to interconnect TSN segments, TSN specific information must be converted to DetNet domain specific ones. TSN Stream ID(s) and stream(s) related parameters/requirements must be converted to a DetNet flow-ID and flow related parameters/ requirements. In some case it may be challenging to determine some egress node related information. For example, it may be not trivial to locate the egress point/interface of a TSN Streams with a multicast destination MAC address. Such scenarios may require interaction between control and management plane functions and between DetNet and TSN domains. Mapping between DetNet flow identifiers and TSN Stream identifiers, if not provided explicitly, can be done by the service proxy function of an MPLS (DetNet) Edge node locally based on information provided Varga, et al. Expires April 29, 2020 [Page 10] Internet-Draft TSN over DetNet MPLS October 2019 for configuration of the TSN Stream identification functions (e.g., Mask-and-Match Stream identification). Triggering the setup/modification of a DetNet flow in the DetNet network is an example where management and/or control plane interactions are required between the DetNet and the TSN network. Configuration of TSN specific functions (e.g., FRER) inside the TSN network is a TSN domain specific decision and may not be visible in the DetNet domain. Service protection interworking scenarios are left for further study. 7. Security Considerations Security considerations for DetNet are described in detail in [I-D.ietf-detnet-security]. General security considerations are described in [I-D.ietf-detnet-architecture]. DetNet MPLS data plane specific considerations are summarized in [I-D.ietf-detnet-mpls]. The primary considerations for the data plane is to maintain integrity of data and delivery of the associated DetNet service traversing the DetNet network. Application flows can be protected through whatever means is provided by the underlying technology. For example, encryption may be used, such as that provided by IPSec [RFC4301] for IP flows and/or by an underlying sub-net using MACSec [IEEE802.1AE-2018] for IP over Ethernet (Layer-2) flows. 8. IANA Considerations This document makes no IANA requests. 9. Acknowledgements The authors wish to thank Norman Finn, Lou Berger, Craig Gunther, Christophe Mangin and Jouni Korhonen for their various contributions to this work. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Varga, et al. Expires April 29, 2020 [Page 11] Internet-Draft TSN over DetNet MPLS October 2019 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, DOI 10.17487/RFC3031, January 2001, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 10.2. Informative References [I-D.ietf-detnet-architecture] Finn, N., Thubert, P., Varga, B., and J. Farkas, "Deterministic Networking Architecture", draft-ietf- detnet-architecture-13 (work in progress), May 2019. [I-D.ietf-detnet-data-plane-framework] Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A., Bryant, S., and J. Korhonen, "DetNet Data Plane Framework", draft-ietf-detnet-data-plane-framework-02 (work in progress), September 2019. [I-D.ietf-detnet-mpls] Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A., Bryant, S., and J. Korhonen, "DetNet Data Plane: MPLS", draft-ietf-detnet-mpls-01 (work in progress), July 2019. [I-D.ietf-detnet-security] Mizrahi, T., Grossman, E., Hacker, A., Das, S., Dowdell, J., Austad, H., Stanton, K., and N. Finn, "Deterministic Networking (DetNet) Security Considerations", draft-ietf- detnet-security-05 (work in progress), August 2019. [I-D.ietf-spring-segment-routing-mpls] Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing with MPLS data plane", draft-ietf-spring-segment-routing-mpls-22 (work in progress), May 2019. [IEEE802.1AE-2018] IEEE Standards Association, "IEEE Std 802.1AE-2018 MAC Security (MACsec)", 2018, . Varga, et al. Expires April 29, 2020 [Page 12] Internet-Draft TSN over DetNet MPLS October 2019 [IEEE8021CB] Finn, N., "Draft Standard for Local and metropolitan area networks - Seamless Redundancy", IEEE P802.1CB /D2.1 P802.1CB, December 2015, . [IEEE8021Q] IEEE 802.1, "Standard for Local and metropolitan area networks--Bridges and Bridged Networks (IEEE Std 802.1Q- 2014)", 2014, . [IEEEP8021CBdb] Mangin, C., "Extended Stream identification functions", IEEE P802.1CBdb /D0.2 P802.1CBdb, August 2019, . [RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, DOI 10.17487/RFC3985, March 2005, . [RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, December 2005, . [RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau, L., and L. Berger, "A Framework for MPLS in Transport Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010, . Authors' Addresses Balazs Varga (editor) Ericsson Magyar Tudosok krt. 11. Budapest 1117 Hungary Email: balazs.a.varga@ericsson.com Varga, et al. Expires April 29, 2020 [Page 13] Internet-Draft TSN over DetNet MPLS October 2019 Janos Farkas Ericsson Magyar Tudosok krt. 11. Budapest 1117 Hungary Email: janos.farkas@ericsson.com Andrew G. Malis Independent Email: agmalis@gmail.com Stewart Bryant Futurewei Technologies Email: stewart.bryant@gmail.com Don Fedyk LabN Consulting, L.L.C. Email: dfedyk@labn.net Varga, et al. Expires April 29, 2020 [Page 14]