



Internet Engineering Task Force (IETF)                         G. Mirsky
Request for Comments: 9634                                      Ericsson
Category: Informational                                          M. Chen
ISSN: 2070-1721                                                   Huawei
                                                                D. Black
                                                                Dell EMC
                                                            October 2024


  Operations, Administration, and Maintenance (OAM) for Deterministic
               Networking (DetNet) with the IP Data Plane

Abstract

   This document discusses the use of existing IP Operations,
   Administration, and Maintenance protocols and mechanisms in
   Deterministic Networking networks that use the IP data plane.

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.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9634.

Copyright Notice

   Copyright (c) 2024 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
   include Revised BSD License text as described in Section 4.e of the
   Trust Legal Provisions and are provided without warranty as described
   in the Revised BSD License.

Table of Contents

   1.  Introduction
   2.  Conventions Used in This Document
     2.1.  Terminology
   3.  Active OAM for DetNet Networks with the IP Data Plane
     3.1.  Mapping Active OAM and IP DetNet Flows
     3.2.  Active OAM Using IP-in-UDP Encapsulation
     3.3.  Active OAM Using DetNet-in-UDP Encapsulation
     3.4.  The Application of Y.1731/G.8013 Using GRE-in-UDP
           Encapsulation
   4.  Active OAM for DetNet IP Interworking with OAM for Non-IP
           DetNet Domains
   5.  IANA Considerations
   6.  Security Considerations
   7.  References
     7.1.  Normative References
     7.2.  Informative References
   Authors' Addresses

1.  Introduction

   [RFC8655] introduces and explains the Deterministic Networking
   (DetNet) architecture.

   Operations, Administration, and Maintenance (OAM) protocols are used
   to detect and localize defects in the network as well as to monitor
   network performance.  Some OAM functions (e.g., failure detection)
   work in the network proactively, while others (e.g., defect
   localization) are usually performed on demand.  These tasks are
   achieved by a combination of active and hybrid OAM methods, as
   defined in [RFC7799].

   [RFC9551] lists the OAM functional requirements for DetNet and
   defines the principles for OAM use within DetNet networks utilizing
   the IP data plane.  The functional requirements can be compared
   against current OAM tools to identify gaps and potential enhancements
   required to enable proactive and on-demand path monitoring and
   service validation.

   This document discusses the use of existing IP OAM protocols and
   mechanisms in DetNet networks that use the IP data plane.

2.  Conventions Used in This Document

2.1.  Terminology

   The term "DetNet OAM" as used in this document means "a set of OAM
   protocols, methods, and tools for Deterministic Networking".

   DetNet:  Deterministic Networking

   OAM:  Operations, Administration, and Maintenance

   ICMP:  Internet Control Message Protocol

   Underlay Network or Underlay Layer:  The network that provides
      connectivity between DetNet nodes.  MPLS networks providing Label
      Switched Path (LSP) connectivity between DetNet nodes are an
      example of the DetNet IP network underlay layer.

   DetNet Node:  A node that is an actor in the DetNet domain.  DetNet
      domain edge nodes and nodes that perform the Packet Replication,
      Elimination, and Ordering Functions within the domain are examples
      of a DetNet node.

3.  Active OAM for DetNet Networks with the IP Data Plane

   OAM protocols and mechanisms act within the data plane of the
   particular networking layer.  Thus, it is critical that the data
   plane encapsulation support OAM mechanisms and enable them to be
   configured so that DetNet OAM packets follow the same path
   (unidirectional or bidirectional) through the network and receive the
   same forwarding treatment in the DetNet forwarding sub-layer as the
   DetNet flow being monitored.

   The DetNet data plane encapsulation in a transport network with IP
   encapsulations is specified in Section 6 of [RFC8939].  For the IP
   underlay network, DetNet flows are identified by the ordered match to
   the provisioned information set that, among other elements, includes
   the IP protocol type, source port number, and destination port
   number.  Active IP OAM protocols like Bidirectional Forwarding
   Detection (BFD) [RFC5880] or the Simple Two-way Active Measurement
   Protocol (STAMP) [RFC8762] use UDP transport and the well-known UDP
   port numbers as the respective destination ports.  For BFD, the UDP
   destination port is specific to the BFD variant, e.g., multihop BFD
   uses port 4784 [RFC5883].

   Thus, a DetNet node must be able to associate an IP DetNet flow with
   the particular test session to ensure that test packets experience
   the same treatment as the DetNet flow packets.  For example, in a
   network where path selection and DetNet functionality are based on
   3-tuples (destination and source IP addresses in combination with the
   Differentiated Services Code Point value), that association can be
   achieved by having the OAM traffic use the same 3-tuple as the
   monitored IP DetNet flow.  In such a scenario, an IP OAM session
   between the same pair of IP nodes would share the network treatment
   with the monitored IP DetNet flow regardless of whether ICMP, BFD, or
   STAMP is used.

   In IP networks, the majority of on-demand failure detection and
   localization is achieved through the use of ICMP, utilizing Echo
   Request and Echo Reply messages, along with a set of defined error
   messages such as Destination Unreachable, which provide detailed
   information through assigned code points.  [RFC0792] and [RFC4443]
   define ICMP for IPv4 and IPv6 networks, respectively.  To utilize
   ICMP effectively for these purposes within DetNet, DetNet nodes must
   establish the association of ICMP traffic between DetNet nodes with
   IP DetNet traffic.  This entails ensuring that such ICMP traffic
   traverses the same interfaces and receives QoS treatment that is
   identical to the monitored DetNet IP flow.  Failure to do so may
   result in ICMP being unable to detect and localize failures specific
   to the DetNet IP data plane.

3.1.  Mapping Active OAM and IP DetNet Flows

   IP OAM protocols are used to detect failures (e.g., BFD [RFC5880])
   and performance degradation (e.g., STAMP [RFC8762]) that affect an IP
   DetNet flow.  For active OAM to be useful, it is essential to ensure
   that specially constructed OAM packets traverse the same set of nodes
   and links and receive the same network QoS treatment as the monitored
   data flow, e.g., a DetNet flow.  When the UDP destination port number
   used by the OAM protocol is assigned by IANA, judicious selection of
   the UDP source port may help achieve co-routedness of OAM with the
   monitored IP DetNet flow in multipath environments, e.g., Link
   Aggregation Group or Equal Cost Multipath, via the use of a UDP
   source port value that results in the OAM traffic and the monitored
   IP DetNet flow hashing to the same path based on the packet header
   hashes used for path selection.  This does assume that forwarding
   equipment along the multipath makes consistent hashing decisions,
   which might not always be true in a heterogeneous environment.  (That
   also applies to the encapsulation techniques described in
   Sections 3.2 and 3.3.)  To ensure the accuracy of OAM results in
   detecting failures and monitoring the performance of IP DetNet, it is
   essential that test packets not only traverse the same path as the
   monitored IP DetNet flow but also receive the same treatment by the
   nodes, e.g., shaping, filtering, policing, and availability of the
   pre-allocated resources, as experienced by the IP DetNet packet.
   That correlation between the particular IP OAM session and the
   monitored IP DetNet flow can be achieved by using DetNet provisioning
   information (e.g., [RFC9633]).  Each IP OAM protocol session is
   presented as a DetNet application with related service and forwarding
   sub-layers.  The forwarding sub-layer of the IP OAM session is
   identical to the forwarding sub-layer of the monitored IP DetNet
   flow, except for information in the "ip-header" grouping item as
   defined in [RFC9633].

3.2.  Active OAM Using IP-in-UDP Encapsulation

   As described above, active IP OAM is realized through several
   protocols.  Some protocols use UDP transport, while ICMP is a
   network-layer protocol.  The amount of operational work mapping IP
   OAM protocols to the monitored DetNet flow can be reduced by using an
   IP/UDP tunnel [RFC2003] to carry IP test packets.  Then, to ensure
   that OAM packets traverse the same set of nodes and links, the IP/UDP
   tunnel must be mapped to the monitored DetNet flow.  Note that in
   such a case, the DetNet domain for the test packet is seen as a
   single IP link.  As a result, transit DetNet IP nodes cannot be
   traced using the usual traceroute procedure, and a modification of
   the traceroute may be required.

3.3.  Active OAM Using DetNet-in-UDP Encapsulation

   Active OAM in IP DetNet can be realized using DetNet-in-UDP
   encapsulation.  Using a DetNet-in-UDP tunnel between IP DetNet nodes
   ensures that active OAM test packets follow the same path through the
   network as the monitored IP DetNet flow packets and receive the same
   forwarding treatment in the DetNet forwarding sub-layer (see
   Section 4.1.2 of [RFC8655]) as the IP DetNet flow being monitored.

   [RFC9566] describes how DetNet with the MPLS-over-UDP/IP data plane
   [RFC9025] can be used to support Packet Replication, Elimination, and
   Ordering Functions (PREOF) to potentially lower packet loss, improve
   the probability of on-time packet delivery, and ensure in-order
   packet delivery in IP DetNet's service sub-layer.  To ensure that an
   active OAM test packet follows the path of the monitored DetNet flow
   in the DetNet service sub-layer, the encapsulation shown in Figure 1
   is used.

         +---------------------------------+
         |                                 |
         |         DetNet App-Flow         |
         |       (original IP) Packet      |
         |                                 |
         +---------------------------------+ <--\
         |            DetNet ACH           |    |
         +---------------------------------+    +--> PREOF-capable
         |       Service-ID (S-Label)      |    |    DetNet IP data
         +---------------------------------+    |    plane encapsulation
         |            UDP Header           |    |
         +---------------------------------+    |
         |            IP Header            |    |
         +---------------------------------+ <--/
         |            Data-Link            |
         +---------------------------------+
         |             Physical            |
         +---------------------------------+

             Figure 1: DetNet Associated Channel Header Format

   *  DetNet ACH - the DetNet Associated Channel Header as defined in
      [RFC9546].

   *  PREOF - Packet Replication, Elimination, and Ordering Functions
      used in the DetNet service sub-layer as defined in [RFC8655].

3.4.  The Application of Y.1731/G.8013 Using GRE-in-UDP Encapsulation

   [RFC8086] has defined the method of encapsulating GRE (Generic
   Routing Encapsulation) headers in UDP.  GRE-in-UDP encapsulation can
   be used for IP DetNet OAM, as it eases the task of mapping an OAM
   test session to a particular IP DetNet flow that is identified by an
   N-tuple.  Matching a GRE-in-UDP tunnel to the monitored IP DetNet
   flow enables the use of Y.1731/G.8013 [ITU.Y1731] as a comprehensive
   toolset of OAM.  The Protocol Type field in the GRE header must be
   set to 0x8902, assigned by IANA to the IEEE 802.1ag Connectivity
   Fault Management (CFM) protocol / ITU-T Recommendation Y.1731.
   Y.1731/G.8013 supports the necessary functions required for IP DetNet
   OAM, i.e., continuity checks, one-way packet loss, and packet delay
   measurements.

4.  Active OAM for DetNet IP Interworking with OAM for Non-IP DetNet
    Domains

   A domain in which the IP data plane provides DetNet service could be
   used in conjunction with a Time-Sensitive Networking (TSN) network
   and a DetNet domain with the MPLS data plane to deliver end-to-end
   service.  In such scenarios, the ability to detect defects and
   monitor performance using OAM is essential.  [RFC9546] identifies two
   OAM interworking models -- peering and tunneling.  Interworking
   between DetNet domains with IP and MPLS data planes is analyzed in
   Section 4.2 of [RFC9546].  In addition, OAM interworking requirements
   and recommendations that apply between a DetNet domain with the MPLS
   data plane and an adjacent TSN network also apply between a DetNet
   domain with the IP data plane and an adjacent TSN network.

5.  IANA Considerations

   This document has no IANA actions.

6.  Security Considerations

   This document describes the applicability of the existing Fault
   Management and Performance Monitoring IP OAM protocols.  It does not
   raise any security concerns or issues in addition to those common to
   networking or already documented in [RFC0792], [RFC4443], [RFC5880],
   and [RFC8762] for the referenced DetNet and OAM protocols.

7.  References

7.1.  Normative References

   [RFC0792]  Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981,
              <https://www.rfc-editor.org/info/rfc792>.

   [RFC2003]  Perkins, C., "IP Encapsulation within IP", RFC 2003,
              DOI 10.17487/RFC2003, October 1996,
              <https://www.rfc-editor.org/info/rfc2003>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/info/rfc4443>.

   [RFC8086]  Yong, L., Ed., Crabbe, E., Xu, X., and T. Herbert, "GRE-
              in-UDP Encapsulation", RFC 8086, DOI 10.17487/RFC8086,
              March 2017, <https://www.rfc-editor.org/info/rfc8086>.

   [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>.

   [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>.

   [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/RFC9025, April
              2021, <https://www.rfc-editor.org/info/rfc9025>.

   [RFC9546]  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/RFC9546, February 2024,
              <https://www.rfc-editor.org/info/rfc9546>.

   [RFC9633]  Geng, X., Ryoo, Y., Fedyk, D., Rahman, R., and Z. Li,
              "Deterministic Networking (DetNet) YANG Data Model",
              RFC 9633, DOI 10.17487/RFC9633, October 2024,
              <https://www.rfc-editor.org/info/rfc9633>.

7.2.  Informative References

   [ITU.Y1731]
              ITU-T, "Operation, administration and maintenance (OAM)
              functions and mechanisms for Ethernet-based networks",
              ITU-T Recommendation G.8013/Y.1731, June 2023.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5883]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883,
              June 2010, <https://www.rfc-editor.org/info/rfc5883>.

   [RFC7799]  Morton, A., "Active and Passive Metrics and Methods (with
              Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
              May 2016, <https://www.rfc-editor.org/info/rfc7799>.

   [RFC8762]  Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
              Two-Way Active Measurement Protocol", RFC 8762,
              DOI 10.17487/RFC8762, March 2020,
              <https://www.rfc-editor.org/info/rfc8762>.

   [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/RFC9551,
              March 2024, <https://www.rfc-editor.org/info/rfc9551>.

   [RFC9566]  Varga, B., Farkas, J., and A. Malis, "Deterministic
              Networking (DetNet) Packet Replication, Elimination, and
              Ordering Functions (PREOF) via MPLS over UDP/IP",
              RFC 9566, DOI 10.17487/RFC9566, April 2024,
              <https://www.rfc-editor.org/info/rfc9566>.

Authors' Addresses

   Greg Mirsky
   Ericsson
   Email: gregimirsky@gmail.com


   Mach(Guoyi) Chen
   Huawei
   Email: mach.chen@huawei.com


   David Black
   Dell EMC
   176 South Street
   Hopkinton, MA 01748
   United States of America
   Email: david.black@dell.com
