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

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Table of Contents

1. Introduction

[RFC8655] introduces and explains Deterministic Networks (DetNet) architecture.¶

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

[I-D.tpmb-detnet-oam-framework] lists the functional requirements toward OAM for DetNet domain. The list can further be used for gap analysis of available OAM tools to identify possible enhancements of existing or whether new OAM tools are required to support proactive and on-demand path monitoring and service validation. Also, the document defines the OAM use principals for the DetNet networks with the IP data plane.¶

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. And thus it is critical that the data plane encapsulation supports OAM mechanisms in such a way that DetNet OAM packets are in-band with a DetNet flow being monitored, i.e., DetNet OAM test packets follow precisely the same path as DetNet data plane traffic both for unidirectional and bi-directional DetNet paths.¶

The DetNet data plane encapsulation in a transport network with IP encapsulations 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, source port number, destination port number. Active IP OAM protocols like Bidirectional Forwarding Detection (BFD) [RFC5880] or Simple Two-way Active Measurement Protocol (STAMP) [RFC8762], use UDP transport and the well-known UDP port numbers as the destination port. 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, that can be achieved with a 3-tuple (destination and source IP addresses in combination with DSCP value) used to identify the 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 protocol is used.¶

Most of on-demand failure detection and localization in IP networks is being done by using the Internet Control Message Protocol (ICMP) Echo Request, Echo Reply and the set of defined error messages, e.g., Destination Unreachable, with the more detailed information provided through code points. [RFC0792] and [RFC4443] define the ICMP for IPv4 and IPv6 networks, respectively. Because ICMP is another IP protocol like, for example, UDP, a DetNet node MUST able to associate an ICMP packet generated by the specified IP DetNet node and addressed to the another IP DetnNet node with an IP DetNet flow between this pair of endpoints.¶

      +---------------------------------+
      |                                 |
      |         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            |
      +---------------------------------+

4. Active OAM for DetNet IP Interworking with OAM of non-IP DetNet domains

A domain in which IP data plane provides DetNet service could be used in conjunction with a TSN and a DetNet domain with MPLS data plane to deliver end-to-end service. In such scenarios, the ability to detect defects and monitor performance using OAM is essential. [I-D.ietf-detnet-mpls-oam] identified two OAM interworking models - peering and tunneling. Interworking between DetNet domains with IP and MPLS data planes analyzed in Section 6.2 of [I-D.ietf-detnet-mpls-oam]. Also, requirements and recommendations for OAM interworking between a DetNet domain with MPLS data plane and OAM of a TSN equally apply to a DetNet domain with an IP data plane.¶

5. IANA Considerations

This document does not have any requests for IANA allocation. This section can be deleted before the publication of the draft.¶

6. Security Considerations

This document describes the applicability of the existing Fault Management and Performance Monitoring IP OAM protocols, and does not raise any security concerns or issues in addition to ones common to networking or already documented for the referenced DetNet and OAM protocols.¶

7. Acknowledgment

TBA¶

Authors' Addresses