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US-12621230-B2 - Time-sensitive network (TSN) node and method of operation

US12621230B2US 12621230 B2US12621230 B2US 12621230B2US-12621230-B2

Abstract

Embodiments include methods performed by a time-sensitive network (TSN) node configured for frame replication and elimination for reliability (FRER). Such methods include receiving a plurality of member streams via a corresponding plurality (n) of disjoint paths in the TSN. Each member stream includes a replication of packets comprising a stream. Such methods include performing the following diagnostics on the received member streams: a first group of diagnostics related to member stream failures, a second group of diagnostics related to packets received out-of-window, a third group of diagnostics related to stream outages, and a fourth group of diagnostics related to recovery timeouts for the TSN node. Other embodiments include TSN nodes configured to perform such methods.

Inventors

  • Balázs Varga
  • Ferenc Fejes
  • János Farkas
  • György Miklós

Assignees

  • TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

Dates

Publication Date
20260505
Application Date
20230322

Claims (20)

  1. 1 . A method performed by a time-sensitive network (TSN) node configured for frame replication and elimination for reliability (FRER), the method comprising: receiving a plurality of member streams via a corresponding plurality (n) of disjoint paths in the TSN, wherein each member stream includes a replication of packets comprising a stream; and performing the following diagnostics on the received member streams: a first group of diagnostics related to member stream failures, a second group of diagnostics related to packets received out-of-window, a third group of diagnostics related to stream outages, and a fourth group of diagnostics related to recovery timeouts for the TSN node, wherein the first, second, and third groups of diagnostics are performed on the received member streams during each of a plurality of consecutive analysis periods and one or more of the following applies: performing the first group of diagnostics for each analysis period comprises determining a number of packets retained and a number of duplicate packets discarded during each analysis period; and each packet includes a sequence number and the TSN node is configured with a lost packets counter and a history window indicating a range of consecutive packet sequence numbers, based on which the second group of diagnostics are performed.
  2. 2 . The method of claim 1 , further comprising, for each packet comprising the stream, retaining the packet received on one of the member streams and discarding duplicates of the packet received on other of the member streams.
  3. 3 . The method of claim 1 , wherein performing the first group of diagnostics for each analysis period further comprises, when the number of duplicate packets discarded during an analysis period is at least a configured threshold amount less than ((n minus 1) times the number of packets retained during the analysis period), entering a packet loss state and generating one or more of the following: a first error signal (SIGNAL_PACKET_ ABSENT) indicating detection of packet loss in one or more member streams; a second error signal (SIGNAL_DYSFUNCTIONAL_PATHS) indicating a number of dysfunctional paths; and a third error signal (SIGNAL_LATENT_ ERROR) indicating the packet loss state.
  4. 4 . The method of claim 3 , wherein the number of dysfunctional paths, indicated by the second error signal, is based on a ratio between the following during the analysis period: the number of duplicate packets discarded, and the number of packets retained.
  5. 5 . The method of claim 3 , wherein performing the first group of diagnostics for each analysis period further comprises exiting the packet loss state and entering a normal state of operation when the number of duplicate packets discarded during a subsequent analysis period is no longer at least the configured threshold amount less than ((n minus 1) times the number of packets retained during the subsequent analysis period).
  6. 6 . The method of claim 1 , wherein performing the first group of diagnostics for each analysis period further comprises generating a fourth error signal (SIGNAL_MORE_PACKETS_THAN_EXPECTED) and entering a too-many-packets-received state, when the number of packets retained during an analysis period is at least a configured threshold amount greater than an expected number of packets retained during the analysis period.
  7. 7 . The method of claim 6 , wherein the fourth error signal (SIGNAL_MORE_PACKETS_THAN_EXPECTED) includes an indication of how many packets more than the expected number of packets were retained, as a percentage of number of expected packets from each member stream during the analysis period.
  8. 8 . The method of claim 1 , wherein performing the second group of diagnostics for each analysis period comprises generating a fifth error signal (SIGNAL_OUTOFWINDOW_PACKETS) when one or more packets retained, during an analysis period, have respective sequence numbers outside of the history window.
  9. 9 . The method of claim 8 , wherein: the TSN node is configured with a rogue packet counter, which is incremented by a number of packets with sequence numbers outside of the history window that are retained during each analysis period; and the fifth error signal (SIGNAL_OUTOFWINDOW_PACKETS) is generated when a value of the rogue packet counter for an analysis period is greater than a previous value of the rogue packet counter for a most recent analysis period.
  10. 10 . The method of claim 9 , wherein the fifth error signal (SIGNAL_OUTOFWINDOW_PACKETS) includes the value of the rogue packet counter for the analysis period.
  11. 11 . The method of claim 1 , wherein performing the third group of diagnostics for each analysis period comprises refraining from incrementing the lost packets counter for up to (size of the history window minus 1) consecutive lost packets immediately after a reset of the TSN node.
  12. 12 . The method of claim 1 , wherein: the TSN node is configured with a consecutive lost packets counter; and performing the third group of diagnostics for each analysis period comprises: incrementing the lost packets counter for each packet expected based on the history window but not received; incrementing the consecutive lost packets counter according to a number of consecutive expected packets that are not received; resetting the lost packets counter to zero at the end of each analysis period; and resetting the consecutive lost packets counter to zero when a packet expected based on the history window is received.
  13. 13 . The method of claim 12 , wherein performing the third group of diagnostics for each analysis period further comprises, when a value of the consecutive lost packets counter is greater than a maximum consecutive lost packets for an analysis period, storing the value of the consecutive lost packets counter as the maximum consecutive lost packets for the analysis period.
  14. 14 . The method of claim 13 , wherein performing the third group of diagnostics for each analysis period further comprises generating a sixth error signal (SIGNAL_STREAM_LOSS) when the maximum consecutive lost packets for the analysis period is greater than a configurable threshold amount.
  15. 15 . The method of claim 14 , wherein the sixth error signal (SIGNAL_STREAM_LOSS) includes the following for the analysis period: the maximum consecutive lost packets, and a total number of lost packets as indicated by the lost packets counter.
  16. 16 . The method of claim 1 , wherein performing the fourth group of diagnostics comprises detecting a recovery timeout event associated with the TSN node and generating a seventh error signal (SIGNAL_RECOVERY_TIMEOUT) indicating the recovery timeout.
  17. 17 . A time-sensitive network (TSN) node configured for frame replication and elimination for reliability (FRER), the TSN node comprising: communication interface circuitry configured to communicate with one or more other TSN nodes; and processing circuitry operably coupled to the communication interface circuitry, wherein the processing circuitry and the communication interface circuitry are configured to: receive a plurality of member streams via a corresponding plurality (n) of disjoint paths in the TSN, wherein each member stream includes a replication of packets comprising a stream; and perform the following diagnostics on the received member streams: a first group of diagnostics related to member stream failures, a second group of diagnostics related to packets received out-of-window, a third group of diagnostics related to stream outages, and a fourth group of diagnostics related to recovery timeouts for the TSN node, wherein the first, second, and third groups of diagnostics are performed on the received member streams during each of a plurality of consecutive analysis periods and one or more of the following applies: the first group of diagnostics are performed for each analysis period based on determining a number of packets retained and a number of duplicate packets discarded during each analysis period; and the TSN node is configured with a lost packets counter and a history window indicating a range of consecutive packet sequence numbers, based on which the second group of diagnostics are performed.
  18. 18 . The TSN node of claim 17 , wherein the processing circuitry and the communication interface circuitry are further configured to, for each packet comprising the stream, retain the packet received on one of the member streams and discard duplicates of the packet received on other of the member streams.
  19. 19 . The TSN node of claim 17 , wherein the processing circuitry and the communication interface circuitry are configured to perform the third group of diagnostics for each analysis period based on refraining from incrementing the lost packets counter for up to (size of the history window minus 1) consecutive lost packets immediately after a reset of the TSN node.
  20. 20 . The TSN node of claim 17 , wherein the processing circuitry and the communication interface circuitry are configured to perform the fourth group of diagnostics based on detecting a recovery timeout event associated with the TSN node and generating a seventh error signal (SIGNAL_RECOVERY_TIMEOUT) indicating the recovery timeout.

Description

TECHNICAL FIELD The present disclosure relates generally to the field of wireless networks and more specifically to improved diagnostics for errors or other conditions that can occur in time-sensitive network (TSN) nodes configured for frame replication and elimination for reliability (FRER). BACKGROUND Industry 4.0 is a term used to refer to a current trend of automation and data exchange in manufacturing. It can include concepts and/or technologies such as cyber-physical systems, the Internet of things (IoT), cloud computing, and cognitive computing. Industry 4.0 is also referred to as the fourth industrial revolution or “I4.0” for short. One scenario or use case for Industry 4.0 is the so-called “smart factory,” which is also referred to as Industrial Internet of Things (IIoT). There are four common principles associated with Industry 4.0. First, “interoperability” requires the ability to connect machines, devices, sensors, and people to communicate with each other via the Internet of Things (IoT) or the Internet of People (IoP). Second, “information transparency” requires information systems to have the ability to create a virtual copy of the physical world by enriching digital models (e.g., of a smart factory) actual with sensor data. For example, this can require the ability to aggregate raw sensor data to higher-value context information. Third, “technical assistance” requires assistance systems to be able to support humans by aggregating and visualizing information comprehensively for making informed decisions and solving urgent problems on short notice. This principle can also refer to the ability of cyber physical systems to physically support humans by conducting a range of tasks that are unpleasant, too exhausting, or unsafe for their human co-workers. Finally, cyber physical systems should have the ability to make decentralized decisions and to perform their tasks as autonomously as possible. In other words, only in the case of exceptions, interferences, or conflicting goals, should tasks be delegated to a higher level. These principles associated with Industry 4.0 support various use cases that place many requirements on a network infrastructure. Simpler use cases include plant measurement while more complex use cases include precise motion control in a robotized factory cell. To address these requirements, the IEEE 802.1 working group (particularly, task group TSN) has developed a Time Sensitive Networking (TSN) standard. TSN is based on the IEEE 802.3 Ethernet standard, a Layer-2 protocol that is designed for “best effort” quality of service (QoS). TSN describes a collection of features intended to make legacy Ethernet performance more deterministic, including time synchronization, guaranteed low-latency transmissions, and improved reliability. The TSN features available today can be grouped into the following categories (shown below with associated IEEE specifications): Time Synchronization (e.g., IEEE 802.1AS);Bounded Low Latency (e.g., IEEE 802.1Qav, IEEE 802.1Qbu, IEEE 802.1Qbv, IEEE 802.1Qch, IEEE 802.1Qcr);Ultra-Reliability (e.g., IEEE 802.1CB, IEEE 802.1Qca, IEEE 802.1Qci);Network Configuration and Management (e.g., IEEE 802.1Qat, IEEE 802.1Qcc, IEEE 802.1Qcp, IEEE 802.1CS). More specifically, 802.1CB specifies a technique called Frame Replication and Elimination for Reliability (FRER) that is intended to avoid frame loss due to equipment failure. FRER divides a Stream into one or more linked Member Streams, thus making the original Stream a Compound Stream. It replicates the packets of the Stream, splitting the copies into the multiple Member Streams, and then rejoins those Member Streams at one or more other points, eliminates the replica (or duplicate) packets, and delivers the reconstituted Stream from those points. Although FRER provides redundancy over maximally disjoint paths, it does not include failure detection and/or switchover. Deterministic Networking (DetNet) is an effort by the Internet Engineering Task Force (IETF) towards specifying deterministic data paths for real-time applications with extremely low data loss rates, packet delay variation (jitter), and bounded latency, such as audio and video streaming, industrial automation, and vehicle control. DetNet operates at the Internet Protocol (IP) layer (i.e., Layer 3) by using a Software-Defined Networking (SDN) layer to provide Integrated Services (IntServ) and Differentiated Services (DiffServ) integration. Moreover, DetNet is intended to deliver service over Layer 2 technologies such as multi-protocol label switching (MPLS) and IEEE 802.1 TSN. DetNet includes a function similar to FRER, called Packet Replication and Elimination Function (PREF). This defined to simplify implementation and facilitate use of the same concept in both Layer-2 (TSN) and Layer-3 (DetNet) networks. In practice, IEEE 802.1CB provides implementation guideline for IETF DetNet PREF. SUMMARY However, the error detection functionality in 802.1CB i