IS-IS Traffic Engineering Extensions For Microburst
draft-ruan-lsr-isis-te-extensions-for-microburst-01

lsr                                                         Z. Ruan, Ed.
Internet-Draft                                               M. Han, Ed.
Intended status: Standards Track                            China Unicom
Expires: 20 January 2027                                   T. Huang, Ed.
                                                               CNIC, CAS
                                                            R. Pang, Ed.
                                                            China Unicom
                                                            19 July 2026

          IS-IS Traffic Engineering Extensions For Microburst
          draft-ruan-lsr-isis-te-extensions-for-microburst-01

Abstract

   This document defines IS-IS and OSPF sub-TLVs and a BGP-Link State
   (BGP-LS) Link Attribute TLV for advertising aggregated measurements
   of microburst activity on a unidirectional link.  The information is
   reported for an identified traffic class and includes event, packet-
   drop, and queue-occupancy statistics.  An Anomalous (A) bit carries a
   locally determined anomaly indication.

   This document specifies the encoding and distribution of the
   information.  Microburst detection, loss attribution, threshold
   selection, and actions taken by a consumer are outside the scope of
   this document.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 20 January 2027.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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
     1.1.  Background  . . . . . . . . . . . . . . . . . . . . . . .   2
     1.2.  Definition of Microburst  . . . . . . . . . . . . . . . .   3
     1.3.  Requirements Analysis . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   3
   3.  Common Microburst Metrics Value . . . . . . . . . . . . . . .   4
   4.  IS-IS Extensions  . . . . . . . . . . . . . . . . . . . . . .   5
   5.  OSPF Extensions . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  BGP-LS Extensions . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Measurement and Advertisement Considerations  . . . . . . . .   8
   8.  Operational Considerations  . . . . . . . . . . . . . . . . .   8
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   11. Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

1.1.  Background

   [RFC8570] defines IS-IS TE extensions for advertising link delay,
   delay variation, packet loss, and bandwidth-related information.
   [RFC7471] defines the corresponding OSPF TE performance metric
   extensions.  For BGP-LS, [RFC8571] defines Link Attribute TLVs that
   carry the IGP TE performance metrics specified in [RFC8570] and
   [RFC7471].  BGP-LS itself is specified in [RFC9552], which obsoletes
   the original BGP-LS specification.

   These specifications describe link performance over an averaging
   interval, but they do not define a metric for short-duration queue
   congestion.  A microburst can cause queue buildup, packet loss, or a
   latency increase without producing a comparable change in an averaged
   metric.  This document therefore defines a common Microburst Metrics
   value and protocol encodings for IS-IS, OSPF, and BGP-LS.  The new
   information supplements the existing TE performance metrics; it does
   not change their definitions or processing rules.

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1.2.  Definition of Microburst

   For the purposes of this document, a microburst is defined as a
   transient, high-intensity traffic burst that causes instantaneous
   queue occupancy for a specific traffic class to exceed a locally
   configured threshold.  Microbursts can have significant negative
   impacts on network performance, including transient congestion,
   unexpected packet loss, latency spikes, and increased jitter-even
   when average link utilization remains low, which can severely degrade
   the quality of latency-sensitive services such as 5G real-time
   services and financial data transmission.

1.3.  Requirements Analysis

   Microburst information can be used by a controller or path-
   computation application when evaluating links for traffic with strict
   loss, latency, or jitter objectives.  It can also support local
   policy that limits lower-priority traffic when transient queue
   congestion is detected.

   The protocol extensions have the following requirements:

   *  IS-IS and OSPF MUST advertise aggregated measurements rather than
      individual microburst events, limiting link-state churn.

   *  Both IGPs MUST use the same value format and units so that a
      consumer can interpret the information consistently.

   *  The information MUST be associated with a traffic class because
      measurements can apply to different queues.

   *  The A bit MUST preserve the anomaly indication defined by the
      originating IGP advertisement.

   *  BGP-LS MUST export the IGP value without changing its fields or
      semantics, and absence of the source IGP attribute MUST NOT be
      represented as a zero-valued metric.

   Nodes that do not support the new TLV or sub-TLV follow the unknown-
   TLV handling rules of the applicable base protocol.

2.  Conventions and Terminology

   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.

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3.  Common Microburst Metrics Value

   The Microburst Metrics value is 30 octets.  Table 1 defines the field
   offsets.

     +==============+====================================+==========+
     | Octet Offset | Field                              | Size     |
     +==============+====================================+==========+
     | 0            | A bit and Reserved                 | 1 octet  |
     +--------------+------------------------------------+----------+
     | 1            | TC                                 | 1 octet  |
     +--------------+------------------------------------+----------+
     | 2-3          | Measurement Interval               | 2 octets |
     +--------------+------------------------------------+----------+
     | 4-5          | Reserved                           | 2 octets |
     +--------------+------------------------------------+----------+
     | 6-9          | Total Microburst Count             | 4 octets |
     +--------------+------------------------------------+----------+
     | 10-13        | Microbursts with Packet Loss Count | 4 octets |
     +--------------+------------------------------------+----------+
     | 14-17        | Maximum Drops per Microburst       | 4 octets |
     +--------------+------------------------------------+----------+
     | 18-21        | Total Microburst Drop Count        | 4 octets |
     +--------------+------------------------------------+----------+
     | 22-25        | Maximum Queue Occupancy            | 4 octets |
     +--------------+------------------------------------+----------+
     | 26-29        | Average Queue Occupancy            | 4 octets |
     +--------------+------------------------------------+----------+

                                 Table 1

   Table 1: Microburst Metrics Value Fields

   All multi-octet fields are encoded in network byte order.

   *A bit:* The most significant bit of octet 0.  The originator sets
   the A bit when the locally selected microburst measurements exceed a
   configured upper threshold.  It clears the bit when the applicable
   measurements fall below a configured reuse threshold.  The use of
   separate upper and reuse thresholds is RECOMMENDED to provide
   hysteresis.  The A bit is a local anomaly indication; this document
   does not define a network-wide threshold.

   *Reserved:* The remaining seven bits of octet 0 and octets 4 and 5.
   The originator MUST set these bits to zero, and a receiver MUST
   ignore them.

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   *TC:* An unsigned 8-bit traffic-class identifier.  The mapping of
   this identifier to a DSCP, IEEE 802.1p priority, forwarding class, or
   queue is an operational matter.  A consumer MUST know the mapping
   before using the value for traffic-class-specific computation.  This
   document does not create a TC codepoint registry.

   *Measurement Interval:* An unsigned 16-bit integer containing the
   duration, in seconds, over which the statistics were collected.  The
   value zero is reserved and MUST NOT be originated.

   *Total Microburst Count:* An unsigned 32-bit integer containing the
   number of detected microbursts during the measurement interval.

   *Microbursts with Packet Loss Count:* An unsigned 32-bit integer
   containing the number of detected microbursts during which one or
   more packet drops were observed on the monitored queue.

   *Maximum Drops per Microburst:* An unsigned 32-bit integer containing
   the largest number of packet drops observed during a single detected
   microburst in the measurement interval.

   *Total Microburst Drop Count:* An unsigned 32-bit integer containing
   the total number of packet drops observed during detected microbursts
   in the measurement interval.

   *Maximum Queue Occupancy:* An unsigned 32-bit integer containing the
   maximum occupancy, in octets, observed on the monitored queue during
   a detected microburst in the measurement interval.

   *Average Queue Occupancy:* An unsigned 32-bit integer containing the
   arithmetic mean queue occupancy, in octets, over the measurement
   interval.  The sampling method and frequency are local measurement
   properties and SHOULD remain stable when successive advertisements
   are compared.

   If a counter or occupancy value exceeds the largest value
   representable by its field, the originator MUST encode the field as
   0xFFFFFFFF.  A receiver MUST interpret 0xFFFFFFFF as a saturated
   value, not as an exact measurement.

4.  IS-IS Extensions

   This document defines a new IS-IS Microburst Metrics sub-TLV using
   the link-attribute encoding conventions of [RFC5305] and [RFC8570].
   The sub-TLV is allocated from the IANA "Sub-TLVs for TLVs 22, 23,
   141, 222, and 223" registry.

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   The sub-TLV MAY appear in the Extended IS Reachability TLV (type 22),
   IS Neighbor Attribute TLV (type 23), inter-AS Reachability
   Information TLV (type 141), MT Intermediate Systems TLV (type 222),
   and MT IS Neighbor Attribute TLV (type 223), subject to the
   applicability recorded in the IANA registry.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Type=TBA1   |   Length=30   |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      |                                                               |
      +              Microburst Metrics Value (30 octets)             +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 1: IS-IS Microburst Metrics Sub-TLV

   The Type field is one octet and has the value TBA1.  The Length field
   is one octet and MUST be set to 30.  The value is encoded as
   specified in the previous section.

   Multiple instances MAY be advertised for a link when measurements are
   available for different TCs.  An originator MUST NOT advertise more
   than one instance for the same TC in the same parent TLV.  A receiver
   MUST ignore an instance whose Length is not 30.

5.  OSPF Extensions

   This document defines a Microburst Metrics sub-TLV for the OSPFv2 TE
   Link TLV defined in [RFC3630] and for the Router-Link TLV in the
   OSPFv3 E-Router-LSA defined in [RFC8362].  The OSPF sub-TLV uses a
   16-bit Type and a 16-bit Length followed by the common value.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |           Length=30           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +              Microburst Metrics Value (30 octets)             +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Padding=0            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 2: OSPF Microburst Metrics Sub-TLV

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   The Type value is TBA2 for OSPFv2 and TBA3 for OSPFv3.  The Length
   field MUST be set to 30 and does not include padding.  Two padding
   octets follow the value to align the sub-TLV on a 32-bit boundary;
   the originator MUST set them to zero, and a receiver MUST ignore
   them.  The field definitions and units are those specified for the
   common value.

   Multiple instances MAY be included for a link when measurements are
   available for different TCs.  An originator MUST NOT advertise more
   than one instance for the same TC in the same parent TLV.  A receiver
   MUST ignore an instance whose Length is not 30.

6.  BGP-LS Extensions

   BGP-LS is specified in [RFC9552], which obsoletes the original BGP-LS
   specification.  The BGP-LS Link Attribute TLVs for advertising IGP TE
   performance metrics are defined in [RFC8571].  This document defines
   a Microburst Metrics Link Attribute TLV for a BGP-LS Link NLRI.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=TBA4           |           Length=30           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +              Microburst Metrics Value (30 octets)             +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 3: BGP-LS Microburst Metrics TLV

   The Type field is a 16-bit value assigned by IANA.  The Length field
   MUST be set to 30.  The field definitions and units are those
   specified for the common value.

   A BGP-LS speaker that exports an IS-IS or OSPF Microburst Metrics
   sub-TLV MUST copy the complete common value into the BGP-LS TLV
   without changing any field.  The Protocol-ID in the BGP-LS NLRI
   identifies the source protocol as specified in [RFC9552].

   A BGP-LS speaker MUST NOT synthesize a zero-valued TLV when the
   source IGP does not advertise the metric.  When the source IGP
   removes the corresponding sub-TLV, the BGP-LS speaker MUST remove the
   mapped TLV from the BGP-LS Attribute.  Absence of the TLV does not
   indicate the absence of microbursts because the TC might not be
   monitored or exported.

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7.  Measurement and Advertisement Considerations

   The detection method is outside the scope of this document.
   Implementations SHOULD use a stable measurement method and
   configuration for a given queue so that successive advertisements can
   be compared.

   Statistics MUST be aggregated over the advertised Measurement
   Interval.  An individual microburst event MUST NOT, by itself, cause
   an advertisement.  An implementation MAY use periodic advertisement,
   threshold-based advertisement, or both, subject to the generation and
   flooding controls of the underlying protocol.

   A change in the A bit MAY cause an advertisement.  Implementations
   SHOULD apply hysteresis and rate limiting to reduce control-plane
   churn.

   Packet drops reported in the value SHOULD include only drops observed
   on the monitored queue during a detected microburst.  Drops
   attributed to physical-layer errors or unrelated conditions SHOULD
   NOT be included.

   If no microburst is detected during an interval, an originator MAY
   advertise zero-valued event and drop counters.  If no instance is
   advertised for a TC, a receiver MUST NOT infer either the presence or
   absence of microbursts.

8.  Operational Considerations

   Measurements can depend on hardware architecture, queue allocation,
   sampling frequency, and local thresholds.  Values advertised by
   different nodes might not be directly comparable unless their
   measurement and TC policies are aligned.

   Frequent changes can cause excessive IGP flooding, BGP-LS updates, or
   unstable path selection.  Operators SHOULD configure measurement
   intervals, thresholds, and advertisement rate limits appropriate for
   the network.  Consumers SHOULD validate measurements and apply
   suitable policy before changing traffic placement.

9.  Security Considerations

   The security considerations of [RFC5305], [RFC8570], [RFC7471],
   [RFC8571], and [RFC9552] apply to the extensions defined in this
   document.  False microburst information can affect path computation
   and traffic placement.

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10.  IANA Considerations

   TBD.

11.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
              (TE) Extensions to OSPF Version 2", RFC 3630,
              DOI 10.17487/RFC3630, October 2003,
              <https://www.rfc-editor.org/info/rfc3630>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <https://www.rfc-editor.org/info/rfc5305>.

   [RFC7471]  Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
              Previdi, "OSPF Traffic Engineering (TE) Metric
              Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
              <https://www.rfc-editor.org/info/rfc7471>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8362]  Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
              F. Baker, "OSPFv3 Link State Advertisement (LSA)
              Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
              2018, <https://www.rfc-editor.org/info/rfc8362>.

   [RFC8570]  Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward,
              D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE)
              Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March
              2019, <https://www.rfc-editor.org/info/rfc8570>.

   [RFC8571]  Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and
              C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of
              IGP Traffic Engineering Performance Metric Extensions",
              RFC 8571, DOI 10.17487/RFC8571, March 2019,
              <https://www.rfc-editor.org/info/rfc8571>.

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   [RFC9552]  Talaulikar, K., Ed., "Distribution of Link-State and
              Traffic Engineering Information Using BGP", RFC 9552,
              DOI 10.17487/RFC9552, December 2023,
              <https://www.rfc-editor.org/info/rfc9552>.

Appendix A.  Acknowledgments

   TBD.

Authors' Addresses

   Zheng Ruan (editor)
   China Unicom
   Beijing
   China
   Email: ruanz6@chinaunicom.cn

   Mengyao Han (editor)
   China Unicom
   Beijing
   China
   Email: hanmy12@chinaunicom.cn

   Tianyi Huang (editor)
   CNIC, CAS
   Beijing
   China
   Email: tyhuang@cnic.cn

   Ran Pang (editor)
   China Unicom
   Beijing
   China
   Email: pangran@chinaunicom.cn

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