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. 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 20 January 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Ruan, et al. Expires 20 January 2027 [Page 1] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 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. Ruan, et al. Expires 20 January 2027 [Page 2] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 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. Ruan, et al. Expires 20 January 2027 [Page 3] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 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. Ruan, et al. Expires 20 January 2027 [Page 4] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 *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. Ruan, et al. Expires 20 January 2027 [Page 5] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 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 Ruan, et al. Expires 20 January 2027 [Page 6] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 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. Ruan, et al. Expires 20 January 2027 [Page 7] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 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. Ruan, et al. Expires 20 January 2027 [Page 8] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 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, . [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, DOI 10.17487/RFC3630, October 2003, . [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, October 2008, . [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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [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, . [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, . [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, . Ruan, et al. Expires 20 January 2027 [Page 9] Internet-Draft IS-IS Traffic Engineering Extensions For July 2026 [RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and Traffic Engineering Information Using BGP", RFC 9552, DOI 10.17487/RFC9552, December 2023, . 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 Ruan, et al. Expires 20 January 2027 [Page 10]