IDR Working Group Z. Li Internet-Draft J. dong Intended status: Standards Track Huawei Expires: 29 April 2027 C. Loibl Next Layer Communications G. Mishra Verizon Inc. Y. Zhu China Telecom S. Zhuang Huawei 26 October 2026 BGP Flow Specification for SRv6 draft-ietf-idr-flowspec-srv6-11 Abstract This document specifies extensions to BGP Flow Specification (BGP-FS) to enable filtering of IPv6 packets based on the structural components of a standard SRv6 Segment Identifier (SID) or an SRv6 Compressed SID (CSID) container present in the IPv6 Destination Address (representing the active segment of an SRv6 path). Both NEXT-CSID and REPLACE-CSID flavors defined in RFC 9800 are supported. Requirements Language 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. 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." Li, et al. Expires 29 April 2027 [Page 1] Internet-Draft BGP Flow Specification for SRv6 October 2026 This Internet-Draft will expire on 29 April 2027. Copyright Notice Copyright (c) 2026 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 4 3. The Flow Specification Encoding for SRv6 . . . . . . . . . . 5 3.1. Component Type TBD1 - Standard SRv6 SID Structure Match . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Component Type TBD2 - SRv6 CSID Dynamic Structure Match . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.3. Encoding Examples . . . . . . . . . . . . . . . . . . . . 10 3.3.1. Example 1: Standard SRv6 SID Structure Match (Type TBD1) . . . . . . . . . . . . . . . . . . . . . . . . 10 3.3.2. Example 2: SRv6 CSID Dynamic Structure Match (Type TBD2) . . . . . . . . . . . . . . . . . . . . . . . . 11 3.3.3. Example 3: Dual Matching on Active CSID and Next CSID (NEXT-CSID Flavor) . . . . . . . . . . . . . . . . . 12 4. Security Considerations . . . . . . . . . . . . . . . . . . . 13 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 8.2. Informative References . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Li, et al. Expires 29 April 2027 [Page 2] Internet-Draft BGP Flow Specification for SRv6 October 2026 1. Introduction [RFC8955] defines the BGP Flow Specification (BGP-FS) Network Layer Reachability Information (NLRI) to distribute traffic filtering rules, which consist of an n-tuple of matching criteria applied to IP packets. [RFC8956] extends this framework to IPv6 data packets. Additionally, [I-D.ietf-idr-flowspec-l2vpn] extends Flowspec rules for Layer 2 Ethernet frames, and [I-D.ietf-idr-flowspec-v2] specifies BGP Flow Specification Version 2. Segment Routing over IPv6 (SRv6) [RFC8754] leverages the IPv6 data plane using a Segment Routing Header (SRH) to instantiate Segment Routing policy paths. The SRv6 Network Programming architecture [RFC8986] defines the standard structure of an SRv6 Segment Identifier (SID), formatted as LOC:FUNCT:ARG. Furthermore, [RFC9800] defines Compressed SRv6 Segment Identifiers (CSIDs) to optimize encoding efficiency, supporting two primary flavors: NEXT-CSID and REPLACE-CSID. In CSID container architecture, multiple CSIDs are packed within a 128-bit IPv6 Destination Address (DA) container. As packets traverse CSID nodes, the active CSID position within the container dynamically changes or shifts. Existing IPv6 BGP-FS components [RFC8956] allow matching against the entire 128-bit IPv6 Destination Address (DA). However, both standard SRv6 SIDs and CSID containers embed structured sub-fields within the IPv6 DA. Filtering traffic based solely on a static 128-bit mask lacks the flexibility needed to apply policy rules to specific SRv6 function IDs or active Compressed SIDs across dynamically shifting DA containers. This document defines two new BGP Flow Specification component types: 1. Component Type TBD1: Standard SRv6 SID Structure Match [RFC8986]. 2. Component Type TBD2: SRv6 CSID Dynamic Structure Match [RFC9800]. The matching field is evaluated against the IPv6 Destination Address (or active SID within an SRH when present, as shown in Figure 1). To support this feature, a BGP-FS NLRI with AFI = 2 (IPv6) MUST be used. Li, et al. Expires 29 April 2027 [Page 3] Internet-Draft BGP Flow Specification for SRv6 October 2026 +-----------------------------+ IPv6 Header| SA | DA |<-- Match Field +--------------------^--------+ | +--------------------|--------+ | +-------------+ | +-------------------+ | | Segment[0] +-------> Loc | Func | Arg | | +-------------+ | +-------------------+ | | Segment[1] | | | +-------------+ | | | ... | | SR Header| +-------------+ | (RFC 8754)| | Segment[n] | | | +-------------+ | | +-------------+ | | ~ Option TLV ~ | | +-------------+ | +-----------------------------+ Figure 1: Match Field 2. Definitions and Acronyms * BGP FS: BGP Flow Specification * FS: Flow Specification * SR: Segment Routing * SRH: SR Header. * SRv6: IPv6 Segment Routing, SRv6 is a method of forwarding IPv6 packets on the network based on the concept of source routing. * SID: Segment Identifier * CSID: Compressed Segment Identifier [RFC9800] * NEXT-CSID: NEXT-CSID Flavor defined in [RFC9800] * REPLACE-CSID: REPLACE-CSID Flavor defined in [RFC9800] In this document, the length parameters defining the constituent parts of a SID or CSID structure are defined as follows: * LOC-Len: Locator Length in bits for a standard 128-bit SRv6 SID (Component Type TBD1). Li, et al. Expires 29 April 2027 [Page 4] Internet-Draft BGP Flow Specification for SRv6 October 2026 * LB-Len: Locator-Block Length in bits for a CSID structure (Component Type TBD2). * LN-Len: Locator-Node Length in bits for a CSID structure. * F-Len: Function Length in bits for a SID or CSID structure. * ARG-Len: Argument Length in bits for a standard 128-bit SRv6 SID. In addition, the sum of LN-Len and F-Len (LN-Len + F-Len) represents the total length of a single CSID (also referred to as the "CSID length"). 3. The Flow Specification Encoding for SRv6 A Flow Specification NLRI consists of zero or more matching components. Components Type 1 through 13 are defined in [RFC8955] and [RFC8956]. This document defines two new component types for SRv6 SID and CSID sub-field filtering. * Component Type TBD1: SRv6 Standard SID Structure Match * Component Type TBD2: SRv6 CSID Dynamic Structure Match 3.1. Component Type TBD1 - Standard SRv6 SID Structure Match An SRv6 SID consists of Locator, Function, and Argument fields as defined in [RFC8986]. In operational scenarios, operators may need to filter traffic matching specific locators, functions, or arguments, or combinations thereof. The new component type TBD1 (Standard SRv6 SID Structure Match) allows fine-grained matching on these individual fields or aggregated field combinations. Encoding: o type (1 octet): Indicates the new component type (TBD1, to be assigned by IANA). o LOC-Len (1 octet): Length of the Locator field in bits. o FUNCT-Len (1 octet): Length of the Function field in bits. o ARG-Len (1 octet): Length of the Argument field in bits. o [op, value]+: A sequence of one or more {operator, value} pairs specifying the matching logic applied to the SID sub-fields. Li, et al. Expires 29 April 2027 [Page 5] Internet-Draft BGP Flow Specification for SRv6 October 2026 Validation Constraint: The sum of LOC-Len, FUNCT-Len, and ARG-Len MUST NOT exceed 128 bits. If (LOC-Len + FUNCT-Len + ARG-Len) > 128, the NLRI is considered malformed, and BGP Error Handling MUST be applied according to [RFC7606] and [RFC4760]. The Operator byte (op) is encoded as follows: 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | e | a | field type|lt |gt |eq | +---+---+---+---+---+---+---+---+ The operator semantics follow the Numeric Operator definition in [RFC8955]: e - end-of-list bit. Set in the last {op, value} pair in the sequence. a - AND bit. If unset, the previous term is logically ORed with the current one. If set, the operation is a logical AND. It should be unset in the first operator byte of a sequence. The AND operator has higher priority than OR for the purposes of evaluating logical expressions. field type: 000: SID's LOC 001: SID's FUNCT 010: SID's ARG 011: SID's LOC:FUNCT 100: SID's FUNCT:ARG 101: SID's LOC:FUNCT:ARG lt, gt, eq - Less-than, Greater-than, and Equal-to comparison operators, evaluated bitwise or numerically between the extracted SID sub-field and the provided value. The length of the Value field following the operator byte is determined by the selected field type, rounded up to the nearest byte boundary (i.e., ceil(bits / 8)). Li, et al. Expires 29 April 2027 [Page 6] Internet-Draft BGP Flow Specification for SRv6 October 2026 +---------------------+-------------------------------------------+ | Field Type | Value Field Length | +=====================+===========================================+ | SID's LOC | ceil(LOC-Len / 8) octets | +---------------------+-------------------------------------------+ | SID's FUNCT | ceil(FUNCT-Len / 8) octets | +---------------------+-------------------------------------------+ | SID's ARG | ceil(ARG-Len / 8) octets | +---------------------+-------------------------------------------+ | SID's LOC:FUNCT | ceil((LOC-Len + FUNCT-Len) / 8) octets | +---------------------+-------------------------------------------+ | SID's FUNCT:ARG | ceil((FUNCT-Len + ARG-Len) / 8) octets | +---------------------+-------------------------------------------+ | SID's LOC:FUNCT:ARG | ceil((LOC-Len+FUNCT-Len+ARG-Len)/8) octets| +---------------------+-------------------------------------------+ 3.2. Component Type TBD2 - SRv6 CSID Dynamic Structure Match [RFC9800] defines Compressed SRv6 Segment Identifiers (C-SIDs) to reduce header overhead, supporting two primary flavors: NEXT-CSID and REPLACE-CSID. Per Section 3 and 4 of [RFC9800], both flavors position the currently active CSID immediately following the Locator-Block (LB) in the IPv6 Destination Address (DA): NEXT-CSID Container Structure: +------------------------------------------------------------------+ | Locator-Block | Active CSID | Next CSID_1 | Next CSID_2 ...|Zeros| +------------------------------------------------------------------+ REPLACE-CSID Container Structure: +------------------------------------------------------------------+ | Locator-Block | Active CSID | Argument | +------------------------------------------------------------------+ Filtering rules MAY target either the Active CSID (applicable to both NEXT-CSID and REPLACE-CSID flavors) or the Next CSID (applicable specifically to the NEXT-CSID flavor). Encoding: o type (1 octet): Indicates component type TBD2 (to be assigned by IANA). o LB-Len (1 octet): Locator-Block Length in bits (e.g., 32 bits). Li, et al. Expires 29 April 2027 [Page 7] Internet-Draft BGP Flow Specification for SRv6 October 2026 o LN-Len (1 octet): Locator-Node Length in bits (e.g., 16 bits). o F-Len (1 octet): Function Length in bits (e.g., 16 bits). o [op, value]+: A sequence of one or more {operator, value} pairs. Validation Constraint: * (LB-Len + LN-Len + F-Len) MUST NOT exceed 128 bits. * LB-Len, LN-Len, and F-Len MUST NOT be 0. * If validation fails, BGP Error Handling MUST be applied according to [RFC7606] and [RFC4760]. * If any field length in bits is not a multiple of 8, the corresponding value field MUST be right-aligned with leading zero padding to the nearest octet boundary. The Operator byte (op) for TBD2 is encoded as: 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | e | a | field type|lt |gt |eq | +---+---+---+---+---+---+---+---+ e - end-of-list bit. Set in the last {op, value} pair in the sequence. a - AND bit. If unset, the previous term is logically ORed with the current one. If set, the operation is a logical AND. It should be unset in the first operator byte of a sequence. The AND operator has higher priority than OR for the purposes of evaluating logical expressions. field type: 000: Locator-Block (LB) 001: Active CSID Node ID (LN) 010: Active CSID Function ID (F) 011: Active CSID (LN:F) 100: Next CSID (LN:F) 101: Full CSID (LB:LN:F) Li, et al. Expires 29 April 2027 [Page 8] Internet-Draft BGP Flow Specification for SRv6 October 2026 110: Next CSID Node ID (LN) 111: Next CSID Function (F) Field Type 101 represents the Full CSID structure combining the Locator-Block (LB) and the Active CSID (LN:F) into a single matching value. Dynamic Match Processing Logic: When evaluating Component Type TBD2 against an incoming IPv6 packet: 1. Locator-Block: Extracted starting at bit offset 0 with length LB- Len. 2. Active CSID: The Active CSID (LN:F) is extracted starting at bit offset LB-Len with length (LN-Len + F-Len). In the context of the evaluating node, this represents the currently active CSID positioned immediately after the Locator-Block in the IPv6 DA. 3. Next CSID: * For NEXT-CSID flavor: The subsequent CSID is extracted immediately following the Active CSID at bit offset (LB-Len + LN-Len + F-Len) with length (LN-Len + F-Len). If the extracted Next CSID is all zeros (indicating no further CSID exists in the container or a padded container), the Next CSID evaluation MUST result in no match (False). * For REPLACE-CSID flavor: Since the REPLACE-CSID structure does not support concatenated subsequent C-SIDs within the IPv6 DA container, any rule evaluating Next CSID (field type 100) against a REPLACE-CSID packet MUST result in no match (False). Li, et al. Expires 29 April 2027 [Page 9] Internet-Draft BGP Flow Specification for SRv6 October 2026 +----------------------+-------------------------------------------+ | Field Type | Value Field Length | +======================+===========================================+ | Locator-Block (LB) | ceil(LB-Len / 8) octets | +----------------------+-------------------------------------------+ | Active CSID Node (LN)| ceil(LN-Len / 8) octets | +----------------------+-------------------------------------------+ | Active CSID Func (F) | ceil(F-Len / 8) octets | +----------------------+-------------------------------------------+ | Active CSID (LN:F) | ceil((LN-Len + F-Len) / 8) octets | +----------------------+-------------------------------------------+ | Next CSID (LN:F) | ceil((LN-Len + F-Len) / 8) octets | +----------------------+-------------------------------------------+ | Full CSID | ceil((LB-Len + LN-Len + F-Len) / 8) octets| +----------------------+-------------------------------------------+ 3.3. Encoding Examples 3.3.1. Example 1: Standard SRv6 SID Structure Match (Type TBD1) Consider a rule targeting all SRv6 traffic directed to Locator 2001:db8:3::/48 with a Function ID within the range [0x0100, 0x0300]. Given: * LOC-Len = 48 bits (6 octets) * FUNCT-Len = 16 bits (2 octets) * ARG-Len = 64 bits (8 octets) Hexadecimal Encoding Sequence: Some Parts of SID | length v LOC==20010db80003 FUN>=100 FUN<=300 0x11 TBD1 30 10 40 01 2001 0db8 0003 4b 0100 8d 0300 ^ ^ ^ | | | Length of LOC FUN ARG Detailed Field Breakdown: Li, et al. Expires 29 April 2027 [Page 10] Internet-Draft BGP Flow Specification for SRv6 October 2026 Decoded: Value 0x11 length 17 octets (if len<240, 1 octet) TBD1 type type TBD1 - SRv6 Standard SID Structure Match 0x30 LOC Length = 48 (bits) 0x10 FUNCT Length = 16 (bits) 0x40 ARG Length = 64 (bits) 0x01 op LOC == 0x2001 value LOC's value = 2001:db8:3 0x0db8 0x0003 0x4b op "AND", FUNCT >= 0x0100 value FUNCT's value = 0100 0x8d op end-of-list, "AND", FUNCT <= 0x0300 value FUNCT's value = 0300 3.3.2. Example 2: SRv6 CSID Dynamic Structure Match (Type TBD2) Consider an SRv6 network using a CSID container structure (applicable to either NEXT-CSID or REPLACE-CSID flavors) with Locator-Block 2001:db8::/32 (LB-Len=32), Node ID length LN-Len=16, and Function ID length F-Len=16. The rule targets traffic where the Active CSID Node ID equals 0x001A. Given: * LB-Len = 32 bits (4 octets) * LN-Len = 16 bits (2 octets) * F-Len = 16 bits (2 octets) Hexadecimal Sequence: 0x07 TBD2 20 10 10 89 001A Detailed Field Breakdown: Li, et al. Expires 29 April 2027 [Page 11] Internet-Draft BGP Flow Specification for SRv6 October 2026 Octet(s) Field Value Description ---------------------------------------------------------- 0x07 Length 7 octets Total length of the Component TBD2 Type TBD2 SRv6 CSID Dynamic Structure Match 0x20 LB-Len 32 bits Locator-Block Length = 32 0x10 LN-Len 16 bits Locator-Node Length = 16 0x10 F-Len 16 bits Function Length = 16 0x89 Op 1 10001001(binary) e=1, field=001(LN),op='==' 0x001A Value 1 0x001A Active CSID Node ID 3.3.3. Example 3: Dual Matching on Active CSID and Next CSID (NEXT-CSID Flavor) In a multi-hop SRv6 domain using the NEXT-CSID flavor, policy rules may require matching both the node currently processing the packet (Active CSID) and the subsequent downstream segment (Next CSID) to enforce strict path-aware traffic filtering. (Note: This dual- matching capability is specific to the NEXT-CSID flavor). Consider a NEXT-CSID network structured with: * Locator-Block Length (LB-Len) = 32 bits (4 octets) * Node ID Length (LN-Len) = 16 bits (2 octets) * Function ID Length (F-Len) = 16 bits (2 octets) Matching Criterion: Filter traffic where: 1. Active CSID (LN:F) equals 0x0001000A 2. AND Next CSID (LN:F) equals 0x0002000B Hexadecimal Sequence: 0x0E TBD2 20 10 10 19 0001000A E1 0002000B Detailed Field Breakdown: Li, et al. Expires 29 April 2027 [Page 12] Internet-Draft BGP Flow Specification for SRv6 October 2026 Octet(s) Field Value Description ---------------------------------------------------------- 0x0E Length 14 octets Total length of the Component TBD2 Type TBD2 SRv6 CSID Dynamic Structure Match 0x20 LB-Len 32 bits Locator-Block Length 0x10 LN-Len 16 bits Locator-Node Length 0x10 F-Len 16 bits Function Length --- Operator 1: Active CSID Match 0x19 Op 1 0x19 binary 00011001 (e=0, a=0, field=011, op='==') 0x0001000A Value 1 0x0001000A Active CSID (LN:F) --- Operator 2: Next CSID Match (AND Relationship) 0xE1 Op 2 0xE1 binary 11100001 (e=1, a=1, field=100, op='==') 0x0002000B Value 2 0x0002000B Next CSID (LN:F) 4. Security Considerations This document introduces no new security vulnerabilities beyond those already documented in [RFC8955] and [RFC8956]. Because Flowspec rules can result in packet dropping or rate-limiting, implementations MUST verify the authorization of BGP peers sending SRv6 Flowspec rules to prevent potential Denial-of-Service (DoS) attacks or traffic hijacking. 5. IANA Considerations Under the "Flow Spec Component Types" registry, IANA is requested to assign the following values: +------+-----------+----------------------------------+-----------+ | Value| IPv4 Name | IPv6 Name | Reference | +------+-----------+----------------------------------+-----------+ | TBD1 | Unassigned| SRv6 Standard SID Structure Match| This Doc | | TBD2 | Unassigned| SRv6 CSID Dynamic Structure Match| This Doc | +------+-----------+----------------------------------+-----------+ Li, et al. Expires 29 April 2027 [Page 13] Internet-Draft BGP Flow Specification for SRv6 October 2026 6. Acknowledgments The authors would like to thank Joel Halpern, Jeffrey Haas, Ketan Talaulikar, Aijun Wang, Dhruv Dhody, Ming Shen and Rainsword Wang for their valuable suggestions and comments. 7. Contributors Huaimo Chen Futurewei Email: hchen.ietf@gmail.com Lei Li Huawei P.R. China Email: lily.lilei@huawei.com Yanhe Fan Casa Systems United States of America Email: yfan@casa-systems.com Lei Liu Fujitsu United States of America Email: liulei.kddi@gmail.com Xufeng Liu Volta Networks United States of America Email: xufeng.liu.ietf@gmail.com 8. References 8.1. Normative References [I-D.ietf-idr-flowspec-v2] Hares, S., Eastlake, D. E., Yadlapalli, C., and S. Maduschke, "BGP Flow Specification Version 2", Work in Progress, Internet-Draft, draft-ietf-idr-flowspec-v2-04, 28 April 2024, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Li, et al. Expires 29 April 2027 [Page 14] Internet-Draft BGP Flow Specification for SRv6 October 2026 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 4760, DOI 10.17487/RFC4760, January 2007, . [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. Patel, "Revised Error Handling for BGP UPDATE Messages", RFC 7606, DOI 10.17487/RFC7606, August 2015, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M. Bacher, "Dissemination of Flow Specification Rules", RFC 8955, DOI 10.17487/RFC8955, December 2020, . [RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed., "Dissemination of Flow Specification Rules for IPv6", RFC 8956, DOI 10.17487/RFC8956, December 2020, . [RFC9800] Cheng, W., Ed., Filsfils, C., Li, Z., Decraene, B., and F. Clad, Ed., "Compressed SRv6 Segment List Encoding", RFC 9800, DOI 10.17487/RFC9800, June 2025, . 8.2. Informative References [I-D.ietf-idr-flowspec-l2vpn] Weiguo, H., Eastlake, D. E., Litkowski, S., and S. Zhuang, "BGP Dissemination of L2 Flow Specification Rules", Work in Progress, Internet-Draft, draft-ietf-idr-flowspec- l2vpn-27, 16 March 2026, . [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, . Li, et al. Expires 29 April 2027 [Page 15] Internet-Draft BGP Flow Specification for SRv6 October 2026 [RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer, D., Matsushima, S., and Z. Li, "Segment Routing over IPv6 (SRv6) Network Programming", RFC 8986, DOI 10.17487/RFC8986, February 2021, . Authors' Addresses Zhenbin Li Huawei 156 Beiqing Road Beijing, 100095 P.R. China Email: robinli314@163.com Jie Dong Huawei 156 Beiqing Road Beijing 100095 P.R. China Email: jie.dong@huawei.com Christoph Loibl Next Layer Communications Mariahilfer Guertel 37/7 1150 Vienna Austria Email: cl@tix.at Gyan S. Mishra Verizon Inc. 13101 Columbia Pike Silver Spring, MD 20904 United States of America Phone: 301 502-1347 Email: gyan.s.mishra@verizon.com Yongqing Zhu China Telecom 109, West Zhongshan Road, Tianhe District Guangzhou 510000 China Li, et al. Expires 29 April 2027 [Page 16] Internet-Draft BGP Flow Specification for SRv6 October 2026 Email: zhuyq8@chinatelecom.cn Shunwan Zhuang Huawei 156 Beiqing Road Beijing 100095 P.R. China Email: zhuangshunwan@huawei.com Li, et al. Expires 29 April 2027 [Page 17]