IDR Working Group J. Song Internet Draft China Mobile Intended status: Standards Track C. Lin Expires: September 01, 2026 New H3C Technologies March 01, 2026 BGP Flow Specification Filter by ClassID draft-song-idr-flowspec-classid-filter-00 Abstract BGP Flowspec mechanism (BGP-FS) [RFC8955] [RFC8956] propagates both traffic Flow Specifications and Traffic Filtering Actions by making use of the BGP NLRI and the BGP Extended Community encoding formats. This document specifies a new BGP-FS component type named ClassID to support ClassID filtering. 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/. 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Expires September, 2026 [Page 1] Internet-Draft FlowSpec by ClassID March, 2026 Table of Contents 1. Introduction...................................................2 2. Requirements Language..........................................4 3. The Flow Specification Encoding for ClassID....................4 4. Use Cases......................................................5 5. IANA Considerations............................................6 5.1. FSv2 IP Basic TLV Components..............................6 6. Security Considerations........................................7 7. Informative References.........................................7 Authors' Addresses................................................9 1. Introduction BGP Flowspec mechanism (BGP-FS) [RFC8955] [RFC8956] propagates both traffic Flow Specifications and Traffic Filtering Actions by making use of the BGP NLRI and the BGP Extended Community encoding formats. As shown in Figure 1, PE2 advertises routes Prefix21, Prefix22, ..., Prefix2n, and PE3 advertises routes Prefix31, Prefix32, ..., Prefix3n. The server sends Flow-Spec rules to PE1 to redirect the traffic for routes Prefix2x and Prefix3x respectively. When there are a large number of routes, a significant amount of BGP Flow-Spec rules need to be deployed. Song, et al. Expires September, 2026 [Page 2] Internet-Draft FlowSpec by ClassID March, 2026 +---------+ | BGP FS | | Server | +--/------+ / +----+ / / +----+ +---+ +----+Prefix 21 +PE1 +-------+ P +---------+PE2 |Prefix 22 +----+ +-+-+ +----+... | | | +----+Prefix 31 +-----------+PE3 |Prefix 32 +----+... Figure 1 To address this issue, when PE2 and PE3 advertise routes, they can include specific routing attributes. For the included routing attributes, various combinations of BGP properties can be used, such as: BGP Standard Community BGP Large Community Extended Community Color AS Path, etc. By extending the BGP-FS component type, filtering of various BGP route attributes can be supported. However, the following issues exist: * Various attributes need to be planned on the device, transmitted across devices, and then traffic steering must be performed using BGP-FS rules on the corresponding devices. * Due to the large number of BGP attributes, extending corresponding BGP-FS component types for each attribute may generate a large volume of BGP FS routes. Song, et al. Expires September, 2026 [Page 3] Internet-Draft FlowSpec by ClassID March, 2026 *BGP needs to update these attributes to the forwarding table. The extensive attribute content results in the forwarding table maintaining a complex BGP attribute list. This document specifies a new BGP-FS component type named ClassID to support ClassID filtering. The device maps various attributes into ClassIDs and updates the corresponding ClassIDs to the forwarding table. The match field is the ClassID of the destination IP address encoded in the Flowspec NLRI. 2. 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 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. The Flow Specification Encoding for ClassID [I-D. draft-ietf-idr-fsv2-ip-basic] defines the Components in the IP Basic TLV. This document proposes a new Component for ClassID information. When filtering using FlowSpec rules, the condition can be specified as the ClassID. This is primarily used for traffic diversion based on the ClassID. Sub-TLV Definition -------- --------------------- TBD - ClassID The ClassID Components has following format: +-------------------------------+ | SubTLV type = TBD (1 octet) | +-------------------------------+ | length (1 octet) | Song, et al. Expires September, 2026 [Page 4] Internet-Draft FlowSpec by ClassID March, 2026 + ------------------------------+ | value (variable) | +-------------------------------+ Type: ClassID(TBD) Filter defines: match for ClassID length: variable value: [numeric_op, value]+ where the value following each numeric_op is a two octets ClassID. 4. Use Cases As shown in Figure 2, on the ingress PE, Route-Policy is configured to map various route attributes into ClassID. These route attributes include Community, Large Community, Extended Community, Color, etc. The BGP Flow-Spec Server deploys BGP Flow-Spec rules by specifying ClassID as the matching condition and Redirect as the action. For traffic steering: First, route attributes are mapped to a unified ClassID through Route-Policy based on traffic characteristics. Then, traffic is redirected to the specified destination router by matching the ClassID against BGP Flow-Spec rules. Song, et al. Expires September, 2026 [Page 5] Internet-Draft FlowSpec by ClassID March, 2026 |Input: |filter = destip + ClassID |Action = redirect V +----------+ |Controller| +----------+ |BGP FS: |NLRI | Filter: ClassID |Action=redirect V +----------+ |Device | +----------+ Route-Policy: (Color, Community, ...) Remark ClassID Flow-Spec: ClassID->redirect Figure 2 5. IANA Considerations 5.1. FSv2 IP Basic TLV Components [I-D. draft-ietf-idr-fsv2-ip-basic] defines the Components in the IP Basic TLV. This document requested to assign a new type code point from "FSv2 IP Basic TLV Components" registry for ClassID. Sub-TLV Definition -------- --------------------- 0 - Reserved 1 - IP Destination prefix 2 - IP Source prefix 3 - IPv4 Protocol / IPv6 Upper Layer Protocol 4 - Port Song, et al. Expires September, 2026 [Page 6] Internet-Draft FlowSpec by ClassID March, 2026 5 - Destination Port 6 - Source Port 7 - ICMPv4 type / ICMPv6 type 8 - ICMPv4 code / ICPv6 code 9 - TCP Flags 10 - Packet length 11 - DSCP 12 - Fragment 13 - Flow Label TBD1- ClassID This document 14-255 Reserved 6. Security Considerations TBD 7. Informative 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, https://www.rfc- editor.org/info/rfc2119>. Song, et al. Expires September, 2026 [Page 7] Internet-Draft FlowSpec by ClassID March, 2026 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006, . [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, . Song, et al. Expires September, 2026 [Page 8] Internet-Draft FlowSpec by ClassID March, 2026 Authors' Addresses Song Jian China Mobile China Email: songjianyjy@chinamobile.com Changwang Lin New H3C Technologies Email: linchangwang.04414@h3c.com Song, et al. Expires September, 2026 [Page 9]