Internet-Draft BGP Flowspec for Statistics December 2023
Bao Expires 10 June 2024 [Page]
IDR Working Group
Intended Status:
Standards Track
L. Bao
Huawei Technologies

BGP Flow Specification Extensions for Traffic Statistics


RFC8955 defines a Border Gateway Protocol Network Layer Reachability Information (BGP NLRI) encoding format that can be used to distribute (intra-domain and inter-domain) traffic Flow Specifications for IPv4 unicast and IPv4 BGP/MPLS VPN services. This allows the routing system to propagate information regarding more specific components of the traffic aggregate defined by an IP destination prefix. It also specifies BGP Extended Community encoding formats, which can be used to propagate Traffic Filtering Actions along with the Flow Specification NLRI. Those Traffic Filtering Actions encode actions a routing system can take if the packet matches the Flow Specification.

This document extends RFC 8955 with New traffic Filtering Actions. statistic for bytes rate per second and statistic for packets rate per second are useful in specified Flow processing scenario.

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 10 June 2024.

1. Introduction

[RFC8955] obsoletes "Dissemination of Flow Specification Rules" [RFC5575] (see Appendix B for the differences). This document also obsoletes "Clarification of the Flowspec Redirect Extended Community" [RFC7674], since it incorporates the encoding of the BGP Flow Specification Redirect Extended Community in Section 7.4.

When performing an action on a flow, you need to continuously observe the flow status, whether packets are continuously sent, and the statistic bytes rate and packets rate for the Flow Specification. This allows you to perform the next step on the flow. Therefore, the Action field in section 7.3 of [RFC8955] needs to be extended to add an action for flow statistics.

1.1. 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 BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

2. Traffic Filtering Actions

Traffic-Action (traffic-action) Sub-Type 0x07 is defined in [RFC8955] (see Section 7.2). The traffic-action Extended Community consists of 6 octets of which only the 2 least significant bits of the 6th octet (from left to right) are defined by this document, as shown in Figure 1.

      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
     | Traffic Action Field                                          |
     | Tr. Action Field (cont.)  |S|T|

            Figure 1: Traffic-Action Extended Community Encoding

The S and T bit are defined as:

  • T Terminal Action (bit 47): When this bit is set, the traffic filtering engine will evaluate any subsequent Flow Specifications (as defined by the ordering procedure in RFC8955 Section 5.1). If not set, the evaluation of the traffic filters stops when this Flow Specification is evaluated.

  • S Sample (bit 46): Enables traffic sampling and logging for this Flow Specification (only effective when set).

Other 2 significant bits of the 6th octet of traffic-action is required to identify and indicate the action of statistics. One bit is statistic-rate-bytes on a flow at an interval of per second. Another bit is statistic-rate-packets on a flow at an interval of per second.

  • SRB Statistic rate bytes per second (bit TBD ): Enables traffic statistic for this Flow Specification for bytes rate per second.

  • SRP Statistic rate packets per second (bit TBD ): Enables traffic statistic for this Flow Specification for packets rate per second.

4. IANA Considerations

The "traffic-action" Extended Community (Section 7.3) defined in [RFC8955] has 46 unused bits, which can be used to convey additional meaning. IANA created and maintains a registry entitled "Traffic Action Fields". IANA has updated the reference for this registry to RFC 8955. as shown in Figure 2.

Two new bits in the Traffic Action Field field are required for statistic-rate-bytes and statistic-rate-packets. The Bit Field and Reference are TBD.

  | Bit | Name                  | Reference |
  | 47  | Terminal Action       | RFC 8955  |
  | 46  | Sample                | RFC 8955  |
  | TBD | statistic-rate-bytes  |    TBD    |
  | TBD | statistic-rate-packets|    TBD    |
 Figure 2: Registry: Traffic Action Fields

5. Acknowledgments

The authors would like to thank Guoqi Xu, Lei Bao, Haibo Wang and Shunwan Zhuang for their review and discussion of this document.

6. References

6.1. Normative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., and D. McPherson, "Dissemination of Flow Specification Rules", RFC 5575, DOI 10.17487/RFC5575, , <>.
Haas, J., Ed., "Clarification of the Flowspec Redirect Extended Community", RFC 7674, DOI 10.17487/RFC7674, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M. Bacher, "Dissemination of Flow Specification Rules", RFC 8955, DOI 10.17487/RFC8955, , <>.

6.2. Informative References

Author's Address

Lei Bao
Huawei Technologies