BIER Working Group X. Min Internet-Draft Z. Zhang Intended status: Standards Track ZTE Corp. Expires: July 12, 2021 Y. Liu China Mobile N. Nainar C. Pignataro Cisco Systems, Inc. January 8, 2021 Bit Index Explicit Replication (BIER) Encapsulation for In-situ OAM (IOAM) Data draft-xzlnp-bier-ioam-01 Abstract In-situ Operations, Administration, and Maintenance (IOAM) collects operational and telemetry information while the packet traverses a particular network domain. Bit Index Explicit Replication (BIER) is an architecture that provides optimal multicast forwarding through a "multicast domain", without requiring intermediate routers to maintain any per-flow state or to engage in an explicit tree-building protocol. The BIER header contains a bit-string in which each bit represents exactly one egress router to forward the packet to. This document outlines the requirements to carry IOAM data in BIER header and specifies how IOAM data fields are encapsulated in BIER header. 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 July 12, 2021. Min, et al. Expires July 12, 2021 [Page 1] Internet-Draft BIER Encap for IOAM Data January 2021 Copyright Notice Copyright (c) 2021 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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 3. Requirements to carry IOAM data in BIER header . . . . . . . 3 4. IOAM data fields encapsulation in BIER header . . . . . . . . 4 5. Considerations . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. Discussion of the encapsulation approach . . . . . . . . 6 5.2. IOAM and the use of the BIER OAM bits . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction In-situ Operations, Administration, and Maintenance (IOAM) collects operational and telemetry information while the packet traverses a particular network domain. [I-D.ietf-ippm-ioam-data] defines different IOAM data fields used to record various telemetry data from the transit nodes. The term "in-situ" refers to the fact that the IOAM data fields are added to the data packets rather than being sent within packets specifically dedicated to OAM. Bit Index Explicit Replication (BIER), as defined in [RFC8279], is an architecture that provides optimal multicast forwarding through a "multicast domain", without requiring intermediate routers to maintain any per-flow state or to engage in an explicit tree-building Min, et al. Expires July 12, 2021 [Page 2] Internet-Draft BIER Encap for IOAM Data January 2021 protocol. The BIER header, as defined in [RFC8296], contains a bit- string in which each bit represents exactly one egress router to forward the packet to. This document outlines the requirements to carry IOAM data in BIER header and specifies how IOAM data fields are encapsulated in BIER header. 2. Conventions Used in This Document 2.1. 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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2.2. Abbreviations Abbreviations used in this document: BFER: Bit Forwarding Egress Router BFIR: Bit Forwarding Ingress Router BIER: Bit Index Explicit Replication GRE: Generic Routing Encapsulation IOAM: In-situ Operations, Administration, and Maintenance OAM: Operations, Administration, and Maintenance 3. Requirements to carry IOAM data in BIER header [I-D.ietf-bier-use-cases] lists many use cases for BIER. Usually there are many multicast flows within one network domain, and some of the multicast flows, such as live video and real-time meeting, are sensitive to packet loss, delay and other factors. The network operator wants to know the real-time statistics for these flows, such as delay, sequence, the ingress/egress interface, and the usage of buffer. So methods are needed for measuring the real-time transportation guarantee of BIER packet. Performance measurement function defined in [I-D.ietf-bier-pmmm-oam] can be used for measuring packet loss and Min, et al. Expires July 12, 2021 [Page 3] Internet-Draft BIER Encap for IOAM Data January 2021 delay. This document attempts to provide a way to collect on-path operational and telemetry information through in-situ OAM. 4. IOAM data fields encapsulation in BIER header The BIER header is defined in [RFC8279]. The BIER OAM header that follows BIER header is defined in [I-D.ietf-bier-ping]. IOAM-Data- Fields can either be carried in BIER using a new type of OAM message which follows the BIER OAM header (referred to as option 1), or be carried in BIER using a new next protocol header which immediately follows the BIER header (referred to as option 2). In this document, option 2 is selected and the reason is discussed in Section 5.1. An IOAM header is added containing the different IOAM-Data-Fields defined in [I-D.ietf-ippm-ioam-data]. In an administrative domain where IOAM is used, insertion of the IOAM header in BIER is enabled at the BFIRs, which also serve as IOAM encapsulating nodes by means of configuration, deletion of the IOAM header in BIER is enabled at the BFERs, which also serve as IOAM decapsulating nodes by means of configuration. The Encapsulation format for IOAM over BIER is defined as follows: Min, et al. Expires July 12, 2021 [Page 4] Internet-Draft BIER Encap for IOAM Data January 2021 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ | BIFT-id | TC |S| TTL | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |Nibble | Ver | BSL | Entropy | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ B |OAM|Rsv| DSCP |Proto = TBD| BFIR-id | I +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ E | BitString (first 32 bits) ~ R +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ~ ~ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ~ BitString (last 32 bits) | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ | IOAM-Type | IOAM HDR Len | Reserved | Next Proto| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I | | O | | A ~ IOAM Option and Data Space ~ M | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ | | | | | Payload + Padding (L2/L3/...) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: IOAM Encapsulation Format within BIER The BIER header and fields are defined in [RFC8296]. Within the BIER header, a 6-bit field as "Proto" (Next Protocol) is used to identify the type of the payload immediately following the BIER header, The "Proto" value is set to TBD when the IOAM header is present. The IOAM related fields in BIER are defined as follows: IOAM-Type: 8-bit field defining the IOAM Option Type, as defined in Section 8.1 of [I-D.ietf-ippm-ioam-data]. IOAM HDR Len: 8-bit unsigned integer. Length of the IOAM header in 4-octet units. Reserved: 10-bit reserved field MUST be set to zero upon transmission and ignored upon receipt. Min, et al. Expires July 12, 2021 [Page 5] Internet-Draft BIER Encap for IOAM Data January 2021 Next Proto: 6-bit unsigned integer that identifies the type of payload immediately following this IOAM option. The semantics of this field are identical to the "Proto" field in [RFC8296]. IOAM Option and Data Space: IOAM option header and data is present as specified by the IOAM-Type field, and is defined in Section 5 of [I-D.ietf-ippm-ioam-data]. Multiple IOAM-Option-Types MAY be included within the BIER encapsulation. For example, if a BIER encapsulation contains two IOAM-Option-Types preceding a data payload, the Next Proto field of the first IOAM option will contain the value of TBD, while the Next Proto field of the second IOAM option will contain the "BIER Next Protocol" number indicating the type of the data payload. Each IOAM Option-Type MUST occur at most once within the same BIER encapsulation header. 5. Considerations This section summarizes a set of considerations on the overall approach taken for IOAM data encapsulation in BIER, as well as deployment considerations. 5.1. Discussion of the encapsulation approach Both the options described in section 4 are supposed to be feasible, nevertheless this document needs to select one as standardized encapsulation for IOAM over BIER. Considering the fact that the encapsulation format option 2 using a new next protocol header is more concise than option 1 using a new type of OAM message, and many other transport protocols, e.g. GRE, use a new next protocol header to encapsulate IOAM data, the encapsulation format option 2 is selected as the standardized one. 5.2. IOAM and the use of the BIER OAM bits [RFC8296] defines a two-bits long field, referred to as OAM. [I-D.ietf-bier-pmmm-oam] describes how to use the two-bits OAM field for alternate marking performance measurement method, and this document would not change the semantics of the two-bits OAM field. The BIER IOAM header and the BIER two-bits OAM field are orthogonal and can co-exist in the same packet header, i.e. a BIER packet with IOAM data can set the OAM field or not, and a BIER packet with OAM field set can also carry IOAM data or not. Min, et al. Expires July 12, 2021 [Page 6] Internet-Draft BIER Encap for IOAM Data January 2021 6. Security Considerations This document does not raise any additional security issues beyond those of the specifications referred to in the list of normative references. 7. IANA Considerations In the "BIER Next Protocol Identifiers" registry defined in [RFC8296], a new Next Protocol Value for IOAM is requested from IANA as follows: +--------------------+---------------+-----------------+------------+ | BIER Next Protocol | Description | Semantics | Reference | | Identifier | | Definition | | +--------------------+---------------+-----------------+------------+ | TBD | In-situ OAM | Section 4 | This | | | (IOAM) | | Document | +--------------------+---------------+-----------------+------------+ Table 1: New BIER Next Protocol Identifier for IOAM 8. Acknowledgements The authors would like to acknowledge Greg Mirsky for his thorough review and very helpful comments. 9. References 9.1. Normative References [I-D.ietf-ippm-ioam-data] Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields for In-situ OAM", draft-ietf-ippm-ioam-data-11 (work in progress), November 2020. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Min, et al. Expires July 12, 2021 [Page 7] Internet-Draft BIER Encap for IOAM Data January 2021 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., Przygienda, T., and S. Aldrin, "Multicast Using Bit Index Explicit Replication (BIER)", RFC 8279, DOI 10.17487/RFC8279, November 2017, . [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation for Bit Index Explicit Replication (BIER) in MPLS and Non- MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 2018, . 9.2. Informative References [I-D.ietf-bier-ping] Nainar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M., and G. Mirsky, "BIER Ping and Trace", draft-ietf-bier- ping-07 (work in progress), May 2020. [I-D.ietf-bier-pmmm-oam] Mirsky, G., Zheng, L., Chen, M., and G. Fioccola, "Performance Measurement (PM) with Marking Method in Bit Index Explicit Replication (BIER) Layer", draft-ietf-bier- pmmm-oam-09 (work in progress), December 2020. [I-D.ietf-bier-use-cases] Nainar, N., Asati, R., Chen, M., Xu, X., Dolganow, A., Przygienda, T., Gulko, A., Robinson, D., Arya, V., and C. Bestler, "BIER Use Cases", draft-ietf-bier-use-cases-12 (work in progress), September 2020. Authors' Addresses Xiao Min ZTE Corp. Nanjing China Email: xiao.min2@zte.com.cn Zheng(Sandy) Zhang ZTE Corp. Nanjing China Email: zhang.zheng@zte.com.cn Min, et al. Expires July 12, 2021 [Page 8] Internet-Draft BIER Encap for IOAM Data January 2021 Yisong Liu China Mobile Beijing China Email: liuyisong@chinamobile.com Nagendra Kumar Nainar Cisco Systems, Inc. 7200-11 Kit Creek Road Research Triangle Park, NC 27709 United States Email: naikumar@cisco.com Carlos Pignataro Cisco Systems, Inc. 7200-11 Kit Creek Road Research Triangle Park, NC 27709 United States Email: cpignata@cisco.com Min, et al. Expires July 12, 2021 [Page 9]