BIER Working Group                                                X. Min
Internet-Draft                                                  Z. Zhang
Intended status: Standards Track                               ZTE Corp.
Expires: 16 July 2022                                             Y. Liu
                                                            China Mobile
                                                               N. Nainar
                                                            C. Pignataro
                                                     Cisco Systems, Inc.
                                                         12 January 2022


  Bit Index Explicit Replication (BIER) Encapsulation for In-situ OAM
                              (IOAM) Data
                        draft-xzlnp-bier-ioam-03

Abstract

   In-situ Operations, Administration, and Maintenance (IOAM) records
   operational and telemetry information in the packet while the packet
   traverses a path in the network.  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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 16 July 2022.






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Copyright Notice

   Copyright (c) 2022 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
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   provided without warranty as described in the Revised 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 . . . . . . . . . . . . . . .   3
   4.  IOAM data fields encapsulation in BIER header . . . . . . . .   4
   5.  Considerations  . . . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  Selecting the encapsulation approach  . . . . . . . . . .   6
     5.2.  Interaction with the BIER OAM field . . . . . . . . . . .   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  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   In-situ Operations, Administration, and Maintenance (IOAM) records
   operational and telemetry information in the packet while the packet
   traverses a path in the network.  [I-D.ietf-ippm-ioam-data] defines
   multiple IOAM options with different IOAM data fields used to record
   various telemetry data from the transit nodes.
   [I-D.ietf-ippm-ioam-direct-export] defines IOAM Direct Export option
   with IOAM data fields, which indicate telemetry data to be collected
   without being embedded in data packets.  The term "in-situ" refers to
   the fact that the OAM data is added to the data packets rather than
   being sent within packets specifically dedicated to OAM.






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   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
   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

   [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.




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   So methods are needed for measuring the real-time transportation
   guarantee of BIER packets.  This document attempts to provide a way
   to record operational and telemetry information in the BIER packets
   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 different IOAM-Data-Fields defined in
   [I-D.ietf-ippm-ioam-data] and [I-D.ietf-ippm-ioam-direct-export].

   In a BIER domain where IOAM is applied, inserting the IOAM header
   into BIER packets is enabled at the BFIRs, which also serve as IOAM
   encapsulating nodes by means of configuration, and deleting the IOAM
   header from BIER packets 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:



























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    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=TBA1 |            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 TBA1 when the IOAM header is present.

   The IOAM related fields in BIER are defined as follows:

      IOAM-Type: An 8-bit field defining the IOAM option type, as
      defined in Section 8.1 of [I-D.ietf-ippm-ioam-data] and
      Section 4.1 of [I-D.ietf-ippm-ioam-direct-export].

      IOAM HDR Len: An 8-bit unsigned integer.  Length of the IOAM
      header in 4-octet units.

      Reserved: A 10-bit reserved field MUST be set to zero upon
      transmission and ignored upon receipt.



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      Next Proto: A 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] and Section 3 of
      [I-D.ietf-ippm-ioam-direct-export].

   Multiple IOAM options MAY be included within a BIER encapsulation.
   For example, if a BIER encapsulation contains two IOAM options
   preceding a data payload, the "Next Proto" field of the first IOAM
   option would be set to the value of TBA1 that indicates a second IOAM
   option follows, while the "Next Proto" field of the second IOAM
   option would be set to the value of "BIER Next Protocol" indicating
   the type of the data payload.  Each type of IOAM option MUST occur at
   most once within a BIER encapsulation.

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.  Selecting 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.  Interaction with the BIER OAM field

   [RFC8296] defines a two-bit field, referred to as OAM.
   [I-D.ietf-bier-pmmm-oam] describes how to use the two-bit OAM field
   for alternate marking performance measurement method.  This document
   would not change the semantics of the two-bit OAM field.  The BIER
   IOAM header and the BIER OAM field are orthogonal and they can co-
   exist in one packet, i.e., a BIER packet with IOAM data can set the
   OAM field and a BIER packet with OAM field set can carry IOAM data
   too.






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6.  Security Considerations

   This document describes the encapsulation of IOAM data fields in
   BIER.  Security considerations of the specific IOAM data fields are
   described in [I-D.ietf-ippm-ioam-data] and
   [I-D.ietf-ippm-ioam-direct-export].

   IOAM is considered a "per domain" feature, where one or several
   operators decide on configuring IOAM according to their needs.  IOAM
   is intended for deployment in limited domains [RFC8799].  As such, it
   assumes that a node involved in IOAM operation has previously
   verified the integrity of the path.  Still, operators need to
   properly secure the IOAM domain to avoid malicious configuration and
   use, which could include injecting malicious IOAM packets into the
   domain.

   As this document describes new protocol fields within the existing
   BIER encapsulation, these are similar to the security considerations
   of [RFC8296].

7.  IANA Considerations

   In the "BIER Next Protocol Identifiers" registry created for
   [RFC8296], a new Next Protocol Value for IOAM is requested from IANA
   as follows:

       +====================+=============+============+===========+
       | BIER Next Protocol | Description | Semantics  | Reference |
       | Identifier         |             | Definition |           |
       +====================+=============+============+===========+
       | TBA1               | In-situ OAM | Section 4  | This      |
       |                    | (IOAM)      |            | Document  |
       +--------------------+-------------+------------+-----------+

                 Table 1: New BIER Next Protocol Identifier

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", Work in Progress, Internet-Draft, draft-



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              ietf-ippm-ioam-data-17, 13 December 2021,
              <https://www.ietf.org/archive/id/draft-ietf-ippm-ioam-
              data-17.txt>.

   [I-D.ietf-ippm-ioam-direct-export]
              Song, H., Gafni, B., Zhou, T., Li, Z., Brockners, F.,
              Bhandari, S., Sivakolundu, R., and T. Mizrahi, "In-situ
              OAM Direct Exporting", Work in Progress, Internet-Draft,
              draft-ietf-ippm-ioam-direct-export-07, 13 October 2021,
              <https://www.ietf.org/archive/id/draft-ietf-ippm-ioam-
              direct-export-07.txt>.

   [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>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [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,
              <https://www.rfc-editor.org/info/rfc8279>.

   [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, <https://www.rfc-editor.org/info/rfc8296>.

9.2.  Informative References

   [I-D.ietf-bier-ping]
              Kumar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M.,
              and G. Mirsky, "BIER Ping and Trace", Work in Progress,
              Internet-Draft, draft-ietf-bier-ping-07, 11 May 2020,
              <https://www.ietf.org/archive/id/draft-ietf-bier-ping-
              07.txt>.










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   [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", Work in
              Progress, Internet-Draft, draft-ietf-bier-pmmm-oam-11, 4
              October 2021, <https://www.ietf.org/archive/id/draft-ietf-
              bier-pmmm-oam-11.txt>.

   [I-D.ietf-bier-use-cases]
              Kumar, N., Asati, R., Chen, M., Xu, X., Dolganow, A.,
              Przygienda, T., Gulko, A., Robinson, D., Arya, V., and C.
              Bestler, "BIER Use Cases", Work in Progress, Internet-
              Draft, draft-ietf-bier-use-cases-12, 10 September 2020,
              <https://www.ietf.org/archive/id/draft-ietf-bier-use-
              cases-12.txt>.

   [RFC8799]  Carpenter, B. and B. Liu, "Limited Domains and Internet
              Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020,
              <https://www.rfc-editor.org/info/rfc8799>.

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


   Yisong Liu
   China Mobile
   Beijing
   China

   Email: liuyisong@chinamobile.com







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   Nagendra Kumar Nainar
   Cisco Systems, Inc.
   7200-11 Kit Creek Road
   Research Triangle Park, NC 27709
   United States of America

   Email: naikumar@cisco.com


   Carlos Pignataro
   Cisco Systems, Inc.
   7200-11 Kit Creek Road
   Research Triangle Park, NC 27709
   United States of America

   Email: cpignata@cisco.com



































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