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BIER Working Group                                                X. Min
Internet-Draft                                                  Z. Zhang
Intended status: Standards Track                               ZTE Corp.
Expires: January 14, 2021                                         Y. Liu
                                                            China Mobile
                                                               N. Nainar
                                                            C. Pignataro
                                                     Cisco Systems, Inc.
                                                           July 13, 2020


  Bit Index Explicit Replication (BIER) Encapsulation for In-situ OAM
                              (IOAM) Data
                        draft-xzlnp-bier-ioam-00

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
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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
   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 January 14, 2021.







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Copyright Notice

   Copyright (c) 2020 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
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   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



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   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.  There are
   many multicast flows in one network.  Some of the flows are sensitive
   for packet loss, delay and other factors, such as live video, real-
   time meeting.  The network administrator wants to know the real-time
   statistics for these flows, such as delay, sequence, the I/O
   interface, and the usage of buffer, and so on.

   So a method need to be used for measuring the packet real-time
   transportation guarantee.  OAM function defined in
   [I-D.ietf-bier-pmmm-oam] can be used for packet loss and delay
   detection.  This document attempts to provide a way to achieve on-
   path telemetry information collection through in-situ OAM.



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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:
































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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 = 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 7.2 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.



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      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 4
      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.  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.








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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-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-ippm-ioam-data]
              Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
              Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
              P., remy@barefootnetworks.com, r., daniel.bernier@bell.ca,
              d., and J. Lemon, "Data Fields for In-situ OAM", draft-
              ietf-ippm-ioam-data-09 (work in progress), March 2020.

   [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>.




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   [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-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-08 (work in progress), May 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-11
              (work in progress), March 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





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   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



























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