SFC                                                         F. Brockners
Internet-Draft                                               S. Bhandari
Intended status: Standards Track                             V. Govindan
Expires: December 2, 2018 September 12, 2019                                 C. Pignataro
                                                              H. Gredler
                                                            RtBrick Inc.
                                                                J. Leddy
                                                               S. Youell
                                                              T. Mizrahi
                                        Huawei Network.IO Innovation Lab
                                                                D. Mozes

                                                             P. Lapukhov
                                                                R. Chang
                                                       Barefoot Networks
                                                            May 31, 2018

                                                          March 11, 2019

 Network Service Header (NSH) Encapsulation for In-situ OAM (IOAM) Data


   In-situ Operations, Administration, and Maintenance (OAM) (IOAM) records
   operational and telemetry information in the packet while the packet
   traverses a path between two points in the network.  This document
   outlines how IOAM data fields are encapsulated in the Network Service
   Header (NSH).

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   This Internet-Draft will expire on December 2, 2018. September 12, 2019.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  IOAM data fields encapsulation in NSH . . . . . . . . . . . .   3
   4.  Considerations  . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Discussion of the encapsulation approach  . . . . . . . .   5
     4.2.  IOAM and the use of the NSH O-bit . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   In-situ OAM (IOAM) (IOAM), as defined in [I-D.ietf-ippm-ioam-data], records
   OAM information within the packet while the packet traverses a
   particular network domain.  The term "in-situ" refers to the fact
   that the OAM data is added to the data packets rather than is being
   sent within packets specifically dedicated to OAM.  This document
   defines how IOAM data fields are transported as part of the Network
   Service Header (NSH) [RFC8300] encapsulation. encapsulation for the Service Function
   Chaining (SFC) [RFC7665].  The IOAM data fields are defined in
   [I-D.ietf-ippm-ioam-data].  An implementation of IOAM which leverages
   NSH to carry the IOAM data is available from the FD.io open source
   software project [FD.io].

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   Abbreviations used in this document:

   IOAM:      In-situ Operations, Administration, and Maintenance

   NSH:       Network Service Header

   OAM:       Operations, Administration, and Maintenance

   SFC:       Service Function Chaining

   TLV:       Type, Length, Value

3.  IOAM data fields encapsulation in NSH

   The NSH is defined in [RFC8300].  IOAM data fields are carried in NSH
   using a next protocol header which follows the NSH MDx metadata TLVs. MD context
   headers.  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 NSH is
   enabled at the NSH tunnel endpoints, which also serve as IOAM encapsulating/
   encapsulating/decapsulating nodes by means of configuration.

    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
   |Ver|O|C|R|R|R|R|R|R|   Length  |  MD Type
   |Ver|O|U|    TTL    |   Length  |U|U|U|U|MD Type| NP = TBD_IOAM |  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  N
   |          Service Path Identifer Identifier              | Service Index |  S
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  H
   |                            ...                                |  |
   |  IOAM-Type    | IOAM HDR len  |    Reserved   | Next Protocol |  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  I
   !                                                               |  O
   !                                                               |  A
   ~                 IOAM Option and Data Space                    ~  M
   |                                                               |  |
   |                                                               |  |
   |                                                               |
   |                                                               |
   |                 Payload + Padding (L2/L3/ESP/...)             |
   |                                                               |
   |                                                               |
   |                                                               |

   The NSH header and fields are defined in [RFC8300].  The "NSH Next
   Protocol" value (referred to as "NP" in the diagram above) is

   The IOAM related fields in NSH 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 Length field contains the length of the IOAM
         header in 4-octet units.

      Reserved bits:  Reserved bits are present for future use.  The
         reserved bits MUST be set to 0x0 upon transmission and ignored
         upon receipt.

      Next Protocol:  8-bit unsigned integer that determines the type of
         header following IOAM protocol.  The semantics of this field
         are identical to the Next Protocol field in [RFC8300].

      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 options MAY be included within the NSH encapsulation.
   For example, if a NSH encapsulation contains two IOAM options before
   a data payload, the Next Protocol field of the first IOAM option will
   contain the value of TBD_IOAM, while the Next Protocol field of the
   second IOAM option will contain the "NSH Next Protocol" number
   indicating the type of the data payload.

4.  Considerations

   This section summarizes a set of considerations on the overall
   approach taken for IOAM data encapsulation in NSH, as well as
   deployment considerations.

4.1.  Discussion of the encapsulation approach

   This section is to support the working group discussion in selecting
   the most appropriate approach for encapsulating IOAM data fields in

   An encapsulation of IOAM data fields in NSH should be friendly to an
   implementation in both hardware as well as software forwarders and
   support a wide range of deployment cases, including large networks
   that desire to leverage multiple IOAM data fields at the same time.

      Hardware and software friendly implementation: Hardware forwarders
      benefit from an encapsulation that minimizes iterative look-ups of
      fields within the packet: Any operation which looks up the value
      of a field within the packet, based on which another lookup is
      performed, consumes additional gates and time in an implementation
      - both of which are desired to be kept to a minimum.  This means
      that flat TLV structures are to be preferred over nested TLV
      structures.  IOAM data fields are grouped into three option
      categories: Trace, proof-of-transit, and edge-to-edge.  Each of
      these three options defines a TLV structure.  A hardware-friendly
      encapsulation approach avoids grouping these three option
      categories into yet another TLV structure, but would rather carry
      the options as a serial sequence.

      Total length of the IOAM data fields: The total length of IOAM
      data can grow quite large in case multiple different IOAM data
      fields are used and large path-lengths need to be considered.  If
      for example an operator would consider using the IOAM trace option
      and capture node-id, app_data, egress/ingress interface-id,
      timestamp seconds, timestamps nanoseconds at every hop, then a
      total of 20 octets would be added to the packet at every hop.  In
      case this particular deployment would have a maximum path length
      of 15 hops in the IOAM domain, then a maximum of 300 octets of
      IOAM data were to be encapsulated in the packet.

   Different approaches for encapsulating IOAM data fields in NSH could
   be considered:

   1.  Encapsulation of IOAM data fields as "NSH MD Type 2" (see
       [RFC8300], section Section 2.5).  Each IOAM data field option (trace,
       proof-of-transit, and edge-to-edge) would be specified by a type,
       with the different IOAM data fields being TLVs within this the
       particular option type.  NSH MD Type 2 offers support for
       variable length meta-data.  The length field is 6-bits, resulting
       in a maximum of 256 (2^6 x 4) octets.

   2.  Encapsulation of IOAM data fields using the "Next Protocol"
       field.  Each IOAM data field option (trace, proof-of-transit, and
       edge-to-edge) would be specified by its own "next protocol".

   3.  Encapsulation of IOAM data fields using the "Next Protocol"
       field.  A single NSH protocol type code point would be allocated
       for IOAM.  A "sub-type" field would then specify what IOAM
       options type (trace, proof-of-transit, edge-to-edge) is carried.

   The third option has been chosen here.  This option avoids the
   additional layer of TLV nesting that the use of NSH MD Type 2 would
   result in.  In addition, this option does not constrain IOAM data to
   a maximum of 256 octets, thus allowing support for very large

4.2.  IOAM and the use of the NSH O-bit

   [RFC8300] defines an "O bit" for OAM packets.  Per [RFC8300] the O
   bit must be set for OAM packets and must not be set for non-OAM
   packets.  Packets with IOAM data included MUST follow this
   definition, i.e. the O bit MUST NOT be set for regular customer
   traffic which also carries IOAM data and the O bit MUST be set for
   OAM packets which carry only IOAM data without any regular data

5.  IANA Considerations

   IANA is requested to allocate protocol numbers for the following "NSH
   Next Protocol" related to IOAM:

                 | Next Protocol | Description | Reference     |
                 | x             | TBD_IOAM    | This document |

6.  Security Considerations

   IOAM is considered a "per domain" feature, where one or several
   operators decide on leveraging and configuring IOAM according to
   their needs.  Still, operators need to properly secure the IOAM
   domain to avoid malicious configuration and use, which could include
   injecting malicious IOAM packets into a domain.

7.  Acknowledgements

   The authors would like to thank Eric Vyncke, Nalini Elkins, Srihari
   Raghavan, Ranganathan T S, Karthik Babu Harichandra Babu, Akshaya
   Nadahalli, Stefano Previdi, Hemant Singh, Erik Nordmark, LJ Wobker,
   and Andrew Yourtchenko for the comments and advice.

8.  References

8.1.  Normative References

              Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
              Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
              P., Chang, R., daniel.bernier@bell.ca, d., and J. Lemon,
              "Data Fields for In-situ OAM", draft-ietf-ippm-ioam-
              data-04 (work in progress), March October 2018.

   [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-

   [RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
              Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
              DOI 10.17487/RFC2784, March 2000, <https://www.rfc-

   [RFC3232]  Reynolds, J., Ed., "Assigned Numbers:

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1700 is Replaced
              by an On-line Database",
              2119 Key Words", BCP 14, RFC 3232, 8174, DOI 10.17487/RFC3232,
              January 2002, <https://www.rfc-editor.org/info/rfc3232>. 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8300]  Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed.,
              "Network Service Header (NSH)", RFC 8300,
              DOI 10.17487/RFC8300, January 2018, <https://www.rfc-

8.2.  Informative References

   [FD.io]    "Fast Data Project: FD.io", <https://fd.io/>.

   [RFC7665]  Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
              Chaining (SFC) Architecture", RFC 7665,
              DOI 10.17487/RFC7665, October 2015, <https://www.rfc-

Authors' Addresses

   Frank Brockners
   Cisco Systems, Inc.
   Hansaallee 249, 3rd Floor

   Email: fbrockne@cisco.com

   Shwetha Bhandari
   Cisco Systems, Inc.
   Cessna Business Park, Sarjapura Marathalli Outer Ring Road
   Bangalore, KARNATAKA 560 087

   Email: shwethab@cisco.com

   Vengada Prasad Govindan
   Cisco Systems, Inc.

   Email: venggovi@cisco.com

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

   Email: cpignata@cisco.com

   Hannes Gredler
   RtBrick Inc.

   Email: hannes@rtbrick.com
   John Leddy

   Email: John_Leddy@cable.comcast.com

   Stephen Youell
   JP Morgan Chase
   25 Bank Street
   London  E14 5JP
   United Kingdom

   Email: stephen.youell@jpmorgan.com

   Tal Mizrahi
   6 Hamada St.
   Yokneam  20692
   Huawei Network.IO Innovation Lab

   Email: talmi@marvell.com tal.mizrahi.phd@gmail.com

   David Mozes

   Email: mosesster@gmail.com

   Petr Lapukhov
   1 Hacker Way
   Menlo Park, CA  94025

   Email: petr@fb.com

   Remy Chang
   Barefoot Networks
   2185 Park Boulevard
   Palo Alto, CA  94306