SFC                                                    F. Brockners, Ed.
Internet-Draft                                          S. Bhandari, Ed.
Intended status: Standards Track                                   Cisco
Expires: September 20, 2020                               March 14, 19, 2020                               September 11, 2019

 Network Service Header (NSH) Encapsulation for In-situ OAM (IOAM) Data
                       draft-ietf-sfc-ioam-nsh-02
                       draft-ietf-sfc-ioam-nsh-03

Abstract

   In-situ Operations, Administration, and Maintenance (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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Table of Contents

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

1.  Introduction

   In-situ OAM (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 for the Service Function
   Chaining (SFC) [RFC7665].  The IOAM data fields 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",
   "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.

   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  IOAM-Data-Fields are carried in NSH
   using a next protocol header which follows the NSH MD context
   headers.  An IOAM header is added containing the different IOAM data
   fields 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/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|U|    TTL    |   Length  |U|U|U|U|MD Type| NP = TBD_IOAM |  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  N
   |          Service Path 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
   TBD_IOAM.

   The IOAM related fields in NSH are defined as follows:

      IOAM-Type:  8-bit field defining the IOAM Option type, IOAM-Option-Type, as defined
         in the IOAM Option-Type Registry (see Section 7.2 of [I-D.ietf-ippm-ioam-data].
         [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. IOAM.  The semantics of this field are
         identical to the Next Protocol field in [RFC8300].

      IOAM Option and Data Space:  IOAM option header  IOAM-Option-Type and data is
         present IOAM-Data-Field
         as specified by the IOAM-Type field, and is defined in field are present (see Section 4
         of [I-D.ietf-ippm-ioam-data]. [I-D.ietf-ippm-ioam-data]).

   Multiple IOAM options IOAM-Option-Types MAY be included within the NSH
   encapsulation.  For example, if a NSH encapsulation contains two IOAM options
   IOAM-Option-Types 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 IOAM-Option-Type 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 discusses several approaches for encapsulating IOAM-
   Data-Fields in selecting NSH and presents the most appropriate approach rationale for encapsulating IOAM data fields the approach chosen
   in
   NSH. this document.

   An encapsulation of IOAM data fields 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 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  IOAM-
   Data-Fields are grouped into three option
      categories: Trace, several categories, including 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: IOAM-Data-Fields: The total length of IOAM
      data IOAM-Data-
   Fields can grow quite large in case multiple different IOAM data
      fields 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 Trace Option-Type
   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 IOAM-Data-Fields in NSH could
   be considered:

   1.  Encapsulation of IOAM data fields IOAM-Data-Fields as "NSH MD Type 2" (see
       [RFC8300], Section 2.5).  Each IOAM data field option (trace, IOAM-Option-Type (e.g.  trace,
       proof-of-transit, and edge-to-edge) would be specified by a type,
       with the different IOAM data fields 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 IOAM-Data-Fields using the "Next Protocol"
       field.  Each IOAM data field option (trace, IOAM-Option-Type (e.g trace, proof-of-transit, and
       edge-to-edge) would be specified by its own "next protocol".

   3.  Encapsulation of IOAM data fields 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
   deployments.

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
   payload.

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.  For additional IOAM
   related security considerations, see Section 8 in
   [I-D.ietf-ippm-ioam-data].

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.  Contributors

   In addition to editors listed on the title page, the following people
   have contributed to this document:

      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.net

      Stephen Youell
      JP Morgan Chase
      25 Bank Street
      London  E14 5JP
      United Kingdom
      Email: stephen.youell@jpmorgan.com

      Tal Mizrahi
      Huawei Network.IO Innovation Lab
      Israel
      Email: tal.mizrahi.phd@gmail.com

      David Mozes
      Email: mosesster@gmail.com

      Petr Lapukhov
      Facebook
      1 Hacker Way
      Menlo Park, CA  94025
      US
      Email: petr@fb.com
      Remy Chang
      Barefoot Networks
      2185 Park Boulevard
      Palo Alto, CA  94306
      US

9.  References

9.1.  Normative References

   [I-D.ietf-ippm-ioam-data]
              Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
              Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
              P., Chang, R., remy@barefootnetworks.com, r., daniel.bernier@bell.ca,
              d., and J. Lemon, "Data Fields for In-situ OAM", draft-ietf-ippm-ioam-
              data-06 draft-
              ietf-ippm-ioam-data-08 (work in progress), July October 2019.

   [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>.

   [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-editor.org/info/rfc8300>.

9.2.  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-editor.org/info/rfc7665>.

Authors' Addresses
   Frank Brockners (editor)
   Cisco Systems, Inc.
   Hansaallee 249, 3rd Floor
   DUESSELDORF, NORDRHEIN-WESTFALEN  40549
   Germany

   Email: fbrockne@cisco.com

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

   Email: shwethab@cisco.com