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Versions: (draft-brockners-sfc-ioam-nsh) 00

sfc                                                         F. Brockners
Internet-Draft                                               S. Bhandari
Intended status: Standards Track                             V. Govindan
Expires: December 2, 2018                                   C. Pignataro
                                                                   Cisco
                                                              H. Gredler
                                                            RtBrick Inc.
                                                                J. Leddy
                                                                 Comcast
                                                               S. Youell
                                                                    JMPC
                                                              T. Mizrahi
                                                                 Marvell
                                                                D. Mozes

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


                 NSH Encapsulation for In-situ OAM Data
                       draft-ietf-sfc-ioam-nsh-00

Abstract

   In-situ Operations, Administration, and Maintenance (OAM) 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).

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 http://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."




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

Copyright Notice

   Copyright (c) 2018 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
   (http://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 . . . . . . . . . . . . . . . . . . . . . . . . .   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) 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.
   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].







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2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   Abbreviations used in this document:

   IOAM:      In-situ Operations, Administration, and Maintenance

   NSH:       Network Service Header

   OAM:       Operations, Administration, and Maintenance

   TLV:       Type, Length, Value

3.  IOAM data fields encapsulation in NSH

   NSH is defined in [RFC8300].  IOAM data fields are carried in NSH
   using a next protocol header which follows the NSH MDx metadata TLVs.
   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/
   decapsulating nodes by means of configuration.


























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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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
   |Ver|O|C|R|R|R|R|R|R|   Length  |  MD Type      | NP = TBD_IOAM |  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  N
   |          Service Path Identifer               | 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, 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.

   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].




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   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
   NSH.

   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.



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   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 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
   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 |
                 +---------------+-------------+---------------+





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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

   [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., daniel.bernier@bell.ca, d., and J. Lemon,
              "Data Fields for In-situ OAM", draft-ietf-ippm-ioam-
              data-02 (work in progress), March 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-
              editor.org/info/rfc2119>.

   [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-
              editor.org/info/rfc2784>.

   [RFC3232]  Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced
              by an On-line Database", RFC 3232, DOI 10.17487/RFC3232,
              January 2002, <https://www.rfc-editor.org/info/rfc3232>.

   [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>.







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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-
              editor.org/info/rfc7665>.

Authors' Addresses

   Frank Brockners
   Cisco Systems, Inc.
   Hansaallee 249, 3rd Floor
   DUESSELDORF, NORDRHEIN-WESTFALEN  40549
   Germany

   Email: fbrockne@cisco.com


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

   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



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   John Leddy
   Comcast

   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
   Marvell
   6 Hamada St.
   Yokneam  20692
   Israel

   Email: talmi@marvell.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








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