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SPRING Working Group                                              Z. Ali
Internet-Draft                                                 R. Gandhi
Intended status: Standards Track                             C. Filsfils
Expires: April 25, 2019                                     F. Brockners
                                                               N. Nainar
                                                            C. Pignataro
                                                     Cisco Systems, Inc.
                                                                   C. Li
                                                                 M. Chen
                                                                  Huawei
                                                                G. Dawra
                                                                LinkedIn
                                                        October 22, 2018


       Segment Routing Header encapsulation for In-situ OAM Data
                     draft-ali-spring-ioam-srv6-00

Abstract

   In-situ Operations, Administration, and Maintenance (IOAM) records
   operational and telemetry information in the data packet while the
   packet traverses a path between two points in the network.  This
   document defines how IOAM data fields are transported as part of the
   Segment Routing with IPv6 data plane (SRv6) 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
   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."

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



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   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
     2.1.  Requirement Language . . . . . . . . . . . . . . . . . . .  3
     2.2.  Abbreviations  . . . . . . . . . . . . . . . . . . . . . .  3
   3.  IOAM Data Field Encapsulation in SRH . . . . . . . . . . . . .  4
   4.  Procedure  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     4.1.  Ingress Node . . . . . . . . . . . . . . . . . . . . . . .  5
     4.2.  SR Segment Endpoint Node . . . . . . . . . . . . . . . . .  5
     4.3.  Egress Node  . . . . . . . . . . . . . . . . . . . . . . .  6
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  6
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  6
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  6
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     8.1.  Normative References . . . . . . . . . . . . . . . . . . .  7
     8.2.  Informative References . . . . . . . . . . . . . . . . . .  7
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  8





1.  Introduction

   In-situ Operations, Administration, and Maintenance (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 IOAM data fields are added to the data packets rather than
   being sent within probe packets specifically dedicated to OAM.

   This document defines how IOAM data fields are transported as part of
   the Segment Routing with IPv6 data plane (SRv6) header
   [I-D.6man-segment-routing-header].

   The IOAM data fields carried are defined in
   [I-D.ietf-ippm-ioam-data], and can be used for various use-cases
   including Performance Measurement (PM) and Proof-of-Transit (PoT).




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2.  Conventions

2.1.  Requirement Language

   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] [RFC8174]
   when, and only when, they appear in all capitals, as shown here.


2.2.  Abbreviations

   Abbreviations used in this document:

   IOAM    In-situ Operations, Administration, and Maintenance

   OAM     Operations, Administration, and Maintenance

   PM      Performance Measurement

   PoT     Proof-of-Transit

   SR      Segment Routing

   SRH     SRv6 Header

   SRv6    Segment Routing with IPv6 Data plane
























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3.  IOAM Data Field Encapsulation in SRH

   The SRv6 encapsulation header (SRH) is defined in
   [I-D.6man-segment-routing-header].  IOAM data fields are carried in
   the SRH, using a single SRH TLV.  The different IOAM data fields
   defined in [I-D.ietf-ippm-ioam-data] are added as sub-TLVs.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  SRH-TLV-Type |     LEN       |    RESERVED                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
   |  IOAM-Type    | IOAM HDR LEN  |    RESERVED                   |  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  I
   !                                                               |  O
   !                                                               |  A
   ~                 IOAM Option and Data Space                    ~  M
   |                                                               |  |
   |                                                               |  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
   |                                                               |
   |                                                               |
   |                 Payload + Padding (L2/L3/...)                 |
   |                                                               |

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

                Figure 1: IOAM data encapsulation in SRH

   SRH-TLV-Type: IOAM TLV Type for SRH is defined as TBA1.

   The fields related to the encapsulation of IOAM data fields in the
   SRH 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 HDR in
      4-octet units.

   RESERVED:  8-bit reserved field MUST be set to zero upon transmission
      and ignored upon receipt.

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



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   The IOAM TLVs MAY change en route [I-D.ietf-ippm-ioam-data].  For the
   IOAM TLVs carried in SRH that can change en route, the most
   significant bit of the SRH-TLV-Type is set
   [I-D.6man-segment-routing-header].  Furthermore, such IOAM TLV in SRH
   is considered mutable for ICV computation, the Type Length, and
   Variable Length Data is ignored for ICV Computation as defined in
   [RFC4302].


4.  Procedure

   This section summarizes the procedure for IOAM data encapsulation in
   SRv6 SRH.  The SR nodes implementing the IOAM functionality follows
   the MTU and other considerations outlined in
   [I-D.6man-extension-header-insertion].

4.1.  Ingress Node

   The ingress node of an SR domain or an SR Policy
   [I-D.spring-segment-routing-policy] may insert the IOAM TLV in the
   SRH of the data packet.  The ingress node may also insert the IOAM
   data about the local information in the IOAM TLV in the SRH.  When
   IOAM data from the last node in the segment-list (Egress node) is
   desired, the ingress uses an Ultimate Segment Pop (USP) SID at the
   Egress node.

4.2.  SR Segment Endpoint Node

   The SR segment endpoint node is any node receiving an IPv6 packet
   where the destination address of that packet is a local SID or a
   local interface address.  As part of the SR Header processing as
   described in [I-D.6man-segment-routing-header] and
   [I-D.spring-srv6-network-programming], the SR Segment Endpoint node
   performs the following IOAM operations.  The description borrows the
   terminology used in [I-D.6man-segment-routing-header].  Specifically,
   n refers to the number of segments encoded in the SRH, "Hdr Ext Len"
   refers to the length of the SRH.  The "SRH Header Len" is the length
   of the SRH header, which is 8 octets
   [I-D.6man-segment-routing-header].

   The SR Segment Endpoint node compares the "Hdr Ext Len" of the SRH
   with the length of the "segment-list" in the SRH.  Specifically, if
   the SRH.Hdr_Ext_Len > n*16 + 8, the node looks for the presence of
   the IOAM TLV in the SRH.  If an IOAM TLV is present in the SRH and is
   supported by the Segment Endpoint Node, the SR segment endpoint node
   MAY modify the IOAM TLV in SRH with local IOAM data as per IOAM draft
   [I-D.ietf-ippm-ioam-data].




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4.3.  Egress Node

   The Egress node is the last node in the segment-list of the SRH. When
   IOAM data from the Egress node is desired, a USP SID advertised by
   the Egress node is used.

   The processing of IOAM TLV at the Egress node is similar to the
   processing of IOAM TLV at the SR Segment Endpoint Node.  The only
   difference is that the Egress node also performs the functionality
   required by the Egress node in an IOAM domain.  E.g., the Egress node
   may telemeter the IOAM data to a controller.


5.  IANA Considerations

   IANA is requested to allocate SRH TLV Type for IOAM TLV data fields
   under registry name "Segment Routing Header TLVs" requested by %[I-
   D.6man-segment-routing-header].

    +--------------+--------------------------+---------------+

    | SRH TLV Type | Description              | Reference     |
    +--------------+--------------------------+---------------+
    | TBA1         | TLV for IOAM Data Fields | This document |
    +--------------+--------------------------+---------------+


6.  Security Considerations

   The security considerations of SRv6 are discussed in
   [I-D.spring-srv6-network-programming] and
   [I-D.6man-segment-routing-header], and the security considerations of
   IOAM in general are discussed in [I-D.ietf-ippm-ioam-data].

   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 Shwetha Bhandari and Vengada Prasad
   Govindan for the discussions on IOAM.






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8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
              RFC2119, March 1997.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", RFC 8174, May 2017.

   [I-D.spring-srv6-network-programming]  Filsfils, C. et al. "SRv6
              Network Programming",
              draft-filsfils-spring-srv6-network-programming, work in
              progress.

   [I-D.6man-segment-routing-header]  Previdi, S., Filsfils, C. et al,
              "IPv6 Segment Routing Header (SRH)",
              draft-ietf-6man-segment-routing-header, work in progress.

   [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., and Bernier, D., "Data
              Fields for In-situ OAM", draft-ietf-ippm-ioam-data, work
              in progress.

   [I-D.spring-segment-routing-policy]  Filsfils, C., et al., "Segment
              Routing Policy Architecture",
              draft-ietf-spring-segment-routing-policy, work in
              progress.


8.2.  Informative References

   [I-D.6man-extension-header-insertion]  D. Voyer, et al., "Insertion
              of IPv6 Segment Routing Headers in a Controlled Domain",
              draft-voyer-6man-extension-header-insertion, work in
              progress.













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Authors' Addresses

   Zafar Ali
   Cisco Systems, Inc.

   Email: zali@cisco.com


   Rakesh Gandhi
   Cisco Systems, Inc.
   Canada

   Email: rgandhi@cisco.com


   Clarence Filsfils
   Cisco Systems, Inc.
   Belgium

   Email: cf@cisco.com


   Frank Brockners
   Cisco Systems, Inc.
   Germany

   Email: fbrockne@cisco.com

   Nagendra Kumar Nainar
   Cisco Systems, Inc.

   Email: naikumar@cisco.com

   Carlos Pignataro
   Cisco Systems, Inc.

   Email: cpignata@cisco.com

   Cheng Li
   Huawei

   Email: chengli13@huawei.com


   Mach(Guoyi) Chen
   Huawei

   Email: mach.chen@huawei.com


   Gaurav Dawra
   LinkedIn

   Email: gdawra.ietf@gmail.com




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