IPPM Working Group                                                X. Min
Internet-Draft                                                 G. Mirsky
Intended status: Standards Track                               ZTE Corp.
Expires: November 14, 2021                                         L. Bo
                                                           China Telecom
                                                            May 13, 2021


        Echo Request/Reply for Enabled In-situ OAM Capabilities
                   draft-xiao-ippm-ioam-conf-state-09

Abstract

   This document describes an extension to the echo request/reply
   mechanisms used in IPv6, MPLS and SFC environments, which can be used
   within an IOAM domain, allowing the IOAM encapsulating node to
   acquire the enabled IOAM capabilities of each IOAM transit node and/
   or IOAM decapsulating node.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on November 14, 2021.

Copyright Notice

   Copyright (c) 2021 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
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   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     2.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   4
   3.  IOAM Capabilities Formats . . . . . . . . . . . . . . . . . .   5
     3.1.  IOAM Capabilities Query TLV in the Echo Request . . . . .   5
     3.2.  IOAM Capabilities Response TLV in the Echo Reply  . . . .   6
       3.2.1.  IOAM Pre-allocated Tracing Capabilities sub-TLV . . .   7
       3.2.2.  IOAM Incremental Tracing Capabilities sub-TLV . . . .   8
       3.2.3.  IOAM Proof of Transit Capabilities sub-TLV  . . . . .   9
       3.2.4.  IOAM Edge-to-Edge Capabilities sub-TLV  . . . . . . .  10
       3.2.5.  IOAM DEX Capabilities sub-TLV . . . . . . . . . . . .  11
       3.2.6.  IOAM End-of-Domain sub-TLV  . . . . . . . . . . . . .  12
   4.  Operational Guide . . . . . . . . . . . . . . . . . . . . . .  13
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     6.1.  IOAM SoR Capability Registry  . . . . . . . . . . . . . .  14
     6.2.  IOAM TSF+TSL Capability Registry  . . . . . . . . . . . .  15
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   The Data Fields for In-situ OAM (IOAM) [I-D.ietf-ippm-ioam-data]
   defines data fields that record OAM information within the packet
   while the packet traverses a particular network domain, which is
   called an IOAM domain.  IOAM can be used to complement OAM mechanisms
   based on, e.g., ICMP or other types of probe packets, and IOAM
   mechanisms can be leveraged where mechanisms using, e.g., ICMP do not
   apply or do not offer the desired results.

   As specified in [I-D.ietf-ippm-ioam-data], within the IOAM-domain,
   the IOAM data may be updated by network nodes that the packet
   traverses.  The device which adds an IOAM data container to the
   packet to capture IOAM data is called the "IOAM encapsulating node".
   In contrast, the device which removes the IOAM data container is
   referred to as the "IOAM decapsulating node".  Nodes within the
   domain that are aware of IOAM data and read and/or write or process
   the IOAM data are called "IOAM transit nodes".  Both the IOAM




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   encapsulating node and the decapsulating node are referred to as
   domain edge devices, which can be hosts or network devices.

   In order to add the correct IOAM data container to the packet, the
   IOAM encapsulating node needs to know the enabled IOAM capabilities
   at the IOAM transit nodes and/or the IOAM decapsulating node as a
   whole, e.g., how many IOAM transit nodes will add tracing data, and
   what kinds of data fields will be added.  A centralized controller
   could be used in some IOAM deployments.  The IOAM encapsulating node
   can acquire these IOAM capabilities info from the centralized
   controller, through, e.g., Netconf/YANG, PCEP, or BGP.  In the IOAM
   deployment scenario where there is no centralized controller,
   Netconf/YANG or IGP may be used for the IOAM encapsulating node to
   acquire these IOAM capabilities info, however, whether Netconf/YANG
   or IGP has some limitations as follows.

   o  When Netconf/YANG is used in this scenario, each IOAM
      encapsulating node (including the host when it takes the role of
      an IOAM encapsulating node) needs to implement a Netconf Client,
      each IOAM transit node and IOAM decapsulating node (including the
      host when it takes the role of an IOAM decapsulating node) needs
      to implement a Netconf Server, the complexity can be an issue.
      Furthermore, each IOAM encapsulating node needs to establish
      Netconf Connection with each IOAM transit node and IOAM
      decapsulating node, the scalability can be an issue.

   o  When IGP is used in this scenario, the IGP domain and an IOAM
      domain don't always have the same coverage.  For example, when the
      IOAM encapsulating node or the IOAM decapsulating node is a host,
      the availability can be an issue.  Furthermore, it might be too
      challenging to reflect IOAM capabilities at the IOAM transit node
      and/or the IOAM decapsulating node if these are controlled by a
      local policy depending on the identity of the IOAM encapsulating
      node.

   This document describes an extension to the echo request/reply
   mechanisms used in IPv6, MPLS and SFC environments, which can be used
   within an IOAM domain where no Centralized Controller exists,
   allowing the IOAM encapsulating node to acquire the enabled IOAM
   capabilities of each IOAM transit node and/or IOAM decapsulating
   node.

   The following documents contain references to the echo request/reply
   mechanisms used in IPv6, MPLS and SFC environments:

   o  [RFC4443] ("Internet Control Message Protocol (ICMPv6) for the
      Internet Protocol Version 6 (IPv6) Specification"), [RFC4884]




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      ("Extended ICMP to Support Multi-Part Messages") and [RFC8335]
      ("PROBE: A Utility for Probing Interfaces")

   o  [RFC8029] ("Detecting Multiprotocol Label Switched (MPLS) Data-
      Plane Failures")

   o  [I-D.ietf-sfc-multi-layer-oam] ("Active OAM for Service Function
      Chains in Networks")

   This feature described in this document is assumedly applied to
   explicit path (strict or loose), because the precondition for this
   feature to work is that the echo request reaches each IOAM transit
   node as live traffic traverses.

2.  Conventions

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

   BGP: Border Gateway Protocol

   E2E: Edge to Edge

   ICMP: Internet Control Message Protocol

   IGP: Interior Gateway Protocol

   IOAM: In-situ Operations, Administration, and Maintenance

   LSP: Label Switched Path

   MPLS: Multi-Protocol Label Switching

   MBZ: Must Be Zero

   MTU: Maximum Transmission Unit

   NTP: Network Time Protocol

   OAM: Operations, Administration, and Maintenance




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   PCEP: Path Computation Element (PCE) Communication Protocol

   POSIX: Portable Operating System Interface

   POT: Proof of Transit

   PTP: Precision Time Protocol

   SFC: Service Function Chain

   TTL: Time to Live

3.  IOAM Capabilities Formats

3.1.  IOAM Capabilities Query TLV in the Echo Request

   In echo request IOAM Capabilities Query uses TLV (Type-Length-Value
   tuple) which have the following format:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Type = IOAM Capabilities Query|            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     .                                                               .
     .                    List of Namespace-IDs                      .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         Figure 1: IOAM Capabilities Query TLV in the Echo Request

   When this TLV is present in the echo request sent by an IOAM
   encapsulating node, it means that the IOAM encapsulating node
   requests the receiving node to reply with its enabled IOAM
   capabilities.  If there is no IOAM capability to be reported by the
   receiving node, then this TLV SHOULD be ignored by the receiving
   node, which means the receiving node SHOULD send echo reply without
   IOAM capabilities or no echo reply, in the light of whether the echo
   request includes other TLV than IOAM Capabilities Query TLV.  List of
   Namespace-IDs MAY be included in this TLV of the echo request.  In
   that case, the IOAM encapsulating node requests only the IOAM
   capabilities that match one of the Namespace-IDs.  The Namespace-ID
   has the same definition as what's specified in
   [I-D.ietf-ippm-ioam-data].

   Type is set to the value that identifies it as an IOAM Capabilities
   Query TLV.




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   Length is the length of the TLV's Value field in octets, including a
   List of Namespace-IDs.

   Value field of this TLV is zero-padded to align to a 4-octet
   boundary.

3.2.  IOAM Capabilities Response TLV in the Echo Reply

   In echo reply IOAM Capabilities Response uses TLV which have the
   following format:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Type = IOAM Capabilities Resp |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     .                                                               .
     .                      List of Sub-TLVs                         .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 2: IOAM Capabilities Response TLV in the Echo Reply

   When this TLV is present in the echo reply sent by an IOAM transit
   node and/or an IOAM decapsulating node, it means that the IOAM
   function is enabled at this node, and this TLV contains the enabled
   IOAM capabilities of the sender.  A list of Sub-TLVs which contains
   the IOAM capabilities SHOULD be included in this TLV of the echo
   reply.  Note that the IOAM encapsulating node or the IOAM
   decapsulating node can also be an IOAM transit node.

   Type is set to the value that identifies it as an IOAM Capabilities
   Response TLV.

   Length is the length of the TLV's Value field in octets, including a
   List of Sub-TLVs.

   Value field of this TLV or any Sub-TLV is zero-padded to align to a
   4-octet boundary.  Based on the data fields for IOAM, specified in
   [I-D.ietf-ippm-ioam-data] and [I-D.ietf-ippm-ioam-direct-export], six
   kinds of Sub-TLVs are defined in this document.  The same type of the
   sub-TLV MAY be in the IOAM Capabilities Response TLV more than once
   only if with a different Namespace-ID.








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3.2.1.  IOAM Pre-allocated Tracing Capabilities sub-TLV

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Sub-type = Pre-allocated trace |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IOAM-Trace-Type                 |    Reserved   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          |          Egress_MTU           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Egress_if_id (short or wide format)         ......           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         Figure 3: IOAM Pre-allocated Tracing Capabilities Sub-TLV

   When this sub-TLV is present in the IOAM Capabilities Response TLV,
   it means that the sending node is an IOAM transit node and IOAM pre-
   allocated tracing function is enabled at this IOAM transit node.

   Sub-type is set to the value that identifies it as an IOAM Pre-
   allocated Tracing Capabilities sub-TLV.

   Length is the length of the sub-TLV's Value field in octets.  If
   Egress_if_id is in the short format, which is 16 bits long, it MUST
   be set to 10.  If Egress_if_id is in the wide format, which is 32
   bits long, it MUST be set to 12.

   IOAM-Trace-Type field has the same definition as what's specified in
   section 5.4 of [I-D.ietf-ippm-ioam-data].

   Reserved field is reserved for future use and MUST be set to zero.

   Namespace-ID field has the same definition as what's specified in
   section 5.3 of [I-D.ietf-ippm-ioam-data], it should be one of the
   Namespace-IDs listed in the IOAM Capabilities Query TLV of echo
   request.

   Egress_MTU field has 16 bits and specifies the MTU of the egress
   direction out of which the sending node would forward the received
   echo request, it should be the MTU of the egress interface or the MTU
   between the sending node and the downstream IOAM transit node.

   Egress_if_id field has 16 bits (in short format) or 32 bits (in wide
   format) and specifies the identifier of the egress interface out of
   which the sending node would forward the received echo request.





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3.2.2.  IOAM Incremental Tracing Capabilities sub-TLV

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Sub-type = Incremental trace  |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IOAM-Trace-Type                 |     Reserved  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          |          Egress_MTU           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Egress_if_id (short or wide format)         ......           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 4: IOAM Incremental Tracing Capabilities Sub-TLV

   When this sub-TLV is present in the IOAM Capabilities Response TLV,
   it means that the sending node is an IOAM transit node and IOAM
   incremental tracing function is enabled at this IOAM transit node.

   Sub-type is set to the value that identifies it as an IOAM
   Incremental Tracing Capabilities sub-TLV.

   Length is the length of the sub-TLV's Value field in octets.  If
   Egress_if_id is in the short format, which is 16 bits long, it MUST
   be set to 10.  If Egress_if_id is in the wide format, which is 32
   bits long, it MUST be set to 12.

   IOAM-Trace-Type field has the same definition as what's specified in
   section 5.4 of [I-D.ietf-ippm-ioam-data].

   Reserved field is reserved for future use and MUST be set to zero.

   Namespace-ID field has the same definition as what's specified in
   section 5.3 of [I-D.ietf-ippm-ioam-data], it should be one of the
   Namespace-IDs listed in the IOAM Capabilities Query TLV of echo
   request.

   Egress_MTU field has 16 bits and specifies the MTU of the egress
   direction out of which the sending node would forward the received
   echo request, it should be the MTU of the egress interface or the MTU
   between the sending node and the downstream IOAM transit node.

   Egress_if_id field has 16 bits (in short format) or 32 bits (in wide
   format) and specifies the identifier of the egress interface out of
   which the sending node would forward the received echo request.





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3.2.3.  IOAM Proof of Transit Capabilities sub-TLV

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Sub-type = POT Capabilities  |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Namespace-ID           | IOAM-POT-Type |P|SoR|Reserved |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 5: IOAM Proof of Transit Capabilities Sub-TLV

   When this sub-TLV is present in the IOAM Capabilities Response TLV,
   it means that the sending node is an IOAM transit node and IOAM proof
   of transit function is enabled at this IOAM transit node.

   Sub-type is set to the value that identifies it as an IOAM Proof of
   Transit Capabilities sub-TLV.

   Length is the length of the sub-TLV's Value field in octets and MUST
   be set to 4.

   Namespace-ID field has the same definition as what's specified in
   section 5.3 of [I-D.ietf-ippm-ioam-data], it should be one of the
   Namespace-IDs listed in the IOAM Capabilities Query TLV of echo
   request.

   IOAM-POT-Type field and P bit have the same definition as what's
   specified in section 5.5 of [I-D.ietf-ippm-ioam-data].  If the IOAM
   encapsulating node receives IOAM-POT-Type and/or P bit values from an
   IOAM transit node that are different from its own, then the IOAM
   encapsulating node MAY choose to abandon the proof of transit
   function or to select one kind of IOAM-POT-Type and P bit, it's based
   on the policy applied to the IOAM encapsulating node.

   SoR field has two bits, which means the size of "Random" and
   "Cumulative" data that are specified in section 5.5 of
   [I-D.ietf-ippm-ioam-data].  This document defines SoR as follow:

      0b00 means 64-bit "Random" and 64-bit "Cumulative" data.

      0b01~0b11: Reserved for future standardization

   Reserved field is reserved for future use and MUST be set to zero.







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3.2.4.  IOAM Edge-to-Edge Capabilities sub-TLV

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Sub-type = E2E Capabilities  |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Namespace-ID           |         IOAM-E2E-Type         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |TSF|TSL|       Reserved        |              MBZ              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Figure 6: IOAM Edge-to-Edge Capabilities Sub-TLV

   When this sub-TLV is present in the IOAM Capabilities Response TLV,
   it means that the sending node is an IOAM decapsulating node and IOAM
   edge-to-edge function is enabled at this IOAM decapsulating node.
   That is to say, if the IOAM encapsulating node receives this sub-TLV,
   the IOAM encapsulating node can determine that the node which sends
   this sub-TLV is an IOAM decapsulating node.

   Sub-type is set to the value that identifies it as an IOAM Edge-to-
   Edge Capabilities sub-TLV.

   Length is the length of the sub-TLV's Value field in octets and MUST
   be set to 8.

   Namespace-ID field has the same definition as what's specified in
   section 5.3 of [I-D.ietf-ippm-ioam-data], it should be one of the
   Namespace-IDs listed in the IOAM Capabilities Query TLV of echo
   request.

   IOAM-E2E-Type field has the same definition as what's specified in
   section 5.6 of [I-D.ietf-ippm-ioam-data].

   TSF field specifies the timestamp format used by the sending node.
   This document defines TSF as follow:

      0b00: PTP timestamp format

      0b01: NTP timestamp format

      0b10: POSIX timestamp format

      0b11: Reserved for future standardization

   TSL field specifies the timestamp length used by the sending node.
   This document defines TSL as follow.



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      When the TSF field is set to 0b00, which indicates the PTP
      timestamp format, the values of the TSL field are interpreted as
      follows:

      0b00: 64-bit PTPv1 timestamp as defined in IEEE1588-2008
      [IEEE1588v2]

      0b01: 80-bit PTPv2 timestamp as defined in IEEE1588-2008
      [IEEE1588v2]

      0b10~0b11: Reserved for future standardization

      When the TSF field is set to 0b01, which indicates the NTP
      timestamp format, the values of the TSL field are interpreted as
      follows:

      0b00: 32-bit NTP timestamp as defined in NTPv4 [RFC5905]

      0b01: 64-bit NTP timestamp as defined in NTPv4 [RFC5905]

      0b10: 128-bit NTP timestamp as defined in NTPv4 [RFC5905]

      0b11: Reserved for future standardization

      When the TSF field is set to 0b10 or 0b11, the TSL field would be
      ignored.

   Reserved field is reserved for future use and MUST be set to zero.

3.2.5.  IOAM DEX Capabilities sub-TLV

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Sub-type = DEX Capabilities  |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IOAM-Trace-Type                 |    Reserved   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          |           Reserved            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 7: IOAM DEX Capabilities Sub-TLV

   When this sub-TLV is present in the IOAM Capabilities Response TLV,
   it means that the sending node is an IOAM transit node and the IOAM
   DEX function is enabled at this IOAM transit node.





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   Sub-type is set to the value that identifies it as an IOAM DEX
   Capabilities sub-TLV.

   Length is the length of the sub-TLV's Value field in octets and MUST
   be set to 8.

   IOAM-Trace-Type field has the same definition as what's specified in
   section 3.2 of [I-D.ietf-ippm-ioam-direct-export].

   Namespace-ID field has the same definition as what's specified in
   section 3.2 of [I-D.ietf-ippm-ioam-direct-export], it should be one
   of the Namespace-IDs listed in the IOAM Capabilities Query TLV of
   echo request.

   Reserved field is reserved for future use and MUST be set to zero.

3.2.6.  IOAM End-of-Domain sub-TLV

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Sub-type = End of Domain    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Namespace-ID           |             MBZ               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 8: IOAM End of Domain Sub-TLV

   When this sub-TLV is present in the IOAM Capabilities Response TLV,
   it means that the sending node is an IOAM decapsulating node.  That
   is to say, if the IOAM encapsulating node receives this sub-TLV, the
   IOAM encapsulating node can determine that the node which sends this
   sub-TLV is an IOAM decapsulating node.  When the IOAM Edge-to-Edge
   Capabilities sub-TLV is present in the IOAM Capabilities Response TLV
   sent by the IOAM decapsulating node, the IOAM End-of-Domain sub-TLV
   doesn't need to be present in the same IOAM Capabilities Response
   TLV, otherwise the End-of-Domain sub-TLV MUST be present in the IOAM
   Capabilities Response TLV sent by the IOAM decapsulating node.  Both
   the IOAM Edge-to-Edge Capabilities sub-TLV and the IOAM End-of-Domain
   sub-TLV can be used to indicate that the sending node is an IOAM
   decapsulating node.  It's recommended to include only the IOAM Edge-
   to-Edge Capabilities sub-TLV if IOAM edge-to-edge function is enabled
   at this IOAM decapsulating node.

   Sub-type is set to the value that identifies it as an IOAM End of
   Domain sub-TLV.





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   Length is the length of the sub-TLV's Value field in octets and MUST
   be set to 4.

   Namespace-ID field has the same definition as what's specified in
   section 5.3 of [I-D.ietf-ippm-ioam-data], it should be one of the
   Namespace-IDs listed in the IOAM Capabilities Query TLV of echo
   request.

4.  Operational Guide

   Once the IOAM encapsulating node is triggered to acquire the enabled
   IOAM capabilities of each IOAM transit node and/or IOAM decapsulating
   node, the IOAM encapsulating node will send echo requests that
   include the IOAM Capabilities Query TLV.  First with TTL equal to 1
   to reach the nearest node, which may be an IOAM transit node or not.
   Then with TTL equal to 2 to reach the second nearest node, which also
   may be an IOAM transit node or not.  And further, increasing by 1 the
   TTL every time the IOAM encapsulating node sends a new echo request,
   until the IOAM encapsulating node receives an echo reply sent by the
   IOAM decapsulating node, which should contain the IOAM Capabilities
   Response TLV including the IOAM Edge-to-Edge Capabilities sub-TLV or
   the IOAM End-of-Domain sub-TLV.  Alternatively, if the IOAM
   encapsulating node knows exactly all the IOAM transit nodes and/or
   IOAM decapsulating node beforehand, once the IOAM encapsulating node
   is triggered to acquire the enabled IOAM capabilities, it can send an
   echo request to each IOAM transit node and/or IOAM decapsulating node
   directly, without TTL expiration.

   The IOAM encapsulating node may be triggered by the device
   administrator, the network management system, the network controller,
   or even the live user traffic.  The specific triggering mechanisms
   are outside the scope of this document.

   Each IOAM transit node and/or IOAM decapsulating node that receives
   an echo request containing the IOAM Capabilities Query TLV will send
   an echo reply to the IOAM encapsulating node, and within the echo
   reply, there should be an IOAM Capabilities Response TLV containing
   one or more sub-TLVs.  The IOAM Capabilities Query TLV contained in
   the echo request would be ignored by the receiving node that is
   unaware of IOAM.

5.  Security Considerations

   Queries and responses about the state of an IOAM domain should be
   processed only from a trusted source.  An unauthorized query MUST be
   discarded by an implementation that supports this specification.
   Similarly, unsolicited echo response with the IOAM Capabilities TLV
   MUST be discarded.  Authentication of echo request/reply that



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   includes the IOAM Capabilities TLV is one of methods of the integrity
   protection.  Implementations could also provide a means of filtering
   based on the source address of the received echo request/reply.  The
   integrity protection for IOAM capabilities information collection can
   also be achieved using mechanisms in the underlay data plane.  For
   example, if the underlay is an IPv6 network, IP Authentication Header
   [RFC4302] or IP Encapsulating Security Payload Header [RFC4303] can
   be used to provide integrity protection.

   Information about the state of the IOAM domain collected in the IAOM
   Capabilities TLV is confidential.  An implementation can use secure
   transport to provide privacy protection.  For example, if the
   underlay is an IPv6 network, confidentiality can be achieved using
   the IP Encapsulating Security Payload Header [RFC4303].

6.  IANA Considerations

   This document requests the following IANA Actions.

   IANA is requested to create a registry group named "In-Situ OAM
   (IOAM) Capabilities Parameters".

   This group will include the following registries:

   o  IOAM SoR Capability

   o  IOAM TSF+TSL Capability

   New registries in this group can be created via RFC Required process
   as per [RFC8126].

   The subsequent sub-sections detail the registries herein contained.

   Considering the TLVs/sub-TLVs defined in this document would be
   carried in different kinds of Echo Request/Reply message, such as
   ICMPv6 or LSP Ping, it is intended that the registries for Type and
   sub-Type would be requested in subsequent documents.

6.1.  IOAM SoR Capability Registry

   This registry defines 4 code points for the IOAM SoR Capability field
   for identifying the size of "Random" and "Cumulative" data as
   explained in section 5.5 of [I-D.ietf-ippm-ioam-data].  The following
   code points are defined in this draft:

      SoR        Description
      ----       -----------
      0b00       64-bit "Random" and 64-bit "Cumulative" data



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   0b01 - 0b11 are available for assignment via RFC Required process as
   per [RFC8126].

6.2.  IOAM TSF+TSL Capability Registry

   This registry defines 3 code points for the IOAM TSF Capability field
   for identifying the timestamp format as explained in section 6 of
   [I-D.ietf-ippm-ioam-data].

   o  When the code point for the IOAM TSF Capability field equals 0b00
      which means PTP timestamp format, this registry defines 2 code
      points for the IOAM TSL Capability field for identifying the
      timestamp length.

   o  When the code point for the IOAM TSF Capability field equals 0b01
      which means NTP timestamp format, this registry defines 3 code
      points for the IOAM TSL Capability field for identifying the
      timestamp length.

   The following code points are defined in this draft:

      TSF        TSL         Description
      ----       ----        -----------
      0b00                   PTP Timestamp Format
                 0b00        64-bit PTPv1 timestamp
                 0b01        80-bit PTPv2 timestamp
      0b01                   NTP Timestamp Format
                 0b00        32-bit NTP timestamp
                 0b01        64-bit NTP timestamp
                 0b10        128-bit NTP timestamp
      0b10                   POSIX Timestamp Format

   Unassigned code points of TSF+TSL are available for assignment via
   RFC Required process as per [RFC8126].

7.  Acknowledgements

   The authors would like to acknowledge Tianran Zhou, Dhruv Dhody,
   Frank Brockners and Cheng Li for their careful review and helpful
   comments.

   The authors appreciate the f2f discussion with Frank Brockners on
   this document.

   The authors would like to acknowledge Tommy Pauly and Ian Swett for
   their good suggestion and guidance.





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8.  References

8.1.  Normative References

   [I-D.ietf-ippm-ioam-data]
              Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields
              for In-situ OAM", draft-ietf-ippm-ioam-data-12 (work in
              progress), February 2021.

   [I-D.ietf-ippm-ioam-direct-export]
              Song, H., Gafni, B., Zhou, T., Li, Z., Brockners, F.,
              Bhandari, S., Sivakolundu, R., and T. Mizrahi, "In-situ
              OAM Direct Exporting", draft-ietf-ippm-ioam-direct-
              export-03 (work in progress), February 2021.

   [IEEE1588v2]
              IEEE, "IEEE Std 1588-2008 - IEEE Standard for a Precision
              Clock Synchronization Protocol for Networked Measurement
              and Control Systems",  IEEE Std 1588-2008, 2008,
              <http://standards.ieee.org/findstds/
              standard/1588-2008.html>.

   [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>.

   [RFC5905]  Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
              "Network Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
              <https://www.rfc-editor.org/info/rfc5905>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [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>.

8.2.  Informative References

   [I-D.ietf-sfc-multi-layer-oam]
              Mirsky, G., Meng, W., Khasnabish, B., and C. Wang, "Active
              OAM for Service Function Chaining", draft-ietf-sfc-multi-
              layer-oam-10 (work in progress), March 2021.




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   [RFC4302]  Kent, S., "IP Authentication Header", RFC 4302,
              DOI 10.17487/RFC4302, December 2005,
              <https://www.rfc-editor.org/info/rfc4302>.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, DOI 10.17487/RFC4303, December 2005,
              <https://www.rfc-editor.org/info/rfc4303>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/info/rfc4443>.

   [RFC4884]  Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
              "Extended ICMP to Support Multi-Part Messages", RFC 4884,
              DOI 10.17487/RFC4884, April 2007,
              <https://www.rfc-editor.org/info/rfc4884>.

   [RFC8029]  Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
              Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
              Switched (MPLS) Data-Plane Failures", RFC 8029,
              DOI 10.17487/RFC8029, March 2017,
              <https://www.rfc-editor.org/info/rfc8029>.

   [RFC8335]  Bonica, R., Thomas, R., Linkova, J., Lenart, C., and M.
              Boucadair, "PROBE: A Utility for Probing Interfaces",
              RFC 8335, DOI 10.17487/RFC8335, February 2018,
              <https://www.rfc-editor.org/info/rfc8335>.

Authors' Addresses

   Xiao Min
   ZTE Corp.
   Nanjing
   China

   Phone: +86 25 88013062
   Email: xiao.min2@zte.com.cn


   Greg Mirsky
   ZTE Corp.
   USA

   Email: gregory.mirsky@ztetx.com





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   Lei Bo
   China Telecom
   Beijing
   China

   Phone: +86 10 50902903
   Email: leibo@chinatelecom.cn












































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