In-situ OAM Direct Exporting
draft-ietf-ippm-ioam-direct-export-00

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IPPM                                                             H. Song
Internet-Draft                                                 Futurewei
Intended status: Standards Track                                B. Gafni
Expires: August 9, 2020                      Mellanox Technologies, Inc.
                                                                 T. Zhou
                                                                   Z. Li
                                                                  Huawei
                                                            F. Brockners
                                                             S. Bhandari
                                                          R. Sivakolundu
                                                                   Cisco
                                                         T. Mizrahi, Ed.
                                             Huawei Smart Platforms iLab
                                                        February 6, 2020

                      In-situ OAM Direct Exporting
                 draft-ietf-ippm-ioam-direct-export-00

Abstract

   In-situ Operations, Administration, and Maintenance (IOAM) is used
   for recording and collecting operational and telemetry information.
   Specifically, IOAM allows telemetry data to be pushed into data
   packets while they traverse the network.  This document introduces a
   new IOAM option type called the Direct Export (DEX) option, which is
   used as a trigger for IOAM data to be directly exported without being
   pushed into in-flight data packets.

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 9, 2020.

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Copyright Notice

   Copyright (c) 2020 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
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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 . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Requirement Language  . . . . . . . . . . . . . . . . . .   3
     2.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  The Direct Exporting (DEX) IOAM Option Type . . . . . . . . .   3
     3.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  The DEX Option Format . . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  IOAM Type . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  IOAM DEX Flags  . . . . . . . . . . . . . . . . . . . . .   6
   5.  Performance Considerations  . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  Topics for Further Discussion . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   IOAM [I-D.ietf-ippm-ioam-data] is used for monitoring traffic in the
   network, and for incorporating IOAM data fields into in-flight data
   packets.

   IOAM makes use of four possible IOAM options, defined in
   [I-D.ietf-ippm-ioam-data]: Pre-allocated Trace Option, Incremental
   Trace Option, Proof of Transit (POT) Option, and Edge-to-Edge Option.

   This document defines a new IOAM option type (also known as an IOAM
   type) called the Direct Export (DEX) option.  This option is used as
   a trigger for IOAM nodes to export IOAM data to a receiving entity

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   (or entities).  A "receiving entity" in this context can be, for
   example, an external collector, analyzer, controller, decapsulating
   node, or a software module in one of the IOAM nodes.

   This draft has evolved from combining some of the concepts of PBT-I
   from [I-D.song-ippm-postcard-based-telemetry] with immediate
   exporting from [I-D.mizrahi-ippm-ioam-flags].

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].

2.2.  Terminology

   Abbreviations used in this document:

   IOAM:      In-situ Operations, Administration, and Maintenance

   OAM:       Operations, Administration, and Maintenance

   DEX:       Direct EXporting

3.  The Direct Exporting (DEX) IOAM Option Type

3.1.  Overview

   The DEX option is used as a trigger for exporting telemetry data to a
   receiving entity (or entities).

   This option is incorporated into data packets by an IOAM
   encapsulating node, and removed by an IOAM decapsulating node, as
   illustrated in Figure 1.  The option can be read but not modified by
   transit nodes.  Note: the terms IOAM encapsulating, decapsulating and
   transit nodes are as defined in [I-D.ietf-ippm-ioam-data].

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                                      ^
                                      |Exported IOAM data
                                      |
                                      |
                                      |
                +--------------+------+-------+--------------+
                |              |              |              |
                |              |              |              |
  User      +---+----+     +---+----+     +---+----+     +---+----+
  packets   |Encapsu-|     | Transit|     | Transit|     |Decapsu-|
  --------->|lating  |====>| Node   |====>| Node   |====>|lating  |---->
            |Node    |     | A      |     | B      |     |Node    |
            +--------+     +--------+     +--------+     +--------+
            Insert DEX       Export         Export       Remove DEX
            option and      IOAM data      IOAM data     option and
            export data                                  export data

                        Figure 1: DEX Architecture

   The DEX option is used as a trigger to export IOAM data.  The trigger
   applies to transit nodes, the decapsulating node, and the
   encapsulating node:

   o  An IOAM encapsulating node configured to incorporate the DEX
      option encapsulates the packet with the DEX option, and MAY export
      the requested IOAM data immediately.  The IOAM encapsulating node
      is the only type of node allowed to push the DEX option.

   o  A transit node that processes a packet with the DEX option MAY
      export the requested IOAM data.

   o  An IOAM decapsulating node that processes a packet with the DEX
      option MAY export the requested IOAM data, and MUST decapsulate
      the IOAM header.

   As in [I-D.ietf-ippm-ioam-data], the DEX option may be incorporated
   into all or a subset of the traffic that is forwarded by the
   encapsulating node.  Moreover, IOAM nodes MAY export data for all
   traversing packets that carry the DEX option, or MAY selectively
   export data only for a subset of these packets.

   The DEX option specifies which data fields should be exported, as
   specified in Section 3.2.  The format and encapsulation of the packet
   that contains the exported data is not within the scope of the
   current document.  For example, the export format can be based on
   [I-D.spiegel-ippm-ioam-rawexport].

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   A transit IOAM node that does not support the DEX option SHOULD
   ignore it.  A decapsulating node that does not support the DEX option
   MUST remove it, along with any other IOAM options carried in the
   packet if such exist.

3.2.  The DEX Option Format

   The format of the DEX option is depicted in Figure 2.  The length of
   the DEX option is either 8 octets or 16 octets, as the Flow ID and
   the Sequence Number fields (summing up to 8 octets) are optional.  It
   is assumed that the lower layer protocol indicates the length of the
   DEX option, thus indicating whether the two optional fields are
   present.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Namespace-ID           |            Flags              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               IOAM-Trace-Type                 |   Reserved    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flow ID (optional)                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Sequence Number  (Optional)               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 2: DEX Option Format

   Namespace-ID    A 16-bit identifier of the IOAM namespace, as defined
                   in [I-D.ietf-ippm-ioam-data].

   Flags           A 16-bit field, comprised of 16 one-bit subfields.
                   Flags are allocated by IANA, as defined in
                   Section 4.2.

   IOAM-Trace-Type A 24-bit identifier which specifies which data fields
                   should be exported.  The format of this field is as
                   defined in [I-D.ietf-ippm-ioam-data].  Specifically,
                   bit 23, which corresponds to the Checksum Complement
                   data field, should be assigned to be zero by the IOAM
                   encapsulating node, and ignored by transit and
                   decapsulating nodes.  The reason for this is that the
                   Checksum Complement is intended for in-flight packet
                   modifications and is not relevant for direct
                   exporting.

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   Reserved        This field SHOULD be ignored by the receiver.

   Flow ID         A 32-bit flow identifier.  If the actual Flow ID is
                   shorter than 32 bits, it is zero padded in its most
                   significant bits.  The field is set at the
                   encapsulating node.  The Flow ID can be uniformly
                   assigned by a central controller or algorithmically
                   generated by the encapsulating node.  The latter
                   approach cannot guarantee the uniqueness of Flow ID,
                   yet the conflict probability is small due to the
                   large Flow ID space.  The Flow ID can be used to
                   correlate the exported data of the same flow from
                   multiple nodes and from multiple packets.

   Sequence Number A 32-bit sequence number starting from 0 and
                   increasing by 1 for each following monitored packet
                   from the same flow at the encapsulating node.  The
                   Sequence Number, when combined with the Flow ID,
                   provides a convenient approach to correlate the
                   exported data from the same user packet.

4.  IANA Considerations

4.1.  IOAM Type

   The "IOAM Type Registry" was defined in Section 7.2 of
   [I-D.ietf-ippm-ioam-data].  IANA is requested to allocate the
   following code point from the "IOAM Type Registry" as follows:

   TBD-type   IOAM Direct Export (DEX) Option Type

   If possible, IANA is requested to allocate code point 4 (TBD-type).

4.2.  IOAM DEX Flags

   IANA is requested to define an "IOAM DEX Flags" registry.  This
   registry includes 16 flag bits.  Allocation should be performed based
   on the "RFC Required" procedure, as defined in [RFC8126].

5.  Performance Considerations

   The DEX option triggers exported packets to be exported to a
   receiving entity (or entities).  In some cases this may impact the
   receiving entity's performance, or the performance along the paths
   leading to it.

   Therefore, rate limiting may be enabled so as to ensure that direct
   exporting is used at a rate that does not significantly affect the

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   network bandwidth, and does not overload the receiving entity (or the
   source node in the case of loopback).  It should be possible to use
   each DEX on a subset of the data traffic, and to load balance the
   exported data among multiple receiving entities.

6.  Security Considerations

   The security considerations of IOAM in general are discussed in
   [I-D.ietf-ippm-ioam-data].  Specifically, an attacker may try to use
   the functionality that is defined in this document to attack the
   network.

   An attacker may attempt to overload network devices by injecting
   synthetic packets that include the DEX option.  Similarly, an on-path
   attacker may maliciously incorporate the DEX option into transit
   packets, or maliciously remove it from packets in which it is
   incorporated.

   Forcing DEX, either in synthetic packets or in transit packets may
   overload the receiving entity (or entities).  Since this mechanism
   affects multiple devices along the network path, it potentially
   amplifies the effect on the network bandwidth and on the receiving
   entity's load.

   In order to mitigate the attacks described above, it should be
   possible for IOAM-enabled devices to limit the exported IOAM data to
   a configurable rate.

   IOAM is assumed to be deployed in a restricted administrative domain,
   thus limiting the scope of the threats above and their affect.  This
   is a fundamental assumption with respect to the security aspects of
   IOAM, as further discussed in [I-D.ietf-ippm-ioam-data].

7.  Topics for Further Discussion

   o  Hop Limit / Hop Count: in order to help correlate and order the
      exported packets, it is possible to include a 1-octet Hop Count
      field in the DEX header (presumably by claiming some space from
      the Flags field).  Its value starts from 0 at the encapsulating
      node and is incremented by each IOAM transit node that supports
      the DEX option.  The Hop Count field value is also included in the
      exported packet.  An alternative approach is to use the Hop_Lim/
      Node_ID data field; if the IOAM-Trace-Type
      [I-D.ietf-ippm-ioam-data] has the Hop_Lim/Node_ID bit set, then
      exported packets include the Hop_Lim/Node_ID data field, which
      contains the TTL/Hop Limit value from a lower layer protocol.  The
      main advantage of the Hop_Lim/Node_ID approach is that it provides
      information about the current hop count without requiring each

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      transit node to modify the DEX option, thus simplifying the data
      plane functionality of Direct Exporting.  The main advantage of
      the Hop Count approach is that it counts the number of IOAM-
      capable nodes without relying on the lower layer TTL, especially
      when the lower layer cannot prvide the accurate TTL information,
      e.g., Layer 2 Ethernet or hierarchical VPN.  It also explicitly
      allows to detect a case where an IOAM-capable node fails to export
      packets.  In order to facilitate the Hop Count approach it is
      possible to use a flag to indicate an optional Hop Count field,
      which enables to control the tradeoff.  On one hand it addresses
      the use cases that the Hop_Lim/Node_ID cannot cover, and on the
      other hand it does not require transit switches to update the
      option if it is not supported or disabled.  Further discussion is
      required about the tradeoff between the two alternatives.

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., remy@barefootnetworks.com, r., daniel.bernier@bell.ca,
              d., and J. Lemon, "Data Fields for In-situ OAM", draft-
              ietf-ippm-ioam-data-08 (work in progress), 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>.

8.2.  Informative References

   [I-D.mizrahi-ippm-ioam-flags]
              Mizrahi, T., Brockners, F., Bhandari, S., Sivakolundu, R.,
              Pignataro, C., Kfir, A., Gafni, B., Spiegel, M., and J.
              Lemon, "In-situ OAM Flags", draft-mizrahi-ippm-ioam-
              flags-00 (work in progress), July 2019.

   [I-D.song-ippm-postcard-based-telemetry]
              Song, H., Zhou, T., Li, Z., Shin, J., and K. Lee,
              "Postcard-based On-Path Flow Data Telemetry", draft-song-
              ippm-postcard-based-telemetry-06 (work in progress),
              October 2019.

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   [I-D.spiegel-ippm-ioam-rawexport]
              Spiegel, M., Brockners, F., Bhandari, S., and R.
              Sivakolundu, "In-situ OAM raw data export with IPFIX",
              draft-spiegel-ippm-ioam-rawexport-02 (work in progress),
              July 2019.

   [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>.

Authors' Addresses

   Haoyu Song
   Futurewei
   2330 Central Expressway
   Santa Clara  95050
   USA

   Email: haoyu.song@huawei.com

   Barak Gafni
   Mellanox Technologies, Inc.
   350 Oakmead Parkway, Suite 100
   Sunnyvale, CA  94085
   U.S.A.

   Email: gbarak@mellanox.com

   Tianran Zhou
   Huawei
   156 Beiqing Rd.
   Beijing  100095
   China

   Email: zhoutianran@huawei.com

   Zhenbin Li
   Huawei
   156 Beiqing Rd.
   Beijing  100095
   China

   Email: lizhenbin@huawei.com

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   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

   Ramesh Sivakolundu
   Cisco Systems, Inc.
   170 West Tasman Dr.
   SAN JOSE, CA 95134
   U.S.A.

   Email: sramesh@cisco.com

   Tal Mizrahi (editor)
   Huawei Smart Platforms iLab
   8-2 Matam
   Haifa  3190501
   Israel

   Email: tal.mizrahi.phd@gmail.com

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