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Inter-Domain Routing Working Group                               Y. Wang
Internet-Draft                                                   T. Zhou
Intended status: Standards Track                                  M. Liu
Expires: January 14, 2021                                         Huawei
                                                                 R. Pang
                                                            China Unicom
                                                                 H. Chen
                                                           China Telecom
                                                           July 13, 2020


    BGP-LS Extensions for In-situ Flow Information Telemetry (IFIT)
                        Capability Advertisement
                draft-wang-idr-bgpls-extensions-ifit-00

Abstract

   This document extends Node and Link Attribute TLVs to Border Gateway
   Protocol-Link State (BGP-LS) to advertise supported In-situ Flow
   Information Telemetry (IFIT) capabilities at node and/or link
   granularity.  An ingress router cannot insert IFIT-Data-Fields for
   packets going into a path unless an egress router has indicated via
   signaling that it has the capability to process IFIT-Data-Fields.  In
   addition, such advertisements would be useful for entities (e.g.
   Path Computation Element (PCE)) to gather each router's IFIT
   capability for achieving the computation of end-to-end Traffic
   Engineering (TE) paths that be able to fulfill the visibility of on-
   path OAM data.

Requirements 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 RFC 2119 [RFC2119].

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 https://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




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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

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

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
   (https://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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  IFIT Capability . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Signaling IFIT Capability Using BGP-LS  . . . . . . . . . . .   5
     4.1.  Node IFIT TLV . . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Link IFIT TLV . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Application . . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   IFIT provides a high-level framework and a reflection-loop solution
   for on-path telemetry [I-D.song-opsawg-ifit-framework].  At present,
   there is a family of emerging on-path telemetry techniques, including
   In-situ OAM (IOAM) [I-D.ietf-ippm-ioam-data], IOAM Direct Export
   (DEX) [I-D.ietf-ippm-ioam-direct-export], Enhanced Alternate Marking
   (EAM) [I-D.ietf-6man-ipv6-alt-mark], etc.

   IFIT is a solution focusing on network domains.  The "network domain"
   consists of a set of network devices or entities within a single



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   Autonomous System (AS).  The part of the network which employs IFIT
   is referred to as the IFIT domain.  One network domain may consist of
   multiple IFIT domains.  An IFIT domain may cross multiple network
   domains.  The family of emerging on-path telemetry techniques may be
   partially enabled in different vendors' devices as an emerging
   feature for various use cases of application-aware network
   operations.  So that in order to dynamically enable IFIT
   functionality in a network domain, it is necessary to advertise the
   information of IFIT option types supported in each device.

   An ingress router cannot insert IFIT-Data-Fields for packets going
   into a path unless an egress router has indicated via signaling that
   it has the capability to process IFIT-Data-Fields.  In addition, such
   advertisements would be useful for entities (e.g.  Path Computation
   Element (PCE)) to gather each router's IFIT capability for achieving
   the computation of end-to-end TE paths that be able to fulfill the
   visibility of on-path OAM data.

   [RFC7752] describes a mechanism by which link-state and TE
   information can be collected from the network outside one Interior
   Gateway Protocols (IGP) area or Autonomous System (AS).  This
   document extends Node and Link Attribute TLVs to BGP-LS to advertise
   supported IFIT capabilities at node and/or link granularity.

2.  Terminology

   Following are abbreviations used in this document:

   o  BGP-LS: Border Gateway Protocol - Link State

   o  IFIT: In-situ Flow Information Telemetry

   o  TE: Traffic Engineering

   o  IOAM: In-situ OAM

   o  PBT: Postcard-Based Telemetry

   o  DEX: IOAM Direct Export

   o  EAM: Enhanced Alternate Marking

   o  IGP: Interior Gateway Protocols

   o  AS: Autonomous System

   o  E2E: Edge-to-Edge




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   o  NLRI: Network Layer Reachability Information

3.  IFIT Capability

   Each IFIT-capable node is configured with a node-id which uniquely
   identifies a node within the associated IFIT domain.  To accommodate
   the different use cases or requirements of in-situ flow information
   telemetry, IFIT data fields updated by network nodes fall into
   different categories which are referred as different IFIT option
   types, including IOAM Trace Option-Types [I-D.ietf-ippm-ioam-data],
   IOAM Edge-to-Edge (E2E) Option-Type [I-D.ietf-ippm-ioam-data], IOAM
   DEX Option-Type [I-D.ietf-ippm-ioam-direct-export] and EAM Option-
   Type [I-D.ietf-6man-ipv6-alt-mark].  A subset or all the IFIT-Option-
   Types and their corresponding IFIT-Data-Fields can be associated to
   an IFIT-Namespace.  Namespace identifiers allow a device which is
   IFIT-capable to determine whether IFIT-Option-Types need to be
   processed.  So that IFIT-Option-Types and Namespace-IDs SHOULD be
   included in IFIT capability information.

   This document defines the IFIT Capability information formed of one
   or more pairs of a 2-octet Namespace-ID and 16-bit Option-Type Flag.

    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_1       |       Option-Type Flag_1      |
   +---------------------------------------------------------------+
   |          Namespace-ID_2       |       Option-Type Flag_2      |
   +---------------------------------------------------------------+
   |              ...              |              ...              |
   +---------------------------------------------------------------+

                       Fig. 1 IFIT Capability Format

   Where:

   o  Namespace-ID: A 2-octet identifier, which must be present and
      populated in all IFIT-Option-Types.  The definition is the same as
      described in [I-D.ietf-ippm-ioam-data].

   o  Option-Type Flag: A 16-bit bitmap, which is defined as:

         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
        +-------------------------------+
        |p|i|d|e|m|       Reserved      |
        +-------------------------------+

   Where:




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   o  p-Flag: IOAM Pre-allocated Trace Option Type flag.  When set, this
      indicates that the router is capable of IOAM Pre-allocated Trace
      [I-D.ietf-ippm-ioam-data].

   o  i-Flag: IOAM Incremental Trace Option Type flag.  When set, this
      indicates that the router is capable of IOAM Incremental Tracing
      [I-D.ietf-ippm-ioam-data].

   o  d-Flag: IOAM DEX Option Type flag.  When set, this indicates that
      the router is capable of IOAM DEX
      [I-D.ietf-ippm-ioam-direct-export].

   o  e-Flag: IOAM E2E Option Type flag.  When set, this indicates that
      the router is capable of IOAM E2E processing
      [I-D.ietf-ippm-ioam-data].

   o  m-Flag: EAM flag.  When set, this indicates that the router is
      capable of processing Enhanced Alternative Marking packets
      [I-D.ietf-6man-ipv6-alt-mark].

   o  Reserved: Must be set to zero upon transmission and ignored upon
      receipt.

   An IFIT node MAY be capable of more than one IFIT option types.  In
   this case, Option-Type Flag can has more than one bit being set.

   In this document, Link IFIT Capability is defined as the supported
   IFIT-Option-Types of the interface associated with the link.  When
   all interfaces associated with links support the same IFIT-Option-
   Type, the Node IFIT Capability SHOULD represent the Link IFIT
   Capability.  Both of Node and Link IFIT Capability information are
   formed of one or more pairs of Namespace-ID and Option-Type Flag.

   When both of Node and Link IFIT Capability are advertised, the Link
   IFIT Capability information MUST take precedence over the Node IFIT
   Capability.  Besides, when a Link IFIT Capability is not signaled,
   then the Node IFIT Capability SHOULD be considered to be the IFIT
   Capability for this link.

4.  Signaling IFIT Capability Using BGP-LS

4.1.  Node IFIT TLV

   The Node IFIT TLV is an optional extension to Node Attribute TLVs
   that may be encoded in the BGP-LS Attribute associated with a Node
   NLRI [RFC7752].  The following format is used:





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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
   +-------------------------------+-------------------------------+
   |               Type            |            Length             |
   +---------------------------------------------------------------+
   |                      Node-IFIT-Capability                     |
   ~                                                               ~
   +---------------------------------------------------------------+


                        Fig. 7 BGP-LS Node IFIT TLV

   Where:

   o  Type: To be assigned by IANA

   o  Length: A 2-octet field that indicates the length of the value.

   o  Node-IFIT-Capability: A multiple of 4-octet field, which is as
      defined in Section 3.

4.2.  Link IFIT TLV

   The Link IFIT TLV is an optional extension to Link Attribute TLVs
   that may be encoded in the BGP-LS Attribute associated with a Link
   NLRI [RFC7752].  The following format is used:

    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            |            Length             |
   +---------------------------------------------------------------+
   |                      Link-IFIT-Capability                     |
   ~                                                               ~
   +---------------------------------------------------------------+


                        Fig. 8 BGP-LS Link IFIT TLV

   Where:

   o  Type: To be assigned by IANA

   o  Length: A 2-octet field that indicates the length of the value.

   o  Link-IFIT-Capability: A multiple of 4-octet field, which is as
      defined in Section 3.




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5.  Application

   As any packet with IFIT-Data-Fields must not leak out from the IFIT
   domain, the IFIT decapsulating node must be able to capture packets
   with IFIT-specific header and metadata and recover their format
   before forwarding them out of the IFIT domain.  Thus, an ingress
   router cannot insert IFIT-Data-Fields for packets going into a path
   unless an egress router has indicated via signaling that it has the
   capability to process IFIT-Data-Fields.  In this case, such
   advertisements are helpful for avoiding the leak of IFIT-specific
   header and metadata.

   In addition, such advertisements would be useful for entities (e.g.
   Path Computation Element (PCE)) to gather each router's IFIT
   capability for achieving the computation of end-to-end TE paths that
   be able to fulfill the visibility of on-path OAM data.  For example,
   for achieving the computation of low-latency SR-TE path, latency is
   expected to be collected at every node that a packet traverses to
   ensure performance visibility into the entire path.  IOAM Trace
   Option-Types is a desired option to have a hop-by-hop latency
   measurement.  If not all nodes on this path are IOAM Trace Option-
   Type capable, an incomplete measurement can have negative impacts on
   SR-TE path computation and adjustment for low-latency assurance.

6.  IANA Considerations

   IANA is requested to allocate values for the following TLV Type from
   the "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and
   Attribute TLVs" registry.

               +------------+-------------+---------------+
               | Code Point | Description | Reference     |
               +------------+-------------+---------------+
               | TBA1       | Node IFIT   | This document |
               | TBA2       | Link IFIT   | This document |
               +------------+-------------+---------------+

7.  Security Considerations

   This document introduces new BGP-LS Node and Link Attribute TLVs for
   the IFIT Capability advertisements at node and/or link granularity.
   It does not introduce any new security risks to BGP-LS.

8.  Acknowledgements

   The authors would like to thank Acee Lindem, Christian Hopps, Robert
   Raszuk, Les Ginsberg, Jeff Tantsura, Rakesh Gandhi and Greg Mirsky
   for the comments and advices.



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9.  References

9.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7752]  "North-Bound Distribution of Link-State and Traffic
              Engineering (TE) Information Using BGP",
              <https://datatracker.ietf.org/doc/rfc7752/>.

9.2.  Informative References

   [I-D.ietf-6man-ipv6-alt-mark]
              "IPv6 Application of the Alternate Marking Method",
              <https://datatracker.ietf.org/doc/draft-ietf-6man-ipv6-
              alt-mark/>.

   [I-D.ietf-ippm-ioam-data]
              "Data Fields for In-situ OAM".

   [I-D.ietf-ippm-ioam-direct-export]
              "In-situ OAM Direct Exporting",
              <https://datatracker.ietf.org/doc/draft-ietf-ippm-ioam-
              direct-export/>.

   [I-D.song-opsawg-ifit-framework]
              "In-situ Flow Information Telemetry Framework",
              <https://datatracker.ietf.org/doc/draft-song-opsawg-ifit-
              framework/>.

Authors' Addresses

   Yali Wang
   Huawei
   156 Beiqing Rd., Haidian District
   Beijing
   China

   Email: wangyali11@huawei.com









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   Tianran Zhou
   Huawei
   156 Beiqing Rd., Haidian District
   Beijing
   China

   Email: zhoutianran@huawei.com


   Min Liu
   Huawei
   156 Beiqing Rd., Haidian District
   Beijing
   China

   Email: lucy.liumin@huawei.com


   Ran Pang
   China Unicom
   9 Shouti South Rd., Haidian District
   Beijing
   China

   Email: pangran@chinaunicom.cn


   Huanan Chen
   China Telecom
   109 West Zhongshan Ave.
   Guangzhou, Guangdong
   China

   Email: chenhuan6@chinatelecom.cn

















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