Support Postcard-Based Telemetry for SRv6 OAM
draft-song-6man-srv6-pbt-00

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6man                                                        H. Song, Ed.
Internet-Draft                                    Futurewei Technologies
Intended status: Standards Track                            July 1, 2019
Expires: January 2, 2020

             Support Postcard-Based Telemetry for SRv6 OAM
                      draft-song-6man-srv6-pbt-00

Abstract

   This document describes a method based on Postcard-based Telemetry
   with Marking for SRv6 on-path OAM, which avoids the extra overhead
   for encapsulating telemetry-related instruction and metadata in SRv6
   packets.

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.

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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   This Internet-Draft will expire on January 2, 2020.

Copyright Notice

   Copyright (c) 2019 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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   (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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  PBT Triggered by Marking for SRv6 . . . . . . . . . . . . . .   3
     2.1.  Data Template . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Postcard Correlation  . . . . . . . . . . . . . . . . . .   3
     2.3.  Operational Considerations  . . . . . . . . . . . . . . .   4
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   The ability to collect the on-path data about SRv6 packets at each
   segment is important for SRv6 OAM, especially for monitoring the
   application-aware services.  The In-situ OAM (IOAM)
   [I-D.brockners-inband-oam-data] trace option can be used for such
   purpose.  However, SRv6's SRH can be large due to the long segment
   list.  The IOAM trace option introduces significant additional
   overhead to the SRv6 packets with its instruction and data trace.
   The large header overhead complicates the packet processing and may
   exceed the forwarding hardware's header processing capability.

   The extra IOAM trace option header also brings some encapsulation
   challenges as documented in [I-D.li-6man-ipv6-sfc-ifit].  Here we
   restate a subtle issue about the IOAM scope: if IOAM header is
   encapsulated as another IPv6 extension header, the juxtaposition of
   IOAM and SRH makes it ambiguous to determine the coverage of IOAM:
   should it be applied to the entire forwarding path or just to the
   segment nodes?

   The PBT-I scheme introduced in
   [I-D.song-ippm-postcard-based-telemetry] partially relieves the
   packet overhead pressure but the encapsulation issues remain.  In

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   this draft, we propose to apply the PBT-M scheme from the same
   document for on-path SRv6 telemetry.

2.  PBT Triggered by Marking for SRv6

   PBT-M requires marking a packet as a trigger to collect on-path data
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