ippm F. Brockners
Internet-Draft S. Bhandari
Intended status: Informational V. Govindan
Expires: January 3, 2018 C. Pignataro
Cisco
H. Gredler
RtBrick Inc.
J. Leddy
Comcast
S. Youell
JMPC
T. Mizrahi
Marvell
D. Mozes
Mellanox Technologies Ltd.
P. Lapukhov
Facebook
R. Chang
Barefoot Networks
July 02, 2017

Encapsulations for In-situ OAM Data
draft-brockners-inband-oam-transport-05

Abstract

In-situ Operations, Administration, and Maintenance (OAM) records operational and telemetry information in the packet while the packet traverses a path between two points in the network. In-situ OAM is to complement current out-of-band OAM mechanisms based on ICMP or other types of probe packets. This document outlines how in-situ OAM data fields can be transported in protocols such as NSH, Segment Routing, VXLAN-GPE, native IPv6 (via extension headers), and IPv4. Transport options are currently investigated as part of an implementation study. This document is intended to only serve informational purposes.

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."

This Internet-Draft will expire on January 3, 2018.

Copyright Notice

Copyright (c) 2017 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 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

This document discusses transport mechanisms for "in-situ" Operations, Administration, and Maintenance (OAM) data fields. In-situ OAM records OAM information within the packet while the packet traverses a particular network domain. The term "in-situ" refers to the fact that the OAM data is added to the data packets rather than is being sent within packets specifically dedicated to OAM. A discussion of the motivation and requirements for in-situ OAM can be found in [I-D.brockners-inband-oam-requirements]. Data types and data formats for in-situ OAM are defined in [I-D.brockners-inband-oam-data].

This document outlines transport encapsulations for the in-situ OAM data defined in [I-D.brockners-inband-oam-data]. This document is to serve informational purposes only. As part of an in-situ OAM implementation study different protocol encapsulations for in-situ OAM data are being explored. Once data formats and encapsulation approaches are settled, protocol specific specifications for in-situ OAM data transport will address the standardization aspect.

The data for in-situ OAM defined in [I-D.brockners-inband-oam-data] can be carried in a variety of protocols based on the deployment needs. This document discusses transport of in-situ OAM data for the following protocols:

This list is non-exhaustive, as it is possible to carry the in-situ OAM data in several other protocols and transports.

A feasibility study of in-situ OAM is currently underway as part of the FD.io project [FD.io]. The in-situ OAM implementation study should be considered as a "tool box" to showcase how "in-situ" OAM can complement probe-packet based OAM mechanisms for different deployments and packet transport formats. For details, see the open source code in the FD.io [FD.io].

2. Conventions

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].

Abbreviations used in this document:

IOAM:
In-situ Operations, Administration, and Maintenance
MTU:
Maximum Transmit Unit
NSH:
Network Service Header
OAM:
Operations, Administration, and Maintenance
POT:
Proof of Transit
SFC:
Service Function Chain
SID:
Segment Identifier
SR:
Segment Routing
VXLAN-GPE:
Virtual eXtensible Local Area Network, Generic Protocol Extension

3. In-Situ OAM Metadata Transport in IPv6

This mechanisms of in-situ OAM in IPv6 complement others proposed to enhance diagnostics of IPv6 networks, such as the IPv6 Performance and Diagnostic Metrics Destination Option described in [I-D.ietf-ippm-6man-pdm-option]. The IP Performance and Diagnostic Metrics Destination Option is destination focused and specific to IPv6, whereas in-situ OAM is performed between end-points of the network or a network domain where it is enabled and used.

A historical note: The idea of IPv6 route recording was originally introduced by [I-D.kitamura-ipv6-record-route] back in year 2000. With IPv6 now being generally deployed and new concepts such as Segment Routing [I-D.ietf-spring-segment-routing] being introduced, it is imperative to further mature the Operations, Administration, and Maintenance mechanisms available to IPv6 networks.

The in-situ OAM options translate into options for an IPv6 hop by hop extension header. The extension header would be inserted by either a host source of the packet, or by a transit/domain-edge node. If the addition of the in-situ OAM Hop-by-Hop Option header would lead to the packet exceeding the MTU of the domain an error should be reported. The methods and procedures of how the error is reported are outside the scope of this document. Likewise if an ICMPv6 forwarding error occurs between encapsulating and decapsulating nodes, the node generating the ICMPv6 error should strip the in-situ OAM Hop-by-Hop Option header before sending the ICMPv6 message to the source.

3.1. In-situ OAM in IPv6 Hop by Hop Extension Header

This section defines in-situ OAM for IPv6 transport. In-situ OAM Options are transported in IPv6 hop-by-hop extension header.

3.1.1. In-situ OAM Hop by Hop Options

IPv6 hop-by-hop option format for carrying in-situ OAM data fields:


+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Option Type  |  Opt Data Len |         Reserved (MBZ)        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |  |
.                                                               .  I
.                     Option Data                               .  O
.                                                               .  A
.                                                               .  M
.                                                               .  .
.                                                               .  O
.                                                               .  P
.                                                               .  T
.                                                               .  I
.                                                               .  O
.                                                               .  N
.                                                               .  |
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+

Option Type          8-bit identifier of the type of option.

Opt Data Len         8-bit unsigned integer.  Length of the
                     Reserved and Option Data field of this option,
                     in octets.

Reserved (MBZ)       16-bit field MUST be filled with zeroes.

Option Data          Variable-length field.  Option-Type-specific
                     data.

In-situ OAM Options are inserted as Option data as follows:

  1. Pre-allocated Tracing Option: The in-situ OAM Preallocated Tracing option defined in [I-D.brockners-inband-oam-data] is represented as a IPv6 option in hop by hop extension header by allocating following type:
    Option Type:
    001xxxxxx 8-bit identifier of the type of option. xxxxxx=TBD_IANA_PRE_TRACE_OPTION_IPV6.
  2. Incremental Tracing Option: The in-situ OAM Incremental Tracing option defined in [I-D.brockners-inband-oam-data] is represented as a IPv6 option in hop by hop extension header by allocating following type:
    Option Type:
    001xxxxxx 8-bit identifier of the type of option. xxxxxx=TBD_IANA_INCR_TRACE_OPTION_IPV6.
  3. Proof of Transit Option: The in-situ OAM POT option defined in [I-D.brockners-inband-oam-data] is represented as a IPv6 option in hop by hop extension header by allocating following type:
    Option Type:
    001xxxxxx 8-bit identifier of the type of option. xxxxxx=TBD_IANA_POT_OPTION_IPV6.
  4. Edge to Edge Option: The in-situ OAM E2E option defined in [I-D.brockners-inband-oam-data] is represented as a IPv6 option in hop by hop extension header by allocating following type:
    Option Type:
    000xxxxxx 8-bit identifier of the type of option. xxxxxx=TBD_IANA_E2E_OPTION_IPV6.

4. In-situ OAM Metadata Transport in IPv4

Transport of in-situ OAM data in IPv4 will use GRE encapsulation.

GRE encapsulation is defined in [RFC2784]. IOAM is defined as a "set of Protocol Types" TBD_IANA_ETHERNET_NUMBER_IOAM_* and follows GRE header. These Protocol Types are defined in [RFC3232] as "ETHER TYPES" and in [ETYPES].

The different IOAM data fields defined in [I-D.brockners-inband-oam-data] are added as TLVs following the GRE header. In an administrative domain where IOAM is used, insertion of the IOAM protocol header in GRE is enabled at the GRE tunnel endpoints which also serve as IOAM encapsulating/decapsulating nodes by means of configuration.

For IOAM the following new GRE protocol types are requested:

  1. IOAM_Trace_Preallocated: TBD_IANA_ETHERNET_NUMBER_IOAM_TRACE_PREALLOCATED
  2. IOAM_Trace_Incremental: TBD_IANA_ETHERNET_NUMBER_IOAM_TRACE_INCREMENTAL
  3. IOAM_POT: TBD_IANA_ETHERNET_NUMBER_IOAM_POT
  4. IOAM_End-to_End: TBD_IANA_ETHERNET_NUMBER_IOAM_E2E

4.1. In-situ OAM Tracing in GRE

The packet formats of the pre-allocated IOAM trace and incremental IOAM trace when transported using GRE are defined as below. See [I-D.brockners-inband-oam-data] for details about pre-allocated and incremental IOAM trace options.

In-situ OAM Trace header following GRE header(Preallocated IOAM trace):

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|C|       Reserved0       | Ver | Protocol Type = IOAM_Trace    |  G
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  R
|      Checksum (optional)      |       Reserved1 (Optional)    |  E
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|     Type      |   IOAM HDR len|        Next Protocol          |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|         IOAM-Trace-Type       |NodeLen|  Flags  | Octets-left |Trace
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |  |
|                        node data list [0]                     |  IOAM
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  D
|                                                               |  a
|                        node data list [1]                     |  t
|                                                               |  a
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                             ...                               ~  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  p
|                                                               |  a
|                        node data list [n-1]                   |  c
|                                                               |  e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                                                               |  |
|                        node data list [n]                     |  |
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |
|                     Payload + Padding (L2/L3/ESP/...)         |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Pre-allocated Trace Option Data MUST be 4-octet aligned:

In-situ OAM Trace header following GRE header(Incremental IOAM trace):

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|C|       Reserved0       | Ver |Protocol Type = IOAM_Trace     |  G
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  R
|      Checksum (optional)      |       Reserved1 (Optional)    |  E
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|     Type      |   IOAM HDR len|        Next Protocol          |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|        IOAM-Trace-Type        |NodeLen|  Flags  | Max Length  |Trace
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |  |
|                        node data list [0]                     |  IOAM
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  D
|                                                               |  a
|                        node data list [1]                     |  t
|                                                               |  a
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                             ...                               ~  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  p
|                                                               |  a
|                        node data list [n-1]                   |  c
|                                                               |  e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                                                               |  |
|                        node data list [n]                     |  |
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |
|                     Payload + Padding (L2/L3/ESP/...)         |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

In-situ OAM Incremental Trace Option Data MUST be 4-octet aligned:

[RFC2784] with Protocol Type set to TBD_IANA_ETHERNET_NUMBER_IOAM_TRACE. IOAM specific fields and header are defined here:

Type:
8-bit unsigned integer defining IOAM header type IOAM_TRACE_Preallocated or IOAM_Trace_Incremental are defined here.
IOAM HDR Len:
8 bits Length field contains the length of the variable metadata octets.
Next Protocol:
16 bits Next Protocol Type field contains the protocol type of the packet following IOAM protocol header. These Protocol Types are defined in [RFC3232] as "ETHER TYPES" and in [ETYPES]. An implementation receiving a packet containing a Protocol Type which is not listed in [RFC3232] or [ETYPES] SHOULD discard the packet.
IOAM-Trace-Type:
16-bit identifier of IOAM Trace Type as defined in [I-D.brockners-inband-oam-data] IOAM-Trace-Types.
Node Data Length:
4-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Flags:
5-bit field as defined in [I-D.brockners-inband-oam-data].
Octets-left:
7-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Maximum-length:
7-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Node data List [n]:
Variable-length field as defined in [I-D.brockners-inband-oam-data].

4.2. In-situ OAM POT in GRE

In-situ OAM POT header following GRE header:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|C|       Reserved0       | Ver | Protocol Type = IOAM_POT      |  G
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  R
|      Checksum (optional)      |       Reserved1 (Optional)    |  E
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|IOAM POT Type|P|   IOAM HDR len|     Next Protocol             |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|                           Random                              |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  P
|                        Random(contd.)                         |  O
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  T
|                         Cumulative                            |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                    Cumulative (contd.)                        |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |
|                     Payload + Padding (L2/L3/ESP/...)         |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

[RFC2784] with Protocol Type set to TBD_IANA_ETHERNET_NUMBER_IOAM_POT. IOAM specific fields and header are defined here:

IOAM POT Type:
7-bit identifier of a particular POT variant that dictates the POT data that is included as defined in [I-D.brockners-inband-oam-data].
Profile to use (P):
1-bit as defined in [I-D.brockners-inband-oam-data] IOAM POT Option.
IOAM HDR Len:
8 bits Length field contains the length of the variable metadata octets.
Next Protocol:
16 bits Next Protocol Type field contains the protocol type of the packet following IOAM protocol header. These Protocol Types are defined in [RFC3232] as "ETHER TYPES" and in [ETYPES]. An implementation receiving a packet containing a Protocol Type which is not listed in [RFC3232] or [ETYPES] SHOULD discard the packet.
Random:
64-bit Per-packet random number.
Cumulative:
64-bit Cumulative value that is updated by the Service Functions.

4.3. In-situ OAM End-to-End in GRE

In-situ OAM End-to-End header following GRE header:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|C|       Reserved0       | Ver | Protocol Type = IOAM_E2E      |  G
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  R
|      Checksum (optional)      |       Reserved1 (Optional)    |  E
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|IOAM_E2E_Type  |   IOAM HDR len|     Next Protocol             |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|      E2E Option data field determined by IOAM-E2E-Type        |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |
|                     Payload + Padding (L2/L3/ESP/...)         |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IOAM E2E Type:
8-bit identifier of a particular E2E variant that dictates the E2E data that is included as defined in [I-D.brockners-inband-oam-data].
IOAM HDR Len:
8 bits Length field contains the length of the variable metadata octets.
Next Protocol:
16 bits Next Protocol Type field contains the protocol type of the packet following IOAM protocol header. These Protocol Types are defined in [RFC3232] as "ETHER TYPES" and in [ETYPES]. An implementation receiving a packet containing a Protocol Type which is not listed in [RFC3232] or [ETYPES] SHOULD discard the packet.
E2E Option data field:
Variable length field as defined in [I-D.brockners-inband-oam-data] IOAM E2E Option.

5. In-situ OAM Metadata Transport in VXLAN-GPE

VXLAN-GPE [I-D.ietf-nvo3-vxlan-gpe] encapsulation is somewhat similar to IPv6 extension headers in that a series of headers can be contained in the header as a linked list. The different iIOAM types are added as options within a new IOAM protocol header in VXLAN GPE. In an administrative domain where IOAM is used, insertion of the IOAM protocol header in VXLAN GPE is enabled at the VXLAN GPE tunnel endpoint which also serve as IOAM encapsulating/decapsulating nodes by means of configuration.

5.1. In-situ OAM Tracing in VXLAN-GPE

The packet formats of the pre-allocated IOAM trace and incremental IOAM trace when transported in VXLAN-GPE are defined as below. See [I-D.brockners-inband-oam-data] for details about pre-allocated and incremental IOAM trace options.

The VXLAN-GPE header and fields are defined in [I-D.ietf-nvo3-vxlan-gpe]. IOAM specific fields and header are defined here:

In-situ OAM Trace header following VXLAN GPE header
(Pre-allocated trace):

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Outer Ethernet Header                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Outer IP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Outer UDP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|R|R|Ver|I|P|R|O|          Reserved             |NP=IOAM_Trace  |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ GPE
|     Virtual Network Identifier (VNI)          | Reserved      |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|      Type     |   IOAM HDR len|    Reserved   | Next Protocol |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|         IOAM-Trace-Type       |NodeLen|  Flags  | Octets-left |Trace
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |  |
|                        node data list [0]                     |  IOAM
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  D
|                                                               |  a
|                        node data list [1]                     |  t
|                                                               |  a
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                             ...                               ~  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  p
|                                                               |  a
|                        node data list [n-1]                   |  c
|                                                               |  e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                                                               |  |
|                        node data list [n]                     |  |
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-<--+
|                                                               |
|                                                               |
|                     Payload + Padding (L2/L3/ESP/...)         |
|                                                               |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Pre-allocated Trace Option Data MUST be 4-octet aligned:

In-situ OAM Trace header following VXLAN GPE header
(Incremental IOAM trace):

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Outer Ethernet Header                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Outer IP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Outer UDP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|R|R|Ver|I|P|R|O|          Reserved             | NP=IOAM_Trace |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ GPE
|     Virtual Network Identifier (VNI)          | Reserved      |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|      Type     |   IOAM HDR len|    Reserved   | Next Protocol |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|        IOAM-Trace-Type        |NodeLen|  Flags  | Max Length  |Trace
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |  |
|                        node data list [0]                     |  IOAM
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  D
|                                                               |  a
|                        node data list [1]                     |  t
|                                                               |  a
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                             ...                               ~  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  p
|                                                               |  a
|                        node data list [n-1]                   |  c
|                                                               |  e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                                                               |  |
|                        node data list [n]                     |  |
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-<--+
|                                                               |
|                                                               |
|                     Payload + Padding (L2/L3/ESP/...)         |
|                                                               |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In-situ OAM Incremental Trace Option Data MUST be 4-octet aligned:

Type:
8-bit unsigned integer defining IOAM header type IOAM_TRACE_Preallocated or IOAM_Trace_Incremental are defined here.
IOAM HDR len:
8-bit unsigned integer. Length of the in-situ OAM HDR in 8-octet units.
Reserved:
8-bit reserved field MUST be set to zero.
Next Protocol:
8-bit unsigned integer that determines the type of header following IOAM protocol. The value is from the IANA registry setup for VXLAN GPE Next Protocol defined in [I-D.ietf-nvo3-vxlan-gpe].
IOAM-Trace-Type:
16-bit identifier of IOAM Trace Type as defined in [I-D.brockners-inband-oam-data] IOAM-Trace-Types.
Node Data Length:
4-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Flags:
5-bit field as defined in [I-D.brockners-inband-oam-data].
Octets-left:
7-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Maximum-length:
7-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Node data List [n]:
Variable-length field as defined in [I-D.brockners-inband-oam-data].

5.2. In-situ OAM POT in VXLAN-GPE

The VXLAN-GPE header and fields are defined in [I-D.ietf-nvo3-vxlan-gpe]. IOAM specific fields and header are defined here:

In-situ OAM POT header following VXLAN GPE header:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Outer Ethernet Header                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Outer IP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Outer UDP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|R|R|Ver|I|P|R|O|          Reserved(MBZ)        |NP = IOAM_POT  |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ GPE
|     Virtual Network Identifier (VNI)          | Reserved      |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|IOAM POT Type|P|   IOAM HDR len|    Reserved   | Next Protocol |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|                           Random                              |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  P
|                        Random(contd.)                         |  O
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  T
|                         Cumulative                            |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                    Cumulative (contd.)                        |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+

IOAM POT Type:
7-bit identifier of a particular POT variant that dictates the POT data that is included as defined in [I-D.brockners-inband-oam-data].
Profile to use (P):
1-bit as defined in [I-D.brockners-inband-oam-data] IOAM POT Option.
IOAM HDR len:
8-bit unsigned integer. Length of the in-situ OAM HDR in 8-octet units
Reserved:
8-bit reserved field MUST be set to zero.
Next Protocol:
8-bit unsigned integer that determines the type of header following IOAM protocol. The value is from the IANA registry setup for VXLAN GPE Next Protocol defined in [I-D.ietf-nvo3-vxlan-gpe].
Random:
64-bit Per-packet random number.
Cumulative:
64-bit Cumulative value that is updated by the Service Functions.

5.3. In-situ OAM Edge-to-Edge in VXLAN-GPE

In-situ OAM Edge-to-Edge in VXLAN GPE header:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Outer Ethernet Header                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Outer IP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Outer UDP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|R|R|Ver|I|P|R|O|          Reserved             |NP = IOAM_E2E  |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ GPE
|     Virtual Network Identifier (VNI)          | Reserved      |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|Type=IOAM_E2E  |   IOAM HDR len  |  Reserved   | Next Protocol |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|      E2E Option data field determined by IOAM-E2E-Type        |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+

Type:
8-bit identifier of a particular E2E variant that dictates the E2E data that is included as defined in [I-D.brockners-inband-oam-data].
IOAM HDR len:
8-bit unsigned integer. Length of the in-situ OAM HDR in 8-octet units
Reserved:
8-bit reserved field MUST be set to zero.
Next Protocol:
8-bit unsigned integer that determines the type of header following IOAM protocol. The value is from the IANA registry setup for VXLAN GPE Next Protocol defined in [I-D.ietf-nvo3-vxlan-gpe].
E2E Option data field:
Variable length field as defined in [I-D.brockners-inband-oam-data] IOAM E2E Option.

6. In-situ OAM Metadata Transport in NSH

6.1. In-situ OAM Tracing in NSH

The packet formats of the pre-allocated IOAM trace and incremental IOAM trace when transported in NSH are defined as below. See [I-D.brockners-inband-oam-data] for details about pre-allocated and incremental IOAM trace options.

In Service Function Chaining (SFC) [RFC7665], the Network Service Header (NSH) [I-D.ietf-sfc-nsh] already includes path tracing capabilities [I-D.penno-sfc-trace]. Tracing information can be carried in-situ as IOAM data fields following NSH MDx metadata TLVs.

In-situ OAM Trace header following NSH MDx header
(Pre-allocated IOAM trace):


 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|Ver|O|C|R|R|R|R|R|R|   Length  |  MD Type      | NP=IOAM_Trace |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  N
|          Service Path Identifer               | Service Index |  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  H
|                            ...                                |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|      Type     |   IOAM HDR len|    Reserved   | Next Protocol |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|         IOAM-Trace-Type       |NodeLen|  Flags  | Octets-left |Trace
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |  |
|                        node data list [0]                     |IOAM
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  D
|                                                               |  a
|                        node data list [1]                     |  t
|                                                               |  a
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                             ...                               ~  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  p
|                                                               |  a
|                        node data list [n-1]                   |  c
|                                                               |  e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                                                               |  |
|                        node data list [n]                     |  |
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-<--+
|                                                               |
|                                                               |
|                     Payload + Padding (L2/L3/ESP/...)         |
|                                                               |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

In-situ OAM Pre-allocated Trace Option Data MUST be 4-octet aligned:

In-situ OAM Trace header following NSH MDx header
(Incremental IOAM trace):

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|Ver|O|C|R|R|R|R|R|R|   Length  |  MD Type      | NP=IOAM_Trace |  N
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  S
|          Service Path Identifer               | Service Index |  H
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                            ...                                |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|      Type     |  IOAM HDR len |    Reserved   | Next Protocol |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+IOAM
|        IOAM-Trace-Type        |NodeLen|  Flags  | Max Length  |Trace
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|                                                               |  |
|                        node data list [0]                     |IOAM
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  D
|                                                               |  a
|                        node data list [1]                     |  t
|                                                               |  a
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                             ...                               ~  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  p
|                                                               |  a
|                        node data list [n-1]                   |  c
|                                                               |  e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                                                               |  |
|                        node data list [n]                     |  |
|                                                               |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-<--+
|                                                               |
|                                                               |
|                     Payload + Padding (L2/L3/ESP/...)         |
|                                                               |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


In-situ OAM Incremental Trace Option Data MUST be 4-octet aligned:

Next Protocol of NSH:
TBD value for IOAM_Trace.
Type:
8-bit unsigned integer defining IOAM header type IOAM_TRACE_Preallocated or IOAM_Trace_Incremental are defined here.
IOAM HDR len:
8-bit unsigned integer. Length of the in-situ OAM HDR in 8-octet units.
Reserved bits and R bits:
Reserved bits are present for future use. The reserved bits MUST be set to 0x0.
Next Protocol:
8-bit unsigned integer that determines the type of header following IOAM protocol.
IOAM-Trace-Type:
16-bit identifier of IOAM Trace Type as defined in [I-D.brockners-inband-oam-data] IOAM-Trace-Types.
Node Data Length:
4-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Flags:
5-bit field as defined in [I-D.brockners-inband-oam-data].
Octets-left:
7-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Maximum-length:
7-bit unsigned integer as defined in [I-D.brockners-inband-oam-data].
Node data List [n]:
Variable-length field as defined in [I-D.brockners-inband-oam-data].

6.2. In-situ OAM POT in NSH

The "Proof of Transit" capabilities (see [I-D.brockners-inband-oam-requirements] and [I-D.brockners-proof-of-transit]) of in-situ OAM can be leveraged within NSH. In an administrative domain where in-situ OAM is used, insertion of the in-situ OAM data into the NSH header is enabled at the required nodes (i.e. at the in-situ OAM encapsulating/decapsulating nodes) by means of configuration.

Proof of transit in-situ OAM data is added as NSH Type 2 metadata:

In-situ OAM POT header following NSH MDx header:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|Ver|O|C|R|R|R|R|R|R|   Length  |  MD Type      |NP = IOAM_POT  |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  N
|          Service Path Identifer               | Service Index |  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  H
|                            ...                                |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|IOAM_POT Type|P|   IOAM HDR len|    Reserved   | Next Protocol |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                           Random                              |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  P
|                        Random(contd.)                         |  O
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  T
|                         Cumulative                            |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                    Cumulative (contd.)                        |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+

Next Protocol of NSH:
TBD value for IOAM_POT.
IOAM POT Type:
7-bit identifier of a particular POT variant that dictates the POT data that is included as defined in [I-D.brockners-inband-oam-data].
Profile to use (P):
1-bit as defined in [I-D.brockners-inband-oam-data] IOAM POT Option.
IOAM HDR len:
8-bit unsigned integer. Length of the in-situ OAM HDR in 8-octet units
Reserved bits and R bits:
Reserved bits are present for future use. The reserved bits MUST be set to 0x0.
Next Protocol:
8-bit unsigned integer that determines the type of header following IOAM protocol.
Random:
64-bit Per-packet random number.
Cumulative:
64-bit Cumulative value that is updated by the Service Functions.

6.3. In-situ OAM Edge-to-Edge in NSH

The "Edge-to-Edge" capabilities (see [I-D.brockners-inband-oam-requirements]) of in-situ OAM can be leveraged within NSH. In an administrative domain where in-situ OAM is used, insertion of the in-situ OAM data into the NSH header is enabled at the required nodes (i.e. at the in-situ OAM encapsulating/decapsulating nodes) by means of configuration.

Edge-to-Edge in-situ OAM data is added as a TLV following NSH MDx metadata:

In-situ OAM E2E header following NSH MDx header:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|Ver|O|C|R|R|R|R|R|R|   Length  |  MD Type      |NP = IOAM_E2E  |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  N
|          Service Path Identifer               | Service Index |  S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  H
|                            ...                                |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|IOAM_E2E_Type  |   IOAM HDR len|    Reserved   | Next Protocol | IOAM
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  E2E
|      E2E Option data field determined by IOAM-E2E-Type        |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+

Next Protocol of NSH:
TBD value for IOAM_E2E.
IOAM E2E Type:
8-bit identifier of a particular E2E variant that dictates the IOAM E2E data that is included as defined in [I-D.brockners-inband-oam-data].
IOAM HDR len:
8-bit unsigned integer. Length of the in-situ OAM HDR in 8-octet units
Reserved bits and R bits:
Reserved bits are present for future use. The reserved bits MUST be set to 0x0.
Next Protocol:
8-bit unsigned integer that determines the type of header following IOAM protocol.
E2E Option data field:
Variable length field as defined in [I-D.brockners-inband-oam-data] IOAM E2E Option.

7. In-situ OAM Metadata Transport in Segment Routing

7.1. In-situ OAM in SR with IPv6 Transport

Similar to NSH, a policy defined using Segment Routing for IPv6 can be verified using the in-situ OAM "Proof of Transit" approach. The Segment Routing Header (SRH) for IPv6 offers the ability to transport TLV structured data, similar to what NSH does (see [I-D.ietf-6man-segment-routing-header]). In an domain where in-situ OAM is used, insertion of the in-situ OAM data is enabled at the required edge nodes (i.e. at the in-situ OAM encapsulating/decapsulating nodes) by means of configuration.

A new "POT TLV" is defined for the SRH which is to carry proof of transit in situ OAM data.

 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     |   RESERVED    |F|   Flags     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|IOAM POT Type|P|                    Reserved (MBZ)             |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                           Random                              |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  P
|                        Random(contd.)                         |  O
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  T
|                         Cumulative                            |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  |
|                    Cumulative (contd.)                        |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+

Type:
To be assigned by IANA.
Length:
20.
RESERVED:
8 bits. SHOULD be unset on transmission and MUST be ignored on receipt.
F:
1 bit. Indicates which POT-profile is active. 0 means the even POT-profile is active, 1 means the odd POT-profile is active.
Flags:
8 bits. No flags are defined in this document.
IOAM POT Type:
7-bit identifier of a particular POT variant that dictates the POT data that is included as defined in [I-D.brockners-inband-oam-data].
Profile to use (P):
1-bit as defined in [I-D.brockners-inband-oam-data] IOAM POT Option.
Reserved (MBZ):
24-bit field MUST be filled with zeroes.
Random:
64-bit per-packet random number.
Cumulative:
64-bit cumulative value that is updated at specific nodes that form the service path to be verified.

7.2. In-situ OAM in SR with MPLS Transport

In-situ OAM "Proof of Transit" data can also be carried as part of the MPLS label stack. Details will be addressed in a future version of this document.

8. IANA Considerations

IANA considerations will be added in a future version of this document.

9. Manageability Considerations

Manageability considerations will be addressed ín a later version of this document..

10. Security Considerations

Security considerations will be addressed ín a later version of this document. For a discussion of security requirements of in-situ OAM, please refer to [I-D.brockners-inband-oam-requirements].

11. Acknowledgements

The authors would like to thank Eric Vyncke, Nalini Elkins, Srihari Raghavan, Ranganathan T S, Karthik Babu Harichandra Babu, Akshaya Nadahalli, Stefano Previdi, Hemant Singh, Erik Nordmark, LJ Wobker, and Andrew Yourtchenko for the comments and advice. The authors would like to acknowledge Craig Hill for contributing GRE IOAM encapsulation. For the IPv6 encapsulation, this document leverages and builds on top of several concepts described in [I-D.kitamura-ipv6-record-route]. The authors would like to acknowledge the work done by the author Hiroshi Kitamura and people involved in writing it.

12. References

12.1. Normative References

[ETYPES] "IANA Ethernet Numbers"
[I-D.brockners-inband-oam-data] Brockners, F., Bhandari, S., Pignataro, C., Gredler, H., Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov, P., <>, R. and d. daniel.bernier@bell.ca, "Data Fields for In-situ OAM", Internet-Draft draft-brockners-inband-oam-data-05, May 2017.
[I-D.brockners-inband-oam-requirements] Brockners, F., Bhandari, S., Dara, S., Pignataro, C., Gredler, H., Leddy, J., Youell, S., Mozes, D., Mizrahi, T., <>, P. and r. remy@barefootnetworks.com, "Requirements for In-situ OAM", Internet-Draft draft-brockners-inband-oam-requirements-03, March 2017.
[I-D.ietf-6man-segment-routing-header] Previdi, S., Filsfils, C., Raza, K., Leddy, J., Field, B., daniel.voyer@bell.ca, d., daniel.bernier@bell.ca, d., Matsushima, S., Leung, I., Linkova, J., Aries, E., Kosugi, T., Vyncke, E., Lebrun, D., Steinberg, D. and R. Raszuk, "IPv6 Segment Routing Header (SRH)", Internet-Draft draft-ietf-6man-segment-routing-header-06, March 2017.
[I-D.ietf-nvo3-vxlan-gpe] Maino, F., Kreeger, L. and U. Elzur, "Generic Protocol Extension for VXLAN", Internet-Draft draft-ietf-nvo3-vxlan-gpe-04, April 2017.
[I-D.ietf-sfc-nsh] Quinn, P. and U. Elzur, "Network Service Header", Internet-Draft draft-ietf-sfc-nsh-13, June 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D. and P. Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, DOI 10.17487/RFC2784, March 2000.
[RFC3232] Reynolds, J., "Assigned Numbers: RFC 1700 is Replaced by an On-line Database", RFC 3232, DOI 10.17487/RFC3232, January 2002.

12.2. Informative References

[FD.io] "Fast Data Project: FD.io"
[I-D.brockners-proof-of-transit] Brockners, F., Bhandari, S., Dara, S., Pignataro, C., Leddy, J., Youell, S., Mozes, D. and T. Mizrahi, "Proof of Transit", Internet-Draft draft-brockners-proof-of-transit-03, March 2017.
[I-D.ietf-ippm-6man-pdm-option] Elkins, N., Hamilton, R. and m. mackermann@bcbsm.com, "IPv6 Performance and Diagnostic Metrics (PDM) Destination Option", Internet-Draft draft-ietf-ippm-6man-pdm-option-13, June 2017.
[I-D.ietf-spring-segment-routing] Filsfils, C., Previdi, S., Decraene, B., Litkowski, S. and R. Shakir, "Segment Routing Architecture", Internet-Draft draft-ietf-spring-segment-routing-12, June 2017.
[I-D.kitamura-ipv6-record-route] Kitamura, H., "Record Route for IPv6 (PR6) Hop-by-Hop Option Extension", Internet-Draft draft-kitamura-ipv6-record-route-00, November 2000.
[I-D.penno-sfc-trace] Penno, R., Quinn, P., Pignataro, C. and D. Zhou, "Services Function Chaining Traceroute", Internet-Draft draft-penno-sfc-trace-03, September 2015.
[RFC7665] Halpern, J. and C. Pignataro, "Service Function Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, October 2015.

Authors' Addresses

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
Vengada Prasad Govindan Cisco Systems, Inc. EMail: venggovi@cisco.com
Carlos Pignataro Cisco Systems, Inc. 7200-11 Kit Creek Road Research Triangle Park, NC 27709 United States EMail: cpignata@cisco.com
Hannes Gredler RtBrick Inc. EMail: hannes@rtbrick.com
John Leddy Comcast EMail: John_Leddy@cable.comcast.com
Stephen Youell JP Morgan Chase 25 Bank Street London, E14 5JP United Kingdom EMail: stephen.youell@jpmorgan.com
Tal Mizrahi Marvell 6 Hamada St. Yokneam, 20692 Israel EMail: talmi@marvell.com
David Mozes Mellanox Technologies Ltd. EMail: davidm@mellanox.com
Petr Lapukhov Facebook 1 Hacker Way Menlo Park, CA, 94025 US EMail: petr@fb.com
Remy Chang Barefoot Networks 2185 Park Boulevard Palo Alto, CA, 94306 US