Supporting In Situ Operations, Administration and Maintenance Using MPLS Network Actions
draft-ietf-mpls-mna-ioam-01
| Document | Type | Active Internet-Draft (mpls WG) | |
|---|---|---|---|
| Authors | Rakesh Gandhi , Greg Mirsky , Tony Li , Haoyu Song , Bin Wen | ||
| Last updated | 2025-03-03 | ||
| Replaces | draft-gandhi-mpls-mna-ioam-dex, draft-mb-mpls-ioam-dex | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
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| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| On agenda | mpls at IETF-122 | ||
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
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| Send notices to | (None) |
draft-ietf-mpls-mna-ioam-01
MPLS Working Group R. Gandhi, Ed.
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track G. Mirsky, Ed.
Expires: 4 September 2025 Ericsson
T. Li
Juniper Networks
H. Song
Futurewei Technologies
B. Wen
Comcast
3 March 2025
Supporting In Situ Operations, Administration and Maintenance Using MPLS
Network Actions
draft-ietf-mpls-mna-ioam-01
Abstract
In situ Operations, Administration, and Maintenance (IOAM), defined
in RFC 9197, is an on-path telemetry method to collect and transport
the operational state and telemetry information using, for example,
Preallocated or Incremental IOAM Option, that can be used to
calculate various performance metrics. RFC 9326 defined the IOAM
Direct Export (IOAM-DEX) Option in which the operational state and
telemetry information are collected according to the specified
profile and exported in a manner and format defined by a local
policy.
MPLS Network Actions (MNA) techniques are meant to indicate actions
to be performed on any combination of Label Switched Paths (LSPs),
MPLS packets, and the node itself, and also to transfer data needed
for these actions. This document explores the MNA mechanisms to
collect and transport the on-path operational state, and telemetry
information IOAM data fields, including IOAM-DEX Option.
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/.
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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 4 September 2025.
Copyright Notice
Copyright (c) 2025 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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in this Document . . . . . . . . . . . . . . 3
2.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Applicability of IOAM Option Types in an MPLS Network . . . . 4
4. Realization of IOAM as an MPLS Network Action . . . . . . . . 5
4.1. Signaling of IOAM as a Post-Stack Data MPLS Network
Action . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Realization of IOAM-DEX as an In-Stack Data MPLS Network
Action . . . . . . . . . . . . . . . . . . . . . . . . . 9
5. Considerations for IOAM and IOAM Direct Export in MPLS
Networks . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Ingress-To-Egress Scope IOAM and IOAM Direct Export Network
Actions . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1.1. Procedure . . . . . . . . . . . . . . . . . . . . . . 13
5.2. Hop-By-Hop Scope IOAM and IOAM Direct Export Network
Actions . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2.1. Procedure . . . . . . . . . . . . . . . . . . . . . . 14
5.3. Node Capability . . . . . . . . . . . . . . . . . . . . . 15
5.4. Nested MPLS Encapsulation . . . . . . . . . . . . . . . . 15
5.5. Readable Label Depth Consideration . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
6.1. IOAM, IOAM-DEX as PSD MNA, and IOAM-DEX-ISD-MNA as an MPLS
Network Action Opcodes . . . . . . . . . . . . . . . . . 15
6.2. Post-Stack Network Action Opcodes . . . . . . . . . . . . 16
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7. Security Considerations . . . . . . . . . . . . . . . . . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Normative References . . . . . . . . . . . . . . . . . . 17
8.2. Informational References . . . . . . . . . . . . . . . . 18
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
In situ OAM (IOAM) [RFC9197] is an on-path telemetry method to
collect and transport the operational state and telemetry information
that can be used to calculate various performance metrics. Several
IOAM Option types (e.g., Pre-allocated and Incremental) use the user
packet to collect the operational state and telemetry information.
Such a mechanism transports the collected information to an IOAM
decapsulating node (typically located at the edge of the IOAM domain
within the data packet). IOAM Direct Export (IOAM-DEX) [RFC9326] is
an IOAM Option type. In IOAM-DEX, the operational state and
telemetry information are collected according to the specified
profile and exported in a manner and format defined by a local
policy.
MPLS Network Actions (MNA) techniques [I-D.ietf-mpls-mna-fwk]
indicate actions to be performed on any combination of Label Switched
Paths (LSPs), MPLS packets, the node itself, and also allow for the
transfer of data needed for these actions. [I-D.ietf-mpls-mna-hdr]
defines mechanisms for carrying Network Action Sub-Stack (NAS) as
part of the MPLS label stack, i.e., In-Stack Data (ISD) MNA solution.
[I-D.jags-mpls-ps-mna-hdr] defines mechanisms for carrying MNA and
Ancillary Data (AD) outside the MPLS label stack, i.e., as Post-Stack
Data (PSD) MNA solution. [I-D.ietf-mpls-mna-usecases] describes
various use cases that can be realized using MNA techniques,
including IOAM Pre-allocated, Incremental, and IOAM-DEX Option types.
This document describes how MNA can be used for collecting and
transporting on-path operational state and telemetry information
using IOAM data fields for IOAM Option types, including IOAM-DEX.
Specifying the mechanism of exporting collected information in case
of the IOAM-DEX Option is outside the scope of this document.
2. Conventions Used in this Document
2.1. Acronyms
OAM: Operations, Administration, and Maintenance
HBH: Hop-By-Hop
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I2E: Ingress-To-Egress
IHS: Ingress-To-Egress (I2E), Hop-By-Hop (HBH) or Select Scope
IOAM: In situ OAM
IOAM-DEX: IOAM Direct Export
IOAM-DEX-ISD-MNA: IOAM Direct Export as In-Stack Data MPLS Network
Action
ISD: In-Stack Data
PSD: Post-Stack Data
PSH: Post-Stack Header
LSP: Label Switched Path
LSE: Label Stack Entry
MPLS: Multiprotocol Label Switching
MNA: MPLS Network Action
NAI: Network Action Indicator
NAS: Network Action Sub-stack
NASL: Network Action Sub-stack Length
2.2. 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.
3. Applicability of IOAM Option Types in an MPLS Network
Pre-allocated, Incremental, and Edge-to-Edge IOAM Option types
[RFC9197] use user packets to collect and transport the operational
state and telemetry information. In some environments, for example,
data center networks, this technique is useful as the available
bandwidth and the use of jumbo frames can accommodate the increase of
the packet payload. This document defines the PSD MNA-based
([I-D.jags-mpls-ps-mna-hdr]) solution supporting Pre-allocated,
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Incremental, and Edge-to-Edge IOAM Option types (Section 4.1).
However, for some use cases, e.g., mobile backhaul, in which network
resources are closely controlled, collecting and transporting the
telemetry information within a data packet may noticeably decrease
the cost-efficiency of network operations. Although the operational
state and telemetry information are essential for network automation
(Section 4 of [RFC8969]), its delivery is not as critical as user
packets. As such, collecting and transporting the operational state
and telemetry information using the management plane is a viable
option for some environments. IOAM-DEX [RFC9326] is capable of
collecting all of IOAM data fields defined in [RFC9197]. The
processing and transport of the collected information are controlled
by a local policy which is outside the scope of this specification.
The performance considerations discussed in Section 5 of [RFC9326]
are applicable here. In this document, the realizations of IOAM-DEX
using ISD MNA approach ([I-D.ietf-mpls-mna-hdr] and PSD MNA
([I-D.jags-mpls-ps-mna-hdr]) are defined in Section 4.2 and
Section 4.1, respectively.
4. Realization of IOAM as an MPLS Network Action
4.1. Signaling of IOAM as a Post-Stack Data MPLS Network Action
The presence of a PSD MNA is signaled using a Network Action Sub-
stack is defined in [I-D.jags-mpls-ps-mna-hdr] and is shown in
Figure 1
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MNA Label | TC |0| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opcode | Data (Format B) |P|IHS|0|U| NASL | NAL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opcode | Data (Format C) |0|U| Data | NAL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label | TC |1| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Post-Stack Header (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ IOAM ~
~ Post-stack Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Payload ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 1: An Example of Network Action Sub-Stack Signaling a Post
Stack Data MNA.
The MNA Label is defined in [I-D.ietf-mpls-mna-hdr].
The IHS scope field defined in [I-D.ietf-mpls-mna-hdr] is used to
indicate that I2E or HBH or Select processing is required for the
Network Action and Ancillary Data.
If both edge and intermediate nodes need to process the IOAM data
fields then IHS scope MUST be set to "HBH, value 0x1". If only edge
nodes need to process the IOAM data fields then IHS scope MUST be set
to "I2E, value 0x0". The HBH scope allows to skip the IOAM data
processing on the intermediate nodes i.e., avoids the need to parse
all IOAM data fields to detect the HBH option type.
The U Flag for Unknown Action Handling is specified in
[I-D.ietf-mpls-mna-hdr].
The Network Action Sub-Stack Length (NASL) is set as specified in
[I-D.ietf-mpls-mna-hdr].
Opcode (7 bits) value is TBA1 (for In-Stack Network Action with PSD
for IOAM) carrying IOAM Option-Type(s) defined in [RFC9197]. Opcode
value is TBA2 (for In-Stack Network Action with PSD for IOAM DEX)
carrying the IOAM DEX Option-Type defined in [RFC9326]. The In-Stack
indication of PSD IOAM and IOAM DEX Network Actions can be carried in
Format B or Format C LSE.
A packet may carry more than one In-Stack Network Actions with PSD
for IOAM and IOAM DEX in an MNA Sub-Stack (for example, for different
IOAM Option-Types). There may be a different In-Stack Network
Actions (other than for the IOAM) in an MNA Sub-Stack.
Data (10 bits, next to the Opcode field) in LSE contains the offset
for PSD for this In-Stack Network Action in 4-octets units after BOS
LSE to the start of the Post-Stack Network Action Opcode. Due to the
Post-Stack Header, minimum value for the offset is 1 (i.e, 4-octets).
Additional IOAM data fields may be added in the In-Stack NAS
additional data LSE Format D as required by the network action.
Length of Network Action (NAL) is set to 0 if no additional LSE
Format D is added for the network action.
The Post-Stack Network Action encoding contains IOAM Post-Stack
Network Action Opcode, length in number of 4-octet units, and IOAM
Option-Type with IOAM data fields in ancillary data as shown in
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Figure 2. The IOAM data fields MUST follow the definitions
corresponding to their IOAM-Option-Types (e.g., see Section 4.4 of
[RFC9197] and Section 3 of [RFC9326]).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label | TC |1| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|N N N N|Version| PS-HDR-LEN | TYPE = POST-STACK-HDR-MNA = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
|PS-NA-OPCODE |R|U| PS-NAL |R|R| BLOCK-NUMBER|IOAM-OPT-TYPE|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ IOAM Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: An Example of Post-Stack Data MNA Carrying IOAM.
The PSD MNA carrying IOAM is shown in Figure 2. The following fields
defined in [I-D.jags-mpls-ps-mna-hdr]:
NNNN: The value of the first nibble is defined in
[I-D.jags-mpls-ps-mna-hdr].
PS-HDR-LEN (8 bits): IOAM PSD MNA Total Length in four-octet units.
This excludes the Post-Stack Header.
TYPE: TYPE is defined for POST-STACK-HDR-MNA (value 1) in
[I-D.jags-mpls-ps-mna-hdr].
The Post-Stack Network Action encoding contains IOAM Post-Stack
Network Action Opcode, length in number of 4-octet units, and IOAM
Option-Type with IOAM data fields in ancillary data as shown in
Figure 1. The IOAM data fields MUST follow the definitions
corresponding to their IOAM-Option-Types (e.g., see Section 4.4 of
[RFC9197] and Section 3 of [RFC9326]).
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label | TC |1| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|N N N N|Version| PS-HDR-LEN | TYPE = POST-STACK-HDR-MNA = 1 |PSH
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|<-+
|PS-NA-OPCODE |R|U| PS-NAL |R|R| BLOCK-NUMBER|IOAM-OPT-TYPE| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I
| | O
| | A
~ IOAM Option and Data Space [RFC9197] [RFC9326] ~ M
| | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
|PS-NA-OPCODE |R|U| PS-NAL |R|R| BLOCK-NUMBER|IOAM-OPT-TYPE| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I
| | O
| | A
~ IOAM Option and Data Space [RFC9197] [RFC9326] ~ M
| | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| |
| |
~ Optional Payload + Padding ~
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Example Post-Stack Network Actions with IOAM and IOAM
Direct Export Data Fields
The Post-Stack Header (PSH) is added with the following fields as
defined in [I-D.jags-mpls-ps-mna-hdr].
NNNN: The first 4-bit as defined in [I-D.jags-mpls-ps-mna-hdr].
PS-HDR-LEN (8 bits): Post-Stack Header Total Length in 4-octet
units. This excludes the Post-Stack Header.
TYPE: TYPE is defined for POST-STACK-HDR-MNA (value 1) in
[I-D.jags-mpls-ps-mna-hdr].
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An IOAM data fields is added in the Post-Stack Network Action
containing the following fields:
PS-NA-OPCODE: IANA allocated value TBA3 (Post-Stack Network Action
for IOAM) for IOAM Option-Type defined in [RFC9197], and TBA4
(Post-Stack Network Action for IOAM DEX) for IOAM DEX Option-Type
defined [RFC9326]. Editor's Note: Post-Stack Network Action Opcode
value TBA3 can be the same value as In-Stack Network Action Opcode
value TBA1 and opcode TBA4 can be the same value as opcode TBA2 to
avoid creating a mapping table.
IOAM-OPT-TYPE: 7-bit field defining the IOAM Option-Type, as defined
in the "IOAM Option-Type Registry" specified in [RFC9197] and
[RFC9326]).
IOAM-HDR-LEN: 7-bit unsigned integer. Length of the IOAM data
fields in 4-octet units. This excludes the first 4-octet unit
starting from PS-NA-OPCODE.
IOAM Option and Data Space: IOAM data fields as specified by the
IOAM-OPT-Type field. IOAM data fields are defined corresponding to
the IOAM-Option-Type (e.g., see Section 4.4 of [RFC9197] and
Section 3 of [RFC9326].
U: The Unknown Post-Stack Network Action handling including
unsupported IOAM Option-Type or IOAM data fields handling.
BLOCK-NUMBER: The Block Number for alternate marking method can be
used to aggregate the IOAM data collected in data plane, e.g., to
compute measurement metrics for each block of a data flow. It is
also used to correlate the IOAM data on different nodes.
4.2. Realization of IOAM-DEX as an In-Stack Data MPLS Network Action
[I-D.ietf-mpls-mna-usecases] recognizes the importance of IOAM in
MPLS networks and lists it as one of the use cases that might be
supported using MNA techniques. [I-D.ietf-mpls-mna-fwk] defines the
architectural elements that compose MNA. This document uses all the
elements of the IOAM-DEX Option-Type format defined in [RFC9326] to
support IOAM-DEX in an MPLS network using MPLS Network Action (MNA)
framework [I-D.ietf-mpls-mna-fwk] and architecture as in-stack data
(ISD) MNA [I-D.ietf-mpls-mna-hdr]. The IOAM-DEX in MNA header is
using LSE Format D, as defined in Section 4.4 [I-D.ietf-mpls-mna-hdr]
mapping IOAM-DEX Option Type format [RFC9326]. In addition to the
requirement to preserve the Bottom of Stack field, the most
significant bit in LSE Format D is always set to 1 avoiding a
possible mix-up of the LSE with one of the Base Special Purpose
Labels. The format of IOAM-DEX in MNA is shown in Figure 4.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Namespace-ID | Resv |0| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| IOAM-Trace-Type-MNA |S|O|R| Ext-Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow ID MNA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number MNA (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: IOAM-DEX Option Type Format for the In-Stack Data MPLS
Network Action Framework
Where fields are defined as follows:
* Namespace-ID is a 16-bit identifier of the IOAM Namespace, as
defined in [RFC9197].
* S is a one-bit the Bottom of Stack [RFC3032].
* Flags is an eight-bit field comprised of eight one-bit subfields.
The subfields in the Flags field are allocated by IANA in IOAM DEX
Flags registry, as defined in Section 4.2 of [RFC9326].
* IOAM-Trace-Type-MNA is a 22-bit field. The interpretation of bit
positions in the IOAM-Trace-Type-MNA is as specified in IANA's
IOAM Trace-Type registry [IANA-IOAM-Trace-Type] from Bit 0 through
Bit 21.
* O is the one-bit flag identical to the interpretation of Bit 22
variable-length Opaque State Snapshot in IANA's IOAM Trace-Type
registry [IANA-IOAM-Trace-Type].
* E is a one-bit flag identical to the interpretation of Bit 23
Reserved in IANA's IOAM Trace-Type registry
[IANA-IOAM-Trace-Type]. E flag can be used to indicate the
presence of the Extended IOAM-Trace-Type-MNA field in the next
Label Stack Element (LSE).
* R (Reserved) is a one-bit flag identical to the interpretation of
Bit 23 in IANA's IOAM Trace-Type registry [IANA-IOAM-Trace-Type].
It MUST be zeroed on the transmission and ignored on receipt.
Similarly to [RFC9197], it is reserved to allow for future
extensions of the IOAM-Trace-Type-MNA bit field.
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* The concatenation of IOAM-Trace-Type-MNA, O, and R fields,
explained above, is identical to IOAM-Trace-Type in the
interpretation of its bits, assigned in IANA's IOAM Trace-Type
registry [IANA-IOAM-Trace-Type]. Also, note that the Bit 7 field,
i.e., checksum complement, is handled as defined in [RFC9326].
* Ext-Flags is a six-bit field comprised of six one-bit subfields.
The allocation of the subfields in the Ext-Flags field is
according to Section 4.3 of [RFC9326]. The allocated flags
indicate the presence of the optional Flow ID and/or Sequence
Number fields in the IOAM-DEX-ISD-MNA header. The length of the
Ext-Flags field in IOAM-DEX Option-Type in MNA is shorter by two
one-bit fields compared to the length of the Extension Flags field
defined in Section 3.2 of [RFC9326]. Mapping of these two bit
positions is for further study. Figure 5 displays the detailed
format of the Ext-Flags field.
* Optional fields, i.e., Flow ID and Sequence Number, according to
[RFC9326], immediately follow the Reserved field used to align
optional fields at the four-octet word boundary. In the case of
IOAM-DEX in MNA, such alignment can be achieved without using
padding.
* Flow ID MNA is an optional four-octet field. The semantics of the
Flow ID MNA field is as of the Flow ID field defined in
Section 3.2 of [RFC9326]. The most significant bit MUST be set to
1. Bit 23 MUST be set according to the definition of Bottom of
Stack field in [RFC3032].
* Sequence Number MNA is an optional four-octet field. The
semantics of the Sequence Number MNA field is as of the Sequence
Number field defined in Section 3.2 of [RFC9326]. The most
significant bit MUST be set to 1. Bit 23 MUST be set according to
the definition of Bottom of Stack field in [RFC3032]. In MPLS
network environments where a label stack information is used for
load-balancing flows, the 19-bit-long part of the Sequence Number
MNA, starting from the Bit 1 position of the LSE, MUST remain
immutable for a particular packet flow that the value of the Flow
ID MNA field identifies. In MPLS networks, where other load-
balancing techniques are used, all bits of the Sequence Number MNA
field can be variated.
0 1 2 3 4 5
+-+-+-+-+-+-+
|F|S|U|U|U|U|
+-+-+-+-+-+-+
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Figure 5: Ext-Flags Field Format
Where fields are defined as follows:
* F - one-bit flag. When the flag is set to 1, it indicates the
presence of the Flow ID field in the IOAM-DEX-ISD-MNA header.
* S - one-bit flag. When the flag is set to 1, it indicates the
presence of the Sequence Number field in the IOAM-DEX-ISD-MNA
header.
* U - unassigned one-bit flag. It MUST be zeroed on transmission
and the value MUST be ignored upon receipt.
To support the direct export of the operational state and telemetry
information, the IOAM-DEX-ISD-MNA blob (binary large object), as
shown in Figure 4 can be placed as part of the ISD block in an MPLS
label stack according to the MNA encoding principles defined in
[I-D.ietf-mpls-mna-hdr]. Using the IHS field, the IOAM-DEX-ISD-MNA
can be performed in Hop-by-Hop, Ingress-to-Egress, or Select modes
[I-D.ietf-mpls-mna-fwk] of collecting the operational state and
telemetry information, as MNA Opcode (Figure 6). Policies
controlling the processing of the collected operational state and
telemetry information, and its transport are outside the scope of
this document.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MNA Label | TC |0| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opcode = TBA6 | Data |P|IHS|0| Res |U| NASL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ IOAM-DEX-ISD-MNA ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: An Example of IOAM-DEX Encapsulation as an MNA Opcode
Where the enclosed elements are defined as follows:
* MNA Label (value TBA5) is a base Special Purpose Label (bSPL)
assigned by IANA per the request in [I-D.ietf-mpls-mna-hdr].
* S - the Bottom of Stack field [RFC3032].
* P, IHS, Res, U, and NASL fields are as specified in Section 4.2 of
[I-D.ietf-mpls-mna-hdr].
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* NASL - number of LSEs that compose the IOAM-DEX-ISD-MNA blob.
* Opcode is MNA-IOAM-DEX opcode (value TBA6) assigned by IANA
Section 6.1.
* IOAM-DEX-ISD-MNA - IOAM Direct Export in In-Stack Data MPLS
Network Action encoding
5. Considerations for IOAM and IOAM Direct Export in MPLS Networks
5.1. Ingress-To-Egress Scope IOAM and IOAM Direct Export Network
Actions
The I2E IOAM data fields carry the IOAM Option-Type(s) that require
processing on the encapsulating and decapsulating nodes only.
The IOAM Option-Type carried can be IOAM Edge-To-Edge Option-Type
(value 3) defined in [RFC9197] as well as DEX Option-Type (value 4)
defined in [RFC9326]. The I2E IOAM data fields SHOULD NOT carry any
IOAM Option-Type that require IOAM processing on the intermediate
nodes as it will not be processed by them when IHS scope is set to
"I2E, value 0x0".
5.1.1. Procedure
The I2E IOAM and IOAM Direct Export Network Action procedure is
summarized as following:
* The encapsulating node inserts an MNA Sub-Stack with the MNA Label
with IHS scope set to "I2E, value 0x0", one or more In-Stack
Network Actions with PSD and one or more IOAM data fields in the
Post-Stack Network Actions in the MPLS packet.
* The intermediate nodes do not process the HBH IOAM data fields.
* The decapsulating node MAY punt the IOAM data fields from the
packet with the receive timestamp to the slow path for processing.
The receive timestamp is required by the various I2E OAM use-
cases, including streaming telemetry. Note that the packet is not
necessarily punted to the control-plane.
* The decapsulating node processes the IOAM data fields using the
procedures defined in [RFC9197] and [RFC9326]. An example of IOAM
processing is to export the IOAM data fields for streaming
telemetry.
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* The decapsulating node MUST remove the Network Actions and IOAM
data fields from the received packet. The decapsulated packet is
forwarded downstream or terminated locally similar to the regular
data packets.
5.2. Hop-By-Hop Scope IOAM and IOAM Direct Export Network Actions
The HBH IOAM data fields carry the Option-Type(s) that require
processing at the intermediate and/or encapsulating and decapsulating
nodes.
The IOAM Option-Type carried can be IOAM Pre-allocated Trace Option-
Type (value 0), IOAM Incremental Trace Option-Type (value 1) and IOAM
Proof of Transit (POT) Option-Type (value 2), and Edge-To-Edge
Option-Type (value 3) defined in [RFC9197] as well as DEX Option-Type
(value 4) defined in [RFC9326].
Editor's note: IPv6 option is not supported for HBH IOAM Incremental
Trace Option-Type (value 1). Similarly, MPLS network action is also
not supported for HBH IOAM Incremental Trace Option-Type (value 1).
5.2.1. Procedure
The Hop-By-Hop IOAM and IOAM Direct Export Network Action procedure
is summarized as following:
* The encapsulating node inserts an MNA Sub-Stack containing MNA
Label, with IHS scope set to "HBH, value 0x1", one or more In-
Stack Network Actions for IOAM with PSD, and one or more IOAM data
fields in the Post-Stack Network Actions in the MPLS packet.
* The intermediate node enabled with HBH IOAM function processes the
data packet including the IOAM data fields as defined in [RFC9197]
and [RFC9326] when the node recognizes the HBH scope in the MNA
Sub-Stack.
* The intermediate node MAY punt the IOAM data fields from the
packet with the receive timestamp to the slow path for processing
when the node recognizes the HBH scope. The receive timestamp is
required by the various HBH OAM use-cases, including streaming
telemetry. Note that the packet is not necessarily punted to the
control-plane.
* The intermediate node forwards the data packet downstream.
* The processing on the decapsulating node is same as I2E case.
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Both HBH and I2E Scope IOAM may be required in an MPLS packet. In
this case, the Post-Stack Network action with HBH IOAM data fields
MUST be added after the BOS and before the Post-Stack Network Action
with I2E IOAM data fields. This way, the RLD for the intermediate
nodes is minimized.
5.3. Node Capability
The decapsulating node that has to remove the IOAM data fields and
perform the IOAM function may not be capable of supporting it. The
encapsulating node needs to know if the decapsulating node can
support the IOAM function. The signaling extension for this
capability exchange is outside the scope of this document.
The intermediate node that is not capable of supporting the IOAM
functions defined in this document, can simply skip the IOAM
processing.
The node that does not recognize the MNA Label received at the top of
the label stack will drop the packet.
5.4. Nested MPLS Encapsulation
When a packet is received with MPLS Encapsulated Network Action for
IOAM, the nested MPLS encapsulating node that needs to add different
Network Action for IOAM, the node MUST add a new MNA Sub-Stack with
the Network Action for IOAM as part of the new MPLS encapsulation.
5.5. Readable Label Depth Consideration
The encapsulating node needs to make sure that the IOAM data fields
in Post-Stack Network Action are added within the Readable Label
Depth (RLD) of the downstream MNA capable nodes in order for them to
be able to process the IOAM.
6. IANA Considerations
6.1. IOAM, IOAM-DEX as PSD MNA, and IOAM-DEX-ISD-MNA as an MPLS Network
Action Opcodes
IANA is requested to codepoints from its Network Action Opcodes
registry (creation requested in [I-D.ietf-mpls-mna-hdr]) as specified
in Table 1.
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+========+===========================================+===========+
| Opcode | Description | Reference |
+========+===========================================+===========+
| TBA1 | In-Stack Network Action with PSD for IOAM | This |
| | | document |
+--------+-------------------------------------------+-----------+
| TBA2 | In-Stack Network Action with PSD for IOAM | This |
| | Direct Export | document |
+--------+-------------------------------------------+-----------+
| TBA6 | IOAM-DEX as an In-Stack Data MPLS Network | This |
| | Action Indicator | document |
+--------+-------------------------------------------+-----------+
Table 1: IOAM-DEX as an In-Stack Data MPLS Network Action Opcode
6.2. Post-Stack Network Action Opcodes
The IOAM and IOAM DEX Network Action Opcodes from Post-Stack Network
Action Opcode registry (to be created by in
[I-D.jags-mpls-ps-mna-hdr]) are defined in this document as follows.
Editor's Note: Post-Stack Network Action Opcode value TBA3 can be the
same value as In-Stack Network Action Opcode value TBA1 and opcode
TBA4 can be the same value as opcode TBA2 to avoid creating a mapping
table.
+=======+====================================+===============+
| Value | Description | Reference |
+=======+====================================+===============+
| TBA3 | Post-Stack Network Action for IOAM | This document |
+-------+------------------------------------+---------------+
| TBA4 | Post-Stack Network Action for IOAM | This document |
| | Direct Export | |
+-------+------------------------------------+---------------+
Table 2: Post-Stack Network Action Opcodes
7. Security Considerations
Security considerations discussed in [RFC9197], [RFC9326], and
[I-D.ietf-mpls-mna-fwk] apply to this document.
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The usage of MPLS extensions defined in this document for IOAM is
intended for deployment in a single network administrative domain.
As such, it assumes that the operator enabling the IOAM operation has
previously verified the integrity of the path. Still, operators need
to properly secure the IOAM in the domain to avoid malicious
configuration and use, which could include injecting malicious IOAM
packets into the domain.
8. References
8.1. Normative References
[I-D.ietf-mpls-mna-fwk]
Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS
Network Actions (MNA) Framework", Work in Progress,
Internet-Draft, draft-ietf-mpls-mna-fwk-15, 27 December
2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
mpls-mna-fwk-15>.
[I-D.ietf-mpls-mna-hdr]
Rajamanickam, J., Gandhi, R., Zigler, R., Song, H., and K.
Kompella, "MPLS Network Action (MNA) Sub-Stack Solution",
Work in Progress, Internet-Draft, draft-ietf-mpls-mna-hdr-
11, 17 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-mpls-
mna-hdr-11>.
[I-D.jags-mpls-ps-mna-hdr]
Rajamanickam, J., Gandhi, R., Zigler, R., Li, T., and J.
Dong, "Post-Stack MPLS Network Action (MNA) Solution",
Work in Progress, Internet-Draft, draft-jags-mpls-ps-mna-
hdr-04, 19 December 2024,
<https://datatracker.ietf.org/doc/html/draft-jags-mpls-ps-
mna-hdr-04>.
[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>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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[RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi,
Ed., "Data Fields for In Situ Operations, Administration,
and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197,
May 2022, <https://www.rfc-editor.org/info/rfc9197>.
[RFC9326] Song, H., Gafni, B., Brockners, F., Bhandari, S., and T.
Mizrahi, "In Situ Operations, Administration, and
Maintenance (IOAM) Direct Exporting", RFC 9326,
DOI 10.17487/RFC9326, November 2022,
<https://www.rfc-editor.org/info/rfc9326>.
8.2. Informational References
[I-D.ietf-mpls-mna-usecases]
Saad, T., Makhijani, K., Song, H., and G. Mirsky, "Use
Cases for MPLS Network Action Indicators and MPLS
Ancillary Data", Work in Progress, Internet-Draft, draft-
ietf-mpls-mna-usecases-15, 23 September 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-mpls-
mna-usecases-15>.
[IANA-IOAM-Trace-Type]
IANA, "IOAM Trace-Type",
<https://www.iana.org/assignments/ioam/ioam.xhtml#trace-
type>.
[RFC8969] Wu, Q., Ed., Boucadair, M., Ed., Lopez, D., Xie, C., and
L. Geng, "A Framework for Automating Service and Network
Management with YANG", RFC 8969, DOI 10.17487/RFC8969,
January 2021, <https://www.rfc-editor.org/info/rfc8969>.
Acknowledgments
The authors would like to thank Patrick Khordoc, Sagar Soni, Shwetha
Bhandari, Vengada Prasad Govindan, Tarek Saad, Stewart Bryant, Xiao
Min, Jaganbabu Rajamanickam, and Cheng Li for providing many useful
comments. The authors would also like to thank Mach Chen, Andrew
Malis, Matthew Bocci, and Nick Delregno for the MPLS-RT expert review
of the early version of this document.
Contributors
The following people have substantially contributed to this document:
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Zafar Ali
Cisco Systems, Inc.
Email: zali@cisco.com
Loa Andersson
Huawei Technologies
Email: loa@pi.nu
Frank Brockners
Cisco Systems, Inc.
Hansaallee 249, 3rd Floor
DUESSELDORF, NORDRHEIN-WESTFALEN 40549
Germany
Email: fbrockne@cisco.com
Voitek Kozak
Comcast
Email: Voitek_Kozak@comcast.com
Authors' Addresses
Rakesh Gandhi (editor)
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
Greg Mirsky (editor)
Ericsson
Email: gregimirsky@gmail.com
Tony Li
Juniper Networks
Email: tony.li@tony.li
Haoyu Song
Futurewei Technologies
United States of America
Email: haoyu.song@futurewei.com
Bin Wen
Comcast
Email: Bin_Wen@cable.comcast.com
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