Supporting In-Situ OAM Direct Export Using MPLS Network ActionsEricssongregimirsky@gmail.comOrange35000 RennesFrancemohamed.boucadair@orange.comJuniper Networkstony.li@tony.li
Routing
MPLS Working GroupInternet-DraftIOAMMPLS Network Action
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 that can be used to calculate various performance metrics.
IOAM Direct Export (IOAM-DEX) is one
of the IOAM Option types, 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 on-path operational state, and telemetry information
can be collected using IOAM-DEX Option in combination with MNA.
Introduction
In-Situ OAM (IOAM) 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) 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
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.
This document describes how MNA can be used for collecting on-path operational state
and telemetry information using IOAM-DEX Option.
Specifying the mechanism of exporting collected information is outside the scope of this document.
Conventions Used in this DocumentIOAM: In-Situ OAMIOAM-DEX: IOAM Direct ExportIOAM-DEX-MNA: IOAM Direct Export in MPLS Network ActionISD: In-Stack DataLSP: Label Switched PathLSE: Label Stack ElementMPLS: Multiprotocol Label SwitchingMNA: MPLS Network ActionNAI: Network Action IndicatorRequirements 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
when, and only when, they appear in all capitals, as shown here.
Applicability of IOAM Option Types in an MPLS Network
Pre-allocated, Incremental, and Edge-to-Edge IOAM Option types 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. But for
other use cases in which network resources are closely controlled, the use of in-band channels for collecting and transporting
the telemetry information may noticeably decrease the cost-efficiency of network operations. Although the operational state and
telemetry information are essential for network automation (Section 4 of ),
its delivery is not as critical as user packets. As such,
collecting and transporting the operational state and telemetry information out-of-band using the management plane
is a viable option for some environments. IOAM-DEX is used to collect IOAM data
defined in . 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 are applicable here.
Realization of IOAM-DEX as an MPLS Network ActionIOAM-DEX Format for an MPLS Network recognizes the importance of IOAM in MPLS networks
and lists it as one of the use cases that might be supported using MNA techniques.
defines the architectural elements that compose MNA.
This document uses all the elements of the IOAM-DEX Option-Type format
defined in to support IOAM-DEX in an MPLS network using
MPLS Network Action (MNA) framework and architecture as in-stack data (ISD) MNA
.
The format of IOAM-DEX in MNA is shown in .
Where fields are defined as follows:
Namespace-ID is a 16-bit identifier of the IOAM Namespace, as defined in .
S is a one-bit the Bottom of Stack .
Flags is an eight-bit field comprised of eight one-bit subfields. The subfields in the Flags field are
allocated by IANA, as defined in Section 4.2 of .
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 from Bit 0 through Bit 21.
O is the one-bit flag that is identical to the interpretation of Bit 22 variable-length Opaque State Snapshot
in IANA's IOAM Trace-Type registry .
R (Reserved) is a one-bit flag. It MUST be zeroed on the transmission and ignored on receipt.
Similarly to , it is reserved to allow for future extensions of the IOAM-Trace-Type-MNA bit field.
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 . The allocated flags indicate the presence of
the optional Flow ID and/or Sequence Number fields in the IOAM-DEX-MNA header.
displays the detailed format of the Ext-Flags field.
Extended IOAM-Trace-Type-MNA is a 22-bit field. The interpretation of bit positions is according to IANA's IOAM Trace-Type registry.
An IOAM-DEX-MNA encoding MAY include none, one, or more LSEs with the Extended IOAM-Trace-Type-MNA field.
Flow ID MNA is an optional 22-bit field. The semantics of the Flow ID MNA field is
as of the Flow ID field defined in Section 3.2 of .
Sequence Number - is an optional 22-bit field. The semantics of the Sequence Number MNA field is
as of the Sequence Number field defined in Section 3.2 of .
Resv fields MUST be zeroed on transmit and ignored on receipt.
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-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-MNA header.
U - unassigned one-bit flag. It MUST be zeroed on transmission and the value MUST be ignored upon receipt.
IOAM-DEX-MNA Encoding as In-Stack Data MPLS Network Action
To support the direct export of the operational state and telemetry information,
the IOAM-DEX-MNA blob (binary large object), as shown in
can be placed as part of the ISD block in an MPLS label stack according to the MNA encoding principles
defined in .
Using the IHS field, the IOAM-DEX-MNA can be performed in Hop-by-Hop,
Ingress-to-Egress, or Select modes of collecting
the operational state and telemetry information. Two encoding options,
as Network Action Indicator (NAI) with Ancillary Data and as an Option, are discussed below.
Policies controlling the processing of the collected operational state and telemetry information,
and its transport are outside the scope of this document.
IOAM-DEX-MNA Encoding as MNA OptionWhere the enclosed elements are defined as follows:
MNA bSPL is a base Special Purpose Label assigned by IANA per the request in .
S - the Bottom of Stack field .
P, IHS, Res, U, and NASL fields are as specified in Section 4.2 of .
NASL - number of LSEs that compose the IOAM-DEX-MNA blob.
Opcode is MNA-IOAM-DEX opcode (TBA1) assigned by IANA .
IOAM-DEX-MNA - IOAM Direct Export in MPLS Network Action encoding
IOAM-DEX-MNA Encoding as a Network Action Indicator with Ancillary DataWhere the enclosed elements are defined as follows:
MNA bSPL is a base Special Purpose Label assigned by IANA per the request in .
S - the Bottom of Stack field .
P, IHS, Res, U, and NASL fields are as specified in Section 4.2 of .
NAIs - Network Action Indicators, including the IOAM-DEX-MNA Indicator (TBA2)
assigned by IANA .
NAL - number of LSEs that compose the IOAM-DEX-MNA blob.
IOAM-DEX-MNA - IOAM Direct Export in MPLS Network Action encoding
IANA ConsiderationsIOAM-DEX-MNA as an MPLS Network Action OptionIANA is requested to assign an IOAM-DEX-MNA codepoint (TBA1) from its Network Action Opcodes registry
as specified in .
IOAM-DEX as MPLS Network Action Option
Option
Description
Reference
TBA1
IOAM-DEX as MPLS Network Action Indicator
This document
IOAM-DEX-MNA as an MPLS Network Action IndicatorIANA is requested to assign an IOAM-DEX-MNA Indicator from its Network Action Flags With Ancillary Data registry
as specified in .
IOAM-DEX in MPLS Network Action Framework
Bit Position
Description
Reference
TBA2
IOAM-DEX in MPLS Network Action Framework
This document
Security Considerations
Security considerations discussed in , , and
apply to this document.
Acknowledgments
TBD
ReferencesNormative ReferencesInformational ReferencesIOAM Trace-TypeIANA