]> Cisco Systems, Inc.

Canada rgandhi@cisco.com

Huawei

China zhoutianran@huawei.com

China Mobile

China lizhenqiang@chinamobile.com

University of Tuebingen

Tuebingen Germany fabian.ihle@uni-tuebingen.de

Comcast

United States of America Bin_Wen@cable.comcast.com

IPPM Working Group The Simple Two-Way Active Measurement Protocol (STAMP) and its optional extensions can be used for Edge-to-Edge (E2E) active measurements. In Situ Operations, Administration, and Maintenance (IOAM) data fields can be used for recording and collecting Hop-by-Hop (HBH) and E2E operational and telemetry information. This document extends STAMP to reflect MPLS Network Action Sub-Stacks and Post-Stack MPLS Headers for HBH and E2E active measurements, for example, using the IOAM data fields.

The Simple Two-Way Active Measurement Protocol (STAMP) provides capabilities for the measurement of various performance metrics in IP networks without the use of a control channel to pre-signal session parameters. defines optional extensions in the form of TLVs for STAMP. STAMP-Test packets are transmitted along a path between a Session-Sender and a Session-Reflector to measure Edge-to-Edge (E2E) performance metrics, such as delay, delay variation, and packet loss along that path. In Situ Operations, Administration, and Maintenance (IOAM) is used for recording and collecting operational and telemetry information while a packet traverses a path between two points in the network. The information from the collected IOAM data fields can be used to support Hop-by-Hop (HBH) and E2E measurement use cases. MPLS packets may carry MPLS Network Action (MNA) Sub-Stacks (NASes), as specified in , and Post-Stack MPLS Headers (PSMHs) for the MNA type, as specified in . specifies MNA Sub-Stacks and PSMHs to carry the IOAM option types specified in and for an MPLS data plane. It may be desirable in some contexts (e.g., diagnostics) to record and collect HBH and E2E operational and telemetry information using active measurement packets between two nodes in a network. This is achieved by using optional STAMP extensions to reflect MPLS NASes and PSMHs as specified in this document. The procedure specified in this document leverages existing implementations at midpoint nodes with an MPLS data plane that supports the NASes and PSMHs, without any additional requirements for processing STAMP-Test packets. This document does not cover use cases in which NAS or PSMH lengths change along the path, or in which NASes or PSMHs are added to or removed from the MPLS header of a Session-Sender test packet along the path. A PSMH can be defined for types other than MNA. This document concerns only PSMHs for the MNA type .

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.

This document uses terms defined in , specifically Session-Sender, Session-Reflector, STAMP-Test packet, symmetric, and symmetrical. This document uses terms defined in , specifically STAMP TLV Flags and Sub-TLVs. The Conformant Reflected Packet STAMP TLV flag defined in is re-used for communicating the error conditions for the STAMP TLVs defined in this document. The error conditions specified for the STAMP TLVs defined in are not applicable to the extensions defined in this document.

Abbreviation Meaning Reference E2EEdge-to-Edge HBHHop-by-Hop IOAMIn Situ Operations, Administration, and Maintenance MPLSMultiprotocol Label Switching MNAMPLS Network Action MTUMaximum Transmission Unit NASNetwork Action Sub-Stack PSMHPost-Stack MPLS Header STAMPSimple Two-Way Active Measurement Protocol TLVType-Length-Value

In the "STAMP Reference Topology" shown in , the STAMP Session-Sender S1 initiates a Session-Sender test packet, and the STAMP Session-Reflector R1 transmits a reply Session-Reflector test packet. The Session-Reflector test packets are transmitted to the Session-Sender S1 on the same path (i.e., the same set of links and nodes as shown in ) or on a different path in the reverse direction from the path taken towards the Session-Reflector R1. Node M1 is a midpoint node along the path that does not perform any STAMP processing. A STAMP-Test packet is not required to transit through the same midpoint node M1 in both directions.

STAMP Reference Topology | | | S1 |=================| M1 |===================| R1 | | |<- - - - - - - - | | - - - - - - - - - | | +-------+ +-------+ Reply Test Packet +-------+ \ / T4 T3 STAMP Session-Sender STAMP Session-Reflector ]]>

T1 is a transmit timestamp and T4 is a receive timestamp added by node S1. T2 is a receive timestamp and T3 is a transmit timestamp added by node R1. All four timestamps are used by the Session-Sender to measure the two-way delay metric as ((T4 - T1) - (T3 - T2)). The "two-way delay" is the sum of the one-way delays in each direction and reflects the delay of the bidirectional path, irrespective of processing delays within the Session-Reflector. Timestamps T1 and T2 are used by the Session-Sender to measure the one-way delay metric as (T2 - T1), also referred to as the near-end (forward direction) delay metric. Note that the delay value (T4 - T3), measured by the Session-Sender, is referred to as the far-end (backward direction) one-way delay metric. The computation of the one-way delay metric requires the clocks on the Session-Sender and Session-Reflector to be synchronized, e.g., using PTPv2 or NTPv4 .

As specified in , the Session-Sender test packets and the Session-Reflector test packets are symmetric in size when including all optional TLVs (but excluding transport and network headers). A Session-Reflector reflects all received STAMP TLVs from the Session-Sender test packet. As specified in , STAMP-Test packets are transmitted with IP/UDP headers. Since midpoint nodes do not process the UDP headers in the packets, they are agnostic to the STAMP-Test packets in the payload. STAMP-Test packets may carry MPLS headers containing NASes and PSMHs. This document defines procedures and STAMP extensions for a Session-Reflector to reflect the received MPLS NASes and PSMHs back to the Session-Sender for both unidirectional and bidirectional measurement types (see ). The IPv4/IPv6 and UDP headers for STAMP-Test packets follow the procedures specified in Section 3.1 of .

This document defines the "Reflected MPLS Header MNA Data" TLV for STAMP (Type TBA1). A Session-Sender uses this TLV to request reflection of a Network Action Sub-Stack (NAS) or Post-Stack MPLS Header (PSMH) received in its test packet. The TLV is carried in Session-Sender and Session-Reflector test packets, and a STAMP-Test packet MAY carry one or more TLVs of this type. The same TLV type is used for NASes and PSMHs. The format of the TLV is shown in .

Reflected MPLS Header MNA Data TLV

The "Reflected MPLS Header MNA Data" TLV fields are defined as follows:

STAMP TLV Flags: The STAMP TLV Flags follow the procedures specified in .

Type: MUST be set to TBA1.

Length: A two-octet field containing the total length, in octets, of the NAS or PSMH to be reflected. It includes the lengths of the Requested MPLS Header MNA Data field and the Received MPLS Header MNA Data field.

Requested MPLS Header MNA Data: A fixed 8-octet field containing the first 8 octets of the target NAS or PSMH to be reflected. This field identifies which NAS or PSMH in the received Session-Sender test packet is copied into the "Reflected MPLS Header MNA Data" TLV when multiple NASes or PSMHs of the same length are present; the selection rules are in .

Received MPLS Header MNA Data: A variable-length field containing the remaining (Length - 8) octets of the NAS or PSMH after its first 8 octets, copied from the received Session-Sender test packet by the Session-Reflector. In Session-Sender test packets, the data in this field MUST be initialized to all zeros.

When a Session-Reflector recognizes the received "Reflected MPLS Header MNA Data" TLV but cannot use it to reflect a received NAS or PSMH, it MUST return the "Reflected MPLS Header MNA Data" TLV with the Conformant Reflected Packet STAMP TLV flag set to 1, following the procedure specified in . This can occur, for example, if:

The requested length does not match the length of the received NAS or PSMH.

The Session-Reflector cannot access the received NASes or PSMHs from the data plane, or the data plane does not support the received NASes or PSMHs.

No NAS or PSMH matches the requested data and length, or the NAS or PSMH is invalid.

More than one NAS or PSMH of the requested length matches a non-zero Requested MPLS Header MNA Data field.

For each NAS or PSMH in a Session-Sender test packet that the Session-Sender requires the Session-Reflector to reflect, the Session-Sender MUST add a corresponding "Reflected MPLS Header MNA Data" TLV (see ) to the test packet. The Session-Sender requests a copy of that NAS or PSMH in the corresponding TLV in the Session-Reflector test packet. An example of a STAMP-Test packet carrying NASes, a PSMH, and their corresponding "Reflected MPLS Header MNA Data" TLVs is shown in .

Example Session-Sender and Session-Reflector Test Packet with Reflected MPLS Header MNA Data TLVs

When a Session-Sender test packet contains multiple NASes or PSMHs that the Session-Sender requires the Session-Reflector to reflect, the corresponding "Reflected MPLS Header MNA Data" TLVs MUST appear in the same order as those headers in the test packet. When the Session-Sender does not require the Session-Reflector to reflect a NAS or PSMH in the Session-Reflector test packet, the Session-Sender MUST NOT add a corresponding "Reflected MPLS Header MNA Data" TLV to its test packet. In this case, the total number of "Reflected MPLS Header MNA Data" TLVs is less than the total number of NASes and PSMHs in the Session-Sender test packet. The number of "Reflected MPLS Header MNA Data" TLVs MUST NOT exceed the total number of NASes and PSMHs in the Session-Sender test packet. If multiple NASes or PSMHs of the same length are present and the Session-Sender requires the Session-Reflector to reflect only some of them, the Session-Sender MUST populate the Requested MPLS Header MNA Data field (see ) with the first 8 octets of the NAS or PSMH to be reflected. - The Session-Sender MUST set to zero each octet in the Requested MPLS Header MNA Data field containing any part of a field that can change in transit (a mutable field), for example, the 13-bit Ancillary Data field in a NAS or the 16-bit Post-Stack Data field in a PSMH. Because zero is a wildcard, the Session-Sender MUST NOT rely on matching a zero-valued octet. For a non-zero value in the Requested MPLS Header MNA Data field, the Session-Sender MUST request selective reflection only if exactly one NAS or PSMH matches. - The Session-Reflector compares only the non-zero octets of the field. The Session-Reflector processes the "Reflected MPLS Header MNA Data" TLVs in order and matches each TLV to the first NAS or PSMH, not already matched by an earlier TLV, that has the requested length and whose octets equal the non-zero octets of the field; an all-zero field therefore matches the next unmatched header of the requested length. Before requesting reflection of MPLS header MNA data, the Session-Sender MUST be configured to request the applicable data from the Session-Reflector. The Session-Reflector MUST apply the local reflection policy specified in before copying header data. When reflection is not permitted by policy, the Session-Reflector MUST NOT copy the requested NAS or PSMH data and MUST return the corresponding TLV with the Conformant Reflected Packet STAMP TLV flag set to 1, following the procedure specified in . When a Session-Reflector supports the "Reflected MPLS Header MNA Data" TLV and receives a Session-Sender test packet containing a valid NAS or PSMH and a corresponding TLV, the following rules apply to requests permitted by the local reflection policy:

If the Requested MPLS Header MNA Data field is not all zeros, the Session-Reflector MUST compare it with the first 8 octets of each NAS or PSMH of the requested length. A zero octet in the requested field MUST match any value; each non-zero octet MUST match the corresponding header octet exactly. The Session-Reflector MUST select the header if exactly one header matches. If no header or more than one header matches, the Session-Reflector MUST return the TLV with the Conformant Reflected Packet STAMP TLV flag set to 1, following the procedure specified in , and MUST NOT copy header data. If the Requested MPLS Header MNA Data field is all zeros, the Session-Reflector MUST select the next unmatched NAS or PSMH of the requested length and copy its first 8 octets into that field.

The Session-Reflector MUST copy the portion of the NAS or PSMH after its first 8 octets into the Received MPLS Header MNA Data field in the Session-Reflector test packet.

When the received Session-Sender test packet contains multiple NASes or PSMHs, the Session-Reflector MUST process them in order, starting with the top of the label stack, and copy each header into its corresponding "Reflected MPLS Header MNA Data" TLV in the Session-Reflector test packet, if such a TLV is present.

When a Session-Reflector receives a Session-Sender test packet containing a NAS or PSMH without a corresponding "Reflected MPLS Header MNA Data" TLV, it cannot copy that header into the Session-Reflector test packet.

Because this procedure leverages existing implementations at midpoint nodes, no additional requirements are imposed related to STAMP when NASes and PSMHs are carried in STAMP-Test packets. Midpoint nodes process these headers using the procedures specified in their defining documents.

For the HBH and Ingress-to-Egress (I2E) scopes, the penultimate node MUST NOT remove the last copy of the NASes and PSMHs. As a result, the egress node receives them, as specified in ("Penultimate Node Responsibilities") and ("Penultimate Node Responsibilities"). For the "Select" scope, the NAS and its corresponding PSMH are removed from a packet at the transit node that processes the NAS. Therefore, they are not received by the egress node. The data plane MUST provide the received MPLS headers containing the NASes and PSMHs from the Session-Sender test packets to the Session-Reflector for both unidirectional and bidirectional measurement types (see ). Similarly, for the reverse direction, the data plane MUST provide the received MPLS headers containing the NASes and PSMHs from the Session-Reflector test packets to the Session-Sender for the bidirectional measurement type (see ).

Each Session-Sender and Session-Reflector needs to know the applicable path MTU for the direction in which it transmits STAMP-Test packets. This information may be provisioned, collected through management protocols, learned through a path-MTU-discovery mechanism such as Path MTU Discovery for IPv6 or through MTU signaling for Label Distribution Protocol , or distributed by a control protocol. The mechanisms for obtaining this information are outside the scope of this document. The transmitting node MUST ensure that the complete STAMP-Test packet, including all applicable MPLS, IP, UDP, STAMP, and "Reflected MPLS Header MNA Data" TLV fields, does not exceed the applicable path MTU. If the packet exceeds this limit, the node MUST remove complete "Reflected MPLS Header MNA Data" TLVs, skipping the HMAC TLV (Type 8) if present, one at a time, starting with the last TLV in the packet, until the packet fits within the path MTU. If an HMAC TLV was present and if any preceding TLV was removed, the HMAC digest MUST be updated as specified in . The remaining TLVs MUST retain their relative order. If removing all "Reflected MPLS Header MNA Data" TLVs does not bring the packet within the path MTU, the node MUST NOT transmit it. The Session-Reflector MUST return requested TLVs that it can process in the order received. The Session-Sender can identify the MTU-driven removal by comparing the ordered TLV sequence it sent with the sequence returned by the Session-Reflector; an intentionally unrequested header has no corresponding TLV in the Session-Sender packet. The Conformant Reflected Packet STAMP TLV flag does not indicate MTU-driven removal.

This document defines the "MNA Header Control" Sub-TLV (Type TBA2) for the "Reflected Test Packet Control" TLV (Type 12) . This Sub-TLV is used to force the Session-Reflector to generate and add matching NASes and PSMHs in the reply test packets. The format of the "MNA Header Control" Sub-TLV is shown in .

MNA Header Control Sub-TLV

The MNA Header Control Sub-TLV fields are defined as follows:

• Sub-TLV Flags: An eight-bit field. The format, values, and interpretation of flags are as defined for STAMP TLV Flags . Flag values are taken from the "STAMP TLV Flags" registry .
• Type: MUST be set to TBA2.
• Sub-TLV Length: A two-octet field equal to the length of the Data field in octets. It MUST be set to 0. Otherwise, if the length is non-zero, the Session-Reflector MUST return the Sub-TLV with the Malformed flag set to 1 in the Sub-TLV Flags field as specified in .

When the "Reflected Test Packet Control" TLV is included only to carry the "MNA Header Control" Sub-TLV, the Session-Sender MUST set the Number of the Reflected Packets field to 1, the Interval Between the Reflected Packets field to 0, and the Length of the Reflected Packet field to 0, so that a single Session-Reflector test packet is returned with the length given by . The bidirectional measurement type requires that support for the "Reflected Test Packet Control" TLV is enabled on the Session-Reflector (). When a Session-Reflector receives a Session-Sender test packet with the "MNA Header Control" Sub-TLV and the Session-Reflector supports this Sub-TLV, the following rules apply:

The Session-Reflector MUST add locally generated matching NASes and PSMHs (headers of the same type carrying the same option types, for example, the same IOAM Option-Type and Namespace-ID) in the Session-Reflector test packets, subject to the relevant MPLS data-plane specifications, in the same order in which the corresponding NASes and PSMHs appear in the received Session-Sender test packet. The generated headers need not be byte-for-byte copies of the received headers.

In the absence of the "MNA Header Control" Sub-TLV in the received Session-Sender test packet, a Session-Reflector MUST omit adding locally generated matching NASes and PSMHs in the Session-Reflector test packet corresponding to the received NASes and PSMHs. This does not preclude the Session-Reflector from adding MPLS headers independently of the received MPLS headers.

The NASes and PSMHs received in the Session-Sender test packets MUST be copied and reflected in the corresponding "Reflected MPLS Header MNA Data" TLVs to the Session-Sender according to the procedure in , regardless of whether the "MNA Header Control" Sub-TLV is present.

If the Session-Reflector cannot add a new matching NAS or PSMH in the Session-Reflector test packet, the Session-Reflector MUST return the "Reflected Test Packet Control" TLV (Type 12) with the Conformant Reflected Packet STAMP TLV flag set to 1 in the Sub-TLV Flags of the "MNA Header Control" Sub-TLV using the procedure specified in . This can occur, for example, when the Session-Reflector does not support the received NAS or PSMH or when the Session-Reflector cannot access the received NASes or PSMHs from the data plane.

STAMP-Test packets MUST NOT carry more than one "MNA Header Control" Sub-TLV in a "Reflected Test Packet Control" TLV (Type 12) . If the "Reflected Test Packet Control" TLV (Type 12) in the Session-Sender test packet contains more than one "MNA Header Control" Sub-TLV, the Session-Reflector MUST return the "Reflected Test Packet Control" TLV (Type 12) with the Conformant Reflected Packet STAMP TLV flag set to 1 in the Sub-TLV Flags of each "MNA Header Control" Sub-TLV, using the procedure specified in .

This document defines two measurement types for the NASes and PSMHs carried in a two-way STAMP session: unidirectional (forward direction only) and bidirectional (forward and reverse directions). These types relate only to whether the Session-Reflector adds locally generated new matching NASes and PSMHs in the Session-Reflector test packets for the reverse path. The Session-Reflector still copies the received NASes and PSMHs into the corresponding "Reflected MPLS Header MNA Data" TLVs (see ) in both measurement types. The measurement type for a STAMP session is locally provisioned on the STAMP Session-Sender. In the bidirectional measurement type: A Session-Reflector adds locally generated matching NASes and PSMHs to the Session-Reflector test packets, subject to the relevant MPLS data-plane specifications, in the same order as the NASes and PSMHs received in the Session-Sender test packets for the reverse-direction measurement. These headers need not be byte-for-byte copies of the received headers; their length and content are local decisions at the Session-Reflector. The STAMP Session-Sender enables this type by adding the "MNA Header Control" Sub-TLV (see ) for the "Reflected Test Packet Control" TLV (Type 12) to the Session-Sender test packets. In the unidirectional measurement type: A Session-Reflector MUST omit adding new matching NASes and PSMHs to the Session-Reflector test packets in response to the NASes and PSMHs received in the Session-Sender test packets. This does not preclude the Session-Reflector from adding MPLS headers independently. This type is the default if the "MNA Header Control" Sub-TLV is absent from the Session-Sender test packet.

IOAM is used for recording and collecting operational and telemetry information while a packet traverses a path between two points in the network. The IOAM data fields are specified in . Examples of data recorded by IOAM Trace Options include per-hop information, such as node ID, timestamp, queue depth, interface identifier, and interface load. The information collected can be used for monitoring paths, proof-of-transit, and troubleshooting failures in the network. IOAM can be used with STAMP-Test packets for active measurements. The procedure and STAMP extensions specified in this document can be used to reflect the collected IOAM data fields back to the Session-Sender, where the Session-Sender can use this information to support HBH and E2E measurement use cases. defines MNA extensions for NASes and PSMHs to carry the IOAM option types specified in for the MPLS data plane. The STAMP Session-Sender and Session-Reflector test packets carry NASes and PSMHs with IOAM option types for recording and collecting HBH and E2E operational and telemetry information for active measurements, as shown in .

Example Session-Sender and Session-Reflector Test Packet for IOAM with Reflected MPLS Header MNA Data TLVs

The Session-Sender node, midpoint nodes, and the Session-Reflector node process the IOAM data fields, as specified in . Note that using the IOAM option type "Incremental Trace Option-Type" is not supported by . IOAM Direct Exporting is applicable to STAMP-Test packets for on-path telemetry use cases. In this case, the Session-Reflector is not required to reflect the IOAM option type, since no IOAM data fields would be recorded in the STAMP-Test packets. Hence, the Session-Sender MUST omit a corresponding "Reflected MPLS Header MNA Data" TLV in Session-Sender test packets for the IOAM Direct Exporting option type.

The operational considerations specified in , , , and apply to the procedures and extensions specified in this document. The management and deployment considerations in also apply when using the IOAM data fields specified in that document. The configuration and state introduced in this document are expected to be covered by the STAMP YANG module . Implementations MUST support the ability to provision the measurement type as unidirectional or bidirectional, as specified in . When reflecting a STAMP-Test packet with the Conformant Reflected Packet STAMP TLV flag set to 1, an implementation SHOULD log the specific error condition locally as well as increment a count for the error condition on the Session-Reflector. Before transmitting STAMP-Test packets, the operator must establish, through explicit configuration or a control-plane mechanism, that the intended receiving endpoint is enabled to receive the configured STAMP traffic and supports the features used by the session. The configuration or control-plane mechanism must cover the endpoint addresses, UDP ports, and traffic profile, including the rate and burst limits specified in Section 9.3 of , and must account for reflected traffic in the reverse direction. Operators must restrict STAMP traffic to configured endpoints using session configuration and appropriate forwarding and access-control policies. Configuring an endpoint to receive STAMP-Test traffic does not, by itself, enable reflection of received MPLS NASes or PSMHs. Implementations MUST provide a configurable local reflection policy on the Session-Reflector. An operator must configure this policy to identify the Session-Senders and header data configured for reflection to avoid exposing the collected network information to Session-Senders. The STAMP session state notifications specified in Section 9.2 of and rate limiting considerations specified in Section 9.3 of also apply to the STAMP-Test sessions using the procedures specified in this document.

The procedure in requires the first 8 octets of each NAS or PSMH to remain unchanged in transit excluding the mutable fields as identified by value 0 when multiple headers of the same length are present and only some are to be copied into STAMP TLVs. Additionally, the procedure specified requires the data plane to provide the received MPLS headers to Session-Senders and Session-Reflectors hosted in the control plane as specified in . For the reasons mentioned above, an operator should verify that the NASes and PSMHs are received correctly at both the Session-Reflector and the Session-Sender.

The security considerations specified in , , , , and apply to the procedure and extensions specified in this document. In addition, the security considerations specified in and also apply when using NASes and PSMHs for IOAM data fields. The security considerations specified in to mitigate attacks also apply to the STAMP-Test packets using the procedure and extensions specified in this document. The procedures specified in this document are intended for deployment in a single network administrative domain. To mitigate any threats, operators should filter STAMP-Test packets at the edges of the network administrative domain. It is assumed that the operator has verified the integrity of the paths in the forward and reverse directions used to transmit STAMP-Test packets so that collected network information is not exposed to an undesired node.

Editorial note: Please remove this section prior to publication. An open-source implementation of STAMP with optional TLVs specified in , MPLS Network Action (with In-Stack and Post-Stack Data), and the IOAM preallocated trace option is available for the Tofino2 platform. It supports unidirectional and bidirectional measurement types for HBH delay measurements across four transit nodes using the extensions specified in this document. - https://github.com/uni-tue-kn/stamp-mpls-mna-poc Contact: Fabian Ihle University of Tuebingen Germany Email: fabian.ihle@uni-tuebingen.de

IANA is requested to allocate the following TLV from the IETF Review range of the "STAMP TLV Types" registry (see: https://www.iana.org/assignments/stamp-tlv-types) under the Simple Two-way Active Measurement Protocol (STAMP) TLV Types registry group: STAMP TLV Types

Value	Description	Reference
TBA1	Reflected MPLS Header MNA Data	This document

IANA is requested to allocate the following sub-TLV from the IETF Review range of the "STAMP Sub-TLV Types" registry (see: https://www.iana.org/assignments/stamp-tlv-types) under the Simple Two-way Active Measurement Protocol (STAMP) TLV Types registry group: Sub-TLV Type for Reflected Test Packet Control TLV

Value	Description	TLV Used	Reference
TBA2	MNA Header Control	Reflected Test Packet Control	This document

Note to the RFC Editor: Please replace all occurrences of TBA1 and TBA2 with the values assigned by IANA.

&RFC2119; &RFC8174; &RFC8762; &RFC8972; &RFC9197; &RFC9326; &RFC9994; &RFC10052; &I-D.ietf-ippm-stamp-ext-hdr; &I-D.ietf-mpls-mna-ps-hdr; &I-D.ietf-mpls-mna-ioam; IANA &RFC3988; &RFC5905; &RFC8201; &I-D.ietf-ippm-stamp-yang; IEEE

The authors of this document would like to thank Greg Mirsky for reviewing this document and providing review comments. The authors would also like to thank Fabian Ihle for implementing the solution defined in this document in Tofino2.