MNA for Metadata in SR-MPLS Service Programming

Introduction defines data plane functionality required to implement service segments and achieve service programming in SR-enabled MPLS and IPv6 networks. Metadata provides contextual information about the data packets which traverse a programmed service path. However, there's yet no standard method to carry service metadata with the SR-MPLS data plane, which make the solution for service programming in SR-MPLS incomplete MPLS Network Action (MNA) is used to indicate action for Label Switched Paths (LSPs) and/or MPLS packets, and to transfer data needed for the action. defines the MNA sub-stack solution for carrying Network Action Indicators and Ancillary Data in the label stack. This document defines MPLS Network Action(MNA) encoding to carry metadata in SR service programming with SR-MPLS data plane.

Terminology 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.

MNA ISD Encoding for Metadata in SR-MPLS Service Programming The metadata in SR-MPLS Service Programming is placed as part of the ISD block in an MPLS label stack according to the MNA encoding principles defined in . Two types of metadata for SR-MPLS service programming are defined: fixed-length service metadata and variable-length service metadata.

Fixed-Length Service Metadata The format of fixed-length service metadata is shown as follows, Where:

The MNA Label is defined in .
S: the Bottom of Stack field [RFC3032].
Opcode: TBA1, indicating the fixed-length service metadata.
R,IHS and U fields are set as specified in .
NASL: The Network Action Sub-Stack Length (NASL) as specified in . The value is 3.
NAL: Network Action Length as specified in . The number of extra LSEs used for servie metadata encoding. The value is 3.
Opcode is MNA-IOAM-DEX opcode (value TBA2) to be assigned by IANA.
Servie Metadata: 102-bit field to carry metadata

Variable-Length Service Metadata The format of variable-length service metadata is shown as follows, Where:

The MNA Label is defined in .
S: the Bottom of Stack field [RFC3032].
Opcode: TBA2, indicating the variable-length service metadata.
R,IHS and U fields are set as specified in .
NASL: The Network Action Sub-Stack Length (NASL) as specified in .
NAL: Network Action Length as specified in . The number of extra LSEs used for servie metadata encoding.
Servie Metadata: The field length depends on the value of NAL.

IANA Considerations IANA is requested to assign codepoints from its Network Action Opcodes registry (creation requested in ) as specified in Table 1.

Security Considerations Security considerations discussed in , and apply to this document.