MPLS Transport Profile (MPLS-TP) Identifiers Following ITU-T Conventions
Extracted elements (24)
Co-routed bidirectional LSPs use a single LSP_Num for both directions because they are provisioned or signaled as a single entity, unlike associated bidirectional LSPs which require separate LSP_Nums.
RFC 6923 augments RFC 6370's AS-number-based (IP/MPLS) identifiers with ITU-T ICC-based equivalents. Both identifier families are not intended for simultaneous use within the same domain; operators choose one convention.
The A1/Z9 notational convention designates sort ordering (A1 = lower, Z9 = higher) but identifier uniqueness depends solely on the uniqueness and scoping of component fields, not on ordering. This ensures the notation does not constrain protocol field sequencing.
This document defines a single MEG_ID format applicable to MPLS-TP Sections, LSPs, and Pseudowires alike, in contrast to RFC 6370 which defines distinct maintenance identifiers for each entity type. This simplification follows ITU-T practice.
Alphabetic characters in the ICC SHOULD be represented with uppercase letters.
The IF_Num value 0 MUST NOT be used to identify an MPLS-TP interface, as it carries special meaning.
The MEP_Index MUST be unique within the MEG. Because the MEG_ID itself is globally unique, the resulting MEP_ID is globally unique by construction.
The Node_ID value zero is reserved and MUST NOT be used.
The UMC MUST be unique within the organization identified by the combination of CC and ICC.
The UMC (Unique MEG ID Code) MUST start with the '/' character, which is not permitted in the ICC itself, ensuring unambiguous decomposition of the MEG_ID and preventing non-uniqueness when the ICC is shorter than six characters.
When an MPLS-TP tunnel is configured, it MUST be assigned a unique IF_ID at each end point.
ICC_Operator_ID-based MIP_IDs are formed by prefixing the IF_ID of the interface on which the MIP resides with the ICC_Operator_ID. For per-node MIP models (one MIP per node), MIP_ID uses the Node_ID with IF_Num=0.
The ICC (ITU Carrier Code) is a string of one to six characters, each alphabetic (A-Z) or numeric (0-9), assigned by national regulatory authorities and maintained by the ITU-T TSB. Characters are coded per ITU-T Recommendation T.50.
The ICC_Operator_ID is used as a drop-in replacement for the Global_ID defined in RFC 6370, prefixed to node, interface, tunnel, LSP, and PW identifiers to provide global uniqueness. The substitution is direct for all RFC 6370 identifiers except MEG, MEP, and MIP IDs, which are redefined in this document.
The ICC_Operator_ID uniquely identifies an operator using ITU-T conventions. It is formed by concatenating a two-character Country Code (CC) and an ITU Carrier Code (ICC) as CC::ICC, serving as a globally unique context for all other MPLS-TP identifiers in place of the Global_ID from RFC 6370.
RFC 6923 extends an existing naming scheme and does not itself introduce new security concerns. However, protocol specifications that use this naming scheme must describe authentication risks and how they are addressed, as participant authentication issues may arise.
An MPLS-TP Point-to-Point Tunnel_ID is formed using end-point Node_IDs and 16-bit unsigned Tunnel_Nums: A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}. The globally unique form prefixes each end with ICC_Operator_ID.
Associated bidirectional LSP_ID uses separate 16-bit LSP_Nums for each unidirectional LSP: A1-{Node_ID::Tunnel_Num::LSP_Num}::Z9-{Node_ID::Tunnel_Num::LSP_Num}. Global form prefixes each side with ICC_Operator_ID.
Co-routed bidirectional LSP_ID appends a single 16-bit unsigned LSP_Num to the Tunnel_ID: A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}::LSP_Num. A single LSP_Num covers both unidirectional LSPs since the entity is provisioned or signaled as one.
The Country Code (CC) is a two-character uppercase alphabetic string (A-Z) per ISO 3166-1. The ICC_Operator_ID is formed as CC::ICC, where CC ensures global uniqueness of the ICC.
The ICC_Operator_ID-based MEP_ID is formed by appending a 16-bit unsigned MEP_Index to the MEG_ID: MEG_ID::MEP_Index. The MEP_Index is administratively assigned.
The Interface Identifier (IF_ID) is a 64-bit value formed by concatenating the 32-bit Node_ID with the 32-bit IF_Num: Node_ID::IF_Num. Global uniqueness is achieved by prefixing ICC_Operator_ID.
The MEG_ID is a string of up to 15 characters structured as CC::ICC::UMC (Country Code, ITU Carrier Code, Unique MEG ID Code). It applies uniformly to MPLS-TP Sections, LSPs, and Pseudowires, unlike RFC 6370 which defines separate maintenance identifiers per entity type.
The PW Path Identifier (PW_Path_ID) uses the ICC_Operator_ID in place of Global_ID. The AII is composed of ICC_Operator_ID, Node_ID, and AC_ID (per RFC 5003), forming: A1-{ICC_Operator_ID::Node_ID::AC_ID}::Z9-{ICC_Operator_ID::Node_ID::AC_ID}.