Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks
Extracted elements (25)
The encodings in this document are intentionally protocol-agnostic so that they can be reused across GMPLS routing protocols (OSPF-TE, IS-IS-TE), the PCE Communication Protocol (PCEP), and future mechanisms. Protocol-specific documents are expected to reference this RFC and define how these fields are carried as sub-TLVs.
The inclusive range Action value in the RB Set Field enables compact encoding of large resource sets. The RFC notes that numbering resource blocks contiguously can allow status updates to exploit this efficiency, reducing routing protocol overhead in large WSON deployments.
The two-action encoding for Resource Block Pool State (integer list vs. bitmap) is chosen because some resource blocks contain multiple resources and require a count (Action=0), while single-element resource blocks are more compactly represented by a single availability bit (Action=1). The encoding matches the structure of the resource pool.
When used with GMPLS routing protocols OSPF (RFC 4203) and IS-IS (RFC 5307), the information fields defined here are intended to appear as nested sub-TLVs; the specific sub-TLV nesting and encapsulation are to be defined in the respective protocol extension documents, not in this RFC.
The number of Input Bit Rates in the Input Bit Rate List Subfield MUST match the number of G-PIDs in the corresponding Acceptable Client Signal List Subfield. Bit rates are encoded in IEEE 754 floating-point format.
The Reserved field in the Resource Block Set Field MUST be set to zero on transmission and MUST be ignored on receipt.
Unrecognized subfield types within the Resource Block Information Field are not processed. If multiple subfields of the same type are present, only the first SHOULD be processed.
Within the Resource Accessibility Field's Link Set Fields, the bidirectional value for the direction parameter is not permitted; each field must be designated as either input or output.
Zero or more Optional Subfields MAY be present in the Resource Block Information Field; the subfield value is padded to 4-byte alignment, and the Length field reports only the value length, not the padding.
Four sub-TLV types are defined for nested subfields of the Resource Block Information Field: Type 1 (Optical Interface Class List), Type 2 (Acceptable Client Signal List), Type 3 (Input Bit Rate List), and Type 4 (Processing Capability List), all of variable length.
The Resource Block Set (RB Set) Field identifies one or more resource blocks within a WSON node. It uses an Action field (8 bits) to indicate either an inclusive list (Action=0) or inclusive range(s) (Action=1) of 32-bit RB identifiers, plus a Connectivity (C) bit, a Reserved field, a 16-bit Length, and variable-length RB Identifier entries.
The Selective Regeneration Pools capability (C=2) is defined but not yet usable: encoding of the pool properties (input/output restrictions and availability) requires an additional specification before this value can be deployed.
IANA created a new top-level registry 'GMPLS Routing Parameters for WSON' and within it a subregistry 'Types for Subfields of WSON Resource Block Information Registry' (Standards Action policy). Initial entries assign Types 1–4 to Optical Interface Class List, Acceptable Client Signal List, Input Bit Rate List, and Processing Capability List; Types 5–65535 are unassigned.
This document defines protocol-independent encodings and does not itself introduce security issues. However, protocol documents that embed these encodings must address risks of inspection, interception, modification, or spoofing of WSON information; a general GMPLS security framework is provided in RFC 5920.
ITU-T G.695 (CWDM) application codes are encoded in the same 64-bit layout as G.959.1, reusing the same field positions; the C prefix field takes value 3 to indicate CWDM, and the 6-bit suffix bitmap has only the F (FEC) bit defined.
ITU-T G.698.1 application codes are mapped to a 64-bit Optical Interface Class field encoding fields B, D, S, c (4-bit channel spacing per RFC 6205), W, y, t, z, v, and F (FEC present) in the first 32 bits; the last 32 bits are reserved and set to zero.
ITU-T G.959.1 application codes (PnWx-ytz / BnWx-ytz) are mapped to 64 bits across two 32-bit words, encoding prefix (p), plural flag (P), channel count n (10 bits), reach class W (4 values), span count x (6 bits), bit-rate y, amplifier type t, fiber type z, and a 6-bit suffix bitmap (F, D, E, r, a, b).
The Acceptable Client Signal List Subfield encodes a 16-bit count of G-PIDs followed by a list of 16-bit IANA-assigned Generalized Protocol Identifiers representing acceptable input client signal types for a resource block.
The Optical Interface Class List Subfield contains I/O flags (indicating whether the list applies to input, output, or both) and an Optical Interface Classes structure. A 1-bit Standard flag (S) distinguishes ITU application codes (S=1, OI Code Points 1–4) from non-ITU codes (S=0). Each Optical Interface Class entry is 64 bits.
The Processing Capability List Subfield encodes a 16-bit Processing Cap ID (0=Reserved, 1=Regeneration, 2=Fault/performance monitoring, 3=Vendor-specific) plus optional additional parameters. For regeneration (Cap ID=1), a 3-bit regenerator type (T: 1R/2R/3R) and 2-bit capability (C: Fixed Point or Selective Pools) are included.
The Resource Accessibility Field encodes the PoolInputMatrix and PoolOutputMatrix as alternating Input/Output Link Set Fields (encoded per RFC 7579) and RB Set Fields. A 1-bit Connectivity (C) flag at byte 9 indicates fixed (C=0) or switched (C=1) port-to-resource connectivity.
The Resource Block Information Field consists of an RB Set Field, three I/O/B shared-fiber flags, and zero or more Optional Subfields in TLV format (2-byte Type, 2-byte Length of value, value padded to 4-byte alignment). The length of the enclosing object determines overall field length.
The Resource Block Pool State Field encodes resource availability using either a list of 16-bit unsigned integers (Action=0, giving the number of available resources per RB) or a bitmap (Action=1, one bit per RB where 0=available, 1=in-use). The bitmap form must be padded to a multiple of 4 bytes.
The Resource Block Shared Access Wavelength Availability Field shares the same I/O/B flag structure as the Resource Wavelength Constraints Field, followed by an RB Set Field and optional Input/Output Available Wavelength Set Fields encoded via RFC 7579 Label Set Fields.
The Resource Wavelength Constraints Field uses three flags (I, O, B) to indicate the presence of Input and/or Output Wavelength Constraints sub-fields, followed by an RB Set Field and optional wavelength constraints encoded via the Label Set Field of RFC 7579. Valid flag combinations are (1,0,0), (0,1,0), (1,1,0), and (0,0,1) only.