Path Computation Element Communication Protocol (PCEP) Extensions for Establishing Relationships between Sets of Label Switched Paths and Virtual Networks
Extracted elements (22)
The VIRTUAL-NETWORK-TLV is defined as a separate mandatory TLV (rather than encoding the VN name directly in the ASSOCIATION object) to allow the identifier to be of variable length and to remain extensible via optional vendor-specific information in VENDOR-INFORMATION-TLV.
The VN association group enables a PCE to jointly optimize all LSPs belonging to a VN, for example by minimizing the load of the most loaded link (MLL) across all VN LSPs at once, rather than optimizing individual LSPs in isolation.
VNAG IDs are dynamic and created by the parent PCE (MDSC) based on VN operations, rather than being operator-configured. This design reflects that the parent PCE determines VN membership in response to customer requests, making static operator assignment of ID ranges unnecessary and potentially conflicting.
Per RFC 8697, if an implementation does not support the VN Association Type (7), it returns a PCErr with Error-Type=26 (Association Error) and Error-value=1 (Association Type is not supported). Implementations must advertise supported Association Types via the ASSOC-Type-List TLV in the OPEN object.
A PCEP speaker MUST include the VN Association Type (7) in the ASSOC-Type-List TLV (within the OPEN object) before using the VNAG object in any PCEP message.
An LSP MUST NOT belong to more than one VNAG. If an implementation encounters more than one VNAG object in a PCEP message, it MUST process the first occurrence and MUST ignore the others.
An operator MUST be allowed to mark LSPs that belong to the same VN; this may also be done automatically based on VN configuration.
If a PCEP speaker receives a VNAG object with a TLV that violates the rules of this document, the speaker MUST send a PCErr with Error-Type=10 (Reception of an invalid object) and Error-value=11 (Malformed object) and MUST close the PCEP session.
Securing the PCEP session using TLS (RFC 8253) is RECOMMENDED when using VN Association, given the additional security risks introduced by LSP associations from a potentially malicious PCEP speaker.
The Virtual Network Identifier SHOULD be a string of printable ASCII characters (0x20 to 0x7E) without a NULL terminator.
The VIRTUAL-NETWORK-TLV Length field MUST be greater than 0, and the TLV MUST be zero-padded to maintain 4-octet alignment.
The VIRTUAL-NETWORK-TLV MUST be included in the VNAG object. If a PCEP speaker receives a VNAG object without it, it MUST send a PCErr with Error-Type=6 (Mandatory Object missing) and Error-value=18 (VIRTUAL-NETWORK-TLV missing) and close the session.
The VN Association Type (7) MUST NOT be present in the Operator-configured Association Range TLV. If an implementation encounters it there, it MUST ignore the associated Start-Assoc-ID and Range values, because VNAG IDs are dynamically created by the parent PCE (MDSC) and operator configuration is not supported.
VN association information MUST be included as part of the first PCRpt message sent by the child PCE after an LSP is instantiated.
In the H-PCE (Hierarchical PCE) / ACTN architecture, the parent PCE (MDSC) sends a PCInitiate message with the VNAG object to bind a new LSP at the child PCE (PNC) to a VN. Subsequent changes to the LSP are reported via PCRpt with the VNAG object, and VN updates trigger PCUpd messages to affected child PCEs.
The VIRTUAL-NETWORK-TLV (Type=65) is a mandatory TLV carried within the VNAG object. It communicates the Virtual Network Identifier — a human-readable symbolic name that uniquely identifies the VN. It may be customer-specified, operator-set, or auto-generated by the PCEP speaker.
The VN Association Group (VNAG) is a new association group that binds a set of LSPs to a Virtual Network (VN). It reuses the generic ASSOCIATION object from RFC 8697 with a new Association Type value of 7 ('VN Association'). The VNAG Identifier is handled identically to the generic Association Identifier defined in RFC 8697.
IANA allocated Error-Type=6, Error-value=18 ('VIRTUAL-NETWORK-TLV missing') in the 'PCEP-ERROR Object Error Types and Values' subregistry within the 'Path Computation Element Protocol (PCEP) Numbers' registry.
IANA assigned value 65 ('VIRTUAL-NETWORK-TLV') in the 'PCEP TLV Type Indicators' subregistry within the 'Path Computation Element Protocol (PCEP) Numbers' registry.
IANA assigned value 7 ('VN Association') in the 'ASSOCIATION Type Field' subregistry within the 'Path Computation Element Protocol (PCEP) Numbers' registry.
Security considerations from RFC 5440, RFC 8231, and RFC 8281 apply to the extensions defined in this document. Additional risks associated with LSP associations from a malicious PCEP speaker are described in RFC 8697 and apply equally to the VN Association Type. Securing the PCEP session using TLS (RFC 8253) is RECOMMENDED.
The VIRTUAL-NETWORK-TLV has a 16-bit Type field (value 65), a 16-bit Length field (MUST be > 0, value portion in octets, TLV zero-padded to 4-octet alignment), and a variable-length Virtual Network Identifier carrying a symbolic name for the VN.