GMPLS RSVP-TE Extensions for Ethernet Operations, Administration, and Maintenance (OAM) Configuration
Extracted elements (26)
Dual-ended Loss Measurement (ITU-T Y.1731) requires no additional OAM configuration Sub-TLV beyond the standard CC Sub-TLV because the measurement piggbacks frame counters on CCMs; it is activated simply by setting the PM/Loss OAM Function Flag alongside the CC flag.
MEP reachability parameters (ESP-MAC DA, ESP-MAC SA, ESP-VID) for PBB-TE connections are derived directly from the GMPLS Ethernet Labels (UPSTREAM_LABEL and Label objects) rather than being carried explicitly in OAM TLVs, avoiding redundant signaling of information already present in the LSP setup.
The document intentionally restricts scope to bidirectional point-to-point PBB-TE connections because Ethernet OAM mechanisms (CCM exchange) are only fully functional when co-routed bidirectional connections are in place; unidirectional ESPs are not supported.
The Remote MEP ID is determined by the initiator node rather than the remote node because each new MAID is uniquely assigned to a single PBB-TE connection, so MEP IDs only need to be unique within the scope of a single MAID.
This document specifies GMPLS RSVP-TE extensions that support, but do not modify, the underlying IEEE 802.1Q-2011 (CFM) and ITU-T Y.1731 OAM mechanisms. The Ethernet OAM entities configured via signaling must conform to those standards' formats and semantics.
If a node does not support the specified CFM version, an error MUST be generated: 'OAM Problem/Unsupported OAM Version'. Similarly, unsupported MD Level generates 'OAM Problem/Unsupported MD Level'.
The combined length of the MD Name and Short MA Name MUST be less than or equal to 44 bytes; violation MUST generate 'OAM Problem/Name Length Problem'. An undefined name format MUST generate the corresponding 'Unknown MD/MA Name Format' error.
The Continuity Check Sub-TLV MUST be present in the Ethernet OAM Configuration Sub-TLV. The CCM Interval (CCM I) field MUST be set according to the 3-bit encoding from IEEE 802.1Q-2011.
The Ethernet OAM Configuration Sub-TLV MUST be carried in the OAM Configuration TLV when Ethernet OAM is configured for an LSP.
The initiator MUST include the OAM Function Flags Sub-TLV in the OAM Configuration TLV, MUST include an Ethernet OAM Configuration Sub-TLV specifying the CCM Interval and MD Level, and MUST include a MEP ID Sub-TLV with two distinct integer values identifying local and remote MEPs.
The MEP ID Sub-TLV MUST be present in the Ethernet OAM Configuration Sub-TLV. When the Transmit (T) flag is set, the corresponding MEP MUST send OAM packets; when the Receive (R) flag is set, the MEP MUST expect to receive OAM packets.
The Short MA Name Sub-TLV MUST be present in the Ethernet OAM Configuration Sub-TLV to unambiguously identify the Maintenance Association for the PBB-TE connection.
When initiating RSVP-TE signaling for a bidirectional Ethernet LSP, the local node MUST include the OAM Configuration TLV with OAM Type set to Ethernet OAM in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES objects.
A Maintenance Association Identifier (MAID) consists of an optional MD Name and a mandatory Short MA Name; both MEPs at each end of a bidirectional connection must be configured with identical MAID values. The combined MD Name + Short MA Name length is limited to 44 bytes.
Eight CCM Interval values are defined with 3-bit encoding per IEEE 802.1Q-2011: Reserved (000), 3 1/3 ms (001), 10 ms (010), 100 ms (011), 1 s (100), 10 s (101), 1 min (110), 10 min (111). Loss of three consecutive CCMs declares connectivity failure.
The Ethernet OAM Configuration Sub-TLV (Type 32) carries Ethernet-specific OAM configuration parameters within the OAM Configuration TLV. It includes a Version field (CFM protocol version), MD Level (3 bits), and nested sub-TLVs.
The OAM Configuration TLV is extended with a new OAM Type value: Ethernet OAM (Type 1), assigned by IANA from the 'RSVP-TE OAM Configuration Registry'. Receiving nodes must look for the Ethernet OAM Configuration Sub-TLV when this type is indicated.
IANA creates an 'Ethernet Sub-TLVs Sub-Registry' within the 'RSVP-TE OAM Configuration Registry'. Types 0 (Reserved), 1 (MD Name), 2 (Short MA Name), 3 (MEP ID), 4 (Continuity Check) are defined; 5–65534 are Unassigned (IETF Review); 65535 is reserved for experimental use.
IANA maintains the 'RSVP-TE OAM Configuration Registry'. This document allocates OAM Type 1 ('Ethernet OAM') in the OAM Types sub-registry and Sub-TLV Type 32 ('Ethernet OAM Configuration Sub-TLV') in the technology-specific range of the OAM Sub-TLVs sub-registry.
Six new Error Value sub-codes are added to the RSVP 'OAM Problem' Error Code: 7 (Unsupported OAM Version), 8 (Unsupported MD Level), 9 (Unknown MD Name Format), 10 (Unknown MA Name Format), 11 (Name Length Problem), 12 (Unsupported CC Interval).
Automatic establishment of OAM entities via RSVP-TE introduces a denial-of-service risk: a remote attacker could overload a network element by sending frequent Path messages requesting liveliness monitoring for a large number of LSPs. This can be mitigated by deploying RSVP message integrity and node authentication per RFC 2747.
The Continuity Check Sub-TLV (Type 4) contains a 4-bit Prio field (MSB enable + 3-bit priority) and a 4-bit CCM Interval field encoding one of 8 defined intervals (3 1/3 ms to 10 min), followed by 24 reserved bits.
The Ethernet OAM Configuration Sub-TLV is a 32-bit-aligned TLV: 16-bit Type (32), 16-bit Length, then a second 32-bit word with 3-bit Version, 3-bit MD Level, and 26 reserved bits, followed by nested sub-TLVs.
The MD Name Sub-TLV (Type 1) carries an 8-bit Format field, 8-bit Name Length, 16 reserved bits, and a variable-length MD Name. The Name Length field is needed to allow non-4-byte-padded MD Name lengths.
The MEP ID Sub-TLV (Type 3) carries a 16-bit Local MEP ID, 1-bit Transmit (T) flag, 1-bit Receive (R) flag, 14 reserved bits, then a 16-bit Remote MEP ID with the same T/R/Reserved layout. MEP IDs are integers in range 1–8191.
The Short MA Name Sub-TLV (Type 2) follows the same layout as the MD Name Sub-TLV: 8-bit Format, 8-bit Name Length, 16 reserved bits, and variable-length Short MA Name.