Transparent Interconnection of Lots of Links (TRILL) Operations, Administration, and Maintenance (OAM) MIB
Extracted elements (26)
The TRILL OAM MIB uses the IEEE8021-CFM-MIB as its basis and augments existing CFM tables rather than defining a standalone MIB. This avoids duplicating objects that are common to both Ethernet OAM and TRILL OAM, minimizing overlap while reusing proven management infrastructure.
TRILL OAM does not support the CFM Link Trace Message (LTM) or Link Trace Reply (LTR). Instead, Path Trace Message/Reply (PTM/PTR) for unicast and Multi-destination Tree Verification Message/Reply (MTVM/MTVR) for multicast are substituted, with CFM statistics for LTM/LTR defaulting per IEEE8021-CFM-MIB.
TRILL's 24-bit Fine-Grained Label (FGL) is represented in the IEEE8021-TC-MIB by reusing value 2 of IEEE8021ServiceSelectorType (originally defined for 24-bit ISIDs), rather than adding a new type, enabling reuse of existing textual conventions for service selector encoding.
Implementation of IEEE8021-CFM-MIB is required because trillOamMepTable augments dot1agCfmMepEntry. CFM objects not applicable to TRILL must be handled by the TRILL backend with appropriate IEEE8021-CFM-MIB-specified default values.
The TRILL OAM MIB imports LldpChassisId, LldpChassisIdSubtype, LldpPortId, and LldpPortIdSubtype from LLDP-MIB to encode port and chassis identification in PTR and MTVR table entries, reusing LLDP type definitions for consistency with existing management data models.
All columns in a trillOamMepFlowCfgTable row MUST have a valid value before the row can be activated via trillOamMepFlowCfgRowStatus. Writable columns in an active row cannot be changed.
Compliant implementations MUST implement all six mandatory conformance groups: trillOamMepMandatoryGroup, trillOamMepFlowCfgTableGroup, trillOamPtrTableGroup, trillOamMtvrTableGroup, trillOamMepDbGroup, and trillOamNotificationGroup.
Rows in trillOamMepTable and trillOamMepDbTable are automatically added or deleted based on row creation and destruction in the parent IEEE8021-CFM-MIB tables (dot1agCfmMepTable and dot1agCfmMepDbTable respectively); implementations have no independent control over row lifecycle.
MTVM (Multi-destination Tree Verification Message) operation is controlled by trillOamMepTxMtvmStatus, trillOamMepTxMtvmMessages (1..1024), trillOamMepTxMtvmTree (tree identifier), and trillOamMepTxMtvmScopeList. Like PTM, it starts at HC=1 and increments until a response or maximum HC.
PTM (Path Trace Message) operation is managed via trillOamMepTxPtmStatus (boolean trigger), trillOamMepTxPtmMessages (count 1..1024), and trillOamMepTxPtmSeqNumber. The PTM is first sent with HC=1 and retransmitted with incrementing HC until a response arrives or the configured maximum is reached.
trillOamFaultAlarm is a NOTIFICATION-TYPE sent to the management entity whenever a MEP loses or restores contact with a peer flow MEP. The notification carries trillOamMepDbFlowState and includes indices to identify the specific MEP and flow reporting the defect.
trillOamMepDbTable augments dot1agCfmMepDbTable with TRILL-specific per-remote-MEP data: flow index, 96-byte flow entropy, flow state (Dot1agCfmRemoteMepState), last state-change timestamp, remote RBridge nickname, and last good CCM sequence number.
trillOamMepFlowCfgTable provides per-flow configuration for a MEP, indexed by Maintenance Domain, MANET, MEP, and a Flow Configuration Index. Each row holds 96-byte Flow Entropy, destination RBridge Nickname, and Hop Count for a specific flow session.
trillOamMepTable augments dot1agCfmMepEntry from IEEE8021-CFM-MIB. Rows are automatically created and destroyed in sync with the parent dot1agCfmMepTable, providing per-MEP TRILL OAM local configuration including RBridge nickname, LBM, PTM, and MTVM transmission parameters.
trillOamMtvrTable stores Multi-destination Tree Verification Reply (MTVR) entries indexed by five fields: Maintenance Domain, MANET, MEP, Transaction Identifier, and receive order. It includes flag, error code, ingress/egress ports, multicast receiver availability, and receiver count.
trillOamPtrTable stores Path Trace Reply (PTR) entries per MEP and Transaction Identifier, capturing hop-count, FCOI flags, error codes, ingress/egress MAC and port IDs, chassis ID, organization-specific TLVs, and next-hop RBridge nicknames returned in each reply.
The TRILL-OAM-MIB module is assigned OID { mib-2 238 }, registering the top-level MIB subtree for TRILL OAM managed objects under the standard mib-2 arc.
SET operations against the TRILL OAM MIB in a non-secure environment without proper protection expose RBridges to attack. Implementations must apply SNMPv3 security or equivalent access controls; if OAM frame rates are high and control-plane policing is absent, destination RBridges may suffer CPU spikes.
The out-of-band reply IP address objects (trillOamMepTransmitLbmReplyIp, trillOamMepTransmitPtmReplyIp, trillOamMepTransmitMtvmReplyIp) are read-create and allow OAM replies to be directed to any IP address, enabling denial-of-service attacks against arbitrary systems if SET operations are not protected.
trillOamMepTxPtmMessages and trillOamMepTxMtvmMessages are read-create objects that control the volume of PTM and MTVM traffic; unprotected write access can be exploited to generate large amounts of CPU-driven OAM traffic, causing CPU spikes on destination RBridges.
The remote MEP flow state machine (trillOamMepDbFlowState, typed as Dot1agCfmRemoteMepState) runs per-flow at each MEP. It transitions between RMEP_FAILED and RMEP_OK states; trillOamMepDbFlowFailedOkTime records the sysUpTime of the last such transition.
Out-of-band reply IP address fields (trillOamMepTransmitLbmReplyIp, trillOamMepTransmitPtmReplyIp, trillOamMepTransmitMtvmReplyIp) are encoded as OCTET STRING of SIZE 4..16, supporting both IPv4 (4 octets) and IPv6 (16 octets) addresses.
The Flow Entropy field (trillOamMepFlowCfgFlowEntropy, trillOamMepTxLbmFlowEntropy, etc.) is encoded as a fixed 96-octet OCTET STRING used to identify a customer flow and determine the exact forwarding path through the TRILL network.
The Hop Count field (trillOamMepTxLbmHC, trillOamMepTxPtmHC, trillOamMepTxMtvmHC, trillOamMepFlowCfgFlowHC) is encoded as Unsigned32 constrained to 1..63, matching the 6-bit TRILL header Hop Count field defined in RFC 6325.
The MTVR Scope List (trillOamMepTxMtvmScopeList) is an OCTET STRING with 2 octets per RBridge in the multi-destination scope, encoding the set of RBridges targeted by an MTVM operation.
The RBridge Nickname field (trillOamMepRName, trillOamMepTxLbmDestRName, etc.) is encoded as Unsigned32 constrained to the range 0..65471, matching the 16-bit nickname space defined in RFC 6325 Section 3.7.