Definitions of Managed Objects for ATM Management
obsoletes
- rfc-1695 — Definitions of Managed Objects for ATM Management Version 8.0 using SMIv2
Extracted elements (29)
AAL5 in an ATM switch is managed via a proprietary virtual (pseudo-ATM) internal interface in ifTable to represent the AAL5 entity as an infrastructure resource, while per-VCC AAL5 performance uses a separate aal5VccTable; this separation allows both entity-level and connection-level management.
atmInterfaceAddressType and atmInterfaceAdminAddress were deprecated and replaced by atmInterfaceSubscrAddress. The new object captures the service-provider-assigned subscriber address on the network side of a public UNI, which is distinct from ifPhysAddress (the host-side address).
atmTrafficQoSClass (RFC 1695) was deprecated and replaced by atmServiceCategory because new insights in ATM traffic management rendered the four QoS class model (A/B/C/D) insufficient; service categories provide a richer and more standards-aligned characterization of VPL/VCL traffic.
ILMI negotiates Max Current VPI/VCI bits as the minimum of both ends' Max Active values because a manager may lack write access to the peer's MIB or the peer may have hardware limitations, so a bilateral mechanism is needed to agree on the usable address space.
The ATM network can be modeled as a single large distributed switch by hiding internal connectivity, enabling Customer Network Management (CNM) to treat a multi-switch VCC/VPC as a simple point-to-point link managed through the link and cross-connect tables.
For the overlapping subset of management information between ILMI MIBs and this memo, every effort was made to retain identical semantics and syntax even though objects use different OBJECT IDENTIFIERs, to reduce divergence between the two management planes.
PVC cross-connects between VPLs and VCLs are managed via atmVpCrossConnectTable and atmVcCrossConnectTable in this MIB. SVC and Soft PVC cross-connects are managed via atmSvcVpCrossConnectTable and atmSvcVcCrossConnectTable in the ATM2-MIB (separate memo); entries with the same cross-connect index must never exist simultaneously in both.
This MIB is specified in SMIv2 but can be translated to SMIv1. The translation is semantically equivalent except that Counter64 objects and machine-readable SMIv2 constructs become textual descriptions, which is not considered a semantic change.
atmVplRowStatus (and atmVclRowStatus) should not be set to active unless atmVplReceiveTrafficDescrIndex and atmVplTransmitTrafficDescrIndex have been set to their desired values; the agent checks resource availability and may refuse the request.
For the ATM cell layer, ifType must be 37; for the AAL5 CPCS layer entity, ifType must be 49; for the proprietary virtual internal interface associated with an AAL entity in an ATM switch, ifType must be 53.
If an ATM interface does not negotiate VPI/VCI bit counts with its peer, the value of atmInterfaceCurrentMaxVpiBits (respectively VciBits) must equal atmInterfaceMaxActiveVpiBits (respectively VciBits).
If the transmit and receive service categories for a VPL or VCL are inconsistent, the agent should refuse the request to set those traffic descriptor indices.
ifPhysAddress for an ATM interface is the ATM address used as the Called Party Address IE for connections terminating at or forwarded through the interface. If the interface has no address, ifPhysAddress is a zero-length octet string.
The agent must deny a request to destroy a row in atmTrafficDescrParamTable if that row is still referenced by any entry in atmVplTable or atmVclTable.
atmInterfaceConfTable contains per-ATM-port configuration indexed by ifIndex, including max VPCs/VCCs (read-write), configured VPCs/VCCs (read-only), max active VPI/VCI bits, ILMI VPI/VCI, neighbor IP/ifName, current negotiated max VPI/VCI bits, and subscriber address.
atmInterfaceCurrentMaxVpiBits and atmInterfaceCurrentMaxVciBits are read-only objects that reflect the negotiated minimum of each interface's Max Active bits and its UNI/NNI peer's Max Active bits, obtained via ILMI. These constrain the VPI/VCI address space actually usable on the link.
atmInterfaceDs3PlcpTable provides DS3 PLCP performance counters (SEFS, unavailable seconds) and alarm state (noAlarm, receivedFarEndAlarm, incomingLOF) per ATM interface that uses DS3 PLCP cell transport.
atmInterfaceTCTable provides TC sublayer state per ATM interface: atmInterfaceOCDEvents counts Out-of-Cell-Delineation events (triggered after seven consecutive HEC violations), and atmInterfaceTCAlarmState indicates noAlarm or lcdFailure (Loss of Cell Delineation maintenance state).
atmTrafficDescrParamIndexNext provides the manager a free AtmTrafficDescrParamIndex value to use when creating a new row in atmTrafficDescrParamTable, avoiding index collisions in multi-manager environments.
atmTrafficDescrParamTable defines ATM traffic descriptor entries with an OID type, up to five Integer32 parameters, a service category (AtmServiceCategory), and a frame-discard flag. VPL and VCL entries reference rows in this table by AtmTrafficDescrParamIndex for both receive and transmit directions.
atmTrafficFrameDiscard (TruthValue, default true) requests the network to treat connection data as frames (e.g., AAL5 CPCS-PDUs) rather than individual cells, enabling whole-frame discard during congestion instead of dropping scattered cells from many frames.
atmVclTable models bi-directional Virtual Channel Links (VCLs), indexed by ifIndex, VPI, and VCI. Each entry carries the same fields as atmVplTable plus AAL type, AAL5 receive/transmit SDU sizes, and AAL5 encapsulation type. Used for PVCs, SVCs, and Soft PVCs.
atmVpCrossConnectTable and atmVcCrossConnectTable represent PVC cross-connections in ATM switches and networks. VPL entries in the same VPC share the same atmVplCrossConnectIdentifier, and the cross-connect is indexed by that value in atmVpCrossConnectTable. SVC and Soft PVC cross-connects are handled in a separate ATM2-MIB.
atmVplTable models bi-directional Virtual Path Links (VPLs), indexed by ifIndex and VPI. Each entry carries admin/oper status, last-change time, receive/transmit traffic descriptor indices, a cross-connect identifier, row status, cast type, and connection kind. Used for PVCs, SVCs, and Soft PVCs.
The AAL5 VCC performance statistics table (aal5VccTable) provides per-VCC AAL5 error counters: PDUs discarded for CRC-32 errors, reassembly timeouts, and oversized SDUs, for each AAL5 virtual connection terminated at an ATM switch or host.
Several objects in this MIB are read-write or read-create (e.g., atmInterfaceMaxVpcs, atmVplAdminStatus, atmVclAdminStatus, traffic descriptor parameters), meaning unauthorized write access could allow modification or teardown of ATM virtual connections and disruption of network service. The SNMPv3 framework with authentication and privacy is recommended to protect access to these objects.
DS3 PLCP alarm state machine has three states: noAlarm (no defects), receivedFarEndAlarm (incoming Yellow Signal received), and incomingLOF (Loss of Frame declared). Transition from failure back to noAlarm occurs when no defects are received for more than 10 seconds.
TC sublayer alarm has two states: noAlarm and lcdFailure (Loss of Cell Delineation defect maintenance state active). OCD events (seven consecutive HEC violations) drive entry into the LCD defect state.
VPL and VCL row lifecycle: createAndWait (reserves VPI or VPI/VCI, allows step-wise parameter setting and error checking) → active (resources committed) → destroy (row deleted, resources released); alternatively createAndGo performs one-shot establishment without step-wise error feedback.