Definitions of Supplemental Managed Objects for ATM Interface
Extracted elements (25)
A VP Tunnel is modeled as an ATM Logical Port (ifType=80, atmLogical) rather than a physical ATM interface (ifType=37) because it connects non-adjacent devices over a VPL used as a trunk, requiring different management attributes: a subset of VPI/VCI space, different ILMI VPI/VCI, and hierarchical ifOperStatus derived from the physical layer beneath.
The atmIntfPvcFailuresTrap is rate-limited by suppressing all traps occurring within atmIntfPvcNotificationInterval of a previous trap on the same interface. This prevents trap storms during widespread failures; managers are expected to poll the atmCurrentlyFailingPVplTable and atmCurrentlyFailingPVclTable for at least this interval.
The configured minimum SVCC VCI (atmInterfaceConfMinSvccVci) is negotiated with the neighbor via ILMI: the current minimum (atmInterfaceCurrentMinSvccVci) is set to the maximum of the two sides' configured values, ensuring both peers use a VCI range that both can support.
The 'low' and 'high' convention for cross-connect entries is based on numerical ordering of ifIndex values: the interface with the lower ifIndex is 'low' and the other is 'high'. This deterministic ordering ensures a single canonical entry for each bi-directional cross-connect, avoiding duplicate rows.
For ATM Logical Port interfaces (VP tunnels), ifInOctets and ifOutOctets support is not mandatory; ifInErrors and ifInUnknownProtos are always zero because HEC and protocol errors are attributed to the underlying physical ATM cell-layer interface (ifType=37) beneath the tunnel.
The ATM2-MIB requires concurrent use of the ATM-MIB (RFC 2515) and ATM-specific textual conventions (RFC 2514). It imports core types (AtmAddr, AtmVcIdentifier, AtmVpIdentifier, AtmTrafficDescrParamIndex, AtmInterfaceType, AtmIlmiNetworkPrefix) from ATM-TC-MIB and table entries from ATM-MIB.
When atmIntfConfigType is set to autoConfig(2), the interface type and side are determined automatically via ATM Forum ILMI auto-configuration procedures; manual configuration of atmIntfConfigSide is not needed. PNNI and BICI interfaces are always symmetric and also do not require side configuration.
Calling party subaddress information SHALL only be transferred to the called party if calling party number delivery is enabled (atmSigSupportClgPtyNumDel = enabled(1)). This dependency is enforced by the object description in atmSigSupportClgPtySubAddr.
The atmSvcVpCrossConnectRowStatus and atmSvcVcCrossConnectRowStatus objects have read-write access solely to allow tear-down of SVC cross-connects; all other cross-connect fields are read-only. This restricts SNMP write access to connection tear-down only.
The ATM2-MIB (atm2MIB) module is a supplement to the ATM-MIB defined in RFC 2515, assigned OID atmMIBObjects 14. It defines 21 tables covering SVC/PVC cross-connects, signalling statistics, address mapping, cell statistics, ILMI, and trap support for ATM switches, services, and hosts.
The atmCurrentlyFailingPVplTable and atmCurrentlyFailingPVclTable list all PVPLs and PVCLs currently not in the 'up' operational state, enabling rapid identification of failing permanent virtual links without continuously polling the entire atmVplTable or atmVclTable.
The atmIfRegisteredAddrTable contains ATM addresses (registered via ILMI or statically configured) usable for calls to/from a switch or service interface. It applies only to switches and network services, not hosts, and does not expose PNNI reachability information.
The atmIlmiSrvcRegTable allows a switch or service to advertise ATM network services (LECS, ANS, ATMARP, MARS, NHRP) to adjacent hosts via ILMI. Each entry associates a service OID (atmIlmiSrvcRegServiceID) with an ATM address and optionally restricts it to a specific interface (value 0 means any interface).
The atmInterfaceExtTable supplements RFC 2515's atmInterfaceConfTable with interface type/side configuration (atmIntfConfigType: autoConfig, ituDss2, atmfUni3Dot0/3Dot1/4Dot0, PNNI, BICI, PVC-only modes) and the negotiated maximum VPI and minimum VCI values per ATM interface.
The atmSigDescrParamTable extends the ATM VCL table to carry signalling parameters from ATM Forum UNI 3.0/3.1, grouped into ATM Adaptation Layer Parameters, Broadband High Layer Information, and Broadband Low Layer Information. Users create entries here to specify signalling characteristics for SVCs.
The atmSigStatTable provides 20 per-interface signalling counters including SSCOP connection events (atmSigSSCOPConEvents), SSCOP errored PDUs (atmSigSSCOPErrdPdus), setup attempts detected/emitted, route/resource unavailability, called/calling party events, message errors, timer expiries, restarts, and established SVCs in/out.
The atmSigSupportTable tracks which ATM UNI signalling Information Elements a switch or service supports, including: Calling Party Number delivery, Calling Party Subaddress, Called Party Subaddress, Broadband High Layer Information, Broadband Low Layer Information, Broadband Repeat Indicator, AAL parameters, and Preferred Carrier Pre-Subscription.
The atmSvcVcCrossConnectTable models each bi-directional SVC VC cross-connect between switched VCLs (including Soft PVCs). It follows the same point-to-point/multipoint entry count rules as the VP cross-connect table, sharing a common atmSvcVcCrossConnectIndex for related entries.
The atmSvcVpCrossConnectTable models each bi-directional SVC VP cross-connect between switched VPLs (including Soft PVPs). A point-to-point cross-connect is one entry; a point-to-multipoint with N leafs is N entries; a multipoint-to-multipoint with N parties is N(N-1)/2 entries, all sharing the same atmSvcVpCrossConnectIndex.
The atmSwitchAddressTable holds one or more ATM endsystem addresses per switch used to identify the switch itself. When no ILMI network prefixes are configured for certain interfaces, network prefixes derived from these switch addresses may be used for ILMI address registration.
The atmVplLogicalPortTable supports creation of ATM Logical Port interfaces (VP tunnels). Creating a VP tunnel requires setting atmVplLogicalPortDef to isLogicalIf on a VPL entry, which causes the agent to allocate a new ifIndex and create corresponding entries in ifTable, atmInterfaceConfTable, atmInterfaceExtTable, and ifStackTable.
The ATM2-MIB defines read-write objects that can modify ATM interface configuration and tear down virtual connections, posing a risk if accessed by unauthorized managers. Implementations must use SNMPv2 (or later) security mechanisms and restrict write access to authenticated management stations, as unauthorized writes could disrupt ATM connectivity.
The atmSvcVcCrossConnectEntry extends the VP cross-connect entry by adding two VCI index fields: atmSvcVcCrossConnectLowVci (AtmVcIdentifier) and atmSvcVcCrossConnectHighVci (AtmVcIdentifier), making a seven-field compound index. The VCI value cannot exceed atmInterfaceMaxVciBits at the respective port.
The atmSvcVpCrossConnectEntry is indexed by five fields: atmSvcVpCrossConnectIndex (INTEGER 1..2147483647), atmSvcVpCrossConnectLowIfIndex (InterfaceIndex), atmSvcVpCrossConnectLowVpi (AtmVpIdentifier), atmSvcVpCrossConnectHighIfIndex (InterfaceIndex), and atmSvcVpCrossConnectHighVpi (AtmVpIdentifier). Additional readable fields are atmSvcVpCrossConnectCreationTime (TimeStamp) and atmSvcVpCrossConnectRowStatus (RowStatus).
VPL and VCL cell counters track total cells and CLP=0 cells; CLP=1 cells are derived by subtraction (total minus CLP=0). Additionally, tagged output cells (CLP=1 cells produced by traffic policing) are counted separately. Valid cells include user and OAM cells but exclude physical-layer idle and unassigned cells.