Definitions of Managed Objects for Monitoring and Controlling the Frame Relay/ATM PVC Service Interworking Function
updated by
- rfc-9141 — Updating References to the IETF FTP Service
Extracted elements (28)
The connection descriptor table separates shared IWF behavioral attributes from the cross-connect index entries. Multiple connections requiring the same DE/CLP mapping, congestion mapping, encapsulation, fragmentation, and ARP settings all reference the same descriptor row, avoiding redundant per-connection storage.
The frAtmIwfConnAdminStatus activation requires that endpoint AdminStatus/OperStatus be brought up first (or as a side-effect). This sequenced provisioning model ensures no traffic is forwarded over the IWF before both PVC endpoints are ready.
Two separate OperStatus objects (frAtmIwfConnAtm2FrOperStatus and frAtmIwfConnFr2AtmOperStatus) track each direction of the IWF independently. This reflects that ATM-to-FR and FR-to-ATM paths may fail independently and need per-direction monitoring.
For interworked connections, the ATM MIB object atmVclCrossConnectIdentifier is set to zero, and frAtmIwfVclCrossConnectIdentifier (defined in this MIB's AUGMENT of atmVclTable) carries the FR/ATM IWF index; the ATM VCL cross-connect table (atmVcCrossConnectTable) does not contain an entry for the interworked connection.
For interworked FR/ATM connections, the frPVCEndptConnectIdentifier in the Frame Relay Service MIB is set to zero and frPVCEndptAtmIwfConnIndex is set to the FR/ATM IWF cross-connect index; the Frame Relay cross-connect table (frPVCConnectTable) does not contain an entry for the interworked connection.
The Frame Relay DTE MIB (RFC 2115) has no relevance to the FR/ATM PVC Service IWF MIB; only the Frame Relay Service MIB (RFC 2954) and the ATM MIB (RFC 2515) serve as technology-specific endpoint MIBs for this IWF.
All rows of frAtmIwfConnectionTable indexed by the same frAtmIwfConnIndex MUST utilize the same frAtmIwfConnectionDescriptor value, and MUST agree on which service the multipoint operation offers (many-FR-to-one-ATM or one-FR-to-many-ATM).
An attempt to set frAtmIwfConnectionDescriptor to a non-existent or inactive row in the Connection Descriptor Table MUST fail with error code 'inconsistentValue'.
Each row of atmVclTable that is not cross-connected to a frame relay PVC MUST return the value zero when frAtmIwfVclCrossConnectIdentifier is read.
Implementations MAY provide support for point-to-multipoint capability using this MIB, even though FRF.8 does not address point-to-multipoint applications of the IWF.
Setting frAtmIwfConnRowStatus to destroy(6) requires that OperStatus/AdminStatus of corresponding endpoints MUST be down(2); if the ATM endpoint is not already down, the deactivation MAY occur as a side-effect, otherwise the destroy MUST fail with error code 'inconsistentValue'.
The frAtmIwfConnDescriptorRowStatus object MUST contain the value 'active(1)' before any connection table entry references the descriptor row. Destruction of a descriptor row MUST fail with 'inconsistentValue' if any connection entry currently references it.
To activate a frAtmIwfConnectionTable row (frAtmIwfConnAdminStatus = up(1)), the OperStatus/AdminStatus of the corresponding endpoints MUST be up(1). Conversely, to deactivate, the atmVclAdminStatus of the ATM endpoint MUST be down(2) before the deactivation completes.
When creating a frAtmIwfConnectionTable row, the frame relay and ATM PVC endpoints MUST already exist and be specified in the index fields. The agent performs all required error checking.
When the IWF is operating in Transparent Mode, frAtmIwfConnFailedFrameTranslate and frAtmIwfConnFailedAal5PduTranslate MUST return noSuchInstance, as those counters are only meaningful in Translation Mode.
frAtmIwfConnClpToDeMappingMode controls CLP-to-DE translation in the ATM-to-FR direction: mode1 sets DE if any cell CLP bit is set; mode2Const0/mode2Const1 set DE to a fixed value. Default is mode1.
frAtmIwfConnCongestionMappingMode controls FECN-to-EFCI mapping in the FR-to-ATM direction. mode1 maps the Q.922 FECN field to the ATM EFCI field; mode2 does not map FECN and always sets EFCI to 'congestion not experienced'. In both modes the IWF may set EFCI if it itself experiences ATM congestion.
frAtmIwfConnDeToClpMappingMode controls DE-to-CLP translation in the FR-to-ATM direction: mode1 copies the Q.922 DE field to ATM CLP; mode2Const0 sets CLP to 0; mode2Const1 sets CLP to 1. Default is mode1.
frAtmIwfConnectionDescriptorTable contains shared attribute sets (descriptor rows) that one or more cross-connect entries may reference via frAtmIwfConnectionDescriptor. Each descriptor captures DE/CLP mapping mode, congestion mapping mode, encapsulation mode, fragmentation, and ARP translation settings.
frAtmIwfConnectionTable contains one row per FR/ATM interworking cross-connection, indexed by frAtmIwfConnIndex, frAtmIwfConnAtmPort, frAtmIwfConnVpi, frAtmIwfConnVci, frAtmIwfConnFrPort, and frAtmIwfConnDlci. Point-to-point connections occupy a single row; point-to-multipoint connections occupy multiple rows sharing the same frAtmIwfConnIndex.
frAtmIwfConnEncapsulationMappingMode selects upper-layer protocol handling: transparentMode (forward unaltered), translationMode (map a subset of encapsulations specified by frAtmIwfConnEncapsulationMappings), or translationModeAll (map all encapsulations). Default is transparentMode.
frAtmIwfConnEncapsulationMappings is a BITS object enumerating which encapsulation translations are active when translationMode is in use: bridgedPdus, bridged802dot6, bPdus, routedIp (NLPID 0xCC), routedOsi, otherRouted, x25Iso8202, and q933q2931. Default is {none}.
frAtmIwfConnIndexNext is a read-only scalar that provides the next available index value for creating frAtmIwfConnectionTable rows. A value of 0 indicates no unassigned entries are available; the agent SHOULD advance the value after each retrieval.
frAtmIwfConnStatusChange is a NOTIFICATION-TYPE that carries frAtmIwfConnAdminStatus, frAtmIwfConnAtm2FrOperStatus, and frAtmIwfConnFr2AtmOperStatus to signal a status change in an interworking connection.
frAtmIwfVclTable AUGMENTs the ATM MIB atmVclTable with a single column, frAtmIwfVclCrossConnectIdentifier, which carries the frAtmIwfConnIndex of the cross-connect entry that links the ATM VCL to a frame relay PVC. Rows not cross-connected to FR return zero.
The FR-ATM-PVC-SERVICE-IWF-MIB module is assigned OID { mib-2 86 }, registering the frAtmIwfMIB MODULE-IDENTITY under the mib-2 subtree.
Several MIB objects carry read-write or read-create access and can affect network operations if SET by unauthorized principals. SNMPv1 alone provides no access control; the document recommends using SNMPv3 with the User-based Security Model (RFC 2574) and the View-based Access Control Model (RFC 2575) to restrict GET/SET access to authorized users only.
Each interworking connection has per-direction operational states (frAtmIwfConnAtm2FrOperStatus and frAtmIwfConnFr2AtmOperStatus), each taking values up(1) or down(2). The frAtmIwfConnAdminStatus triggers transitions: setting to up(1) requires endpoint AdminStatus/OperStatus to be up first; setting to down(2) requires the ATM endpoint AdminStatus to be down first.