Management Information Base for Frame Relay DTEs Using SMIv2
obsoletes
- rfc-1315 — Management Information Base for Frame Relay DTEs
Extracted elements (30)
Configuring Frame Relay DLCIs as individual ifTable entries is explicitly not recommended and not directly supported by this MIB, because demand circuits make it impossible to pre-create individual ifEntries. The frCircuitLogicalIfIndex mechanism is provided instead for associating higher-layer protocols with subsets of DLCIs.
Frame Relay is modeled as a multi-access medium rather than a group of point-to-point connections. This single-interface-with-many-virtual-connections model allows a network manager to group all virtual connections with their corresponding physical connection, simplifying diagnostics and troubleshooting.
Due to conversion from SMIv1 to SMIv2, table index objects have MAX-ACCESS of read-only rather than not-accessible, which is atypical for SMIv2 index objects. This deviation was required for backward compatibility with RFC 1315.
frCompliance0 defines the compliance statement for objects and the trap defined in RFC 1315 (the SMIv1 predecessor), using mandatory groups frPortGroup0 and frCircuitGroup0. This allows implementations to claim conformance to either the new RFC 2115 profile or the legacy RFC 1315 profile.
ifInBroadcastPkts and ifOutBroadcastPkts are always zero for Frame Relay interfaces because there are no broadcast frames in Frame Relay. ifPromiscuousMode and ifConnectorPresent are both set to false(2).
Compliant implementations MUST support the frPortGroup and frCircuitGroup object groups. The frErrGroup, frTrapGroup, and frNotificationGroup are optional and used for debugging and asynchronous notification management respectively.
If a SET of frDlcmiMaxSupportedVCs is attempted with a value less than zero or higher than the agent's maximal capability, the agent should respond badValue.
Per-DLCI frDLCIStatusChange traps should not be generated when the reason for the state change is the DLCMI going down, to avoid trap storms.
frCircuitCommittedBurst (Bc) is the maximum data in bits the network agrees to transfer under normal conditions during the measurement interval. frCircuitExcessBurst (Be) is the maximum uncommitted data bits the network will attempt to deliver; defaults to ifSpeed if not configured. frCircuitThroughput determines the measurement interval T = Bc/throughput, or T = Be/ifSpeed when both Bc and throughput are zero.
frCircuitLogicalIfIndex allows a virtual ifEntry to be associated with a DLC or set of DLCs for higher-layer protocol binding (e.g., PPP/Frame Relay, IP addressing). It normally equals frDlcmiIfIndex but differs when a subset of VCs needs its own logical interface with an appropriate ifType.
frCircuitMulticast indicates the VC type: unicast(1), oneWay(2), twoWay(3), or nWay(4) multicast service. Default is unicast. Defined per FRF.7 Frame Relay Forum multicast specification.
frCircuitReceivedDEs and frCircuitSentDEs count frames with the Discard Eligibility (DE) bit set, indicating frames eligible for discard during congestion. frCircuitSentDEs counts frames where the local DTE sets DE to indicate excess burst data that should be dropped preferentially.
frCircuitReceivedFECNs counts frames received with the Forward Explicit Congestion Notification bit set (either by the remote DTE or a switch with a congested trunk queue). frCircuitReceivedBECNs counts frames received with the Backward Explicit Congestion Notification bit set.
frCircuitSentOctets and frCircuitReceivedOctets count the full frame relay header and payload bytes but exclude flag characters and CRC. This clarification was added from RFC 1315.
frCircuitTable is indexed by (frCircuitIfIndex, frCircuitDlci) and contains per-virtual-circuit statistics and configuration including state, FECN/BECN counters, sent/received frame and octet counts, committed burst, excess burst, throughput, multicast type, discard counts, DE flag counters, and row status. The management virtual circuit (DLCI 0) is included in this table.
frDLCIStatusChange is a NOTIFICATION-TYPE that carries frCircuitState and fires when a virtual circuit is created, invalidated, or toggles between active and inactive. Per-DLCI traps should not be generated if the state change is due to the DLCMI going down.
frDlcmiAddress specifies the Q.922 address format in use: q921(1) for 13-bit DLCI, q922March90(2) for 11-bit, q922November90(3) for 10-bit, and q922(4) for the final standard. frDlcmiAddressLen indicates the address length as twoOctets(2), threeOctets(3), or fourOctets(4) including the control portion.
frDlcmiErrorThreshold (Counter N392) is the maximum number of unanswered Status Enquiries accepted before declaring the interface down, range 1..10, default 3. frDlcmiMonitoredEvents (Counter N393) is the number of polling intervals over which the error threshold is counted, range 1..10, default 4.
frDlcmiPollingInterval (Timer T391) specifies the number of seconds between successive status enquiry messages, with a range of 5..30 seconds and a default of 10. frDlcmiFullEnquiryInterval (Counter N391) is the number of status enquiry intervals before a full status enquiry is issued, range 1..255, default 6.
frDlcmiState enumerates the active DLCMI scheme: noLmiConfigured(1), lmiRev1(2), ansiT1617D(3), ansiT1617B(4), itut933A(5), and ansiT1617D1994(6). This determines which DLCI is used for link management.
frDlcmiTable contains configuration parameters for the Data Link Connection Management Interface (DLCMI) on each Frame Relay interface, indexed by frDlcmiIfIndex (InterfaceIndex). It includes the LMI scheme, address format, polling timers, error thresholds, and row status.
frErrFaultTime records sysUpTime when the interface was taken down due to excessive errors, defined as when the DLCMI exceeds frDlcmiErrorThreshold errors within frDlcmiMonitoredEvents polling intervals.
frErrTable, indexed by frErrIfIndex, captures the most recent error per interface including type, raw error data (up to 1600 octets of the erroneous frame starting with the Q.922 address), timestamp, fault count, and time of last fault. frErrFaults counts how many times the interface has gone down since initialization.
frErrType enumerates error classes: unknownError(1), receiveShort(2) — frame too short to demultiplex, receiveLong(3) — frame exceeded maximum length, illegalAddress(4), unknownAddress(5) — VC not active or disabled, dlcmiProtoErr(6), dlcmiUnknownIE(7), dlcmiSequenceErr(8), dlcmiUnknownRpt(9), noErrorSinceReset(10).
frTrapState enables or disables frDLCIStatusChange trap generation (enabled(1)/disabled(2), default disabled). frTrapMaxRate specifies the minimum milliseconds between trap emissions (0..3600000, default 0 meaning no minimum); implementations may drop or queue traps if events occur faster than this rate.
ifHCInOctets and ifHCOutOctets (64-bit octet counters) are only required for Frame Relay interfaces when ifSpeed is at or above 155 Mbits/s, consistent with the high-capacity counter requirements of RFC 1573.
The DLCI textual convention defines the range of Data Link Connection Identifier values as Integer32(0..8388607). The actual usable range varies by interface configuration; normally 0..1023 but may be configured up to 0..2^23.
Security issues for this MIB are entirely covered by the SNMP Security Architecture and have not been expanded within the MIB itself. No additional MIB-specific security provisions are defined.
frCircuitState has three states: invalid(1), active(2), and inactive(3). In the absence of a DLCMI, rows may be created by setting state to active or deleted by setting it to invalid; inactive temporarily disables a circuit. Use of 'invalid' is deprecated in favor of frCircuitRowStatus.
frDlcmiStatus represents the Frame Relay interface state as determined by DLCMI performance: running(1) when initialization is complete, fault(2) when the error threshold is exceeded, and initializing(3) at system startup. If no DLCMI is running, the interface stays in the running state indefinitely.