Management Information Base for Frame Relay DTEs
obsoleted by
- rfc-2115 — Management Information Base for Frame Relay DTEs Using SMIv2
Extracted elements (27)
Frame Relay is modeled as a multi-access media rather than a group of point-to-point connections. This treats the physical connection as a single interface with many virtual destinations, enabling a network manager to group all virtual circuits with their corresponding physical connection for simpler diagnostics.
Textual conventions Index (range 1..ifNumber) and DLCI (range 0..DLCINumber) are introduced purely for readability and have no effect on syntax or semantics of managed objects. Objects defined using these types are always encoded as their underlying primitive types, requiring no changes to SMI or SNMP.
Each ifEntry in the standard MIB Interface Table with an ifType of Frame Relay represents a Q.922 interface. Zero or more virtual circuit entries in frCircuitTable are layered onto this ifEntry and are correlated via the Index textual convention (range 1..ifNumber).
frErrData MUST contain at minimum the Q.922 Address of the erroneous frame or as much as was delivered; it is desirable to include all information up to the PDU.
If a SET on frDlcmiMaxSupportedVCs specifies a value less than zero or higher than the agent's maximal capability, the agent SHOULD respond with badValue.
frCircuitCommittedBurst (default 0, meaning no commitment) indicates the maximum data in bits the network agrees to transfer under normal conditions during the measurement interval, per T1.617-1991 Section 6.5.19.
frCircuitCreationTime and frCircuitLastTimeChange are TimeTicks objects recording the sysUpTime at which the virtual circuit was created (via DLCMI or SetRequest) and at which its state last changed, respectively.
frCircuitExcessBurst indicates the maximum uncommitted data bits the network will attempt to deliver over the measurement interval. If not configured at entry creation, it defaults to the value of ifSpeed.
frCircuitReceivedBECNs is a Counter of frames received with the Backward Explicit Congestion Notification bit set since the virtual circuit was created, as defined in T1.618-1991 Section 3.3.4.
frCircuitReceivedFECNs is a Counter of frames received from the network with the Forward Explicit Congestion Notification bit set since the virtual circuit was created, as defined in T1.618-1991 Section 3.3.3.
frCircuitTable (frame-relay 2) contains information about individual DLCIs and their corresponding virtual circuits, indexed by frCircuitIfIndex and frCircuitDlci. Each entry tracks state, congestion counters, traffic statistics, timestamps, and traffic-contract parameters.
frCircuitThroughput (default 0, meaning no commitment) is the average Frame Relay Information Field bits per second across the UNI. The measurement interval T is derived as frCircuitCommittedBurst/frCircuitThroughput when both are non-zero, or frCircuitExcessBurst/ifSpeed when both are zero.
frDLCIStatusChange is an enterprise trap (enterprise frame-relay, trap number 1) carrying frCircuitIfIndex, frCircuitDlci, and frCircuitState. It fires when a virtual circuit is created, invalidated, or transitions between active and inactive states, serving as the Frame Relay analogue to the SNMP Link Up/Link Down traps.
frDlcmiAddress specifies the Q.922 address format in use: q921(1) with 13-bit DLCI, q922March90(2) with 11-bit DLCI, q922November90(3) with 10-bit DLCI, or q922(4) for the final standard. This determines how DLCIs are encoded on the interface.
frDlcmiAddressLen indicates the address field length in octets: two-octets(2), three-octets(3), or four-octets(4). For Q.922 format, the length covers the entire address including the control portion.
frDlcmiErrorThreshold (range 1..10, default 3) is the maximum number of unanswered Status Enquiries the equipment accepts before declaring the interface down, corresponding to ANSI T1.617-1991 Counter N392.
frDlcmiFullEnquiryInterval (range 1..255, default 6) is the number of status enquiry intervals that must pass before a full status enquiry message is issued, corresponding to ANSI T1.617-1991 Counter N391.
frDlcmiMonitoredEvents (range 1..10, default 4) is the number of status polling intervals over which the error threshold is counted. If ErrorThreshold errors occur within MonitoredEvents intervals, the interface is marked down; corresponds to ANSI T1.617-1991 Counter N393.
frDlcmiMulticast indicates whether the Frame Relay interface uses a multicast service: nonBroadcast(1) or broadcast(2).
frDlcmiPollingInterval (range 5..30 seconds, default 10) is the interval between successive status enquiry messages, corresponding to ANSI T1.617-1991 Timer T391.
frDlcmiState selects the active DLCI Management scheme on a Frame Relay interface: noLmiConfigured(1), lmiRev1(2), ansiT1-617-D(3), or ansiT1-617-B(4). The chosen scheme also implies which DLCI is used for management traffic.
frDlcmiTable (frame-relay 1) contains per-interface parameters for the Data Link Connection Management Interface, indexed by frDlcmiIfIndex. It configures LMI scheme, address format, polling timers, error thresholds, maximum VCs, and multicast capability.
frErrTable (frame-relay 3) contains per-interface error information, indexed by frErrIfIndex. Each entry records the type of the last error, up to a full copy of the erroneous frame, and the sysUpTime at detection.
frErrType enumerates the last error seen on a Frame Relay interface: unknownError(1), receiveShort(2), receiveLong(3), illegalDLCI(4), unknownDLCI(5), dlcmiProtoErr(6), dlcmiUnknownIE(7), dlcmiSequenceErr(8), dlcmiUnknownRpt(9), noErrorSinceReset(10).
frTrapState (frame-relay-globals 1, default disabled) is a read-write object that controls whether the system generates the frDLCIStatusChange trap. Values are enabled(1) and disabled(2).
Security issues are explicitly not discussed in this memo. The MIB includes read-write objects (DLCMI configuration, circuit state, traffic contract parameters) accessible via SNMP, but no access-control or authentication guidance is provided.
frCircuitState defines three states for a virtual circuit: active(2), inactive(3), and invalid(1). In the absence of a DLCMI, rows may be created by setting state to active and deleted by setting state to invalid; setting inactive temporarily disables a circuit without removing its row.