Definitions of Managed Objects for Frame Relay Service Level Definitions
updated by
- rfc-9141 — Updating References to the IETF FTP Service
Extracted elements (26)
Both 32-bit (Counter32) and 64-bit (Counter64 / CounterBasedGauge64) variants of all frame and octet counters are provided because Counter64 cannot be translated to SMIv1. Devices capable of SMIv2 should support the high-capacity variants; the MIB notes that some machine-readable information is lost in SMIv1 translation but semantics are preserved.
Four reference points are required to fully characterize bidirectional PVC performance: transmit and receive reference points at each end. A single device may aggregate both directions only if it has access to remote-device information; otherwise two devices must be monitored. Six valid two-device and single-device reference point combination models are defined.
Scheduled outage time (ExcludedTime) required for Virtual Connection Availability and Mean Time Between Service Outages calculations is deliberately omitted from the MIB. It often relates to specific dates and moving maintenance windows that devices cannot track reliably, so it is maintained by network management software instead.
Three data collection methods are supported — remote polling of free-running counters in frsldPvcDataTable, built-in sampling via frsldPvcSampleTable/frsldSmplCtrlTable, and user history (RFC 2021) — to accommodate devices that support only a subset. This avoids mandating a single collection architecture.
The IF-MIB (RFC 2233/2863) is required for ifIndex information. The Frame Relay DTE MIB (RFC 2115) and Frame Relay Network Services MIB (RFC 2954) are not required but provide DLCI information. DLCI state must be correlated with frCircuitState/frPVCEndptRcvdSigStatus from those MIBs to determine PVC readiness.
The MIB applies to frame relay interfaces with ifType frameRelay(32) or frameRelayService(44). Proprietary reference points (otherTxLocalRP, otherRxLocalRP, etc.) MAY exist anywhere in the network not covered by the standard reference points; their meaning is defined by the device manufacturer.
This MIB is compliant to SMIv2 but can be translated to SMIv1 with loss of Counter64 objects and some machine-readable information converted to text. The translated MIB must be semantically equivalent except where objects are omitted because no translation is possible.
A row in frsldPvcCtrlTable MUST exist in order for a row to exist in any other table in this MIB module. The rows added to this table MUST have a valid ifIndex and an ifType related to frame relay, and the reference points referred to by frsldPvcCtrlTransmitRP and frsldPvcCtrlReceiveRP MUST be supported.
Each time a discontinuity in the counters occurs, frsldPvcCtrlLastPurgeTime MUST be set to the value of sysUpTime. This object serves as the discontinuity timer for all counters in frsldPvcDataTable.
If any one of the necessary reference points does not exist in the combination of the two monitoring devices, it is not possible to monitor the FRF.13-defined SLA between the two reference points on that PVC.
If frsldPvcCtrlDelayType is roundTrip, the manager SHOULD divide the value of DelayAvg (frsldPvcSmplDelayAvg) by two to obtain the frame transfer delay. If frsldPvcCtrlDelayType is oneWay, the value SHOULD be used as-is.
It is recommended that all statistics for a single PVC be collected in a single PDU when using remote polling. The grouping of information for bidirectional SLA calculation SHOULD be from ingress to egress in each flow direction.
The data in frsldPvcCtrlTable and frsldSmplCtrlTable SHOULD persist through power cycles, though rows may be reprovisioned as notReady(3) if the underlying DLCI does not persist. The data collected in frsldPvcDataTable and frsldPvcSampleTable SHOULD NOT persist through power cycles since the reference TimeStamp is no longer valid.
The value of frsldPvcCtrlStatus MUST be active(1) before frsldSmplCtrlStatus can transition to active(1). If frsldPvcCtrlStatus becomes anything other than active(1) while frsldSmplCtrlStatus is not active(1), frsldSmplCtrlStatus SHOULD be set to notReady(3).
When frsldPvcCtrlStatus is set to destroy(6), all associated sample control, sample, and data table rows MUST also be destroyed. Similarly, when frsldSmplCtrlStatus is set to destroy(6), all associated sample rows will also be destroyed.
When the DLCI does not exist and frsldPvcCtrlStatus is not active(1), the status SHOULD report notReady(3). If frsldPvcCtrlDeleteOnPurge is all(3), all associated rows SHOULD be deleted after the purge interval.
frsldCapabilities group provides three capability-discovery objects: frsldPvcCtrlWriteCaps (writable objects in PVC control table), frsldSmplCtrlWriteCaps (writable objects in sample control table), and frsldRPCaps (bitmask of reference points the device supports). Four memory-management objects (frsldMaxPvcCtrls, frsldNumPvcCtrls, frsldMaxSmplCtrls, frsldNumSmplCtrls) control allocation limits.
frsldPvcCtrlPurge (0..172800 seconds, default 0) defines the delay after a DLCI disappears before automatic purge of sample history and reset of data counters to zero. frsldPvcCtrlDeleteOnPurge determines whether none(1), sampleControls(2), or all(3) associated rows are deleted on purge.
frsldPvcCtrlTable is the central control table indexed by {ifIndex, frsldPvcCtrlDlci, frsldPvcCtrlTransmitRP, frsldPvcCtrlReceiveRP}. It holds per-PVC configuration including the measurement domain (transmit and receive reference points), delay probe parameters (packet frequency, frame size, delay type, timeout), and purge controls.
frsldPvcDataTable holds accumulated free-running counters per PVC: frames and octets offered/delivered within CIR and in excess of CIR (both 32-bit Counter32 and 64-bit Counter64 variants), plus UnavailableTime (TimeTicks) and Unavailables (Counter32). It shares the same index as frsldPvcCtrlTable.
frsldPvcSampleTable contains historical samples of delay (min, max, avg in Gauge32), delivery ratios, and availability per sample bucket, indexed by {ifIndex, DLCI, TransmitRP, ReceiveRP, frsldSmplCtrlIdx, frsldPvcSmplIdx}. Sample entries include start and end timestamps to detect collection period discontinuities.
frsldSmplCtrlTable is an optional table controlling the sampling of data, indexed additionally by frsldSmplCtrlIdx (1..256). Key objects are frsldSmplCtrlColPeriod (collection interval in seconds), frsldSmplCtrlBuckets (desired bucket count), and frsldSmplCtrlBucketsGranted (actual allocated buckets).
FrsldTxRP is a textual convention enumerating 12 transmit reference points: srcLocalRP(1), ingTxLocalRP(2), tpTxLocalRP(3), eqiTxLocalRP(4), eqoTxLocalRP(5), otherTxLocalRP(6), and the remote variants (7–12). FrsldRxRP mirrors this for receive-side reference points. Together they define the measurement domain.
The FRSLD-MIB module is registered under the OID { mib-2 95 }, assigned by IANA as part of the mib-2 subtree. This is the top-level OID for the Frame Relay Service Level Definitions MIB.
Section 10 addresses security considerations for the FRSLD-MIB. Write access to frsldPvcCtrlTable and frsldSmplCtrlTable objects could allow an unauthorized user to disrupt service level monitoring, alter measurement reference points, or trigger purges of historical data. Implementations should use SNMPv3 with authentication and privacy to protect management traffic and restrict write access to authorized managers.
Upon setting frsldPvcCtrlStatus to active(1), the row enters one of three states: (1) DLCI known and active — data collection proceeds; (2) DLCI not yet created — row stays notReady(3) and no data/sample rows are created; (3) DLCI removed — behavior governed by frsldPvcCtrlDeleteOnPurge. Transition to destroy(6) cascades deletion to all dependent rows.