Definitions of Managed Objects for SMDS Interfaces using SMIv2
obsoletes
- rfc-1304 — Definitions of Managed Objects for the SIP Interface Type
Extracted elements (26)
RFC 1694 replaces RFC 1304 by defining a MIB module compliant with the SNMPv2 SMI while remaining semantically identical to the RFC 1304 definitions. Many SIP Level 3 objects were deprecated and moved to the MIB-II ifTable because the improved interpretation of the Interfaces Group (RFC 1573) allows them to be represented there without semantic changes; only object identifiers and descriptors changed.
The ipOverSMDS objects are specified as read-only but agents may optionally expose them as read-write to allow authorized management stations to reconfigure Logical IP Subnetwork addressing over SMDS without requiring a separate configuration protocol.
Implementation experience showed that sipL3UnrecognizedIndividualDAs and sipL3UnrecognizedGAs were not supported in practice; both are deprecated in this MIB without replacement.
Six SIP Level 3 objects from RFC 1304 (sipL3ReceivedIndividualDAs, sipL3ReceivedGAs, sipL3SentIndividualDAs, sipL3SentGAs, sipL3Errors, sipL3InvalidSMDSAddressTypes) are deprecated in favor of their ifTable equivalents (ifInUcastPkts, ifInMulticastPkts, ifOutUcastPkts, ifOutMulticastPkts, ifInErrors, ifInUnknownProtos) with no semantic change.
The SIP Level 3 MIB objects apply to all four SMDS access methods: SIP-based (SIP L1/L2/L3 + PLCP), DXI-based, ATM-based (SIP L3 over ATM), and Frame Relay-based (SIP L3 over FR). Lower-layer objects for ATM and Frame Relay are defined in separate MIB modules (RFC 1695, RFC 1604).
For SMDS interfaces: ifType must be set to 31, ifMtu to 9232, ifPromiscuousMode to false(2), ifConnectorPresent to false(2), and ifLinkUpDownTrapEnable to disabled(2). These are fixed values with no configuration flexibility.
The compliance statement (smdsCompliance) mandates sipLevel3Stuff for all SMDS interfaces. sipLevel2Stuff, sipDS1PLCPStuff, sipDS3PLCPStuff, sipIPApplicationsStuff, and sipDxiStuff are each mandatory only for interfaces that run the corresponding protocol (SIP L2, DS1 PLCP, DS3 PLCP, IP-over-SMDS per RFC 1209, or DXI respectively).
ifSpeed for SMDS interfaces is set to peak bandwidth in bits per second from the supporting Level 2 protocol (e.g., 1.17 Mbps for SIP DS1 SNIs; 1.536 Mbps for DXI DS1 DXI-SNIs). ifHighSpeed is the user data rate in Mbps, set to zero when less than 1 Mbps.
sipDS1PLCPSEFSs and sipDS3PLCPSEFSs are Counter32 objects counting Severely Errored Framing Seconds (one-second intervals with one or more SEF events). A SEF event is declared on errors in both A1 and A2 framing octets, or two consecutive invalid/nonsequential Path Overhead Identifier octets.
sipDS1PLCPUASs and sipDS3PLCPUASs are Counter32 objects counting Unavailable Seconds encountered by the DS1 and DS3 PLCPs respectively, as defined by Bellcore TR-TSV-000773.
sipL2BomOrSSMsMIDErrors counts SSM L2PDUs with MID not equal to zero and BOM L2PDUs with MID equal to zero. sipL2EomsMIDErrors counts EOMs with no matching active receive process or with MID equal to zero.
sipL2MidCurrentlyActiveErrors counts received BOM L2PDUs for which a reassembly process for that MID is already active. Accumulated correct segmentation units are discarded, and sipL2ReceivedCounts is still incremented by 1.
sipL2PayloadLengthErrors counts L2 PDUs with invalid payload lengths: SSM L2PDU payload must be 28–44 octets; BOM or COM L2PDU payload must be exactly 44 octets; EOM L2PDU payload must be 4–44 octets.
sipL3PDUErrorTable logs the latest occurrence of 12 syntactic SIP L3PDU error types indexed by interface and error type, storing source address (sipL3PDUErrorSA), destination address (sipL3PDUErrorDA), and a sysUpTime timestamp; a zero timestamp means no valid entry exists.
sipL3PDUErrorType enumerates 12 error types: erroredDAFieldFormat(1), erroredSAFieldFormat(2), invalidBAsizeFieldValue(3), invalidHdrExtLength(4), invalidHdrExtElementLength(5), invalidHdrExtVersionElementPositionLenthOrValue(6), invalidHdrExtCarSelectElementPositionLenghtValueOrFormat(7), hePADError(8), beTagMismatch(9), baSizeFieldNotEqualToLengthField(10), incorrectLength(11), mriTimeout(12).
sipL3VersionSupport is a read-only Integer32 bitmask encoding supported SIP versions: 2^(V-1) is summed for each supported version V. A port supporting versions 1 and 2 yields value 3 (LSB = version 1).
SMDSAddress is a textual convention encoding a 60-bit SMDS address as an OCTET STRING of SIZE 8, with the 4 most significant bits set to 1100 for individual addresses or 1110 for group addresses. Display hint '1h:' is specified.
The DXI group (sipDxiTable) provides per-interface counters: sipDxiCrc (CRC16 or CRC32 type in use), sipDxiOutDiscards (congestion-caused discards), sipDxiInErrors (checksum/size/format errors), sipDxiInAborts (abort flag sequences), sipDxiInTestFrames and sipDxiOutTestFrames (Heart Beat Poll frames), and sipDxiHbpNoAcks (HBP no-acknowledge timeouts).
The IP-over-SMDS group (ipOverSMDSTable) maps IP addresses to SMDS addressing for Logical IP Subnetwork (LIS) support per RFC 1209: ipOverSMDSHA holds the SMDS individual address, ipOverSMDSLISGA the LIS group address for all SNI members, and ipOverSMDSARPReq the SMDS address for ARP requests.
The SIP Level 2 group (sipL2Table) provides per-interface counters: sipL2ReceivedCounts and sipL2SentCounts for unerrored L2PDUs, plus six error counters for HCS/CRC, payload length, sequence number, MID-currently-active, BOM/SSM MID, and EOM MID errors.
The RFC explicitly states that security issues are not discussed in this memo, providing no guidance on access control, authentication, or protection of the SNMP managed objects defined herein.
sipDS1PLCPAlarmState and sipDS3PLCPAlarmState each define three states: noAlarm(1) when no alarms are present; receivedFarEndAlarm(2) triggered by receipt of an incoming Yellow Signal; incomingLOF(3) triggered by a Loss of Frame failure condition as defined in TR-TSV-000773.
SMDS address subfield format: 60 bits encode up to 15 BCD decimal digits, left-most most significant, with unused digit positions padded on the right with ones. For country code 0001, the subsequent 40 bits must be BCD-encoded 10-digit addresses and the remaining 16 LSBs must be all ones.
The Header Extension Carrier Selection element must appear second in the Header Extension with Type=1, Length equal to 4, 6, or 8, and Value containing four BCD-encoded decimal digits specifying the Carrier Identification Code (CIC). A missing, mispositioned, or invalid-CIC element is counted as an error.
The Header Extension Version element (Type=0, Length=3, Value=1) must appear first within the Header Extension; any Type=0 element outside the first three octets is an error. The Header Extension PAD must not be 9 octets long, and if non-zero must follow all elements and begin with at least one all-zero octet.
The SIP L3PDU BAsize field is invalid if its value is less than 32, exceeds 9220 octets without CRC32 or 9224 octets with CRC32, or is not a multiple of 4 octets. The Header Extension Length field must equal 3, and each Header Extension element length must not exceed 12.