Definitions of Managed Objects for the Ethernet-like Interface Types using SMIv2
obsoleted by
- rfc-2358 — Definitions of Managed Objects for the Ethernet-like Interface Types
Extracted elements (28)
A dedicated loopback test (dot3TestLoopBack) was defined to replace the standard loopback test from RFC 1229, as the new test exercises internal MAC chip memory and data paths rather than relying on the old RFC 1229 definition.
Attributes already represented in MIB-II or the Generic Interface Extensions MIB (octet counts, frame counts, promiscuous status, MAC address, multicast info) are not redundantly defined in this MIB to avoid duplication.
dot3StatsEtherChipSet was added to replace ifExtnsChipSet, which was removed as part of the Interface MIB Evolution effort; it allows a manager to correlate statistics with a specific chip and account for known chip anomalies.
IEEE 802.3 Layer Management conventions require that received frames with multiple error conditions be counted exclusively according to the first error status presented to the LLC, preventing double-counting across alignment, FCS, and frameTooLong counters.
ifPhysAddress stores the IEEE 802.3 address in canonical bit order with the Group Bit as the low-order bit of the first octet (0x01 set for multicast); if the address cannot be determined, a zero-length octet string is returned.
Implementation of TDR and loopback tests is not required because many common interface chips do not support one or both; they are provided as a convenience for a common invocation method where supported.
Chipset OID definitions under dot3ChipSets (dot3 8) are retained for backward compatibility with pre-RFC 1573 systems; RFC 1573 removes the ifExtnsChipSet object which they previously supported.
The ifRcvAddressTable includes all IEEE 802.3 unicast, multicast, and broadcast addresses for locally-consumed packets; for bridge interfaces, unicast addresses accepted only for forwarding are excluded.
This MIB applies to interfaces with ifType values ethernet-csmacd(6), iso88023-csmacd(7), and starLan(11); all three map to EtherLike-MIB in the same manner with no implementation differences.
This MIB does not provide for sublayer layering; virtual circuits are not applicable. RFC 1573 compliance areas (layering, virtual circuits, ifTestTable, ifRcvAddressTable, ifPhysAddress, ifType) are each addressed individually.
When used with the pre-RFC 1573 interface group (RFC 1213), the relationship between an Ethernet-like interface and an ifIndex is one-to-one; the same ifIndex value directly identifies corresponding dot3Stats instances.
Standard MIBs do not include objects for returning TDR test results; any needed result objects MUST be provided in the vendor-specific MIB.
The etherStatsGroup is MANDATORY for SNMPv2 entities with Ethernet-like interfaces; the etherCollisionTableGroup is optional but its implementation in systems with the necessary metering is highly recommended.
dot3CollTable (dot3 5) provides a collision histogram indexed by ifIndex and dot3CollCount (1..16); dot3CollFrequencies (Counter32) counts MAC frames experiencing exactly N collisions before transmission.
dot3ErrorInitError (dot3Errors 1) and dot3ErrorLoopbackError (dot3Errors 2) are OBJECT IDENTIFIERs used as values for ifTestCode to provide diagnostic detail when a test sets ifTestResult to failed(7).
dot3StatsAlignmentErrors (Counter32) counts frames received that are not an integral number of octets in length and fail the FCS check; incremented when alignmentError status is returned by the MAC service to the LLC.
dot3StatsEtherChipSet (OBJECT IDENTIFIER) identifies the MAC chipset used to realize the interface; implementors should identify the MAC chip or the chip gathering transmit/receive statistics.
dot3StatsFCSErrors (Counter32) counts frames received that are an integral number of octets in length but fail the FCS check; incremented when frameCheckError status is returned by MAC service.
dot3StatsInternalMacTransmitErrors (Counter32) counts frames where transmission fails due to internal MAC sublayer errors not covered by late collisions, excessive collisions, or carrier sense errors; meaning is implementation-specific.
dot3StatsLateCollisions (Counter32) counts collisions detected later than 512 bit-times (51.2 microseconds on 10 Mbit/s) into a packet transmission; late collisions are also counted in generic collision statistics.
dot3StatsMultipleCollisionFrames (Counter32) counts successfully transmitted frames inhibited by more than one collision; mutually exclusive with dot3StatsSingleCollisionFrames.
dot3StatsSingleCollisionFrames (Counter32) counts successfully transmitted frames inhibited by exactly one collision; frames counted here are also counted in ifOutUcastPkts/ifOutMulticastPkts/ifOutBroadcastPkts.
dot3StatsSQETestErrors (Counter32) counts SQE TEST ERROR messages generated by the PLS sublayer, as defined in ANSI/IEEE 802.3-1985 section 7.2.2.2.4.
dot3StatsTable (dot3 2) is a table of statistics for Ethernet-like interfaces, indexed by dot3StatsIndex which is identical to the corresponding ifIndex value.
dot3TestLoopBack (dot3Tests 2) is a full-duplex loopback test of MAC chip memory, data paths, and logic; can only execute when the interface is offline and the MAC chip should remain offline after test completion.
dot3TestTdr (dot3Tests 1) is the Time-Domain Reflectometry test; its result is the time interval in 10 MHz ticks (100 ns units) between TDR transmission start and subsequent collision detection or carrier deassertion.
The EtherLike-MIB module is assigned OID mib-2 35 (etherMIB MODULE-IDENTITY). It defines managed objects for Ethernet-like network interfaces and updates RFC 1398.
RFC 1650 explicitly states that security issues are not discussed in this memo; no access control, authentication, or confidentiality requirements are specified for the MIB objects defined here.