OSPF Version 2 Management Information Base
obsoleted by
- rfc-1253 — OSPF Version 2 Management Information Base
obsoletes
- rfc-1248 — OSPF Version 2 Management Information Base
Extracted elements (27)
DEFVAL clauses are included for most objects to support conceptual row creation via SNMP Set-Request; management stations should include all read-write objects when creating a row, while agents need only require those objects for which no default can be intuited. Counter and Gauge objects lack DEFVAL because they are zeroed on row creation.
In the absence of a standard SNMP security architecture it is acceptable for implementations to treat the numerous read-write objects in this MIB as read-only and provide an alternative (non-SNMP) interface for modification, because the MIB is designed for SNMP management rather than mere monitoring.
Interface metrics are placed in a separate ospfIfMetricTable rather than inline in ospfIfTable to simplify handling of multiple TOS values and to provide flexibility if the IP TOS definition changes in the future.
The default TOS 0 metric is defined as 10^8 / ifSpeed, yielding values such as 1 for ≥100 Mbps, 10 for Ethernet, 65 for T1, and 10416 for 9.6 Kbps links. This provides unambiguous and proportional cost values derived automatically from interface speed.
The simplest OSPF process configuration requires only a single SET of ospfAdminStat := enabled, after which the router automatically discovers all IP interfaces, assigns them to backbone area 0.0.0.0, derives TOS 0 metrics from ifSpeed, and uses default timer values (Hello 10s, Dead 40s, Retransmit 5s, Transit Delay 1s, Poll 120s).
For addressless interfaces (no IP address assigned), ospfAddressLessIf and related index objects take the value of the corresponding ifIndex from the Internet Standard MIB, while interfaces with IP addresses use the value 0; this scheme unifies instancing across both interface types.
ospfVirtIfAreaID, the transit area for a virtual link, must not be 0.0.0.0 (the backbone); virtual links always traverse a non-backbone transit area to connect a disconnected area back to the backbone.
ospfIfHelloInterval must be the same for all routers attached to a common network; ospfIfRtrDeadInterval must likewise be the same for all routers on a common network.
ospfVirtIfHelloInterval and ospfVirtIfRtrDeadInterval must be the same for the virtual neighbor on both ends of the virtual link.
ospfExternLSACksumSum is a 32-bit unsigned sum of LS checksums for all AS external (type 5) LSAs in the link-state database; ospfAreaLSACksumSum is the analogous sum per area excluding type-5 LSAs. Both sums can detect database changes and compare databases between two routers.
ospfIfAuthKey is an OCTET STRING storing the simple-password authentication key for an interface; when the key is shorter than 8 octets it is left-adjusted and zero-filled to 8 octets. When read, this object always returns an octet string of length zero to protect the key.
ospfLsdbSequence is a signed 32-bit integer starting at 0x80000001 and incrementing to 0x7FFFFFFF, used to detect old and duplicate LSAs; larger values indicate more recent advertisements. ospfLsdbChecksum stores the Fletcher checksum of the complete LSA excluding the age field, allowing age to be incremented without updating the checksum.
Textual conventions introduced in this MIB include AreaID and RouterID (both IpAddress format), Metric (INTEGER 1..0xFFFF), BigMetric (INTEGER 1..0xFFFFFF), TruthValue, Status (enabled/disabled), Validation (valid/invalid), PositiveInteger, HelloRange (1..0xFFFF), UpToMaxAge (1..3600), InterfaceIndex, DesignatedRouterPriority (0..0xFF), and TOSType (0..31).
The OSPF MIB General Variables group (ospfGeneralGroup, OID ospf 1) contains router-wide parameters including ospfRouterId (32-bit router identifier), ospfAdminStat (enabled/disabled), ospfVersionNumber (read-only, value 2), ospfAreaBdrRtrStatus, ospfASBdrRtrStatus, ospfExternLSACount, ospfExternLSACksumSum, ospfTOSSupport, ospfOriginateNewLSAs, and ospfRxNewLSAs.
The ospfAreaRangeTable (OID ospf 5) stores IP address range summaries configured to be propagated from an area to reduce routing information exported beyond its borders, indexed by ospfAreaRangeAreaID and ospfAreaRangeNet. Each entry pairs an IP network address with a subnet mask.
The ospfAreaTable (OID ospf 2) describes configured parameters and cumulative statistics for each OSPF area the router is attached to, indexed by ospfAreaId. Fields include ospfAuthType (0=none, 1=simplePassword), ospfImportASExtern, ospfSpfRuns (Dijkstra SPF calculation count), ospfAreaBdrRtrCount, ospfASBdrRtrCount, ospfAreaLSACount, and ospfAreaLSACksumSum.
The ospfHostTable (OID ospf 6) lists directly attached hosts and the metrics (per TOS) to advertise for them as host routes, indexed by ospfHostIpAddress and ospfHostTOS.
The ospfIfMetricTable (OID ospf 8) stores TOS-specific metrics for non-virtual interfaces, indexed by ospfIfMetricIpAddress, ospfIfMetricAddressLessIf, and ospfIfMetricTOS. The default TOS 0 metric is computed as 10^8 / ifSpeed; the value 0xFFFF means 'no route via this TOS'.
The ospfIfTable (OID ospf 7) augments the ifTable with OSPF-specific interface parameters including ospfIfType (broadcast/nbma/pointToPoint), ospfIfRtrPriority, ospfIfTransitDelay, ospfIfRetransInterval, ospfIfHelloInterval, ospfIfRtrDeadInterval, ospfIfPollInterval, ospfIfState, ospfIfDesignatedRouter, ospfIfBackupDesignatedRouter, ospfIfEvents, and ospfIfAuthKey.
The ospfLsdbTable (OID ospf 4) represents the OSPF Link State Database, indexed by ospfLsdbAreaId, ospfLsdbType, ospfLsdbLSID, and ospfLsdbRouterId. LSA types are routerLink(1), networkLink(2), summaryLink(3), asSummaryLink(4), and asExternalLink(5). The table is intended primarily for network debugging.
The ospfNbrTable (OID ospf 10) describes non-virtual OSPF neighbors, indexed by ospfNbrIpAddr and ospfNbrAddressLessIndex. Fields include ospfNbrRtrId, ospfNbrOptions (bit 0=external LSA support, bit 1=TOS metric support), ospfNbrPriority, ospfNbrState, ospfNbrEvents, ospfNbrLSRetransQLen, and ospfNBMANbrStatus.
The ospfStubAreaTable (OID ospf 3) describes the default metrics that an Area Border Router will advertise into a stub area, indexed by ospfStubAreaID and ospfStubTOS. Fields are ospfStubMetric (BigMetric) and ospfStubStatus (Validation).
The ospfVirtIfTable (OID ospf 9) describes OSPF virtual links, indexed by ospfVirtIfAreaID (the transit area, which must not be 0.0.0.0) and ospfVirtIfNeighbor (the far-end RouterID). Fields mirror the physical interface table but ospfVirtIfState is limited to down(1) and pointToPoint(4).
The ospfVirtNbrTable (OID ospf 11) is a read-only table of virtual neighbor information derived from the virtual interface configuration, indexed by ospfVirtNbrArea and ospfVirtNbrRtrId. Fields include ospfVirtNbrIpAddr, ospfVirtNbrOptions, ospfVirtNbrState, ospfVirtNbrEvents, and ospfVirtNbrLSRetransQLen.
The Security Considerations section explicitly states that security issues are not discussed in this memo, despite the MIB containing read-write objects that can modify OSPF configuration and ospfIfAuthKey objects that store plaintext authentication keys.
ospfIfState defines seven OSPF interface states: down(1), loopback(2), waiting(3), pointToPoint(4), designatedRouter(5), backupDesignatedRouter(6), and otherDesignatedRouter(7). The default state is down.
ospfNbrState and ospfVirtNbrState both define eight neighbor relationship states: down(1), attempt(2), init(3), twoWay(4), exchangeStart(5), exchange(6), loading(7), and full(8), matching OSPF Version 2 Section 10.1.