IF-INVERTED-STACK-MIB

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Organization: IETF Interfaces MIB Working Group

Last Updated: 2000-06-14

Category: Device Management, Network Interfaces

Description: Provides an inverted interface stack table that efficiently maps lower-layer interfaces to their higher-layer interfaces, complementing the standard ifStackTable.

IPNetwork Monitor uses several OIDs from this MIB in network discovery and polling the applicable devices. Start monitoring IF-INVERTED-STACK-MIB with a free 30-day trial of IPNetwork Monitor.

What Is IF-INVERTED-STACK-MIB?

IF-INVERTED-STACK-MIB is a vendor-neutral IETF standards-track MIB that defines the Inverted Stack Table, a companion to the standard ifStackTable from IF-MIB (RFC 2863) that lets a manager efficiently look up which higher-layer interfaces sit above a given lower-layer interface. It exposes a single conceptual table, ifInvStackTable/ifInvStackEntry, containing the status of each inverted (higher-layer, lower-layer) interface stacking relationship, plus the associated conformance groups and compliance statements. Rather than exposing hardware performance counters directly, it supports monitoring the software-level interface stacking topology of a device, useful for confirming that layered interfaces (e.g., a VLAN, tunnel, or PPP interface stacked over a physical port) are correctly bound, which matters when diagnosing why traffic on a logical interface isn't reaching its underlying physical interface. It explicitly depends on and complements the IETF IF-MIB's ifTable and ifStackTable, from which it derives its interface indexing. It's typically deployed alongside IF-MIB on any SNMP-managed network device that has multiple layered/stacked interfaces, such as routers or switches using tunneling, VLAN sub-interfaces, or link aggregation. Engineers implementing or auditing this functionality typically reference the IF-INVERTED-STACK-MIB RFC/standard documentation for the authoritative specification.

IPNetwork Monitor allows you to monitor SNMP objects defined in IF-INVERTED-STACK-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

vendor-neutral, standards-based MIB, not tied to a specific manufacturer
any SNMP-managed router or switch with layered/stacked interfaces

Monitoring Examples

A management station polls ifInvStackTable/ifInvStackEntry and reads ifInvStackStatus (indexed by the higher-layer and lower-layer ifIndex pair) to confirm a given logical interface is correctly stacked over its expected physical or lower-layer interface. If an expected stacking relationship's ifInvStackStatus is absent or shows notInService, it would reveal that a logical interface (e.g., a sub-interface or tunnel) has become unbound from its underlying interface, which could explain a traffic black hole. The ifInvMIBObjects group also carries ifInvConformance/ifInvGroups/ifInvCompliances objects, which are conformance statements rather than runtime data.

What Can Be Monitored

interface stacking relationship status
higher-layer to lower-layer interface binding

Imported Objects

From IF-MIB

ifStackGroup2	OBJECT-GROUP
ifStackHigherLayer	OBJECT-TYPE
ifStackLowerLayer	OBJECT-TYPE

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-SMI

MODULE-IDENTITY
OBJECT-TYPE
mib-2

From SNMPv2-TC

RowStatus

OIDs

OID symbolic	OID numeric	Type	Access	Description
ifInvertedStackMIB	1.3.6.1.2.1.77			The MIB module which provides the Inverted Stack Table for interface sub-layers.
ifInvMIBObjects	1.3.6.1.2.1.77.1
ifInvStackTable	1.3.6.1.2.1.77.1.1		not-accessible	A table containing information on the relationships between the multiple sub-layers of network interfaces. In particular, it contains information on which sub-layers run 'underneath' which other sub-layers, where each sub-layer corresponds to a conceptual row in the ifTable. For example, when the sub-layer with ifIndex value x runs underneath the sub-layer with ifIndex value y, then this table contains: ifInvStackStatus.x.y=active For each ifIndex value, z, which identifies an active interface, there are always at least two instantiated rows in this table associated with z. For one of these rows, z is the value of ifStackHigherLayer; for the other, z is the value of ifStackLowerLayer. (If z is not involved in multiplexing, then these are the only two rows associated with z.) For example, two rows exist even for an interface which has no others stacked on top or below it: ifInvStackStatus.z.0=active ifInvStackStatus.0.z=active This table contains exactly the same number of rows as the ifStackTable, but the rows appear in a different order.
ifInvStackEntry	1.3.6.1.2.1.77.1.1.1		not-accessible	Information on a particular relationship between two sub- layers, specifying that one sub-layer runs underneath the other sub-layer. Each sub-layer corresponds to a conceptual row in the ifTable.
ROW ifInvStackStatus	1.3.6.1.2.1.77.1.1.1.1	RowStatus	read-only	The status of the relationship between two sub-layers. An instance of this object exists for each instance of the ifStackStatus object, and vice versa. For example, if the variable ifStackStatus.H.L exists, then the variable ifInvStackStatus.L.H must also exist, and vice versa. In addition, the two variables always have the same value. However, unlike ifStackStatus, the ifInvStackStatus object is NOT write-able. A network management application wishing to change a relationship between sub-layers H and L cannot do so by modifying the value of ifInvStackStatus.L.H, but must instead modify the value of ifStackStatus.H.L. After the ifStackTable is modified, the change will be reflected in this table.
ifInvConformance	1.3.6.1.2.1.77.1.2
ifInvGroups	1.3.6.1.2.1.77.1.2.1
ifInvStackGroup	1.3.6.1.2.1.77.1.2.1.1			A collection of objects providing inverted information on the layering of MIB-II interfaces.
ifInvCompliances	1.3.6.1.2.1.77.1.2.2
ifInvCompliance	1.3.6.1.2.1.77.1.2.2.1			The compliance statement for SNMP entities which provide inverted information on the layering of network interfaces.

RFC description

Interface sub-layer stack relationship representation showing which layers run underneath others.

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Download IF-INVERTED-STACK-MIB

What Is IF-INVERTED-STACK-MIB?

Supported Devices

Monitoring Examples

What Can Be Monitored

This MIB depends on

Related MIBs

RFC description