IEEE8021-SPANNING-TREE-MIB

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Organization: IEEE 802.1 Working Group

Last Updated: 2018-06-28

Category: Protocol: STP, Standard: IEEE 802, Technology: Switching/L2, VLAN and Bridging

Description: IEEE 802.1 MIB for Spanning Tree Protocol (802.1D) managing bridge topology, port states, and STP parameters.

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What Is IEEE8021-SPANNING-TREE-MIB?

This is a vendor-neutral IEEE 802.1D/802.1Q standards MIB for Spanning Tree Protocol, derived from the IETF BRIDGE-MIB (RFC 4188), used to manage classic per-bridge spanning tree state on Ethernet switches. It exposes bridge protocol specification, priority, designated root, root cost/port, timer settings (max age, hello time), and topology-change counters/timestamps. Its monitoring value is primarily network stability: a growing topology-change counter combined with a recent time-since-topology-change value strongly suggests a flapping link, a loop, or a misconfigured bridge causing repeated STP reconvergence and possible packet loss. It explicitly derives from the IETF BRIDGE-MIB and is used together with the related IEEE8021-MSTP-MIB when a bridge runs MSTP rather than plain STP. It is typically deployed on any enterprise/campus/data-center Ethernet switch that participates in spanning tree loop prevention. Engineers implementing or auditing this functionality typically reference the IEEE8021-SPANNING-TREE-MIB RFC/standard documentation for the authoritative specification.

IPNetwork Monitor allows you to monitor SNMP objects defined in IEEE8021-SPANNING-TREE-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, IEEE 802.1D/802.1Q standards-based MIB, not tied to a specific manufacturer
Ethernet bridge or switch running Spanning Tree Protocol

Monitoring Examples

An operator walks ieee8021SpanningTreeTable (keyed by ieee8021SpanningTreeComponentId) to read ieee8021SpanningTreeDesignatedRoot and ieee8021SpanningTreeRootCost, confirming the expected switch is the STP root and that root cost/root port match the intended topology. A rising ieee8021SpanningTreeTopChanges value paired with a small ieee8021SpanningTreeTimeSinceTopologyChange indicates recent, possibly repeated, reconvergence events; checking ieee8021SpanningTreeMaxAge and ieee8021SpanningTreeHelloTime confirms whether the bridge's timers match the network's configured STP parameters, ruling out a timer mismatch as the cause.

What Can Be Monitored

designated root bridge and root cost/port
topology change count and recency
STP timers (max age, hello time)
protocol specification/version
bridge priority

Imported Objects

From BRIDGE-MIB

BridgeId
Timeout

From IEEE8021-TC-MIB

IEEE8021BridgePortNumber
IEEE8021PbbComponentIdentifier
ieee802dot1mibs	OBJECT-IDENTITY

From SNMPv2-CONF

MODULE-COMPLIANCE
NOTIFICATION-GROUP
OBJECT-GROUP

From SNMPv2-SMI

Counter64
Integer32
MODULE-IDENTITY
NOTIFICATION-TYPE
OBJECT-TYPE
TimeTicks

From SNMPv2-TC

TruthValue

How to Use in IPNetwork Monitor

Example using ieee8021SpanningTreeTopChanges OID:

Select a device implementing IEEE8021-SPANNING-TREE-MIB as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type ieee8021SpanningTreeTopChanges into the Find box to locate it in the OID tree, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. The total number of topology changes detected by this Bridge since the management entity was last reset or initialized. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a Counter64-type OID, Value bounds is the most useful condition here — trigger an alert if the counter increases sharply between polls relative to its normal baseline (in topology changes), since an unexpected spike often reflects a real change in traffic or activity. Click Finish to create the monitor; you can adjust any parameter later.

OIDs

OID symbolic	OID numeric	Type	Access	Description
ieee8021SpanningTreeMib	1.3.111.2.802.1.1.3			The Spanning-Tree MIB module for managing devices that support IEEE 802.1Q. This MIB module is derived from the IETF BRIDGE-MIB, RFC 4188. Unless otherwise indicated, the references in this MIB module are to IEEE Std 802.1Q. Copyright (C) IEEE (2014). This version of this MIB module is part of IEEE Std 802.1Q; see the draft itself for full legal notices.
ieee8021SpanningTreeNotifications	1.3.111.2.802.1.1.3.0
NTF ieee8021SpanningTreeNewRoot	1.3.111.2.802.1.1.3.0.1			The ieee8021SpanningTreeNewRoot notification indicates that the sending agent has become the new root of the Spanning Tree; the notification is sent by a Bridge soon after its election as the new root, e.g., upon expiration of the Topology Change Timer, immediately subsequent to its election.
NTF ieee8021SpanningTreeTopologyChange	1.3.111.2.802.1.1.3.0.2			A ieee8021SpanningTreeTopologyChange notification is sent by a Bridge when any of its configured ports transitions from the Learning state to the Forwarding state, or from the Forwarding state to the Blocking state. The notification is not sent if a ieee8021SpanningTreeNewRoot notification is sent for the same transition.
ieee8021SpanningTreeObjects	1.3.111.2.802.1.1.3.1
ieee8021SpanningTreeTable	1.3.111.2.802.1.1.3.1.1		not-accessible	A table that contains information related to STP about every Bridge.
ieee8021SpanningTreeEntry	1.3.111.2.802.1.1.3.1.1.1		not-accessible	A list of objects containing information for each Bridge about the Spanning Tree Protocol for that Bridge.
OID ieee8021SpanningTreeComponentId	1.3.111.2.802.1.1.3.1.1.1.1	IEEE8021PbbComponentIdentifier	not-accessible	The component identifier is used to distinguish between the multiple virtual Bridge instances within a PBB. In simple situations where there is only a single component the default value is 1.
INT ieee8021SpanningTreeProtocolSpecification	1.3.111.2.802.1.1.3.1.1.1.2	INTEGER	read-only	An indication of what version of the Spanning Tree Protocol is being run. The value 'decLb100(2)' indicates the DEC LANbridge 100 Spanning Tree protocol. IEEE 802.1D implementations will return 'ieee8021d(3)'. New enumerated values may be added in the future to the definition of this object to reflect future versions of the IEEE Spanning Tree protocol.
I32 ieee8021SpanningTreePriority	1.3.111.2.802.1.1.3.1.1.1.3	Integer32	read-write	The value of the write-able portion of the Bridge ID (i.e., the first two octets of the (8 octet long) Bridge ID). The other (last) 6 octets of the Bridge ID are given by the value of ieee8021BridgeBaseBridgeAddress. On Bridges supporting IEEE 802.1t or IEEE 802.1w, permissible values are 0-61440, in steps of 4096. The value of this object MUST be retained across reinitializations of the management system.
TIK ieee8021SpanningTreeTimeSinceTopologyChange	1.3.111.2.802.1.1.3.1.1.1.4	TimeTicks	read-only	The time (in hundredths of a second) since the last time a topology change was detected by the Bridge entity. For RSTP, this reports the time since the tcWhile timer for any port on this Bridge was nonzero.
C64 ieee8021SpanningTreeTopChangesEx	1.3.111.2.802.1.1.3.1.1.1.5	Counter64	read-only	The total number of topology changes detected by this Bridge since the management entity was last reset or initialized. Discontinuities in the value of the counter can occur at re-initialization of the management system.
BRI ieee8021SpanningTreeDesignatedRoot	1.3.111.2.802.1.1.3.1.1.1.6	BridgeId	read-only	The Bridge identifier of the root of the spanning tree, as determined by the Spanning Tree Protocol, as executed by this node. This value is used as the Root Identifier parameter in all Configuration Bridge PDUs originated by this node.
I32 ieee8021SpanningTreeRootCost	1.3.111.2.802.1.1.3.1.1.1.7	Integer32	read-only	The cost of the path to the root as seen from this Bridge.
IEE ieee8021SpanningTreeRootPort	1.3.111.2.802.1.1.3.1.1.1.8	IEEE8021BridgePortNumber	read-only	The port number of the port that offers the lowest cost path from this Bridge to the root Bridge.
TIM ieee8021SpanningTreeMaxAge	1.3.111.2.802.1.1.3.1.1.1.9	Timeout	read-only	The maximum age of Spanning Tree Protocol information learned from the network on any port before it is discarded, in units of hundredths of a second. This is the actual value that this Bridge is currently using.
TIM ieee8021SpanningTreeHelloTime	1.3.111.2.802.1.1.3.1.1.1.10	Timeout	read-only	The amount of time between the transmission of Configuration Bridge PDUs by this node on any port when it is the root of the spanning tree, or trying to become so, in units of hundredths of a second. This is the actual value that this Bridge is currently using.
I32 ieee8021SpanningTreeHoldTime	1.3.111.2.802.1.1.3.1.1.1.11	Integer32	read-only	This time value determines the interval length during which no more than two Configuration Bridge PDUs shall be transmitted by this node, in units of hundredths of a second.
TIM ieee8021SpanningTreeForwardDelay	1.3.111.2.802.1.1.3.1.1.1.12	Timeout	read-only	This time value, measured in units of hundredths of a second, controls how fast a port changes its spanning state when moving towards the Forwarding state. The value determines how long the port stays in each of the Listening and Learning states, which precede the Forwarding state. This value is also used when a topology change has been detected and is underway, to age all dynamic entries in the Filtering Database. [Note that this value is the one that this Bridge is currently using, in contrast to ieee8021SpanningTreeBridgeForwardDelay, which is the value that this Bridge and all others would start using if/when this Bridge were to become the root.]
TIM ieee8021SpanningTreeBridgeMaxAge	1.3.111.2.802.1.1.3.1.1.1.13	Timeout	read-write	The value that all Bridges use for MaxAge when this Bridge is acting as the root. Note that IEEE Std 802.1D-1998 specifies that the range for this parameter is related to the value of ieee8021SpanningTreeBridgeHelloTime. The granularity of this timer is specified by IEEE Std 802.1D-1998 to be 1 second. An agent may return an SNMP badValue error (or its equivalent if another protocol is used) if a set is attempted to a value that is not a whole number of seconds. The value of this object MUST be retained across reinitializations of the management system.
TIM ieee8021SpanningTreeBridgeHelloTime	1.3.111.2.802.1.1.3.1.1.1.14	Timeout	read-write	The value that all Bridges use for HelloTime when this Bridge is acting as the root. The granularity of this timer is specified by IEEE Std 802.1D-1998 to be 1 second. An agent may return an SNMP badValue error (or its equivalent if another protocol is used) if a set is attempted to a value that is not a whole number of seconds. The value of this object MUST be retained across reinitializations of the management system.
TIM ieee8021SpanningTreeBridgeForwardDelay	1.3.111.2.802.1.1.3.1.1.1.15	Timeout	read-write	The value that all Bridges use for ForwardDelay when this Bridge is acting as the root. Note that IEEE Std 802.1D-1998 specifies that the range for this parameter is related to the value of ieee8021SpanningTreeBridgeMaxAge. The granularity of this timer is specified by IEEE Std 802.1D-1998 to be 1 second. An agent may return an SNMP badValue error (or its equivalent if another protocol is used) if a set is attempted to a value that is not a whole number of seconds. The value of this object MUST be retained across reinitializations of the management system.
INT ieee8021SpanningTreeVersion	1.3.111.2.802.1.1.3.1.1.1.16	INTEGER	read-write	The version of Spanning Tree Protocol the Bridge is currently running. The values are directly from the IEEE standard. New values may be defined as future versions of the protocol become available. The value 'stp(0)' indicates the Bridge is running the Spanning Tree Protocol specified in IEEE Std 802.1D-1998. The value 'rstp(2)' indicates the Bridge is running RSTP specified in IEEE 802.1Q. The value 'mstp(3)' indicates the Bridge is running MSTP specified in Clause 13 of IEEE Std 802.1Q. The value of this object MUST be retained across reinitializations of the management system.
I32 ieee8021SpanningTreeRstpTxHoldCount	1.3.111.2.802.1.1.3.1.1.1.17	Integer32	read-write	The value used by the Port Transmit state machine to limit the maximum transmission rate. This is used by Bridges that are running RSTP. The value of this object MUST be retained across reinitializations of the management system.
ieee8021SpanningTreePortTable	1.3.111.2.802.1.1.3.1.2		not-accessible	A table that contains port-specific information for the Spanning Tree Protocol.
ieee8021SpanningTreePortEntry	1.3.111.2.802.1.1.3.1.2.1		not-accessible	A list of objects containing information maintained by every port about the Spanning Tree Protocol state for that port.
OID ieee8021SpanningTreePortComponentId	1.3.111.2.802.1.1.3.1.2.1.1	IEEE8021PbbComponentIdentifier	not-accessible	The component identifier is used to distinguish between the multiple virtual Bridge instances within a PBB. In simple situations where there is only a single component the default value is 1.
IEE ieee8021SpanningTreePort	1.3.111.2.802.1.1.3.1.2.1.2	IEEE8021BridgePortNumber	not-accessible	The port number of the port for which this entry contains Spanning Tree Protocol management information.
I32 ieee8021SpanningTreePortPriority	1.3.111.2.802.1.1.3.1.2.1.3	Integer32	read-write	The value of the priority field that is contained in the first (in network byte order) octet of the (2 octet long) Port ID. The other octet of the Port ID is given by the value of ieee8021SpanningTreePort. On Bridges supporting IEEE 802.1t or IEEE 802.1w, permissible values are 0-240, in steps of 16. The value of this object MUST be retained across reinitializations of the management system.
INT ieee8021SpanningTreePortState	1.3.111.2.802.1.1.3.1.2.1.4	INTEGER	read-only	The port's current state, as defined by application of the Spanning Tree Protocol. This state controls what action a port takes on reception of a frame. If the Bridge has detected a port that is malfunctioning, it will place that port into the broken(6) state. For ports that are disabled (see ieee8021SpanningTreePortEnabled), this object will have a value of disabled(1). The values disabled, blocking, listening, and broken correspond to the Clause 12 port state of 'Discarding'. The value learning corresponds to the Clause 12 port state of 'Learning'. The value forwarding corresponds to the Clause 12 port state of 'Forwarding'.
T/F ieee8021SpanningTreePortEnabled	1.3.111.2.802.1.1.3.1.2.1.5	TruthValue	read-write	The enabled/disabled status of the port. A value of true(1) means the spanning-tree protocol is enabled for this port. The value of this object MUST be retained across reinitializations of the management system.
I32 ieee8021SpanningTreePortPathCost	1.3.111.2.802.1.1.3.1.2.1.6	Integer32	read-write	The contribution of this port to the path cost of paths towards the spanning tree root which include this port. Table 13-4 recommends defaults and ranges for Port Path Cost values, in inverse proportion to the speed of the attached LAN. If this object is used to set the Path Cost it is possible to restore the default setting using the ieee8021SpanningTreeRstpPortAdminPathCost object. Table 13-4 recommends defaults and ranges for Port Path Cost values, in inverse proportion to the speed of the attached LAN. If this object is used to set the Path Cost it is possible to restore the default setting using the ieee8021MstpPortAdminPathCost object. The value of this object MUST be retained across reinitializations of the management system.
BRI ieee8021SpanningTreePortDesignatedRoot	1.3.111.2.802.1.1.3.1.2.1.7	BridgeId	read-only	The unique Bridge Identifier of the Bridge recorded as the Root in the Configuration BPDUs transmitted by the Designated Bridge for the segment to which the port is attached.
I32 ieee8021SpanningTreePortDesignatedCost	1.3.111.2.802.1.1.3.1.2.1.8	Integer32	read-only	The path cost of the Designated Port of the segment connected to this port. This value is compared to the Root Path Cost field in received Bridge PDUs.
BRI ieee8021SpanningTreePortDesignatedBridge	1.3.111.2.802.1.1.3.1.2.1.9	BridgeId	read-only	The Bridge Identifier of the Bridge that this port considers to be the Designated Bridge for this port's segment.
OCT ieee8021SpanningTreePortDesignatedPort	1.3.111.2.802.1.1.3.1.2.1.10	OCTET STRING	read-only	The Port Identifier of the port on the Designated Bridge for this port's segment.
C64 ieee8021SpanningTreePortForwardTransitions	1.3.111.2.802.1.1.3.1.2.1.11	Counter64	read-only	The number of times this port has transitioned from the Learning state to the Forwarding state. Discontinuities in the value of the counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime object of the associated interface (if any).
T/F ieee8021SpanningTreeRstpPortProtocolMigration	1.3.111.2.802.1.1.3.1.2.1.12	TruthValue	read-write	When operating in RSTP (version 2) mode, writing true(1) to this object forces this port to transmit RSTP BPDUs. Any other operation on this object has no effect and it always returns false(2) when read.
T/F ieee8021SpanningTreeRstpPortAdminEdgePort	1.3.111.2.802.1.1.3.1.2.1.13	TruthValue	read-write	The administrative value of the Edge Port parameter. A value of true(1) indicates that this port should be assumed as an edge-port, and a value of false(2) indicates that this port should be assumed as a non-edge-port. Setting this object will also cause the corresponding instance of ieee8021SpanningTreeRstpPortOperEdgePort to change to the same value. Note that even when this object's value is true(1), the value of the corresponding instance of ieee8021SpanningTreeRstpPortOperEdgePort can be false(2) if a BPDU has been received. The value of this object MUST be retained across reinitializations of the management system.
T/F ieee8021SpanningTreeRstpPortOperEdgePort	1.3.111.2.802.1.1.3.1.2.1.14	TruthValue	read-only	The operational value of the Edge Port parameter. The object is initialized to the value of the corresponding instance of ieee8021SpanningTreeRstpPortAdminEdgePort. When the corresponding instance of ieee8021SpanningTreeRstpPortAdminEdgePort is set, this object will be changed as well. This object will also be changed to false(2) on reception of a BPDU.
I32 ieee8021SpanningTreeRstpPortAdminPathCost	1.3.111.2.802.1.1.3.1.2.1.15	Integer32	read-write	The administratively assigned value for the contribution of this port to the path cost of paths toward the spanning tree root. Writing a value of '0' assigns the automatically calculated default Path Cost value to the port. If the default Path Cost is being used, this object returns '0' when read. This complements the object ieee8021SpanningTreePortPathCost, which returns the operational value of the path cost. The value of this object MUST be retained across reinitializations of the management system.
ieee8021SpanningTreePortExtensionTable	1.3.111.2.802.1.1.3.1.3		not-accessible	A table that contains port-specific information for the Spanning Tree Protocol.
ieee8021SpanningTreePortExtensionEntry	1.3.111.2.802.1.1.3.1.3.1		not-accessible	A list of additional objects containing information maintained by every port about the Spanning Tree Protocol state for that port.
T/F ieee8021SpanningTreeRstpPortAutoEdgePort	1.3.111.2.802.1.1.3.1.3.1.1	TruthValue	read-write	The administrative value of the Auto Edge Port parameter. A value of true(1) indicates if the Bridge detection state machine (BDM, 13.31) is to detect other Bridges attached to the LAN, and set ieee8021SpanningTreeRstpPortOperEdgePort automatically. The default value is true(1) This is optional and provided only by implementations that support the automatic identification of edge ports. The value of this object MUST be retained across reinitializations of the management system.
T/F ieee8021SpanningTreeRstpPortAutoIsolatePort	1.3.111.2.802.1.1.3.1.3.1.2	TruthValue	read-only	The operational value of the Isolate Port parameter. A value of true(1) indicates a Designated Port will transition to discarding if both ieee8021SpanningTreeRstpPortAdminEdgePort and ieee8021SpanningTreeRstpPortAutoEdgePort are FALSE and the other Bridge presumed to be attached to the same point-to-point LAN does not transmit periodic BPDUs. This is optional and provided only by implementations that support the automatic identification of edge ports.
T/F ieee8021SpanningTreeRstpPortIsolatePort	1.3.111.2.802.1.1.3.1.3.1.3	TruthValue	read-only	The operational value of the Isolate Port parameter. A value of true(1), Set by the Bridge detection state machine (BDM, 13.31), indicates when the Spanning Tree Protocol Entity of a neighboring Bridge has apparently failed .
ieee8021SpanningTreeConformance	1.3.111.2.802.1.1.3.2
ieee8021SpanningTreeCompliances	1.3.111.2.802.1.1.3.2.1
ieee8021SpanningTreeCompliance	1.3.111.2.802.1.1.3.2.1.1			The compliance statement for devices supporting the Spanning Tree Protocol.
ieee8021SpanningTreeRstpCompliance	1.3.111.2.802.1.1.3.2.1.2			The compliance statement for devices supporting RSTP.
ieee8021SpanningTreeGroups	1.3.111.2.802.1.1.3.2.2
ieee8021SpanningTreeGroup	1.3.111.2.802.1.1.3.2.2.1			Bridge level Spanning Tree data for this device.
ieee8021SpanningTreeRstpGroup	1.3.111.2.802.1.1.3.2.2.2			Bridge level Rstp data for this device.
ieee8021SpanningTreePortGroup	1.3.111.2.802.1.1.3.2.2.3			Spanning Tree data for each port on this device.
ieee8021SpanningTreeRstpPortGroup	1.3.111.2.802.1.1.3.2.2.4			Rstp data for each port on this device.
ieee8021SpanningTreeNotificationGroup	1.3.111.2.802.1.1.3.2.2.5			Group of notifications.
ieee8021SpanningTreeRstpFragileGroup	1.3.111.2.802.1.1.3.2.2.6			Rstp fragile Bridge data for each port on this device.

RFC description

Manages IEEE 802.1Q spanning tree protocol on network switches to prevent loops and optimize network topology.

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Download IEEE8021-SPANNING-TREE-MIB