FORE-BRIDGE-MIB

All MIBs › FORE-BRIDGE-MIB

Organization: FORE

Last Updated: 1999-11-05

Category: ATM, VLAN and Bridging, Vendor: Fore Systems (ATM)

Description: Fore Systems bridge MIB providing MAC address learning, spanning tree, and forwarding table management for bridging on ForeRunner ATM switches.

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What Is FORE-BRIDGE-MIB?

FORE-BRIDGE-MIB is Fore Systems' vendor-specific MIB extending Ethernet bridging management to ATM switch ports, allowing ForeRunner ASX ATM switches to participate in transparent bridging and spanning tree alongside conventional Ethernet segments. It exposes bridge data source configuration, a count of bridging entities, and a spanning-tree-over-ATM port table covering per-port priority, state, enable status, path cost, and designated root/cost information. Its monitoring value is chiefly software/protocol status: bridgeStpAtmPortState reveals whether an ATM bridge port is in a spanning-tree forwarding, blocking, or listening state, while bridgeStpAtmPortEnable and bridgeStpAtmPortDesignatedRoot/DesignatedCost help diagnose spanning tree topology and loop-prevention behavior across the ATM fabric. It follows the conventions of the standard IEEE 802.1D bridge/spanning-tree model (as reflected in the IETF BRIDGE-MIB) but adapts them specifically for ATM ports rather than importing that MIB directly. It was deployed on Fore Systems ForeRunner ASX ATM switches used to bridge Ethernet traffic over ATM backbones in the 1990s. Engineers can download the FORE-BRIDGE-MIB file directly to load it into their MIB browser.

IPNetwork Monitor allows you to monitor SNMP objects defined in FORE-BRIDGE-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

Fore Systems ForeRunner ASX ATM switches

Monitoring Examples

Polling bridgeStpAtmPortTable/bridgeStpAtmPortEntry by bridgeStpAtmPort lets an operator check bridgeStpAtmPortState and bridgeStpAtmPortEnable to confirm whether a given ATM bridge port is actively forwarding traffic or has been blocked by spanning tree. bridgeStpAtmPortPriority and bridgeStpAtmPortPathCost determine that port's role in spanning tree topology calculations, while bridgeStpAtmPortDesignatedRoot and bridgeStpAtmPortDesignatedCost show which switch is currently considered the root bridge from that port's perspective. An ATM port unexpectedly stuck in a blocking bridgeStpAtmPortState when it should be forwarding would indicate a spanning tree topology change or misconfigured path cost.

What Can Be Monitored

ATM bridge port spanning tree state
port enable/priority/path cost
designated root and designated cost
number of bridging entities
bridge data source configuration

Imported Objects

From BRIDGE-MIB

BridgeId

From Fore-Common-MIB

preDot1qVlanMIB

OBJECT-IDENTITY

From SNMPv2-SMI

Counter32
Integer32
MODULE-IDENTITY
OBJECT-TYPE

From SNMPv2-TC

DisplayString

How to Use in IPNetwork Monitor

Example using bridgeStpAtmPortForwardTransitions OID:

Select a Fore Systems ForeRunner ASX ATM switch (Ethernet bridging/spanning-tree over ATM) 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 bridgeStpAtmPortForwardTransitions 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 number of times this port has transitioned from the Learning state to the Forwarding state. 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 Counter32-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, 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
foreBridgeExtensions	1.3.6.1.4.1.326.1.8.2			Fore ASX ethernet bridge mib extensions.
STR bridgeDataSource	1.3.6.1.4.1.326.1.8.2.1	DisplayString	read-write	This object specifies the name of the bridge that is currently visable via SNMP accesses to the Bridge MIB (RFC-1493). If there is no bridge of that name, then accesses to objects in the Bridge MIB will return noSuchName errors. The factory default value for this object is 'default'
I32 bridgeNumberOfEntities	1.3.6.1.4.1.326.1.8.2.2	Integer32	read-only	This object specifies the number of logical bridges in the system.
bridgeStpAtmPortTable	1.3.6.1.4.1.326.1.8.2.3		not-accessible	A table that contains atm port-specific information for the Spanning Tree Protocol.
bridgeStpAtmPortEntry	1.3.6.1.4.1.326.1.8.2.3.1		not-accessible	A list of information maintained by every atm port about the Spanning Tree Protocol state for that port.
STR bridgeStpAtmPort	1.3.6.1.4.1.326.1.8.2.3.1.1	DisplayString	read-only	The port number of the port for which this entry contains Spanning Tree Protocol management information.
I32 bridgeStpAtmPortPriority	1.3.6.1.4.1.326.1.8.2.3.1.2	Integer32	read-write	The value of the priority field which 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 bridgeStpAtmPort.
INT bridgeStpAtmPortState	1.3.6.1.4.1.326.1.8.2.3.1.3	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.
INT bridgeStpAtmPortEnable	1.3.6.1.4.1.326.1.8.2.3.1.4	INTEGER	read-write	The enabled/disabled status of the port.
I32 bridgeStpAtmPortPathCost	1.3.6.1.4.1.326.1.8.2.3.1.5	Integer32	read-write	The contribution of this port to the path cost of paths towards the spanning tree root which include this port.
BRI bridgeStpAtmPortDesignatedRoot	1.3.6.1.4.1.326.1.8.2.3.1.6	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 bridgeStpAtmPortDesignatedCost	1.3.6.1.4.1.326.1.8.2.3.1.7	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 bridgeStpAtmPortDesignatedBridge	1.3.6.1.4.1.326.1.8.2.3.1.8	BridgeId	read-only	The Bridge Identifier of the bridge which this port considers to be the Designated Bridge for this port's segment.
OCT bridgeStpAtmPortDesignatedPort	1.3.6.1.4.1.326.1.8.2.3.1.9	OCTET STRING	read-only	The Port Identifier of the port on the Designated Bridge for this port's segment.
C32 bridgeStpAtmPortForwardTransitionsEx	1.3.6.1.4.1.326.1.8.2.3.1.10	Counter32	read-only	The number of times this port has transitioned from the Learning state to the Forwarding state.
INT bridgeStpEnable	1.3.6.1.4.1.326.1.8.2.4	INTEGER	read-write	The enabled/disabled status of the bridge.

RFC description

FORE Systems ATM bridge extensions MIB for managing bridge entities and Spanning Tree Protocol on ATM ports.

Start monitoring Fore Systems ForeRunner ASX ATM switch (Ethernet bridging/spanning-tree over ATM) with a free 30-day trial of IPNetwork Monitor. Import MIBs, browse SNMP OIDs, create custom SNMP monitors, configure alerts, and monitor any SNMP-enabled network device from a single console.

Download FORE-BRIDGE-MIB