BRIDGE-MIB

Defines managed objects for managing MAC bridges as defined by IEEE 802.1D, including bridge port status, forwarding database, and spanning tree protocol parameters.

BRIDGE-MIB is a vendor-neutral IETF standards module (RFC 4188) that defines the managed objects for monitoring and managing IEEE 802.1D MAC bridges, covering the bridge's base identity, its per-port table, and Spanning Tree Protocol (STP) state. It exposes categories of data including bridge identity and port count (dot1dBaseBridgeAddress, dot1dBaseNumPorts), per-port operational parameters and discard counters (dot1dBasePortTable, dot1dBasePortDelayExceededDiscards, dot1dBasePortMtuExceededDiscards), and spanning-tree protocol configuration and status (dot1dStpProtocolSpecification, dot1dStpPriority). In terms of hardware/software status monitoring, this module is primarily used to track port-level health and forwarding behavior, for example detecting ports discarding frames due to STP topology-change delays or oversized frames, and confirming which STP variant a bridge is running, plus dot1dNotifications for fault-style trap events like topology changes. It commonly builds on IF-MIB, since each bridge port maps to an ifIndex via dot1dBasePortIfIndex, and is often paired with vendor STP extensions or P-BRIDGE-MIB/Q-BRIDGE-MIB for priority and VLAN handling. It is deployed on any Ethernet switch or bridging device that implements IEEE 802.1D bridging and spanning tree, from enterprise switches to smaller managed switches, making this bridge mib one of the most commonly polled modules for STP-aware port monitoring.

An administrator would poll dot1dBasePortTable/dot1dBasePortEntry, correlating dot1dBasePortIfIndex to the corresponding IF-MIB interface, to check dot1dBasePortDelayExceededDiscards and dot1dBasePortMtuExceededDiscards for a rising discard count that signals STP topology instability or an MTU mismatch on that port. They would also poll dot1dStpProtocolSpecification to confirm which spanning-tree variant is active and dot1dStpPriority to verify the bridge's configured priority in root-bridge elections, and would watch for dot1dNotifications traps indicating a topology change event that could explain a brief network flap.

Manages IEEE 802.1D MAC bridges including spanning tree protocol state, port settings, and forwarding database as defined in RFC 4188, which obsoletes the original RFC 1493 definition.