6 STP States
by David Sudjiman ~ August 31st, 2008. Filed under: Cisco.NOTE—The current IETF Bridge MIB (IETF RFC 1493) uses disabled, blocking, listening, learning, forwarding, and broken dot1dStpPortStates. The learning and forwarding states correspond exactly to the Learning and Forwarding Port States specified in this standard. Disabled, blocking, listening, and broken all correspond to the Discarding Port State — while those dot1dStpPortStates serve to distinguish reasons for discarding frames the operation of the Forwarding and Learning processes is the same for all of them. The dot1dStpPortState broken represents the failure or unavailability of the port’s MAC as indicated by MAC_Operational FALSE; disabled represents exclusion of the port from the active topology by management setting of the Administrative Port State to Disabled; blocking represents exclusion of the port from the active topology by the spanning tree algorithm [computing an Alternate or Backup Port Role (17.7)]; listening represents a port that the spanning tree algorithm has selected to be part of the active topology (computing a Root Port or Designated Port role) but is temporarily discarding frames to guard against loops or incorrect learning.
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