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CCIE Routing and Switching Exam Certification Guide

Chapter Description

Prepare for the CCIE Routing and Switching Exam with this excellent study resource. Review such topics as MAC address format, VLAN trunking, transparent bridge functions, and much more.

Transparent Bridge Port States

Each port of a transparent bridge exists in the following states:

  • Disabled—The port is inactive and does not participate in STP.

  • Blocking—When a port is enabled, it first moves to a blocked state before listening to the network. In this state, it does not participate in frame forwarding. It receives Bridge PDUs and sends them for processing.

  • Listening—When the bridge determines that the port should participate in frame forwarding, it changes to the listening state. In this state, the bridge still does not forward frames and does not learn of network MAC addresses. The bridge does receive and process BPDUs and network management frames.

  • Learning—The bridge port still discards incoming frames or frames switched over for forwarding. The bridge begins to incorporate MAC addresses associated with this port. BPDU and network management messages are still processed.

  • Forwarding—This is the full functional state for a bridged port. In this state, the bridge does not discard incoming frames and forwards them to other ports; the bridge also forwards frames out the port. BPDUs and network management frames are still processed.