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ccna exam grading.7 TCA flagFigure 14-6 RSTP BPDU Format3 RSTP can proactively confirm that a port can safely transition to the forwarding state without relying on any timers to make that determination.4 RSTP defines edge ports. An edge port is a switch end that will never be used to connect to another switch deviceChapter 14 STP and Switch Stacking .223 .Ports. When enabled. such ports immediately transition to the forwarding state. the execution of the spanning-tree portfast command under the port configures that switch port as an edge port.5 Non-edge ports are divided into 2 link types: point-to-point (Point-to-Point) and shared (Shared). The link type is determined automatically by RSTP (a full-duplex link is a Point-to-Point type, and a half-duplex is a Shared type), but can be changed using configuration commands. RSTP achieves fast convergence only on point-to-point type links.RSTP is able to be backward compatible with IEEE802.Id. the way RSTP sends BPDUs and fills the flag bytes is slightly different from positive EE802. Since BPDUs are used as a keepalive detection mechanism, three consecutive non-received BPDUs indicate that the bridge has lost connectivity with its adjacent root bridge or designated bridge. Fast aging means that faults can be detected quickly.RSTP ports have only 3 states: drop, learn, and forward.1 Discarding ( Discarding): This state occurs during stable active topologies and during topology synchronization and changes. The discarding state prohibits the forwarding of data frames and thus prevents Layer 2 loops.