RSTP (Rapid Spanning Tree)

RSTP (802.1W) in the enhancement of STP (802.1D)

  • RSTP was crated by IEEE to get rid of the slow convergence of STP where it takes 50 seconds to bring the port up from Discarding (Blocking) to Forwarding state.

  • RSTP convergence is in few seconds (3 Hello Timers) or withing few milliseconds of a Physical Link failure.

  • It does it so quickly because there is no Listening mode in RSTP. Ports can directly move from Discarding mode to Learning & Forwarding Mode.

  • RSTP is backwards-compatible with standard STP (you can run STP & RSTP in the same Network)

  • RSTP has inbuilt Cisco proprietary features like Backbone fast, Uplink fast, Portfast, BPDU Filter.

  • In RSTP, Not only RB but all the other Non-Root Bridges will also be sending & receiving the BPDUs to make the convergence faster.

  • RSTP Port roles are slightly different as compared to STP

  • RSTP is enabled by default on newer Cisco Switches which skips the Listening & Learning State that means PortFast is also enabled by default on RSTP running Switches on Edge ports.

  • Another method of preventing Loop / preventing hackers attack is using BPDU Guard.

Reference:

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