Explanation/Reference:
Section: Enterprise Network Design Explanation
Explanation:
The 802.1w Rapid Spanning Tree Protocol (RSTP) standard natively includes PortFast, UplinkFast, and BackboneFast. PortFast enables a port to immediately access the network by transitioning the port into the Spanning Tree Protocol (STP) forwarding state without passing through the listening and learning states.
Configuring BPDU filtering on a port that is also configured for PortFast causes the port to ignore any bridge protocol data units (BPDUs) it receives, effectively disabling STP.
UplinkFast increases convergence speed for an access layer switch that detects a failure on the root port with backup root port selection by immediately replacing the root port with an alternative root port.
BackboneFast increases convergence speed for switches that detect a failure on links that are not directly connected to the switch.
802.1D is the traditional STP implementation to prevent switching loops on a network. Traditional STP, which Cisco training and reference materials refer to simply as 802.1D, is more formally known as the
802.1D1998 standard. Although PortFast, UplinkFast, and BackboneFast can be used with 802.1D, it does not contain those features natively. Traditional STP converges slowly, so the 802.1w RSTP standard was developed by the Institute of Electrical and Electronics Engineers (IEEE) to address the slow transition of an 802.1D port to the forwarding state. RSTP is backward compatible with STP, but the convergence benefits provided by RSTP are lost when RSTP interacts with STP devices. The features of 802.1w, including PortFast, UplinkFast, and BackboneFast, were integrated into the 802.1D2004 standard, and the traditional STP algorithm was replaced with RSTP.
The 802.1s Multiple Spanning Tree (MST) standard is used to create multiple spanning tree instances on a network. Implementing MST on a switch also implements RSTP. However, the 802.1s standard does not natively include PortFast, UplinkFast, and BackboneFast within the specification.
Reference:
CCDA 200-310 Official Cert Guide, Chapter 3, Cisco STP Toolkit, pp. 103-105 Cisco: Understanding Rapid Spanning Tree Protocol (802.1w): Conclusion