300-115 question 174 discussion


What two things occur when an RSTP edge port receives a BPDU? (Choose two.)

  • A. The port immediately transitions to the forwarding state.
  • B. The switch generates a Topology Change Notification BPDU.
  • C. The port immediately transitions to the err-disable state.
  • D. The port becomes a normal STP switch port.
Created 5 months ago by thewildones


https://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/24062-146.html Edge Ports The edge port concept is already well known to Cisco spanning tree users, as it basically corresponds to the PortFast feature. All ports directly connected to end stations cannot create bridging loops in the network. Therefore, the edge port directly transitions to the forwarding state, and skips the listening and learning stages. Neither edge ports or PortFast enabled ports generate topology changes when the link toggles. An edge port that receives a BPDU immediately loses edge port status and becomes a normal spanning tree port. At this point, there is a user-configured value and an operational value for the edge port state.


Notification—Unlike IEEE 802.1D, which uses TCN BPDUs, the RSTP does not use them. However, for IEEE 802.1D interoperability, an RSTP switch processes and generates TCN BPDUs.