Cisco Certified Network Professional Practice Test

What characterizes the BPDU communication in the RSTP?

1. Only sent during initialization

2. Sent on every port at hello interval

3. Sent only by root ports

4. Periodic broadcasts every 30 seconds

The correct answer is: Sent on every port at hello interval

BPDU (Bridge Protocol Data Unit) communication in Rapid Spanning Tree Protocol (RSTP) is characterized by being sent on every port at a defined hello interval. This continuous communication helps maintain the state of the network topologies and ensures the quick convergence capabilities that RSTP is known for. In RSTP, BPDUs are utilized not only for the root bridge election but also for the maintenance of the active topology. By sending BPDUs on every port, the protocol ensures that all switches in the network can rapidly communicate their state and detect any changes, such as link failures or additions. The hello interval typically defaults to 2 seconds, which allows for a fast response to network changes. This frequent communication is essential for the protocol's efficiency and rapid convergence, making it more responsive than the original Spanning Tree Protocol (STP). Other options, such as being sent only during initialization or only by root ports, do not accurately capture the essence of RSTP's functionality. The protocol requires BPDUs to be communicated regularly across all ports to keep all switches informed of the network state and its topology, not just during initialization or from a single point. Likewise, the notion of periodic broadcasts every 30 seconds does not align with