STP Advanced STP — Questions and Answers
Question 1: What is Rapid Spanning Tree Protocol (RSTP)?
- IEEE 802.1w, an evolution of STP providing faster convergence (1-2 seconds) (Correct answer)
- A completely different protocol
- A slower version of STP
- An encryption protocol
Correct answer: IEEE 802.1w, an evolution of STP providing faster convergence (1-2 seconds)
RSTP dramatically reduces convergence time from 30-50 seconds to 1-2 seconds through improved state transitions.
Question 2: What are the RSTP port roles?
- Root, Designated, Alternate, Backup, Disabled (Correct answer)
- Only Root and Designated
- Forwarding and Blocking
- Primary and Secondary
Correct answer: Root, Designated, Alternate, Backup, Disabled
RSTP defines five port roles that determine each ports function in the spanning tree topology.
Question 3: What is an alternate port in RSTP?
- A backup to the root port that can immediately take over if the root port fails (Correct answer)
- A port that alternates between states
- A port for alternate VLANs
- A port connected to an alternate network
Correct answer: A backup to the root port that can immediately take over if the root port fails
The alternate port provides a pre-calculated backup path to the root bridge, enabling rapid failover.
Question 4: What is MSTP (Multiple Spanning Tree Protocol)?
- IEEE 802.1s, which maps multiple VLANs to a reduced number of spanning tree instances (Correct answer)
- A protocol for multiple networks
- A backup spanning tree
- A multicast protocol
Correct answer: IEEE 802.1s, which maps multiple VLANs to a reduced number of spanning tree instances
MSTP reduces resource usage by mapping multiple VLANs to fewer spanning tree instances while still providing per-VLAN path optimization.
Question 5: What is the proposal/agreement mechanism in RSTP?
- A handshake between switches that allows rapid transition to forwarding state without timer delays (Correct answer)
- A contract between vendors
- A VLAN negotiation
- An IP address request
Correct answer: A handshake between switches that allows rapid transition to forwarding state without timer delays
The proposal/agreement mechanism allows RSTP to bypass the listening and learning states, enabling sub-second convergence.
Question 6: What is edge port in RSTP?
- A port connected to an end device that transitions immediately to forwarding state (Correct answer)
- A port at the network edge router
- A port with the highest priority
- A port connecting to another switch
Correct answer: A port connected to an end device that transitions immediately to forwarding state
Edge ports (equivalent to PortFast) are connected to end devices and can immediately forward traffic without risking loops.
STP Advanced STP
What is Rapid Spanning Tree Protocol (RSTP)?