Which three statements about RSTP are true? (Choose three.)
A.
RSTP significantly reduces topology reconverging time after a link failure.
B.
RSTP expands the STP port roles by adding the alternate and backup roles.
C.
RSTP port states are blocking, discarding, learning, or forwarding.
D.
RSTP provides a faster transition to the forwarding state on point-to-point links than STP does.
E.
RSTP also uses the STP proposal-agreement sequence.
F.
RSTP uses the same timer-based process as STP on point-to-point links.
Explanation:
One big disadvantage of STP is the low convergence which is very important in switched network.
To overcome this problem, in 2001, the IEEE with document 802.1w introduced an evolution of the
Spanning Tree Protocol: Rapid Spanning Tree Protocol (RSTP), which significantly reduces the
convergence time after a topology change occurs in the network. While STP can take 30 to 50
seconds to transit from a blocking state to a forwarding state, RSTP is typically able to respond
less than 10 seconds of a physical link failure.
RSTP works by adding an alternative port and a backup port compared to STP. These ports are
allowed to immediately enter the forwarding state rather than passively wait for the network to
converge.
RSTP bridge port roles:
* Root port– A forwarding port that is the closest to the root bridge in terms of path cost*
Designated port– A forwarding port for every LAN segment* Alternate port– A best alternate
path to the root bridge. This path is different than using the root port. The alternative port moves to
the forwarding state if there is a failure on the designated port for the segment.* Backup port– A
backup/redundant path to a segment where another bridge port already connects. The backup
port applies only when a single switch has two links to the same segment (collision domain). To
have two links to the same collision domain, the switch must be attached to a hub.* Disabled port
– Not strictly part of STP, a network administrator can manually disable a port