Port States and Roles Flashcards

Which STP port role is assigned to the port that provides the best path from a non-root switch to the root bridge?

Answer: Root Port

Each non-root switch has exactly one Root Port, which is the port offering the lowest-cost path toward the root bridge.

On each network segment, which STP port role is responsible for forwarding traffic toward the root bridge on behalf of that segment?

Answer: Designated Port

The Designated Port on each segment is the one elected to forward traffic from that segment toward the root bridge.

In RSTP (802.1w), what is the name of the port role that provides an alternate path to the root bridge and can quickly take over if the Root Port fails?

Answer: Alternate Port

The Alternate Port in RSTP is a blocking port that offers a redundant path to the root bridge and can rapidly transition to Root Port if needed.

What port role does the root bridge assign to ALL of its active ports?

Answer: Designated Port

All active ports on the root bridge are Designated Ports because the root bridge always has the best path cost (zero) to itself.

In RSTP, which port role is in Discarding state and provides a backup to a Designated Port on the SAME switch segment?

Answer: Backup Port

A Backup Port is an RSTP port role that provides redundancy for a Designated Port on the same shared segment, but it stays in Discarding state.

How is the Root Port selected when two ports on the same switch have equal path costs to the root bridge?

Answer: By the lowest port priority then lowest port ID

When path costs are tied, STP uses the lowest sender Bridge ID, then lowest port priority, and finally lowest port ID (number) as tiebreakers.

A port that is administratively shut down in STP is in which port state?

Answer: Disabled

The Disabled state applies to ports that have been administratively shut down and do not participate in STP at all.