Stp port role

Q: How deeply does Acing the CCNA Exam: Volume 1 Fundamentals and Protocols cover stp port role?

Defines four RSTP roles and their conditions, then stops short of configuration procedures.

As explained in Acing the CCNA Exam: Volume 1 Fundamentals and Protocols

An STP port role is a spanning-tree assignment that determines how a switch port participates in the loop-free topology.

An STP port role determines how a switch port participates in a loop-free Layer 2 topology. Root and designated ports forward traffic; alternate and backup ports block traffic to prevent loops. section 15.2.3 section 14.0

In RSTP, identify roles by their path and relationship to the designated bridge:

Root: the forwarding port that provides the switch’s only active path toward the root bridge. section 15.2.3
Designated: the forwarding port pointing away from the root bridge; each segment has exactly one. section 15.2.3
Alternate: a blocked path toward the root bridge that can transition to forwarding if the root port fails. section 15.2.3
Backup: a blocked path to the same segment through another port on the same switch, usually involving a hub. section 15.2.3

Reading Cisco output

show spanning-tree may display Root/FWD, Desg/FWD, Altn/BLK, or Back/BLK. SW1 G0/1 is alternate, while SW3 G0/1 is backup when both switches have multiple connections to one segment.

How Acing the CCNA Exam: Volume 1 Fundamentals and Protocols covers it

Cover of Acing the CCNA Exam: Volume 1 Fundamentals and Protocols

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Related concepts

root portincludes · A root port is the single port selected on a non-root switch to provide its active path toward the root bridge.
backup portincludes · A backup port is an RSTP port that provides a redundant path to the same network segment as a designated port on the same switch.
non-designated portincludes · A non-designated port is an STP port role that does not provide the selected forwarding path for its network segment and is placed in a nonforwarding state to prevent Layer 2 loops.
designated portincludes · A designated port is an STP port in the forwarding state that provides the preferred path away from the root bridge for a network segment.
stp port stateconfigures · An STP port state is an operational condition that determines whether a switch port participates in control messaging, learns MAC addresses, and forwards data frames.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 1 Fundamentals and Protocols. The section links point to the parts of the book it draws on.