Chapter 2 - Spanning Tree Protocol Terms Flashcards
bridge protocol data unit (BPDU)
A network packet that is used to identify a hierarchy and
notify of changes in the topology.
configuration BPDU
The BPDU that is responsible for switches electing a root bridge and
communicating the root path cost so that a hierarchy can be built.
hello time
The time interval for which a BPDU is advertised out of a port.
designated port (DP)
A network port that receives and forwards BPDUs to other
downstream switches.
forward delay
The amount of time that a port stays in a listening and learning state.
local bridge identifier
A combination of the advertising switch’s bridge system MAC, the
system ID extension, and the system priority of the local bridge.
Max Age
The timer that controls the maximum length of time that passes before a bridge
port saves its BPDU information.
root bridge
The topmost switch in an STP topology. The root bridge is responsible for
controlling STP timers, creating configuration BPDUs, and processing topology change BPDUs.
All ports on a root bridge are designated ports that are in a forwarding state.
root bridge identifier
A combination of the root bridge system MAC address, system ID
extension, and system priority of the root bridge.
root path cost
The cost for a specific path toward the root switch.
root port
The most preferred switch port that connects a switch to the root bridge. Often this
is the switch port with the lowest root path cost.
system priority
A 4-bit value that indicates the preference for a switch to be root bridge.
system ID extension
A 12-bit value that indicates the VLAN that the BPDU correlates to.
topology change notification (TCN)
BPDU that is advertised toward the root bridge to
notify the root of a topology change on a downstream switch.
