User manual

C HAPTER 8 | Spanning Tree Algorithm
Displaying Interface Settings for STA
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ES-2000 Series
◆ Forward Transitions – The number of times this port has transitioned
from the Learning state to the Forwarding state.
◆ Designated Cost – The cost for a packet to travel from this port to the
root in the current Spanning Tree configuration. The slower the media,
the higher the cost.
◆ Designated Bridge – The bridge priority and MAC address of the
device through which this port must communicate to reach the root of
the Spanning Tree.
◆ Designated Port – The port priority and number of the port on the
designated bridging device through which this switch must
communicate with the root of the Spanning Tree.
◆ Oper Path Cost – The contribution of this port to the path cost of
paths towards the spanning tree root which include this port.
◆ Oper Link Type – The operational point-to-point status of the LAN
segment attached to this interface. This parameter is determined by
manual configuration or by auto-detection, as described for Admin Link
Type in STA Port Configuration on page 113.
◆ Oper Edge Port – This parameter is initialized to the setting for Admin
Edge Port in STA Port Configuration on page 113 (i.e., true or false),
but will be set to false if a BPDU is received, indicating that another
bridge is attached to this port.
◆ Port Role – Roles are assigned according to whether the port is part of
the active topology connecting the bridge to the root bridge (i.e., root
port), connecting a LAN through the bridge to the root bridge (i.e.,
designated port), or is an alternate or backup port that may provide
connectivity if other bridges, bridge ports, or LANs fail or are removed.
The role is set to disabled (i.e., disabled port) if a port has no role
within the spanning tree.
Figure 61: STA Port Roles
Alternate port receives more
useful BPDUs from another
bridge and is therefore not
selected as the designated
port.
x
R: Root Port
A: Alternate Port
D: Designated Port
B: Backup Port
RR
ADB