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Spanning Tree Algorithms (STA)
FX-DS110-APE
90
STA Parameters
STA's function on two levels, bridge level and port level. Multiple
timers are used to periodically check the proper operation of bridges
and ports. The following section describes the parameters and
terms used in this product.
Bridge Level
Root bridge
First, the bridge is determined using the bridge identifier (bridge
priority level and Ethernet address) of the bridge. The bridge
identifier of the root bridge is the smallest.
If more than one bridge exists with the same priority level, the root
bridge is determined by Ethernet address.
Designated bridges
In each LAN segment, the bridge having the lowest root path cost
to the root bridge is the designated bridge. The designated bridge
serves to carry the packages of that LAN segment.
If more than one bridge is connected to the same LAN segment, and
the root path costs are exactly the same, the bridge with the smallest
bridge identifier becomes the designated bridge.
Bridge priority
The priority level can be set in the range 0 to 65535. The smaller
this number, the higher the priority. If priorities are changed, all
bridges and root bridges in the network will be re-determined.
Root path cost
The total path cost from the designated bridge to the root bridge is
the root path cost. The root path cost of the root bridge is zero.
BPDU effective time (Max Age Time)
Set in the range from 6 to 40 (seconds). If the bridge does not
receive a packet notifying the existence of a root bridge within this
time, the system assumes there is a failure in the root bridge, and
determines a new root bridge.