User`s manual

NPort S8000 Series Switch Featured Functions
6-19
topology.
Hello time (sec.)
Setting Description Factory Default
Numerical value input
by user
The root of the Span
ning Tree topology periodically sends out a
“hello”
message to other devices on the network to check if the
topology is healthy. The “hello time”
is the amount of time the
root waits between sending hello messages.
2
Forwarding Delay
Setting Description Factory Default
Numerical value input
by user
The amount of time this device waits before checking to see if it
should change to a different state.
15 (sec.)
Max. Age (sec.)
Setting Description Factory Default
Numerical value input
by user
If this device is not the root, and it has not received a hello
message from the root in an amount of time equal to “Max.
Age,”
then this device will reconfigure itself as a root. Once two
or more devices on the network are recognized as a root, the
devices will renegotiate to set up a new Spanning Tree
topology.
20
Enable RSTP per Port
Setting
Description
Factory Default
Enable/Disable Select to enable the port as a node on the Spanning Tree
topology.
Disabled
NOTE
We suggest not enabling the Spanning Tree Protocol once the port is connected to a device (PLC, RTU, etc.) as
opposed to network equipment. The reason is that it will cause unnecessary negotiation.
Port Priority
Setting Description Factory Default
Numerical value
selected by user
Increase this port’s priority as a node on the Spanning Tree
topology by entering a lower number.
128
Port Cost
Setting Description Factory Default
Numerical value input
by user
Input a higher cost to indicate that this port is less suitable as a
node for the Spanning Tree topology.
200000
Configuration Limits of STP/RSTP
The Spanning Tree Algorithm places limits on three of the configuration items described previously:
[Eq. 1]: 1 sec ≦ Hello Time ≦ 10 sec
[Eq. 2]: 6 sec ≦ Max. Age ≦ 40 sec
[Eq. 3]: 4 sec ≦ Forwarding Delay ≦ 30 sec
These three variables are further restricted by the following two inequalities:
[Eq. 4]: 2 * (Hello Time + 1 sec) ≦ Max. Age ≦ 2 * (Forwarding Delay – 1 sec)
The NPort S8000’s firmware will alert you immediately if any of these restrictions are violated. For example,
setting