User`s manual

NPort 6000 Series User’s Manual Module Settings
6-6
Forward Delay: The amount of time this device waits before checking to see if it should change
to a different state. The factory default is 15 (sec.).
Max. Age (sec.): 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.
Enable RSTP (per port): Select to enable the port as a node in the Rapid Spanning Tree topology.
The factory default is “disabled.”
Port Priority: Increase this port’s priority as a node in the Spanning Tree topology by entering a
smaller number. The factory default is 128.
Port Cost: Input a higher cost to indicate that this port is less suitable as a node for the Spanning
Tree topology. The factory default is 200000.
Port Status: Indicates the current Spanning Tree status of this port. “Forwarding” for normal
transmission, or “Blocking” to block transmission..
Configuration Limits of RSTP/STP:
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 * (Forwardin≦≦ g Delay – 1 sec)
The NPort’s firmware will alert you immediately if any of these restrictions are violated. For
example, setting:
Hello Time = 5 sec, Max. Age = 20 sec, and Forwarding Delay = 4 sec does not violate Eqs. 1
through 3, but does violate Eq. 4, since in this case,
2 * (Hello Time + 1 sec) = 12 sec, and 2 * (Forwarding Delay – 1 sec) = 6 sec.
You can remedy the situation in many ways. One solution is simply to increase the Forwarding
Delay value to at least 11 sec.
HINT: Perform the following steps to avoid guessing:
Step 1: Assign a value to “Hello Time” and then calculate the left most part of Eq. 4 to get the
lower limit of “Max. Age.”
Step 2: Assign a value to “Forwarding Delay” and then calculate the right most part of Eq. 4 to
get the upper limit for “Max. Age.”
Step 3: Assign a value to “Forwarding Delay” that satisfies the conditions in Eq. 3 and Eq. 4.
NM-GPRS/GSM
This section applies to NPort 6000 server’s that have the NM-GPRS/GSM module installed. From
the left navigation panel, click Network Settings Æ Module to configure GSM/GPRS Settings.
The various configuration items are described in detail below the figure.