Moxa Technologies EtherDevice User Manual page 69

Configuration Limits
We should point out that the Spanning Tree Algorithm places certain
limits on three of the configuration items described above:
[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)
MOXA EtherDevice Server'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 any number of ways. One solution is to
simply increase the Forwarding Delay value to at least 11 sec.
MOXA EtherDevice Server User's Manual 3-41
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