24 Configuring and Monitoring the Switch DNswitch 800
When the Switch Becomes Root Figure 3-16. STA Configuration - When the Switch Becomes Root
Parameter Default Description
Hello Time 2 The time interval (in seconds) at which the root
device transmits a configuration message.
The minimum value is 1.
The maximum value is the lower of
10 or [(Max. Message Age / 2) -1].
Max (Message) Age 20 The maximum time (in seconds) a device can
wait without receiving a configuration message
before attempting to reconfigure. All device ports
(except for designated ports) should receive
configuration messages at regular intervals. Any
port that ages out STA information (provided in
the last configuration message) becomes the
designated port for the attached LAN. If it is a root
port, a new root port is selected from among the
device ports attached to the network.
The minimum value is the higher of
6 or [2 x (Hello Time + 1)].
The maximum value is the lower of
40 or [2 x (Forward Delay - 1)].
Forward Delay 15 The maximum time (in seconds) the root device
will wait before changing states (i.e., listening to
learning to forwarding). This delay is required
because every device must receive information
about topology changes before it starts to forward
frames. In addition, each port needs time to listen
for conflicting information that would make it
return to a blocking state; otherwise, temporary
data loops might result.
Maximum value is 30.
Minimum value is the higher of 4 or [(Max.
Message Age / 2) + 1].