Planet GSW-1602SF User Manual page 84

The following are the user-configurable STP parameters for the port or port group level:
Variable
Port Priority
Port Cost
Default Spanning-Tree Configuration
3. Illustration of STP
A simple illustration of three switches connected in a loop is depicted in the below diagram. In this example, you can
anticipate some major network problems if the STP assistance is not applied.
If switch A broadcasts a packet to switch B, switch B will broadcast it to switch C, and switch C will broadcast it to back to
switch A and so on. The broadcast packet will be passed indefinitely in a loop, potentially causing a network failure. In this
example, STP breaks the loop by blocking the connection between switch B and C. The decision to block a particular
connection is based on the STP calculation of the most current Bridge and Port settings.
The Hello Time cannot be longer than the Max. Age. Otherwise, a configuration error will
occur.
Observe the following formulas when setting the above parameters:
Max. Age _ 2 x (Forward Delay - 1 second)
Max. Age _ 2 x (Hello Time + 1 second)
Description
A relative priority for each
port –lower numbers give a higher priority
and a greater chance of a given port being
elected as the root port
A value used by STP to evaluate paths –
STP calculates path costs and selects the
path with the minimum cost as the active
path
Feature
Enable state
Port priority
Port cost
Bridge Priority
User's Manual of GSW-1602SF / GSW-2404SF
Default Value
128
200,000-100Mbps Fast Ethernet ports
20,000-1000Mbps Gigabit Ethernet
ports
0 - Auto
Default Value
STP disabled for all ports
128
0
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