Graco GE-DS-242-POE Manual De Usuario
Chapter 4: Web-Based Management
74
GE-DS-242-PoE Managed Ethernet Switch User Manual
Default Spanning-Tree Configuration
Feature
Default Value
Enable state
STP disabled for all ports
Port priority
128
Port cost
0
Bridge Priority
32,768
NOTE:
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)
• Max. Age _ 2 x (Forward Delay - 1 second)
• Max. Age _ 2 x (Hello Time + 1 second)
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.
Now, if switch A broadcasts a packet to switch C, then switch C will drop the packet
at port 2 and the broadcast will end there. Setting-up STP using values other than the
defaults, can be complex. Therefore, you are advised to keep the default factory
settings and STP will automatically assign root bridges/ports and block loop
connections. Influencing STP to choose a particular switch as the root bridge using
the Priority setting, or influencing STP to choose a particular port to block using the
Port Priority and Port Cost settings is, however, relatively straight forward.
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.
Now, if switch A broadcasts a packet to switch C, then switch C will drop the packet
at port 2 and the broadcast will end there. Setting-up STP using values other than the
defaults, can be complex. Therefore, you are advised to keep the default factory
settings and STP will automatically assign root bridges/ports and block loop
connections. Influencing STP to choose a particular switch as the root bridge using
the Priority setting, or influencing STP to choose a particular port to block using the
Port Priority and Port Cost settings is, however, relatively straight forward.