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Stackable NWay Ethernet Switch User's Guide
the Root Bridge. If it turns out that your Switch has the lowest
Bridge Identifier, it will become the Root Bridge.
Bridge Forward Delay The Forward Delay can be from 4 to
30 seconds. This is the time any port on the Switch spends in
the listening state while moving from the blocking state to the
forwarding state.
Observe the following formulas when you set the above
parameters:
1.
Max. Age = 2 x (Forward Delay - 1 second)
Max. Age = 2 x (Hello Time + 1 second)
2.
Port Priority
lower the number, the greater the probability the port will be
chosen as the Root Port.
Illustration of STA
A simple illustration of three Bridges (or the Switch) connected in a
loop is depicted in Figure 5-1. In this example, you can anticipate
some major network problems if the STA assistance is not applied.
For instance, if Bridge 1 broadcasts a packet to Bridge 2, Bridge 2
will broadcast it to Bridge 3, and Bridge 3 will broadcast it to Bridge
1 and so on. The broadcast packet will be passed indefinitely in a
loop, causing a serious network failure.
To alleviate network loop problems, STA can be applied as shown in
Figure 5-2. In this example, STA breaks the loop by blocking the
connection between Bridge 1 and 2. The decision to block a particular
connection is based on the STA calculation of the most current Bridge
and Port settings. Now, if Bridge 1 broadcasts a packet to Bridge 3,
then Bridge 3 will broadcast it to Bridge 2 and the broadcast will end
there.
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A Port Priority can be from 0 to 255. The
Switch Management Concepts
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