Specifications

124 VH-2402-L3 Management Guide 9033691-01
Note: The Hello Time cannot be longer than the Max. Age.
Otherwise, a configuration error will occur.
• Max. Age The Max. Age can be from 6 to 40 seconds. At
the end of the Max. Age, if a BPDU has still not been
received from the Root Bridge, your Switch will start
sending its own BPDU to all other Switches for
permission to become the Root Bridge. If it turns out that
your Switch has the lowest Bridge Identifier, it will
become the Root Bridge.
• Forward Delay Timer 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.
Note: 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)
• Port Priority A Port Priority can be from 0 to 255. The
lower the number, the greater the probability the port will
be chosen as the Root Port.
• Port Cost A Port Cost can be set from 1 to 65535. The
lower the number, the greater the probability the port will
be chosen to forward packets.
Illustration of STP
A simple illustration of three Bridges (or three switches)
connected in a loop is depicted below. In this example, you
can anticipate some major network problems if the STP
assistance is not applied. If Bridge A broadcasts a packet to
Bridge B, Bridge B will broadcast it to Bridge C, and Bridge
C will broadcast it to back to Bridge A ... and so on. The
broadcast packet will be passed indefinitely in a loop,
potentially causing a network failure.
STP can be applied as shown in Figure 2-4. In this example,
STP breaks the loop by blocking the connection between
Bridge B and C. The decision to block a particular