DES-3326S Layer 3 Fast Ethernet Switch User’s Guide
transmissions of BPDU packets sent by the Root Bridge to tell all other Switches that it is indeed the Root Bridge. If you set a Hello Time for your Switch, and it is not the Root Bridge, the set Hello Time will be used if and when your Switch becomes the Root Bridge.
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.
66 | Switch Management and Operating Concepts |
