BPDU Fields
Some of the fields in the BPDU include:
■ Root bridge ID—The BID of the current root.
■ Sender’s root path cost—The cost to the root.
■ Sender’s bridge ID—Sender’s priority concatenated to MAC.
■ Sender’s port ID—The port number, transmitted as final tie-breaker.
■ Hello time—Two seconds by default.
■ Forward Delay—15 seconds by default.
■ Max Age—20 seconds by default.