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reconfigure. All device ports (except for designated ports) should receive
configuration messages at regular intervals. Any port that ages out STA
information (provided in the last configuration message) becomes the
designated port for the attached LAN. If it is a root port, a new root port
is selected from among the device ports attached to the network.
(References to “ports” in this section mean “interfaces,” which includes
both ports and trunks.)
-Default: 20
- Minimum: The higher of 6 or [2 x (Hello Time + 1)].
- Maximum: The lower of 40 or [2 x (Forward Delay - 1)]
• Forward Delay – The maximum time (in seconds) this device will wait
before changing states (i.e., discarding to learning to forwarding). This
delay is required because every device must receive information about
topology changes before it starts to forward frames. In addition, each
port needs time to listen for conflicting information that would make it
return to a discarding state; otherwise, temporary data loops might result.
-Default: 15
- Minimum: The higher of 4 or [(Max. Message Age / 2) + 1]
-Maximum: 30
Configuration Settings for RSTP
The following attributes apply to both RSTP and MSTP:
• Path Cost Method – The path cost is used to determine the best path
between devices. The path cost method is used to determine the range
of values that can be assigned to each interface.
- Long: Specifies 32-bit based values that range from 1-200,000,000.
(Thisisthedefault.)
- Short: Specifies 16-bit based values that range from 1-65535.
• Transmission Limit – The maximum transmission rate for BPDUs is
specified by setting the minimum interval between the transmission of
consecutive protocol messages. (Range: 1-10; Default: 3)
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