PLANET FGSW-2840 - Manual (Page 121)

User’s Manual of FGSW-2840 / FGSW-4840S
121
Enter a value from 1 to 10 in seconds to specify the interval to send BPDU
packets. It is used to test the links. 2*(Hello Time + 1) ≤ Max Age. The default
value is 2 seconds.
 Hello Time
Enter a value from 6 to 40 in seconds to specify the maximum time the Managed
Switch can wait without receiving a BPDU before attempting to reconfigure. The
default value is 20 seconds.
 Max Age
Enter a value from 4 to 30 in seconds to specify the time for the port to transit its
state after the network topology is changed. 2*(Forward Delay-1) ≥ Max Age. The
default value is 15 seconds.
 Forward Delay
Enter a value from 1 to 20 to set the maximum number of BPDU packets
transmitted per Hello Time interval. The default value is 5pps.
 TxHoldCount
Enter a value from 1 to 40 to set the maximum number of hops that occur in a
specific region before the BPDU is discarded. The default value is 20 hops.
 Max Hops
Buttons
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 The forward delay parameter and the network diameter are correlated. A too small forward
delay parameter may result in temporary loops. A too large forward delay may cause a network
unable to resume the normal state in time. The default value is recommended.
 An adequate hello time parameter can enable the Managed Switch to discover the link failures
occurred in the network without occupying too much network resources. A too large hello time
parameter may result in normal links being regarded as invalid when packets drop occurred in
the links, which in turn result in spanning tree being regenerated. A too small hello time
parameter may result in duplicated configuration being sent frequently, which increases the
network load of the switches and wastes network resources. The default value is
recommended.
 A too small max age parameter may result in the switches regenerating spanning trees
frequently and cause network congestions to be falsely regarded as link problems. A too large
max age parameter result in the switches unable to find the link problems in time, which in turn
handicaps spanning trees being regenerated in time and makes the network less adaptive. The
default value is recommended.
 If the TxHold Count parameter is too large, the number of MSTP packets being sent in each
hello time may be increased with occupying too much network resources. The default value is
recommended.