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User’s Manual of FGSW-2620VM / FGSW-2620PVM
77
4.5.2 STP Parameters
STP Operation Levels
The Switch allows for two levels of operation: the switch level and the port level. The switch level forms a spanning tree
consisting of links between one or more switches. The port level constructs a spanning tree consisting of groups of one or
more ports. The STP operates in much the same way for both levels.
On the switch level, STP calculates the Bridge Identifier for each switch and then sets the Root
Bridge and the Designated Bridges.
On the port level, STP sets the Root Port and the Designated Ports.
The following are the user-configurable STP parameters for the switch level:
Parameter Description Default Value
Bridge Identifier(Not user
configurable
except by setting priority
below)
A combination of the User-set priority and
the switch’s MAC address.
The Bridge Identifier consists of two parts:
a 16-bit priority and a 48-bit Ethernet MAC
address 32768 + MAC.
32768 + MAC
Priority
A relative priority for each switch – lower
numbers give a higher priority and a greater
chance of a given switch being elected as
the root bridge.
32768
Hello Time
The length of time between broadcasts of
the hello message by the switch.
2 seconds
Maximum Age Timer
Measures the age of a received BPDU for a
port and ensures that the BPDU is discarded
when its age exceeds the value of the
maximum age timer.
20 seconds
Forward Delay Timer
The amount time spent by a port in the
learning and listening states waiting for a
BPDU that may return the port to the
blocking state.
15 seconds
The following are the user-configurable STP parameters for the port or port group level:
Variable Description Default Value
Port Priority
A relative priority for each
port –lower numbers give a higher priority
and a greater chance of a given port being
elected as the root port.
128