Planet WGS-4215 Series User Manual page 172

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
Bridge Identifier(Not user
configurable
except by setting priority
below)
Priority
Hello Time
Maximum Age Timer
Forward Delay Timer
Description
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
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
The length of time between broadcasts of
the hello message by the switch
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.
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.
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User's Manual of WGS Managed Series
Default Value
32768 + MAC
32768
2 seconds
20 seconds
15 seconds