Bridge Protocol Data Units - D-Link DGS-3308TG User Manual

The following are the user-configurable STP parameters for the port or port group level:

Bridge Protocol Data Units

For STP to arrive at a stable network topology, the following information is used:
The unique switch identifier
The path cost to the root associated with each switch port
The port identifier
STP communicates between switches on the network using Bridge Protocol Data Units (BPDUs). Each BPDU contains the
following information:
The unique identifier of the switch that the transmitting switch currently believes is the root switch
Hello Time The length of time between
broadcasts of the hello message
by the switch
Maximum Age Measures the age of a received
Timer BPDU for a port and ensures
that the BPDU is discarded
when its age exceeds the value
of the maximum age timer.
Forward Delay The amount time spent by a
Timer port
listening states waiting for a
BPDU that may return the port
to the blocking state.
Table 5-7. STP Parameters – Switch Level
Variable Description
Port Priority
Port Cost
Table 5-8. STP Parameters – Port Group Level
switch – lower numbers give
a higher priority and
greater chance of a given
switch being elected as the
root bridge
in the learning
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
A value used by STP to
evaluate paths –
calculates path costs
selects the path with the
minimum cost as the active
path.
30
8-port Gigabit Ethernet Switch User's Guide
a
2 seconds
20 seconds
15 seconds
and
Default
Value
32768
19 – 100Mbps
STP Fast Ethernet
and ports
4 – 1000Mbps
Gigabit
Ethernet ports