3Com 7700 Configuration Manual page 178

170 C 8: STP O
HAPTER PERATION
bridge is configured as an edge port, RSTP will automatically detect and
reconfigure it as a non-EdgePort.
After the network topology changes, if a configured non-EdgePort changes to an
EdgePort and is not connected to any other port, you should configure it as an
EdgePort manually because RSTP cannot configure a non-EdgePort as an EdgePort
automatically.
Configure the port directly connected to the terminal as an EdgePort, so that the
port can transfer immediately to the forwarding state.
By default, all the Ethernet ports are configured as non-EdgePort.
Setting the Path Cost of the Specified Port
The path cost of Ethernet port is related to the speed of a link connected to the
port.
Perform the following configurations in Ethernet port view.
Table 12 Set the Path Cost of the Port
Operation
Set path cost of the specified port
Restore the default path cost of the
specified port
The path cost of an Ethernet port is related to its link speed. The higher the link
speed, the lower the path cost should be configured. RSTP can automatically
detect the link speed on the current Ethernet port and convert it to the
corresponding path cost. Note that configuring path cost of an Ethernet port
causes the recalculation of the spanning tree.The default value is recommended
and let RSTP calculate the path cost on the current Ethernet port.
By default, the bridge gets the path cost of a port according to the link speed
directly.
Setting the Priority of a Port
The port priority is an important point for deciding if the port can be a root port. In
the calculation of the spanning tree, the port with the highest priority will be
selected as the root assuming all other conditions are the same.
Perform the following configurations in Ethernet port view.
Table 13 Setting the Priority of a Specified Port
Operation
Set the priority of a specified
port
Restore the default priority of
the specified port
By setting the priority of an Ethernet port, you can put an Ethernet port into the
final spanning tree. Generally, the lower the value, the higher priority the port has
and the more likely it is that this Ethernet port will be included in the spanning
Command
stp cost cost
undo stp cost
Command
stp port priority port-priority
undo stp port priority