3Com 4200G 12-Port Configuration Manual page 148

134 C 20: MSTP C
HAPTER
Port Priority
Configuration
ONFIGURATION
Configure in Ethernet port view.
■
<S4200G> system-view
System View: return to User View with Ctrl+Z.
[4200G] interface GigabitEthernet1/0/1
[4200G-GigabitEthernet1/0/1] stp instance 1 cost 2000
Configuration example (B)
1 Change the path cost of GigabitEthernet1/0/1 port in spanning tree instance 1 to the
default one calculated with the IEEE 802.1D-1998 standard.
Configure in system view.
■
<S4200G> system-view
System View: return to User View with Ctrl+Z.
[4200G] undo stp interface GigabitEthernet1/0/1 instance 1 cost
[4200G] stp pathcost-standard dot1d-1998
Configure in Ethernet port view.
■
<S4200G> system-view
System View: return to User View with Ctrl+Z.
[4200G] interface GigabitEthernet1/0/1
[4200G-GigabitEthernet1/0/1] undo stp instance 1 cost
[4200G-GigabitEthernet1/0/1] quit
[4200G] stp pathcost-standard dot1d-1998
Port priority is an important criterion on determining the root port. In the same
condition, a port with higher port priority is more potential to become the root port
than another port with lower priority.
A port on a MSTP-enabled switch can have different port priorities and play different
roles in different spanning tree instances. This enables packets of different VLANs to
be forwarded along different physical paths, so that load balancing can be achieved
by VLANs.
You can configure port priority in the following two ways.
Configuring port priority in system view
Table 107 Configure port priority for specified ports in system view
Operation
Enter system view
Configure port priority
for specified ports
Configuring port priority in Ethernet port view
Table 108 Configure port priority for a specified port in Ethernet port view
Operation
Enter system view
Enter Ethernet port
view
Configure port priority
for the port
Changing port priority of a port may change the role of the port and put the port into
state transition.
Command
system-view
stp interface interface-list
instance instance-id port
priority priority
Command
system-view
interface interface-type
interface-number
stp [ instance instance-id ] port
priority priority
Description
—
Required
The default port priority is 128.
Description
—
—
Required.
The default port priority is 128.