3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring Leaf Nodes 123
Configuration example I
# Configure the path cost of Ethernet 1/1/1 in MST instance 1 to 2000.
<Sysname> system-view
[Sysname] interface ethernet 1/1/1
[Sysname-Ethernet1/1/1] stp instance 1 cost 2000
Configuration example II
# Configure MSTP to automatically calculate the path cost of Ethernet 1/1/1 based
on the IEEE 802.1D-1998 standard.
<Sysname> system-view
[Sysname] interface ethernet 1/1/1
[Sysname-Ethernet1/1/1] undo stp instance 1 cost
[Sysname-Ethernet1/1/1] quit
[Sysname] stp pathcost-standard dot1d-1998
Configuring Port Priority The priority of a port is an import basis that determines whether the port can be
elected as the root port of device. If all other conditions are the same, the port
with the highest priority will be elected as the root port.
On an MSTP-compliant device, a port can have different priorities in different MST
instances, and the same port can play different roles in different MST instances, so
that data of different VLANs can be propagated along different physical paths,
thus implementing per-VLAN load balancing. You can set port priority values
based on the actual networking requirements.
Configuration procedure
Follow these steps to configure the priority of a port or a group of ports:
n
■ When the priority of a port is changed, MSTP will re-compute the role of the
port and initiate a state transition.
■ Generally, a lower configured value priority indicates a higher priority of the
port. If you configure the same priority value for all the Ethernet ports on the a
device, the specific priority of a port depends on the index number of that port.
Changing the priority of an Ethernet port triggers a new spanning tree
computing process.
To do... Use the command... Remarks
Enter system view system-view -
Enter Ethernet
interface view
or port group
view
Enter Ethernet
interface view
interface interface-type
interface-number
User either command
Configured in Ethernet
interface view, the setting is
effective on the current port
only; configured in port
group view, the setting is
effective on all ports in the
port group
Enter port
group view
port-group { manual
port-group-name |
aggregation agg-id }
Configure port priority stp [ instance instance-id ]
port priority priority
Optional
128 for all Ethernet ports by
default