4000 Router Series Layer 2 - LAN Switching Configuration Guide

Configuring path costs of ports

Step Command Remarks

1. Enter system view.

system-view N/A

2. Enter Layer 2 Ethernet

interface view.

interface interface-type interface-number N/A

3. Configure the path cost of the

ports.

• In STP/RSTP mode:

stp cost cost

• In MSTP mode:

stp [ instance instance-list ] cost cost

By default, the system

automatically calculates the

path cost of each port.

NOTE:

hen the path cost of a port chan

es, the system re-calculates the role of the port and initiates a state

transition.

Configuration example

# In MSTP mode, specify the device to calculate the default path costs of its ports by using IEEE

802.1d-1998, and set the path cost of Ethernet 2/3 to 200 on MSTI 2.

<Sysname> system-view

[Sysname] stp pathcost-standard dot1d-1998

Cost of every port will be reset and automatically re-calculated after you change the

current pathcost standard. Continue?[Y/N]:y

Cost of every port has been re-calculated.

[Sysname] interface ethernet 2/3

[Sysname-Ethernet2/3] stp instance 2 cost 200

Configuring the port priority

The priority of a port is a factor that determines whether the port can be elected as the root port of a

device. If all other conditions are the same, the port with the highest priority is elected as the root port.

On a spanning tree device, a port can have different priorities and play different roles in different

spanning trees, so that data of different VLANs can be propagated along different physical paths,

implementing per-VLAN load balancing. You can set port priority values based on the actual networking