Switch User Manual

1-31
Configuring the Path Cost for a Port
The path cost parameter reflects the rate of the link connected to the port. For a port on an
MSTP-enabled device, the path cost may be different in different spanning tree instances. You can
enable flows of different VLANs to travel along different physical links by configuring appropriate path
costs on ports, so that VLAN-based load balancing can be implemented.
Path cost of a port can be determined by the device or through manual configuration.
Standards for calculating path costs of ports
Currently, the device can calculate the path costs of ports based on one of the following standards:
z dot1d-1998: Adopts the IEEE 802.1D-1998 standard to calculate the default path costs of ports.
z dot1t: Adopts the IEEE 802.1t standard to calculate the default path costs of ports.
z legacy: Adopts the proprietary standard to calculate the default path costs of ports.
Follow these steps to specify the standard for calculating path costs:
To do… Use the command… Remarks
Enter system view
system-view
—
Specify the standard for
calculating the default path
costs of the links connected to
the ports of the device
stp pathcost-standard
{ dot1d-1998 | dot1t | legacy }
Optional
By default, the legacy standard
is used to calculate the default
path costs of ports.
Table 1-7 Transmission speeds and the corresponding path costs
Transmissio
n speed
Operation mode
(half-/full-duplex)
802.1D-1998 IEEE 802.1t
Proprietary
standard
0
—
65,535 200,000,000 200,000
10 Mbps
Half-duplex/Full-duplex
Aggregated link 2 ports
Aggregated link 3 ports
Aggregated link 4 ports
100
95
95
95
200,000
1,000,000
666,666
500,000
2,000
1,800
1,600
1,400
100 Mbps
Half-duplex/Full-duplex
Aggregated link 2 ports
Aggregated link 3 ports
Aggregated link 4 ports
19
15
15
15
200,000
100,000
66,666
50,000
200
180
160
140
1,000 Mbps
Full-duplex
Aggregated link 2 ports
Aggregated link 3 ports
Aggregated link 4 ports
4
3
3
3
200,000
10,000
6,666
5,000
20
18
16
14
10 Gbps
Full-duplex
Aggregated link 2 ports
Aggregated link 3 ports
Aggregated link 4 ports
2
1
1
1
200,000
1,000
666
500
2
1
1
1
Normally, the path cost of a port operating in full-duplex mode is slightly less than that of the port
operating in half-duplex mode.