H3C Technologies H3C WX3000 Series Unified Switches - Manual (Page 199)

22-30
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 22-7 Transmission speeds and the corresponding path costs
Transmission
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.
When calculating the path cost of an aggregated link, the 802.1D-1998 standard does not take the
number of the ports on the aggregated link into account, whereas the 802.1T standard does. The
following formula is used to calculate the path cost of an aggregated link:
Path cost = 200,000/ link transmission speed,