3Com Switch 4800G 24-Port - Page 225

Configuring Leaf Nodes 225
Configuring the
Maximum Transmission
Rate of Ports
Refer to “Configuring the Maximum Transmission Rate of Ports” on page 220 in
the section about root bridge configuration.
Configuring Ports as
Edge Ports
Refer to “Configuring Ports as Edge Ports” on page 221 in the section about root
bridge configuration.
Configuring Path Costs
of Ports
Path cost is a parameter related to the rate of port-connected links. On an
MSTP-compliant device, ports can have different priorities in different MST
instances. Setting an appropriate path cost allows VLAN traffic flows to be
forwarded along different physical links, thus to enable per-VLAN load balancing.
The device can automatically calculate the default path cost; alternatively, you can
also configure the path cost for ports.
Specifying a standard that the device uses when calculating the default
path cost
You can specify a standard for the device to use in automatic calculation for the
default path cost. The device supports the following standards:
■ dot1d-1998: The device calculates the default path cost for ports based on
IEEE 802.1d-1998.
■ dot1t: The device calculates the default path cost for ports based on IEEE
802.1t.
■ legacy: The device calculates the default path cost for ports based on a private
standard.
Follow these steps to specify a standard for the device to use when calculating the
default path cost:
To do… Use the command… Remarks
Enter system view system-view -
Specify a standard for the device to use
when calculating the default path cost of
the link connected with the device
stp pathcost-standard
{ dot1d-1998 | dot1t |
legacy }
Optional
legacy by default
Table 43 Link speed vs. path cost
Link speed Duplex state 802.1d-1998 802.1t Private standard
0 - 65535 200,000,000 200,000
10 Mbps Single Port
Aggregated Link 2 Ports
Aggregated Link 3 Ports
Aggregated Link 4 Ports
100
100
100
100
2,000,000
1,000,000
666,666
500,000
2,000
1,800
1,600
1,400
100 Mbps Single Port
Aggregated Link 2 Ports
Aggregated Link 3 Ports
Aggregated Link 4 Ports
19
19
19
19
200,000
100,000
66,666
50,000
200
180
160
140