3com MSR 20-20 참조 매뉴얼

In the calculation of the path cost value of an aggregated link, 802.1D-1998 does 
not take into account the number of ports in the aggregated link. Whereas, 
802.1T takes the number of ports in the aggregated link into account. The 
calculation formula is: Path Cost = 200,000,000/link speed (in 100 kbps), where 
link speed is the sum of the link speed values of the non-blocked ports in the 
aggregated link.

# Configure the device to calculate the default path cost for ports based on IEEE 
802.1D-1998.

<Sysname> system-view

[Sysname] stp pathcost-standard dot1d-1998 

# Configure the device to calculate the default path cost for ports based on IEEE 
802.1t.

<Sysname> system-view

[Sysname] stp pathcost-standard dot1t 

stp point-to-point { auto | force-false | force-true }

undo stp point-to-point

Ethernet interface view, port group view

100Mbps 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 

1000Mbps Single 

Port

Aggregated 
Link 2 Ports

Aggregated 
Link 3 Ports

Aggregated 
Link 4 Ports 

4

4

4

4 

20,000

10,000

6,666

5,000 

20

18

16

14 

10Gbps Single 

Port

Aggregated 
Link 2 Ports

Aggregated 
Link 3 Ports

Aggregated 
Link 4 Ports 

2

2

2

2 

2,000

1,000

666

500 

2

1

1

1

Table 110   Link speed vs. path cost