3com 5500-ei pwr Instrução De Instalação

 

1-31 

1,000 Mbps 

Full-duplex 
Aggregated link 2 ports 
Aggregated link 3 ports 
Aggregated link 4 ports 

4 
3 
3 
3 

20,000 
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 

2,000 
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 = 200,000,000 / link transmission rate 

Where, “link transmission rate” is the sum of the rates of all the unblocked ports on the aggregated link 
measured in 100 Kbps. 

Follow these steps to configure the path cost for specified ports in system view: 

Enter system view 

— 

Configure the path cost for 
specified ports 

 interface-list 

[ instance instance-id ] cost 
cost

 

Required 
An MSTP-enabled switch can 
calculate path costs for all its 
ports automatically. 

 

Follow these steps to configure the path cost for a port in Ethernet port view: 

Enter system view 

— 

Enter Ethernet port view 

 interface-type 

 

— 

Configure the path cost for the 
port 

 [ instance instance-id ] 

 cost 

Required 
An MSTP-enabled switch can 
calculate path costs for all its 
ports automatically. 

 

Changing the path cost of a port may change the role of the port and put it in state transition. Executing 
the stp cost command with the instance-id argument being 0 sets the path cost on the CIST for the port. 

# Configure the path cost of Ethernet 1/0/1 in MSTI 1 to be 2,000.