3com S7906E Manuel De Montage

 

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If you change the standard that the device uses in calculating the default path cost, the port path 
cost value set through the stp cost command will be invalid. 

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When the path cost of a port is changed, MSTP will re-calculate the role of the port and initiate a 
state transition. If you use 0 as instance-id, you are setting the path cost of the CIST. 

 

# Specify that the device use 802.1d-1998 when calculating the default path costs of its ports. 

<Sysname> system-view 

[Sysname] stp pathcost-standard dot1d-1998 

# Set the path cost of GigabitEthernet 2/0/3 on MSTI 2 to 200.  

<Sysname> system-view 

[Sysname] interface gigabitethernet 2/0/3 

[Sysname-GigabitEthernet2/0/3] stp instance 2 cost 200 

The priority of a port is an important factor in determining whether the port can be elected as the root 
port of a device. If all other conditions are the same, the port with the highest priority will be elected as 
the root port. 

On an MSTP-enabled device, a port can have different priorities in different MSTIs, and the same port 
can play different roles in different MSTIs, so that data of different VLANs can be propagated along 
different physical paths, thus implementing per-VLAN load balancing. You can set port priority values 
based on the actual networking requirements. 

Make this configuration on the leaf nodes only.  

Follow these steps to configure the priority of a port or a group of ports: 

Enter system view 

 

— 

Enter Ethernet interface 
view, or Layer 2 
aggregate interface 
view 

interface interface-type 
interface-number 

Enter 
interface view 
or port group 
view 

Enter port group view 

port-group manual 
port-group-name 

Required 
Use either command. 

Configure the port priority 

[ instance 

instance-id 

] port priority 

 

Optional 
128 for all ports by default.