3Com Switch 7750 Configuration Guide Guide

244 CHAPTER 29: MSTP CONFIGURATION
Path cost = 200,000,/ link transmission speed,
Where the link transmission speed is the sum of the speeds of the unblocked ports
on the aggregated link, which is measured in 100 Kbps.
Configuring the path costs of ports
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.
Configuration example (A)
# Configure the path cost of Ethernet1/0/1 port in spanning tree instance 1 to be
2,000.
1 Configure in system view.
<SW7750> system-view
[SW7750] stp interface ethernet1/0/1 instance 1 cost 2000
2 Configure in Ethernet port view.
<SW7750> system-view
[SW7750] interface ethernet1/0/1
[SW7750-Ethernet1/0/1] stp instance 1 cost 2000
Configuration example (B)
# Change the path cost of Ethernet1/0/1 port in spanning tree instance 1 to the
default one calculated with the IEEE 802.1D-1998 standard.
1 Configure in system view.
<SW7750> system-view
[SW7750] stp pathcost-standard dot1d-1998
2 Configure in Ethernet port view.
<SW7750> system-view
[SW7750] interface ethernet1/0/1
Tabl e 175 Configure the path cost for specified ports in system view
Operation Command Description
Enter system view system-view -
Configure the path cost for
specified ports
stp interface interface-list [
instance instance-id ] cost
cost
Required
A MSTP-enabled switch can
calculate path costs for all its
ports automatically.
Tabl e 176 Configure the path cost for a port in Ethernet port view
Operation Command Description
Enter system view system-view -
Enter Ethernet port view
interface interface-type
interface-number
-
Configure the path cost for
the port
stp [ instance instance-id ]
cost cost
Required
A MSTP-enabled switch can
calculate path costs for all its
ports automatically.