User`s manual

The lower the assigned port path cost is, the more likely that port will be accessed. The default port path cost for a 10
Mbps or 100 Mbps port is the result of the equation:
Path cost = 1000/LAN speed (in Mbps)
Therefore, for 10 Mbps ports, the default port path cost is 100. For 100 Mbps ports, it is 10. To allow for faster
networks, the port path cost for a 1000 Mbps port is set by the standard at 4.
The default values for path cost is determined by the operating port speed:
• For ports operating in 1000Mb speed, the path cost is 20000
• For ports operating in 100Mb speed, the path cost is 200000
• For ports operating in 10Mb speed, the path cost is 2000000
To configure spanning-tree, click on the STP Port Configuration hyperlink.
Use the scroll bar on the right side of the screen to view additional ports. The following example shows setting port 7
priority to 99 using the STP Port Configuration screen.
9.4.2 Global STP Bridge Configuration
All of the bridges (a switch is a complex bridge) on the network communicate with each other using special packets of
data called Bridge Protocol Data Units (BPDUs). The information exchanged in the BPDUs allows the bridges on the
network to do the following:
• Elect a single bridge to be the root bridge
• Calculate the shortest path from each bridge to the root bridge
• Select a designated bridge on each segment, which lies closest to the root and forwards all traffic to it
• Select a port on each bridge to forward traffic to the root
83 Asante IntraCore IC36240 User’s Manual