Learning by Doing: CISCO Certified Network ... - SCN Research

Figure 2—STP showing cost of 10.
6. We are looking at one with a cost of 110 because the 100 is added to the 10 for a total
cost between two devices. Our “pure” cost for that line is 10.
7. Let’s test the backup line. Unplug any one of the Ax/Bx cables that appears with
green lights on both ends. Within 60 seconds the redundant backbone line amber
light will turn green. This indicates the switch is going through the five STP states.
Repeat steps 2-4 to return cabling to their original settings.
Supplemental Activity or Challenge Lab:
1. Try doing this lab with as many switches as you can. Sounds silly but it can be
tricky.
2. Start a ping storm by using many very large icmp packets. See what this does to your
network performance and the time it takes for STP to bring up back up lines.
Geeze…you thought it took long before.
So What Have I Learned Here?
To set up redundant lines between switches we just need to know which ports to use for
best service. It really doesn’t matter which ones we use but certain ones are more
preferred to others. In the next lab we will change settings.
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