166 CHAPTER 10 Network Troubleshooting Troubleshooting bridges and switches Ensure to follow the 80/20 rule, which states that 80 percent of network traffic should be local (occurring on the same side of the bridge or switch), and not more than 20 percent should cross the bridge or switch. Looping can occur when there is more than one active bridge or switch on a network and the bridges and switches don't know the location of a destination computer. Be sure to use the Spanning Tree Protocol when multiple bridges exist on the network. TROUBLESHOOTING THE NETWORK LAYER When troubleshooting the network layer, you'll be most concerned with routers and TCP/IP addressing. Troubleshooting routers Check for configuration errors or misconfiguration issues on each router Check for a routing loop by using the tracert or traceroute command Verify that a route exists to the destination network