 To summarize, what we have to do at each layer is to look at the function of each layer. For example, function of physical layer is to provide connectivity, right? So ensure that all the wires are in place, the switches are turned on, etc. The function of network layer is to route packets to the correct network, to the correct on the correct path, etc. And there are tools available, some of which we saw already, use those tools to verify that each layer is actually performing those functions correctly. Now let us actually do some troubleshooting.