Below is the file 'PROCESS' from this revision. You can also download the file.

Design.

We want to find the L2/L3 path from host A to host B.

We know the IP address of host A.
Look up the MAC address of host A using the ARP tables on the router for the router servicing the subnet containing host A.
Use our adjacency information to find out which switch the router is plugged into for that VLAN.