The best way to learn about the Internet is to focus on that part, ignoring the local network. This tool read a pcap file and strips out the local Ethernet information. This means stripping out things that are purely Ethernet, like bridging protocols and ARP. It also means stripping out anything before the IP header.
robertdavidgraham/pcap-strip
Strips out datalink headers (like Ethernet), leaving behind just the raw IP packets.