Chapter 2 focuses specifically on how Ethernet works.
From defining broadcast domains to dealing with ethernet frame MAC addressing, he begins with the foundational basics. He talks about duplex and speed for negotiating the connection, which both sides of the link need to agree upon.
He explains MTU (maximum transmission unit) and why mucking with reducing it below the default is almost certainly going to be problematic. He also suggests ways to deal with situations where you can’t help but do so.
Lucas follows up with a quick explanation about the differences in category numbering for the wires that handle the transmissions. The higher the number, the better, but higher costs can be prohibitive. Work with what you can, but plan for higher when you can.
He moves into a quick explanation for using several troubleshooting tools, such as ping, arp, and “neighborhood discovery” (ND.)
Finally, he covers Virtual LANs (VLANs) to add a tag to an Ethernet Frame. This allows traffic for multiple networks to flow over a single cable, without confusing where the packet should go.
He sprinkles in some more troubleshooting tools such as netstat, as well as tools to configure the ethernet layer (ifconfig and ethtool,) before closing the chapter out.
This chapter is important for the fundamentals of the “Data Link” layer (and to some extent the Physical Layer.) Next week’s chapter covers “Layer 3” (Network Layer.) This is mostly the “IP” layer in “TCP/IP” terms.
Thanks for reading!