Seriously, Cisco Press. What is your problem? I used to think you were incompetent. Now I think you’re deliberately evil. They explicitly stated that transport layer traffic that uses UDP is called a “datagram.” That stands to reason. After all, UDP is a TLA for “User Datagram Protocol.” Then, immediately afterwards, they state (emphasis mine):
However, this book refers to data formed in the transport layer as a segment, data at the network layer as a datagram or packet, and data at the link layer as a frame.
No rhyme. No reason. Just fiat. “Hey, we know that it’s standard practice to call a specific type of Layer 4 traffic a datagram, but we’re gonna call Layer 3 traffic a datagram. Or we might also call it a packet too, JUST ‘CAUSE WE’RE GANGSTAH LIKE THAT!”
For those wondering, I’m brushing up on my networking knowledge by going through “Interconnecting Cisco Network Devices, Part 1 (ICND1): CCNA Exam 640-802 and ICND1 Exam 640-822 (2nd Edition)” It’s already caused me to make the first part in this series. A series which will likely have many sequels.
I’m not even halfway through it and already finding some annoying inconsistencies. I thought I left things like this behind when I stopped reading MS Press books. Apparently vendor endorsed books have a disproportionate amount of fail in them.