Also, about that undefined BGP. I'm not sure if this will help explain why BGP wasn't explained, but this is from NTT OSRG (Open-source Research Group), so probably they thought that everyone knew what BGP is (since that you probably won't encounter this otherwise).
Cloudflare has already a good explanation on how it works, so I'll just point everyone out to this article: https://www.cloudflare.com/learning/security/glossary/what-i...
Also, about that undefined BGP. I'm not sure if this will help explain why BGP wasn't explained, but this is from NTT OSRG (Open-source Research Group), so probably they thought that everyone knew what BGP is (since that you probably won't encounter this otherwise).
Also, they have a Rust version: https://github.com/osrg/rustybgp