Found in 2 comments on Hacker News
mmaunder · 2022-03-05 · Original thread
This is known as the BGP book:

It goes into detail. If you're just starting out, get a Network+, Security+ or any other systems administration, security or networking certification that covers the basics of networking and internetworking.

eddyg · 2021-07-08 · Original thread
Well that was not what I expected. (Especially the “there’s really nothing difficult” part.)

If you really want to understand BGP, read

or, if you’re looking for something online:

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