I'm having trouble understanding the second diagram in the article. I can make sense of a directed graph, but this one has thin horizontal lines with arrows leaving them in both directions. These lines look like dividers, not nodes, so I'm not sure how to interpret it.

I think the intention is to show the divide between Amazon's and Cloudflare's responsibility, over the piece of fibre linking their network devices together. It would have been clearer to continue the lines and just put a dotted divider between them I feel.