I tried to find a good way to illustrate packets in a simple protocol and went for the bytefield package for latex (pdf manual https://texdoc.org/serve/bytefield.pdf/0 ). It is a bit heavy, as if requiring latex wasn't heavy enough, so at first I dismissed it and thought there would be something simpler. But I couldn't find anything else that I liked so I stuck with it and think it was worthwhile in the end, the output looks great and is very clear.