The mechanics of producing your book - the typesetting system
Unlike some other publishers, we very strongly prefer you to produce "camera ready copy" ("CRC"): from experience, we know this works best, and makes the process of writing quicker and more satisfying for you. Our typesetting system of choice is LaTeX. This is free software, and available for just about every platform, but see below if you hate LaTeX. (If you don't want to or can't produce camera ready copy, it's not a show stopper: we can of course typeset your finished manuscript.)
For diagrams, we prefer Inkscape, which is a free, WYSIWYG, SVG (Scalable Vector Graphics) graphics editor. (If you use Adobe Illustrator and can output SVG format, that may also be suiitable.) We have a large set of standard Inkscape components that you can use for diagrams of computer networks, etc., and a set of guidelines for diagrams.
If you prefer non-WYSIWYG graphics (and they can make it much easier to maintain a consistent style of illustration over a whole book), consider MetaPost, which works extremely well with LaTeX, and is free.
We provide style guidelines, and a skeleton document that you fill in with your material. The camera-ready copy that you produce is in PostScript or PDF format. We use what you produce more or less as is.
Because CRC makes the production process easier for us, as well as you, we pay a higher royalty rate for CRC books.