Dear Sir or Madam:
A basic understanding of LAN and WAN technologies and related products–especially those your company already uses or plans to acquire in the next 12-24 months–is probably essential to your ability to function well as a manager over such areas. That said, you can probably get most of what you need to know out of a couple or three good books on the subject. Likewise, a decent working knowledge of TCP/IP (the protocol suite that enables the Internet and most private networks to function) is also essential.
As it happens, I’ve written a couple of textbooks in this area, both for Course Technology: Networking Essentials (4th edition) and Guide to TCP/IP (3rd edition). You could do worse than to read those, but you should also look into Andrew Tanenbaum’s Computer Networking book (the latest version I’ve got is the fourth, but there may be a 5th edition out by now), and Jeffrey Beasley’s Networking , 2e. On the TCP/IP side, Charlese Kozierok’s TCP/IP Guide is a phenomenal reference, and Douglas Comer’s TCP/IP (volume 1) is probably the best-known and most respected introduction to that subject matter around. You might also want to consider purchasing a Network+ prep book (for the CompTIA exam of the same name) and working through that material as well.
In the interim, you’ll have no choice but to rely on your techs. Make it clear you’ll be working hard to come up to speed, and let them know you will do your best to develop sufficient technical background to understand your job fully and fairly.
Good luck in your new position. It sounds like you’re going to be broadening your technical and business horizons!