I work in a Mobile Telephony Switching Environment, and rapidly, my switch floor is filling up with Black boxes with the Cisco Brand name on them. So I decided its about time I started finding out what these boxes do. While being slightly disappointed that the book is very US centric- always mentioning T1's T3's and SONET standards to the almost total exclusion of E1's and SDH, it is still a very readable, accessible and informative text. The example and figures give good background to the concepts covered. All things said and done I have found little to fault this book (other than the US thing) and would recommend it to anyone setting out to find out more about Cisco technology. A colleague of mine is starting down the CCNA route and having looked at it himself was very impressed with what it covers- better than the recommended reading for his course he said!