Good book on VPN?

I'll be the first to say I despise VPN.

We stay so far away from it because we work heavily in RDS and SharePoint so VPN has never really been the top product we go after.

As we move a lot more into multisite, even with RDS we're doing a lot more site to site VPN with hardware devices. That thankfully is simple.

Client side VPN seems to be a constant struggle. I have a basic understanding of it, and an excellent understanding of networking, but really lack on the how's and why's of VPN.

3 new clients all with quite a few Mac's and we need VPN. That adds a whole other level to this and I'm not getting anywhere without truly understanding everything.

Seems like VPN could withstand a massive simplification, when I look at the OSX VPN client we're using there are 50 unique options to be set.

So I'm looking for a recommendation on a good book on VPN, SSL, IPSEC, etc...something that explains what each of those options are, what they mean, why they are there. The problem is most guides are how-to's, not why-to's.

I found this one http://www.amazon.com/Demystifying-Puzzle-Artech-Computer-Security/product-reviews/1580530796/ref=cm_cr_dp_see_all_btm?ie=UTF8&showViewpoints=1&sortBy=bySubmissionDateDescending

But that's about it. Lot of Cisco books out there but we do not use Cisco and I prefer to focus on the concept rather than a specific product.

Thanks