An excellent book on using Linix to build routers. It provides a very through description of how to use ipchains in conjunction with forwarding, masquarading, accounting, etc.
The book is organized around chapters which describe how to build: a LAN router,an extranet router, a frame relay router, an internet router, a satellite office router, and an internet services router.
The book would make an excellent basis for a series of lab exercises.
Another excellent feature is appendix C, which describes how one can use VMware to experiment with virtual network configurations.
Students (and instructors) should be aware that there are some minor typos in the text and diagrams - for example figure C.1 has two subnets labelled "A", the righthand one should be "B".