the first tcp/ip illustrated volume provides a very solid foundation for the low-level protocols, though there is probably some newer stuff and best-practices not covered in it (it was published in 94).
i've never read any books on the stuff, but i used to work at an isp and learned about larger-scale routing concepts just by gleaning it from cow-orkers. unless you're going to work at an isp or do network administration for a large network, you're probably not going to interact with bgp, eigrp, asn's and other concepts much, if any.
that said, you can subscribe to the nanog mailing list (be prepared for lots of boring "can someone from xyz network contact me off-list" threads), play around with the various public route servers available, and if you're really interested, setup a test network with openbgpd or quagga.
i've never read any books on the stuff, but i used to work at an isp and learned about larger-scale routing concepts just by gleaning it from cow-orkers. unless you're going to work at an isp or do network administration for a large network, you're probably not going to interact with bgp, eigrp, asn's and other concepts much, if any.
that said, you can subscribe to the nanog mailing list (be prepared for lots of boring "can someone from xyz network contact me off-list" threads), play around with the various public route servers available, and if you're really interested, setup a test network with openbgpd or quagga.