Browse Books

Reviewer: John George Fletcher

This book provides an extremely broad, although often shallow, discussion and explanation of the increasingly widespread TCP/IP protocol suite. It is therefore certain to become quite popular. The book proceeds in a bottom-up fashion. The chapters cover (1) introduction and overview, (2) review of underlying network technologies, (3) internetworking concept and architectural model, (4) internet addresses, (5) mapping internet addresses to physical addresses (ARP), (6) determining an internet address at startup (RARP), (7) internet protocol: connectionless datagram delivery (IP), (8) routing IP datagrams, (9) internet protocol: error and control messages (ICMP), (10) protocol layering, (11) user datagram protocol, (12) reliable stream transport service (TCP), (13) the core gateway system (GGP), (14) autonomous systems and confederations (EGP), (15) interior gateway protocols (RIP, HELLO, GATED), (16) transparent gateways and subnet addressing, (17) client-server model of interaction, (18) the domain name system, (19) application level services, and (20) internet research and engineering problems. The presentation is very clear and without obvious errors. It is recommended to those who want to understand the general structure of TCP/IP protocols and their message formats. The book fails, however, in two related ways. First of all, for someone who would like to understand the rationale of the TCP/IP design—why one design choice was made rather than another—it often gives no clue; one wonders whether the designers were aware of all the available alternatives. In some areas a knowledgeable reader would prefer more detail on the workings of a protocol, if only to learn how certain pitfalls that are not noted in the text have been avoided (if indeed they have). This lack of depth leads to the second failure: the book is not, as it claims to be, a good textbook for learning about networking. A textbook is expected to cover not just one but all of the major techniques for achieving a given purpose, and is supposed to explain the necessity of the various features and steps in a protocol; it should also compare and contrast protocol features with similar concepts from other parts of computer science and indicate the generality from which specific features derive. Finally, it should use as examples protocols that represent what is best technically, a requirement that the TCP/IP suite cannot meet all (perhaps not even most) of the time. Including the necessary material among the book's many exercises, which is done in only some cases, is insufficient: exercises should be for using and extending, not for acquiring, a basic core of understanding. A few of the many points lacking adequate discussion follow: why instead of a single address leading directly to a process, two addresses handled by two protocols are used; a general model of hierarchical addresses and routing algorithms for them (which should be of logarithmic complexity); making links reliable as an alternative to testing them with special packets; why the bottom four layers of the TCP/IP suite are not mapped one-to-one onto the bottom four layers of the ISO model (since it seems that the only difficulty is a confusion about the meaning of the word “network”); why IP addresses are checksummed twice (once in each of two layers); how timer-based protocols work and why TCP uses handshaking instead; just what hazards (e.g., replay) a transport layer protocol must avoid and how handshaking avoids them; why the Internet hierarchical naming structure for computers is not integrated with the one for files; and why the two schemes present their path names in opposing order.