If you’ve ever been responsible for a network, you know that sinking feeling: your pager has gone off at 2 a.m., the network is broken, and you can’t figure out why by using a dial-in connection from home. You drive into the office, dig out your protocol analyzer, and spend the next fourhours trying to put things back together before the staff shows up for work.When this happens, you often find yourself looking at the low-level guts of the Internet protocols: you’re deciphering individual packets, trying to figure out what is (or isn’t) happening. Until now, the only real guide to the protocols has been the Internet RFCs–and they’re hardlywhat you want to be reading late at night when your network is down. There hasn’t been a good book on the fundamentals of IP networking aimed at network administrators–until now.Internet Core Protocols: The Definitive Guide contains all the information you need for low-level network debugging. It provides thorough coverage of the fundamental protocols in the TCP/IP suite: IP, TCP, UDP, ICMP, ARP (in its many variations), and IGMP. (The companion volume, Internet Application Protocols: The Definitive Guide, provides detailed information about the commonly used application protocols, including HTTP, FTP, DNS, POP3, and many others). It includes many packet captures, showing you what to look for and how to interpret all the fields. It has been brought up to date with the latest developments in real-world IP networking. The CD-ROM included with the book contains Shomiti’s "Surveyor Lite, " a packet analyzer that runs on Win32 systems, plus the original RFCs, should you need them for reference. Together, this package includes everything you need to troubleshoot your network–except coffee.