Information Technology Reference
In-Depth Information
7
CHAPTER
Troubleshooting TCP/IP
The sections in this chapter describe common features of TCP/IP and provide solutions to some of the
most common TCP/IP problems. The following items will be covered:
TCP/IP Introduction
•
Tools for Troubleshooting IP Problems
•
General IP Troubleshooting Theory and Suggestions
•
Troubleshooting Basic IP Connectivity
•
Troubleshooting Physical Connectivity Problems
•
Troubleshooting Layer 3 Problems
•
Troubleshooting Hot Standby Router Protocol (HSRP)
•
TCP/IP Introduction
In the mid-1970s, the Defense Advanced Research Projects Agency (DARPA) became interested in
establishing a packet-switched network to provide communications between research institutions in the
United States. DARPA and other government organizations understood the potential of packet-switched
technology and were just beginning to face the problem that virtually all companies with networks now
have—communication between dissimilar computer systems.
With the goal of heterogeneous connectivity in mind, DARPA funded research by Stanford University
and Bolt, Beranek, and Newman (BBN) to create a series of communication protocols. The result of this
development effort, completed in the late 1970s, was the Internet Protocol suite, of which the
Transmission Control Protocol (TCP) and the Internet Protocol (IP) are the two best-known protocols.
The most widespread implementation of TCP/IP is IPv4 (or IP version 4). In 1995, a new standard, RFC
1883—which addressed some of the problems with IPv4, including address space limitations—was
proposed. This new version is called IPv6. Although a lot of work has gone into developing IPv6, no
wide-scale deployment has occurred; because of this, IPv6 has been excluded from this text.
Internet Protocols
Internet protocols can be used to communicate across any set of interconnected networks. They are
equally well suited for local-area network (LAN) and wide-area network (WAN) communications. The
Internet suite includes not only lower-layer specifications (such as TCP and IP), but also specifications
for such common applications as e-mail, terminal emulation, and file transfer. Figure 7-1 shows some of
the most important Internet protocols and their relationships to the OSI reference model.
