T
his chapter is dedicated to covering essential TCP/IP trouble-
shooting skills and tools. Generic commands such as
ping
and
traceroute
will be applied to network problems. We will also use the
debug
command
to provide insight into router interaction regarding the TCP/IP suite.
Problem isolation techniques that are used in troubleshooting LAN,
WAN, and routing protocols will be outlined and implemented. Routing
protocols that will be covered include RIP, IGRP, EIGRP, and OSPF.
In addition to detailed problem-solving techniques, quick reference sum-
mary charts are located at the end of the chapter. These tables help to quickly
associate a cause to many TCP/IP symptoms.
TCP/IP Router Diagnostic Tools
S
everal tools exist to aid in detecting and isolating TCP/IP suite prob-
lems. Some of these tools were mentioned in previous chapters, and some are
new as they apply to the TCP/IP suite.
Because the TCP/IP suite of protocols is so extensively used, numerous
troubleshooting targets can be identified and analyzed. Each of these targets
requires a different set of diagnostic tools to effectively identify and isolate
failures.
ping
and
traceroute
Commands
These tools can easily be used in TCP/IP networks to test for reachability and
hop-by-hop path connectivity. It is important to use these two tools in con-
junction. It may be possible to ping a certain device, but perhaps the ICMP
requests are taking the wrong route to the host.
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