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Appendix B: Ping and TCP/IP Debugging Tools
Appendix B. Ping and TCP/IP Debugging Tools
What is TCP/IP: TCP/IP is set of standards first developed by
ARPA (USA DOD’s Advance Research Projects Agency) that
define how information is routed over the Internet. And because
of its Internet popularity, TCP/IP is the most popular protocol
operating over twisted-pair cabling and therefore is the most
popular protocol used by Ethernet (the standard for local area
networking).
Why learn about TCP/IP: Once the LPV has established that
your cables and network devices are working at the hardware
level, your next step is to check out the software level of your
network. Understanding the basics of TCP/IP and gaining a
familiarity with your operating system's built-in network
debugging tools helps you diagnose and troubleshoot network
problems at the software level.
TCP/IP basics: TCP/IP has 4 layers:
1. The lowest layer is the Physical layer that deals with cabling.
2. The next layer is the Internet layer. This is the IP layer (internet
protocol) and it describes the assigning of an IP address to
each data packet that is transmitted (all data on the internet
must have a destination address associated with it and this is
referred to as an IP address. The address can refer to a
workstation on your local network or a server on the Internet
thousands of miles away.
3. The next layer is the Transport layer. Because data packets can
travel through networks and the Internet using many different
routes, they will not necessarily arrive in the same order as
they were sent. There needs to be a mechanism that reassem-
bles the packets in the proper sequence. This is the job of the
“TCP” (transmission control protocol), and it resides in this
layer.
4. Layer 4, the highest layer, is the Application layer. This is
where Ethernet and many other software tools reside.