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•
A second alternative is to use the configuration and test software provided by the adapters manufacturer. If you bought the adapter as a separate purchase, you probably already have
this software. If your adapter came with your computer, you may have to go to the manufacturers web page and download the software. This approach can be helpful,
particularly with configuration errors. For example, a combination adapter might be configured for coaxial cable while you are trying to use it with twisted pair. You may be able
to change interrupts, DMA channels, memory locations, bus mastering configuration, and framing types with this software.
Using diagnostic software has a couple of limitations. First, the software may not check for some problems and may seemingly absolve a faulty card. Second, the software may not be
compatible with the operating system you are using. This is particularly likely if you are using something like Linux or FreeBSD on an Intel platform.
•
The third alternative is to swap the card for one that is known to work. This presumes that you have a spare card or are willing to remove one from another machine. It also presumes
that you arent having problems that may damage some other component in the computer or the new card. Even though I generally keep spare cards on hand, I usually leave this test until
last whenever possible.
3.3 Software Testing with ping
Thus far, I have described ways to examine electrical and mechanical problems. The tools described in this section, ping and its variants, focus primarily on the software problems and the interaction of
software with hardware. When these tools successfully communicate with remote systems, you have established basic connectivity. Your problem is almost certainly at a higher level in your system.
With these tools, you begin with the presumption that your hardware is working correctly. If the link light is out on the local host, these tools will tell you nothing you dont already know. But if you
simply suspect a hardware problem somewhere on your network, these tools may help you locate the problem. Once you know the location of the problem, you will use the techniques previously
described to resolve it. These tools can also provide insight when your hardware is marginal or when you have intermittent failures.
3.3.1 ping
While there are several useful programs for analyzing connectivity, unquestionably ping is the most commonly used program. As it is required by the IP RFC, it is almost always available as part of the
networking software supplied with any system. In addition, numerous enhanced versions of ping are available at little or no cost. There are even web sites that will allow you to run ping from their sites.
Moreover, the basic idea has been adapted from IP networks to other protocols. For example, Ciscos implementation of ping has an optional keyword to check connectivity among routers using
AppleTalk, DECnet, or IPX. ping is nearly universal.
ping was written by Mike Muuss.
[2]
Inspired by echo location, the name comes from sounds sonar makes. The name ping is frequently described as an acronym for Packet InterNet Groper. But,
according to Muusss web page, the acronym was applied to the program after the fact by someone else.
TE AM
FL Y
Team-Fly
®
42
[2]
For more on the background of ping as well as a review of the book The Story About Ping, an alleged allegory of the ping program, visit Muusss web page at
http:ftp.arl.mil~mikeping.html .
3.3.2 How ping Works
