Testing a TCP/IP protocol stack

If you are running under TCP/IP, there are several applications that you can use to test the compatibility of the client computer and server computer TCP/IP protocol stack. The ping utility provided with many TCP/IP packages is useful for testing the IP network layer.

Using ping to test the IP layer

Each IP layer has an associated address—a four-integer period-separated number (such as 191.72.109.12). Ping takes as an argument an IP address and attempts to send a single packet to the named IP protocol stack.

First, determine if your own protocol stack is operating correctly by “pinging” your own computer. For example, if your IP address is 191.72.109.12, enter:

ping 191.72.109.12

at the command line prompt and wait to see if the packets are routed at all. If they are, the output will appear similar to the following:

c:> ping 191.72.109.12
Pinging 191.72.109.12 with 32 bytes of data:
Reply from 191.72.109.12: bytes=32 time<.10ms TTL=32
Reply from 191.72.109.12: bytes=32 time<.10ms TTL=32
Reply from 191.72.109.12: bytes=32 time<.10ms TTL=32
...

If the ping works, then the computer is able to route packets to itself. This is reasonable assurance that the IP layer is set up correctly. Ask someone else running TCP/IP for their IP address and try pinging their computer.

Ensure that you can ping the computer running the database server from the client computer before proceeding.

Using Telnet to test the TCP/IP stack

To further test the TCP/IP stack, start a server application on one computer, and a client program on the other computer, and test whether they can communicate properly.

There are several applications commonly provided with TCP/IP implementations that can be used for this purpose. The following procedure shows how to use the telnet command to test the TCP/IP stack.

Start a Telnet server process (or daemon) on one machine. Check your TCP/IP software documentation to see how to do this. For a typical command line Telnet program, type the following instruction at the command prompt:
```
telnetd
```
Start the Telnet client process on the other machine, and see if you get a connection. Again, check your TCP/IP software documentation to see how to do this. For command line programs, you typically type the following instruction:
```
telnet server_name
```
where server_name is the name or IP address of the computer running the Telnet server process.

If a Telnet connection is established between these two machines, the protocol stack is stable and the client and server should be able to communicate using the TCP/IP link between the two computers. If a Telnet connection cannot be established, there is a problem. You should ensure that your TCP/IP protocol stack is working correctly before proceeding.