Testing Connection using TCP/IP

by Johannes Helmig [Published on 16 Sept. 2001 / Last Updated on 16 Sept. 2001]

Usually, when connecting Windows95 systems, NetBEUI is used as network protocol, because the Microsoft "win95-server" (also called "Microsoft File and Print Sharing") can be most easily setup with NetBEUI protocol (you can also used TCP/IP or IPX/SPX, but that is a little more complicated)

But when you think, that everything is setup properly, but you CANNOT get any connection, you need to establish first, what and where something is wrong in the complete setup:

whether the hardware (network board and cables) work properly to identify, whether you have a Hardware or Software problem.

For that, the TCP/IP protocol supplied with Windows95/98/ME/NT4/2000 offers a small,
but powerful tool called : 'ping'. (You can also use the NET DIAG test), allowing to make a connection test on a much simpler setup, but TCP/IP PING can also be used to test a WAN
connections
) :

"What is ping actually doing ?"
Remember the movies on sub-marines, where they are searching each other sending out a search-signal , which sounds like 'ping' and where they get back an echo from another sub-marine ?
That is EXACTLY, what the 'ping' utility does:

send out a signal
and get an echo back

That is part of any TCP/IP ( regardless of the operating system): on receiving a 'ping', it sends the signal back to its origin.


To setup TCP/IP for this 'ping' test, in case it is not yet already installed
( for more detailed info: TCP/IP basics) :
* add in addition to your existing network protocol TCP/IP
(in the "Network" applet in "Control-panel", tab : "Configuration", select "add") :

In the window "Select Network Component Type", select "Protocol", then "Add" :


choose "Microsoft" and then the "TCP/IP".
* do NOT exit the Network applet, you first MUST configure TCP/IP.
(If you do EXIT and restart, you get a warning on "DHCP": ignore it,
go back to the Network in Control-panel and configure the IP-address)
* select the TCP/IP-protocol in the Network-applet, then select "properties":
* on the tab:"IP-address", select the radio-button to "define the IP-address",
enter on the first PC as address 192.168.10.1,
on the second PC as address 192.168.10.2,
enter as subnet-mask 255.255.255.0 :

then close it.
* reboot Windows.


If TCP/IP is installed but configured to: "obtain an IP address automatically":

then you need to find out, which IP-address has been assigned by a DHCP-server or by the
Windows98/ME/2000 IP-Auto-Configuration :
- find out the IP-address assigned to you.


Open a DOS-box, and on PC#1, typ: ping 192.168.10.2
This will send now an Ethernet package to the system with that IP-address, which is here PC#2. And every system properly configured with TCP/IP will send that packet back:
the reply will be (for a test to IP-address 192.168.10.2 ) :
Pinging 192.168.10.2 with 32 bytes of data:
Reply from 192.168.10.2: bytes=32 time.......


If it comes back ("Reply from...") , then your Ethernet board and cables seem to be fine, you
have a network software setup-problem, check the setup of the protocol (if IPX/SPX was used), check permissions and sharing, user-names and workgroup-names.

However, if the answer to your PING displays :
Pinging 192.168.10.2 with 32 bytes of data:
Request timed out.

'ping' did NOT get an answer back (' Request timed out'), try first if you can make the
'ping' from the other system (sometimes 'ping' works only in ONE direction, it may have been
disabled on one system).

If 'ping' does not work in both direction, then you have most probably a hardware problem,
which could be the network board, the cable , the hub(if using 10baseT) or the t-connectors or the
terminators (if using 10base2). (no joke: I know somebody, who went from Los Angelas to Hawaii
just for that, he swapped a T-connector and then the network worked, checking later that
t-connector showed a microscopic crack, not visible with the naked eye).

If you are using a FastEthernet network, it could also be that the network card and the hub did
not properly configure themself for the Media Speed and/or the Duplex-Mode.

In professional networks, I would suggest now the use of Ethernet cable testers, which put a test-signal on the cable and can tell you, if the cable is o.k. or bad and then also WHERE is is bad.



Answer from PING:
"
Destination host unreachable"

This error message of PING indicates, that you tried to test the connection
to a system NOT on the same subnet (where a direct connection is possible),
but via a Gateway/Router on a different subnet (for more info on this issue,
please see the section of
Gateway/Router of TCP/IP-Bascis).
But you did not define a Gateway address: :


Enter a valid Gateway/Router-address:


When testing a TCP/IP connection via a Gateway/Router, you need to be
aware about very single step:

1) The PING signal is send to the Gateway/Router (is the gateway defined ?)


2) The Gateway passes the PING signal on to the destination system
(or if required to the next Gateway/Router, until it reaches it destination subnet)


3) The destination signal replies by generating the PING ECHO
(is the destination system configured for the Gateway/Router, so that it is able to send back the signal ? )


4) The Gateway/Router receives the PING Echo and sends it back to the
source-system:


When setting up Gateways/Routers, don't forget to setup ALL system, which the signal is traveling through from the source to the destination AND BACK.
If "Ping" does not get back a reply from a connection via router(s), use the "tracert" command
to find out, how far your test-signal got and where it got stuck.

And if you have problems, enter the PING command on both systems, it may give you an error message indicating the problem (like a missing Gateway definition).

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