Networking with 2 computers

[Johnny]

Lab environment:
2 computers
No DHCP server
No Router
No Switch

I know the faster way to make two computers to talk to each other is using a
cross-over cable and assign static IP address on each one of them.

Somone told me there is another way to do it, and I just want to confirm
this with the experts here. He said two computers can talk to each other just
by computer_name, without any IP address.

My question: How reliable is this?

PROS & CONS?

All the comments are welcome.

Thanks

J.

 

[John Wunderlich]

Lab environment:
2 computers
No DHCP server
No Router
No Switch

I know the faster way to make two computers to talk to each other
is using a cross-over cable and assign static IP address on each
one of them.

Somone told me there is another way to do it, and I just want to
confirm this with the experts here. He said two computers can talk
to each other just by computer_name, without any IP address.

My question: How reliable is this?

Well, technically, you will have an IP address. If you connect two
computers configured for DHCP together with a cross-cable and wait a
while, each computer will give the "Little or no connectivity" error
message and then automatically assign themselves a random 169.254.x.x
(IIRC) address. (This assumes that in the network control panel for
your NIC, under TCP/IP Properties "Alternate Configuration" Tab you
have the "Obtain an IP address automatically" checked -- which should
be default), Once this happens, they can freely communicate using
this ad-hoc IP address. Microsoft networking establishes connectivity
using Names and Broadcasts, so as long as there are no firewalls in
place and neither machine is a P-Type node, you are good to go.


-- John

 

[AJR]

You can set up an ad-hoc wireless network. The "Someone" was not
politically correct - in the "olden days" (pre XP) computer names were
resolved by "NetBIOS" (IP address resolution). Much simpler to assign IP
address via TCP/IP properties.

 

[Johnny]

Hi John,

Thanks for responding, I tried this without setting any thing in the TCP/IP
preperties, just put a cross-over cable between these two computers, sometime
the connection cannot be reach. It does not establish the communication
everytime I restart these two comptuers.
If I shutdown both of them, then I turn on the PC-1 and wait until it gets
to the desktop, then I power on the PC-2, the application we are running does
not always work (no communication). How reliable is this type of setting vs.
assign an IP address on each one of them, and then add the IP and
computername in the HOSTS file, so the computername can be always reached.

J

 

[Johnny]

AJR,

Can "Ad-Hoc" work with wired network (XP to XP)?

J.

 

[John Wunderlich]

Hi John,

Thanks for responding, I tried this without setting any thing in
the TCP/IP preperties, just put a cross-over cable between these
two computers, sometime the connection cannot be reach. It does
not establish the communication everytime I restart these two
comptuers. If I shutdown both of them, then I turn on the PC-1 and
wait until it gets to the desktop, then I power on the PC-2, the
application we are running does not always work (no
communication). How reliable is this type of setting vs. assign an
IP address on each one of them, and then add the IP and
computername in the HOSTS file, so the computername can be always
reached.

J

Besides the IP Address negotiation, there is also line speed, duplex,
and signal direction negotiation. Since both ends of the line are
trying to detect speed & duplex simultaneously, it is not unusual for
each end to come up with a different answer. (A router/switch is fixed
so that only the computer end is negotiating -- but with two computers,
both ends are simultaneously negotiating). If you go into the Device
manager (Start->Run->"devmgmt.msc") and double-click on your NIC card
and go to the "Advanced" tab, there should be an entry for Speed &
Duplex. This is usually set to "Auto". Manually setting this to the
same speed at both ends and "Full Duplex" instead of "Auto" should
improve initial connectivity problems. Newer NICs also self-sense
direction (i.e. a regular cable may work instead of a cross cable). I
haven't found a manual setting for this.

Once connection is established, Windows networking should work just as
well either way. If you are using an application like FTP to transfer
files, then the Fixed IP method takes the randomness of the IP address
out of the mix but otherwise should work equally well.

HTH,
John

 

[Johnny]

John,

Is this what they called "APIPA"?
What is the difference between APIPA vs. Ad-Hoc?

J.

 

[Jack-MVP]

Hi
It might be that "Someone" meant to run the two with NetBEUI and crossover
cable.
NetBEUI does not work with IPs but with computers names.
If the computers have any other Network/Internet connection, then you need
TCP/IP anyway.
Configuring two computers with static IPs take few minutes.
In any case if you want to play with Win XP and NetBEUI.
http://www.ezlan.net/netbeui.html
Jack (MS, MVP-Networking)

 

[Johnny]

hi Jack,

I used to configure NetBEUI back in the old days for DOS
network/Win95/98/NT/XP.
But now we don't use NetBEUI any more, this person is saying to use
"Link-Local Address" I guess it's the same as APIPA to communicate these two
computers.
I just don't understand why he preferred to use APIPA instead of
conventional IP for network. How reliable is this APIPA?

J.

 

[John Wunderlich]

John,

Is this what they called "APIPA"?
What is the difference between APIPA vs. Ad-Hoc?

J.

Yes. This is APIPA
<http://msdn.microsoft.com/en-us/library/aa505918.aspx>

"Ad-Hoc", as far as I know, is a method for two wireless computers to
connect directly to each other without use of an Access Point or
Wireless Router. It may use APIPA to assign an IP address.
<http://en.wikipedia.org/wiki/Ad-hoc_network>

My use of the word "ad-hoc" was the standard English language
definition.
-- John

 

[Johnny]

John,

Is APIPA reliable, is this a good option to be used for business?

J.

 

[Jack-MVP]

Hi
The world is full of mysteries, and this might be one of them. .
I have No clue what, and why. If "SomeOne" can not explain clearly, and you
do not have any unusual specific needs, then forget about it.
Jack (MS, MVP-Networking)

 

[Johnny]

Needs: commmunicate by name between these 2 computers, via cross-over or
switch.

 

[John Wunderlich]

John,

Is APIPA reliable, is this a good option to be used for business?

J.

I have found it (APIPA) to be fairly reliable in that when a DHCP
server is not available the computers will assign themselves an APIPA
address.

Other factors such as negotiating speed / duplex may not be as reliable
depending on the hardware used.

-- John

 

[Jack-MVP]

Then install NetBEUI ( it takes 3 minutes).
NetBEUI can leave in parallel to TCP/IP, so No other changes are needed.
Jack (MS, MVP-Networking)

 

[AJR]

Johnny - first thanks to Jack - NetBEUI vice NetBIOS - "ad-hoc" pertains to
a wireless connection between two computers - wired are referred to as
"peer-to-peer".