Peer-to-Peer Networking (2 machines)

Here's some guidelines for connecting one machine to another machine using Ethernet, with no other machines on the network. In this case, you don't need a hub; you just need to connect the wires between the two machines correctly. Refer to my page on color codes for detailed instructions on plugs and jacks.

To connect two machines to each other without a hub, you need a "cross-over" patch cable, which crosses the transmit and receive pairs, the orange and green pairs in normal wiring.

  One End     Cable  The Other End
TR+   pin 1 -------- pin 3 RCV+
TR-   pin 2 -------- pin 6 RCV-
RCV+  pin 3 -------- pin 1 TR+
RCV-  pin 6 -------- pin 2 TR-

Alternatively, you can connect two wall jacks back-to-back, swapping the orange and green pairs, to make a "two-port hub". Then you can use straight-through patch cords between each of the machine and one of the "hub" jacks. This is used to connect two 10baseT transceivers directly together, as in connecting the transceiver on your Mac to a transceiver on another Mac. I suppose you could connect a Mac to a PC, but why would anyone want to?. :-)

One more excellent suggestion was contributed by (Isaac Wingfield). Make the crossover cable using a very short cable with a standard RJ-45 plug pinout on one end and a wall jack, cross-wired, on the other end. Then you use a single standard straight-through patch cord. Using this small cross-over "extension cord" prevents having two kinds of patch cords around and makes it very obvious what it is.

The information below was kindly contributed by Butler Crittenden ( in San Francisco. This deals with the issue of wiring a 10baseT connection directly between two computers, without a hub. The "transmit" and "receive" pairs need to be swapped in the wiring.

Installing RJ-45 plugs on the ends of a Cat 5 wire or Cat 3 wire for a peer-to-peer, two-computer network using PCI and/or 16-bit network cards

Cat 3 wire looks like Cat 5 wire, both with 8 wires (4 pairs) of the standard colors for Cat 5. For the standard Ethernet hookup (Cat 3 or 5 wire), after trimming off the outer casing by the length set by the crimping/trimming tool (about 1/2 inch) and exposing the small wires, clip off the brown-white/brown and blue-white/blue pairs. Inside the RJ-45 plugs the channels for pins 4, 5, 7, and 8 are left empty.

WITH THE CLIP SIDE FACING DOWN! (Note: pins 1,2,3, and 6 are the only ones used.)

Complete Wiring for Cross-Over cable:

On one end      The Other end
Pin     Wire color     Pin
1       white/orange    3
2       orange/white    6
3       white/green     1
4       blue/white      4
5       white/blue      5
6       green/white     2
7       white/brown     7
8       brown/white     8
Tip: After crimping with my tool the clip was flattened and did not click in when inserted in the network card. A GENTLE lifting with my thumbnail solved the problem.

Also worth pointing out to anyone doing this in Windows 95:

In Control Panel/Network, the following are required. I'm tempted to say "the following ONLY are required and others should be removed," as I recall a companion protocol for each that installs automatically and actually prevents the network from operating. Anyway, the following worked twice for me and for a friend:
1. Dial-Up Adapter

2. NE2000 Compatible
    Driver Type         Enhanced mode (32  and 16 bit) NDIS
    Bindings            IPX/SPX-... checked
                        NetBEUI-... checked

3. IPX/SPX-compatible Protocol --- NE2000 Compatible
    Bindings            same as 2
    Advanced            defaults and KEY setting "Set this protocol to be
                            default protocol"  NOT checked
    NetBIOS             "I want to enable NetBIOS over IPS/SPX"  NOT checked

4. NetBEUI -- NE2000 Compatible
    Bindings            same as 2
    Advanced            defaults and "Set this protocol to be the default
                            protocol" NOT checked

5. TCP/IP -- Dial-Up Adapter

6. File and Printer sharing for Microsoft Networks
The above works, with a peer-to-peer two-computer network, which operates fine with 10base-T. (COAX cable does not require such wiring and permits more than two computers to be installed without a hub.) I have experienced one quirk, which may require a different setting. When I send files back and forth they almost always arrive intact. The one exception is that twice I've sent a version of Netscape that I downloaded as a self-extracting .exe and had it fail on the receiving end. That is, it extracts and sets up normally on the computer on which it was originally downloaded, but not on the second computer after "copying" it to a directory on that second computer via my network. Perhaps a "default" in number 2 or 3 above needs to be changed.

Step by step guide for setting on Windows 95 software...
With Pictures!

This link was suggested by Maurice Nusom. It is a real clear guide, with screen shots and everything.

For any Windows users who might be curious, here's how you do the same thing on a Macintosh. Click Here

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