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Configuring IPNetRouter for Dual Ethernet

Here's the nitty gritty on exactly how I converted a single ethernet IPNetRouter (IPNR) configuration to dual ethernet. This assumes you have read my configuring IPNR page. Previous disclaimers apply, and here's a new one:
  1. Installing new hardware and reconfiguring network settings may disrupt your Mac/network/Internet access. Don't do this right before an important deadline.

Here are the specific steps to take.
  1. Shut down the gateway Mac. Install the new ethernet card. You may need to install driver software. I bought an Asante 100/10 card and found it necessary to install the driver.

  2. Unplug the ethernet cable from the built in port and plug it into the new ethernet port.

  3. Follow the ethernet from the cable modem to the uplink port of your ethernet hub. Unplug it from the uplink port and plug it into the built-in ethernet of the gateway Mac. The Mac should now have an ethernet wire going directly to the cable modem without any intervening hub. The schematic is to the right.

Restart the Mac. Open the AppleTalk control panel and set it to "Connect via:" the PCI card. The exact wording on your system may differ from mine.

Start IPNR using your working single ethernet config file. Follow these steps:
  1. Bring down the interface from the built-in ethernet to the LAN. Do this by highliting that row, uncheck the "Bring Up" box, and click "Add." Note that when there was only one ethernet port, it was labeled "Ethernet." Now with the new card installed, IPNR automatically refers to it as "Ethernet built-in." Clever.
  2. Keeping this same interface highlited, use the "Configure Interface" controls to select the new ethernet port, check "Bring Up," then click "Add." You will see that, rather than modifying the highlited interface, a new interface is created in an empty row. The IP address and Mask should be identical to the downed interface. See my example to the right.
  3. Note that you do not need to alter the interface which communicates with the cable modem; even though its connection to your Mac is now direct and not thru the hub, logically, nothing has changed.

Note: the specific settings in the "Configure Interface" part of the above window are purely a function of when I grabbed my screen shots, and are not intended to teach or confuse.

Don't be upset if you can't make the old interface disappear even if you click "remove." I had to manually edit my config file with BBEdit and restart to clean up the window.

Save your new configuration once you've verified it works. Rename if necessary, put a new alias in startup items, or whatever your setup is. Consider using my gatewaySetup script if you have MacOS 8.5 or newer. If you have been using this script, open it, make a trivial change (type a space and erase it), recompile, and resave. Otherwise, it may still open the old config file even it it has been renamed.

Closing Thoughts

Adding a second ethernet card has dramatically improved network performance. I have downloaded a 7 Meg file in one minute flat. This is over twice as fast as what I was achieving with a single ethernet setup. I would like to hear from anyone who puts this information to good use. My e-mail address is on the IPNetRouter Teaching Index page. If you have questions/problems, posting to the NetTalk Mailing List is probably the best way to go.

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