Note: For a tutorial on
how to setup MIDI on your Mac computer, click here. Then, if you want to setup MIDI over LAN, go back to this article and continue reading.
Wouldn't it be cool if you can setup a MIDI network without all the cables and instead just use your local area network? And woudn't it be twice as cool if it's a wireless network???
Here are the step-by-step procedure for setting up MIDI over LAN using Apple's built-in MIDI over Lan feature. Yes! Apple has built-in MIDI networking and I bet most of you didn't know that.
What are some uses of MIDI over LAN?
1. Let's say you have softsynths on several computers. If you load all these softsynths on a single computer, you'd get cpu overloads. So you decidedd to distribute the load to several computers (or a second computer) and have the other computers play the softsynths while your main computer is used as your sequencer.
2. Clean up those cables. Using wireless LAN, you can have a MIDI network running virtually, without wires.
3. Your softsynth is only PowerPC compatible and does not have a Universal Binary available yet... (example: Spectrasonics Atmosphere, Trilogy, etc). But your main sequencer is an Intel Mac. How can you use your old softsynths? Answer: Run your sequencer on the Intel Mac and access the softsynths running on the PowerPC via MIDI over LAN.
My 1st computer is a PowerMac G5 Dual 2.5Ghz. My 2nd computer is an Intel MacBook. For this discussion, let's say I want to run my sequencer (Digital Performer 5.11 Universal Binary version) on the MacBook, and access/play Spectrasonics Atmosphere running on the PowerMac G5.
Step #1. On the G5, open up Utilities under Applications and run the program Audio Midi Setup.

Step #2. When Audio Midi Setup opens up, click on MIDI Devices. You'd see your current MIDI Setup.

Step #3. Double-click the Network icon. Then configure it as follows:

Create a Session, by clicking the [+] button under "My Sessions." Give it a descriptive name.
You'd see this session name show up as the Local Name. Click the "Enabled" checkbox and leave the port number as is, 5004. You may change the Bonjour name of your computer. You may also change the security settings "Who may connect to me:".
Step #4. On your laptop, or 2nd computer... do the same thing. Open up the Audio Midi Setup, click on Network, and Midi Devices.

You should see the 1st computer you setup (i.e. it's Bonjour name), under "Directory." Make sure Enabled is checked, then select the G5Mac computer (i.e. the 1st computer) and click Connect.
If the connection is successful, you'd see G5Mac as a Participant.

Step #5. Go back to your 1st computer, and you should see the name of the 2nd computer as a Participant. Now, we've verified that both computers are talking to one another.
But the proof is in the pudding. So run your favorite softsynth (in a host sequencer) or stand-alone if it's stand-alone capable.
In the MIDI Network setup, I changed the Live Routings to select the Network destination as Atmosphere-1.

Then in my MacBook, I have Digital Performer sequencer running. I created a MIDI Track, and set the OUTPUT destination to "Network-1." I hit a few keys on my midi controller and the Atmosphere softsynth running on my G5 starts playing. The latency is almost non-existant. It's instantaneous.... provided you use Live Routings.
If you fail to use Live Routings, and instead MIDI has to go to another sequencer, there may be some latency delay. So it is important that you use Live Routings and point it to the softsynth you want to play.