"Dual-connected" active FireWire networks cause slowdowns

MacFixIt reader Alfie Johnson reports an issue where establishing a FireWire networking connection (FireWire over IP) from one Mac to another, then establishing another FireWire networking connection in the opposite direction results in a dramatic slowdown of transfer speeds.

He writes:

"I needed to transfer about 500MB of files from my PowerBook to an external FireWire hard drive on my iMac. Thinking that AirPort would be too slow I proceeded to hook the two computers together via a FireWire cable to use FireWire networking. I shut down AirPort and then connected to my iMac from the PowerBook via the Finder and tried to copy the files from the PowerBook to the iMac. Although I had logged in as an administrator a permissions problem wouldn't let the copy proceed. Not wanting to take the time to figure that one out I then connected the same way from the iMac to the PowerBook and proceeded to start the file copy from the iMac.

"The first batch of files was about 100MB and the Finder on the iMac was telling me it was going to take about 5 minutes. After about a minute and only 20MB transferred (and thinking FireWire should be much faster than this) I remembered that the network connection from the PowerBook to the iMac wasn't needed anymore so I proceeded to close that connection. Immediately the transfer rate picked up and the other 80MB transferred in just a few seconds. The remaining 400MB copied quickly also.

"So it appears at first glance that having 'dual' connections over a FireWire network causes some sort of slowness."

If you are experiencing slower-than-usual FireWire IP transfer speeds, try making sure that the connection is not simultaneously established on both systems. Also, if you are performing a one-way transfer, using FireWire target disk mode is often faster and in some instances more convenient

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