Networking Older Macs – Link Speed Auto-Negotiation

After my last post providing the back story of the Macintosh IIfx, this next one logically ought to concern itself with my efforts to dual boot System 6 onto a Mac IIfx that was delivered with System 7.5.5 already on it. However, as happens all too often, I ran into a roadblock right out of the gate. Despite the presence of a networking card that the seller assured me was fully functional, I was unable to get my Mac IIfx to connect to the Happy Macs lab internal network. Resolving this matter unearthed an issue of some small interest, Ethernet link speed auto-negotiation, and so as a prelude to dual booting System 6, I will delve into this somewhat arcane topic for just a moment.

I have used a vintage Linksys 10/100 switch to connect most of the older Macs in the Happy Macs lab with no troubles at all. The oldest of the Macs thus connected is a Macintosh IIsi running System 6.08, and connected via an Apple networking card (Apple Ethernet Twisted-pair transceiver M0437LL/A).

Linksys 10_100 Switch (Reduced)

The “new” Macintosh IIfx came preloaded with Mac OS 7.5.5 and a Farallon EtherMac II-TP networking card. The seller confirmed that the machine connected to his local network just fine, and in fact included pictures of it running an early web browser.

Farallon EtherMac IItp

Therefore, one of the first things I did with this machine was to hook it up to the internal network of the lab via my proven Linksys switch. Since I am writing a post on this topic, it will come as no surprise to find that this did not work!

I was not overly concerned to start with, assuming some form of software configuration issue. Since I was going to reload the machine with System 6.08 anyway, I decided to wait until I had done so before getting too involved in trying to get networking up and running. In due course, I did in fact load the Mac IIfx with System 6.08, replicated the networking software configuration and settings that were working so well on my Mac IIsi, and then wondered in frustration why it would work so well on that machine but not at all on the Mac IIfx!

I focused immediately on what was different and relevant between the two – the networking card. I found Farallon drivers for it and loaded those, to no avail. I tinkered with the software lineup and configuration, again to no avail. I began to suspect that the networking card itself might not have survived the trip intact, and started to look for the same Apple card that was doing such a fine job in my IIsi.

While I shopped, I did a little research on line to see if this was perhaps a well-known problem. I didn’t find anything of great interest on the topic, but this lack of information did cause me to think in a little more depth about the problem, and ultimately I vectored off into the area of link speed auto-negotiation, something I came to find out that all modern switches do, and most vintage ones did not. The reason is simplicity itself. The standard used for auto-negotiation, IEEE 802.3u (“Fast Ethernet”), was released in 1995. My non-communicative Mac IIfx was released in 1990!

The Farallon networking card was clearly also released sometime in this period, but just when was not clear. It’s documentation said that it supported IEEE 802.3, but it did not mention IEEE 802.3u. However, even if 802.3u was supported by the hardware, perhaps something was missing in the Mac OS 6.08 software layers that was being handled in firmware on the Apple networking card?

I never did answer this question, and so must leave it hanging for your consideration should you ever run into a similar bind. At this point, I took a different turn. IF auto-negotiation was the issue, this could be tested for easily by simply removing the need for it – get a 10 Mbps switch and try that. I decided to do just this, but in a “modern way”. I found an inexpensive managed switch that would allow me to manually set the speed of a link and thus eliminate auto-negotiation entirely. In this case, I chose the NetGear ProSAFE GS108PE, ordered one on Amazon and it arrived a few days later.

Netgear ProSafe GS108PE Switch (802x510)

To make a long story short, I plugged the new switch in, used its built in web interface to set the speed of one of the links to 10 Mbps Half Duplex, plugged the cable from the Mac IIfx into the selected link and it came up right away! I have been using it successfully ever since and can report that it is very stable. A whole lot of files have been transferred over the network via that switch since that day.

We can learn a few things from this exercise:

  • Some older networking cards will successfully establish a link with a modern auto-negotiating switch and some won’t. I have unearthed various reports since then indicating that various cards by Asante do quite well, as do the Apple card I mentioned above. See this link for model numbers:http://www.people.fas.harvard.edu/~netmgr/ether.mac.html

I cannot vouch for the cards mentioned of course, and the article does not indicate what sort of switch these cards were tested against, so your mileage may vary.

  • If you have none of the above cards, you may wish to approach the issue of network connectivity with some patience. My experience suggests that a managed switch with the link speeds set to 10 Mbps Half Duplex may save you a great deal of grief.
  • Apple made a good networking hardware “back in the day”!

Good luck networking your older Mac!

 

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