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Mac’s dirty little Ethernet secret

Ethernet and AppleTalk issues are surprisingly common in mixed environments.

Mac users face problems with Mac Ethernet and AppleTalk when trying to manage a single network of different clients. Take Troy City Schools in New York, for example. It found that AppleTalk doesn’t always get along with some of the standard networking environments, especially TCP/IP. But it–and you–can find a solution.

Even with AppleTalk turned off (on a Windows NT network), Apple NIC cards don’t always do “pure” IP very well. The NIC cards built into Power Mac G4s have trouble recognizing standard IP Ethernet. Some users have tried installing Assante PCI NIC cards in their networked G4s. This solves the problem except for one major gotcha: The G4s sometimes go looking for the network through their built-in cards and, finding no connection, lock up in the process.

What’s more, the 3Com NIC cards on some servers have a default setting that doesn’t work with built-in Mac cards. Apple has acknowledged the problem, and changed their built-in NIC cards for Mac OS X. This should alleviate the problem with G4s shipped after April 2002, no matter what the server NIC card says. That is, if you’re running Mac OS X. For G4 clients with Mac OS 9.x, the built-in card is still problematic.

The built-in Ethernet cards in Macs don’t use the PCI bus; they run on the motherboard. Otherwise, you could just pull the Mac NIC card out and replace it with another card. But since the cards can’t be removed, Mac OS 9 sometimes tries to use the built-in card despite the fact that there’s no cable attached.

The Ethernet interfaces are built onto the various logic boards, which is why it’s critical to have the latest updates to Open Transport. A good rule is to disable the .enet driver (built-in Ethernet, in other words) with the Extensions Manager when you replace its function with a PCI-based Ethernet solution. Also, you should always trash the network preferences and the AppleShare prefs, zap the PRAM, and rebuild the desktop. Generally, these steps will result in a trouble-free installation.

Of course, all this doesn’t help if you have older G4s and pre-flat panel iMacs that still experience the problem. If this is the case, your best option still may be to put a new NIC card in. But first you should make sure there’s not a software solution that will work.

Terry Davis, senior systems engineer at Asante Technologies, says AppleTalk was a wonderful protocol back in 1986 when MacOffice (a project that mutated into AppleWorks, ClarisWorks, then to AppleWorks again) was supposed to ship. In fact, it still coexists pretty well in any network, though Davis says you should watch out for the following:

-Spanning Tree Protocol (STP) is a bridge protocol that ensures that you don’t have a loop in an Ethernet network. In most instances you will need to turn this off on the ports that connect to Beige G3 or later Macs. AppleTalk and the faster Macs conflict with STP, meaning the network will appear and disappear depending on the state of STP (e.g., blocking, learning, forwarding) and the instance of the Mac boot process.

-For some reason, AppleTalk Net and Node numbers on Macs up to and including the latest G4s will assume the same AppleTalk Net and Node number, while in a switched network with STP they will conflict and devices will ghost in and out of the network. The fix here is to lock down manual AppleTalk Net and Node numbers just as you would for IP.

o Duplex MisMatch. For some reason, modern Macs from the iMac forward have a problem with auto-negotiation. Some will work fine with NWay, but some won’t. “I usually lock down the ports that attach to Macs to 100MBS and full-duplex,” Davis says. “Some will work in this manner and some will actually prefer to auto-negotiate. This will cause performance problems in the entire network. I think it actually does have something to do with the Ethernet interface. This is where most people will replace it with a third-party NIC. When you do this, you need to disable the built-in Ethernet interface via the Extension Managers.”

-The issue with Macs not being able to work in a pure IP network can’t be blamed entirely on the Mac hardware. Even when AppleTalk packets are relied on to start the connection, it’s more of an application problem. “It’s the reliance on those ol’ trusty LaserWriter printers that still require AppleTalk that will force AppleTalk on the Net for some time,” Davis says. “Mac OS X is doing a great job in setting the scene for AppleTalk’s eventual demise.”

-Speaking of Mac OS X, it solves many problems, but brings a new one to the table. If you are running Classic and AppleTalk under the new operating system, you can have a double whammy in having to duplicate AppleTalk addresses to and from the same computer. It’s best to disable AppleTalk under Mac OS X, according to Davis.

You may also want to check out some of Asante’s own products, such as the new IntraCore 3524 series of workgroup switches.

Meanwhile, Reid Lewis, president of Group Logic, a company that makes network workflow products, says the reason people use AppleTalk is that it’s still a good protocol. The problem is that it didn’t become a standard. If you’re still using it, you should consider switching to TCP/IP, Lewis says, adding that TCP/IP can be six or more times faster than AppleTalk while using the same amount of data. TCP/IP also doesn’t have the problem with “chattiness.”

“When you’re using TCP/IP, the communication on the network is only what’s needed,” he says. “AppleTalk is always self-configuring, so often there’s too much chatting going on, and this affects performance. If we’re talking about half a dozen computers, it’s not that big a deal. But when we’re talking about hundreds, it is.”

TCP/IP also beats AppleTalk for routability, he says. The latter wasn’t built for an environment in which there are lots of computers and “connections all over the place,” Lewis says. TCP/IP was designed for such an environment.

And if you’re using both protocols, you’re doing too much work. While Group Logic supports both for most functions, Lewis recommends going strictly with TCP/IP. The company’s products don’t support AppleTalk printing because there are other solutions that do this and TCP/IP printing is up to three times faster, Lewis says.

Some folks have improved the speed and reliability of file and print server support in mixed Mac/Windows networks by using ExtremeZ-IP from Group Logic. The aforementioned Troy City schools system is one of the institutions that have found this to be a satisfactory solution.

ExtremeZ-IP is a specialized file-and-print services system that uses the TCP/IP protocol to increase throughput between Mac clients and a Microsoft Windows NT or Windows 2000 server. Troy City Schools use it to speed file access and simplify support tasks across the district’s network.

Dan Shyne, computer network manager for Troy Schools, says the school system started out using Services for Macintosh, a Windows server facility that supports file and print services for Mac network clients. “But we had problems with servers maxing out RAM and clients dropping off the network,” he says, “which is why we moved to ExtremeZ-IP.”

Besides getting rid of memory and connectivity problems, Shyne says the speed with which clients can access files has increased substantially on Windows NT, and that the improvement in ease of use on both platforms is “huge.” That’s important for the school district, where most users are students or teachers accessing grade-book programs and a variety of documents.

ExtremeZ-IP supports a total of about 1,600 individuals at the district, somewhat evenly divided between two servers. ExtremeZ-IP enables the district to centralize storage of those resources on only a few servers, which helps Shyne in his efforts to support the network, according to Dale Gardner of Group Logic. And Shyne says it’s much easier to walk over to the server room than it is to drive to schools to fix a problem.

Lewis says he wasn’t aware of the hardware problems related to NIC cards. However, there was a problem with the Ethernet driver in an early version of Mac OS 9 that could cause Macs to unexpectedly disconnect from a file server. The problem only affected people connected with TCP/IP and not AppleTalk. The solution is a downloadable driver dubbed EtherNet 2.0.

The Apple EtherNet Update 2 consists of version 2.4.3 of the Apple Ethernet extension. This improves AppleShare connections in high-traffic network environments. When you use certain Mac OS 9 applications while connected to AppleShare volumes, disconnections can occur. You may see “TickleTimeout” disconnect messages in the Mac OS X Server 10 Apple File Service access log. The Apple Ethernet Extension 2.4.3 prevents these disconnections from occurring. You can download the driver (an 1186 file) from the MacUpdates Web site. It requires Mac OS 9.2.1 or later. As for recent Apple systems, Lewis says Macs released over the past year or so don’t need anything extra for general functionality.

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