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By Hervey Allen(hervey@oregon.uoregon.edu)
Last January, people using older Macintosh computers occasionally experienced difficulties accessing off-campus Internet sites. The only machines affected were Macs that still use the MacTCP (or "Classic") style of network software.
These incidents underscored the fact that MacTCP is a very old implementation of the TCP/IP protocol and never implemented proper support for this protocol. The TCP/IP protocol is used for Internet access by such applications as Netscape, Telnet, email programs, FTP, and USENET News.
When MacTCP was last updated, some features available in the TCP/IP protocol were still not in widespread use, but lately advanced network features are becoming more common. One such feature is the ability to "mark" network traffic to give it priority for applications such as Voice Over IP (VOIP), i.e. making phone calls via the Internet. At some point this service may become integral on the UO campus.
To implement a service like VOIP, a feature called Type of Service (ToS) is often set for some packets on our network. In January, one of our network service providers turned on this feature. When they did this, MacTCP Macs, which fail to implement this part of the TCP/IP protocol correctly, could no longer connect to any site that was accessed via this provider.
The problem is a diret result of MacTCP's inability to fully support features in the TCP/IP protocol, the protocol used for Internet access by such applications as Netscape, Telnet, email programs, FTP, and USENET News. For the time being, this problem has been resolved by artificially resetting certain ToS bits for all incoming IP traffic at the UO. However, this is only a short-term solution and problems with MacTCP are likely to recur with increasing frequency as time goes on.
In short, in the future no version of Apple MacTCP can be relied upon to work correctly as newer networking features are implemented.
No MacTCP updates are forthcoming. We have contacted Apple directly, and they have confirmed that Apple will not develop an update for MacTCP to resolve this issue. (MacTCP was last updated in 1994 and has been considered a legacy product for several years.)
This means that sooner rather than later, all MacTCP Macs must be upgraded to use Open Transport. (While it's also possible to install a third-party patch, we don't recommend it.)
If you can access the Internet on your Mac, go to the Apple menu, choose the Control Panel, and look for "MacTCP." If it's there, that's the network protocol your Mac is using. If instead you see a control panel called TCP/IP, you'll know your Mac is using Open Transport.
Recommended Upgrades. If you're using MacTCP you'll need to upgrade your Mac operating software by January 1, 2001, when our network "quick fix" will be retired. Both our short- and long-term upgrade recommendations are listed below:
Note that current UO students, faculty, and staff may obtain Mac OS 8.1 at no cost from the CC Public Domain server on UOnet, and the Documents Room (205 Computing Center) has a CD to lend.
Because this problem is quite complex, the Microcomputer Services staff has created a web page explaining it in depth. This page (http://micro.uoregon.edu/macintosh/mactcp.html) lists all your options, memory requirements, machines for which there is no solution (any 68020 Mac, like an SE or Plus), our recommendations, and much more. Please read it carefully before directing questions and concerns to our staff.
If you still have questions after reviewing the information on our web page, email a consultant at microhelp@oregon, or call 346-4412.