Open Transport provides individual computer users with many benefits. Two of the most visible and important benefits relate to making networking more accessible:

Ease of Switching Network Configurations

Integrated Online Help

Open Transport provides significant new flexibility in setting up network configurations. A network manager can recommend or require configuration settings for users on the network, or allow users to determine their own settings.

Open Transport also improves support for centralized configuration management. For example, Open Transport/TCP supports the Dynamic Host Configuration Protocol (DHCP), letting network managers administer addressing and other TCP/IP configuration information from a central server.

Open Transport makes it easier and more cost-effective to develop Macintosh-based applications for a wide variety of customers. With Open Transport, the Mac OS has built-in networking and communications based on cross-platform industry standards, including the POSIX compliant X/Open Transport Interface (XTI), Unix STREAMs and Data Link Provider Interface (DLPI). Applications written to support Open Transport can directly support a wide range of networking environments (serial, dial-up network, LAN, and WAN), and multiple protocols (AppleTalk, TCP/IP, serial, and others) from a common code base.

Questions and Answers About Performance

Answer: Open Transport is written to take advantage of the PowerPC processor -- it is native code. This provides the necessary foundation for increased networking performance in the Mac OS. To realize performance gains, however, it is equally important that networking applications also be accelerated for Power Macintosh, and that applications adopt the new Open Transport XTI-based programming interfaces.

The built-in "backward compatibility" support for existing AppleTalk and TCP/IP applications continues, for technical reasons, to run as 680x0 code in emulation on Power Macintosh. This protects a customer's investment in networking applications, but also obscures underlying performance increases from the native protocol implementations.

Question: When will new or updated applications that support the native Open Transport APIs become available?

Answer: Some new applications and updated versions of existing applications are native and use Open Transport now. More will be shipping this year. Contact the specific third-party vendor for more details on their product release plans.

Question: How much faster will native Open Transport applications be?

Answer: Networking performance is influenced by many factors. Customers will see the highest performance networking when using Power Macintosh native applications that fully support Open Transport APIs. Performance will be greater with protocols that use larger datagram sizes¬such as TCP/IP¬than with AppleTalk (which has a fixed and limited datagram size). On high-speed datalinks (such as fast Ethernet, FDDI, and ATM), the performance of the network interface card (NIC) driver code is also a significant factor. Comparative shopping for NICs - based on price, service, reliability, and performance -- will be in order.

Open Transport v1.0 - running on the built-in Ethernet of the Power Macintosh 9500 - has been clocked at 9,300 Kbps throughput using low-level TCP/IP benchmarks. A pre-release version of a third party Open Transport-native implementation of 'nfs' protocols was benchmarked at 8,400 Kbps. Both figures approach theoretical maximum performance for 10 Mbps Ethernet. AppleTalk performance is somewhat lower, with low-level benchmarking coming in at a bit over 7,500 Kbps throughput.

Question: Does the new native code include Ethernet drivers for Macintosh onboard Ethernet adapters?

Answer: The Power Macintosh 9500 ships with a new native DLPI Ethernet driver for built-in Ethernet. Future PCI bus Macintosh computers also include native Ethernet drivers. Power Macintosh 61xx/71xx/81xx models currently have 680x0-based drivers; these should be updated to native drivers in the first half of 1996.

Question: What about high-speed networking connections like fast Ethernet, ATM, and FDDI?

Answer: The Open Transport engineering team is working with NIC developers to create high-performance DLPI drivers for high-speed datalinks. This is a cooperative effort, with some work remaining on both driver code and on Open Transport. We expect that high-speed datalink NIC drivers based on Open Transport v1.1 will be fully competitive with other PCI networking products. Of course, performance tuning will be an ongoing priority, as Apple intends to always offer a platform capable of industry leading network performance.

Question: Will developers ship NICs for fast Ethernet, FDDI, or ATM based on Open Transport v1.0, or will they wait for the performance tuning planned for v1.1?

Answer: Each developer will make an independent decision to bring their product to market at such time as they are satisfied with the combined performance and reliability of their product with Open Transport.

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