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Cross-Platform Network Basics: Part 1

For pre-OS X Mac operating systems

In order for Windows and Mac OS machines to network together, they must be running three levels of common network hardware and software:

On this page:

Cross-Platform Network Basics, Part 2:

Network Interface Hardware

Windows PCs and Macintoshes can be connected to the same wire using the same network interface hardware. Network interfaces for PCs typically come as add-in cards. All Macs have at least one type of network interface-LocalTalk, and many models include a second-Ethernet. You can add Macs to additional types of networks by adding the appropriate network interface card. Along with the network interface hardware, each computer runs low-level driver software that comes with the computer or the network interface card.


Ethernet is the most popular type network interface in Windows PCs and Macs. It is usually the first choice for a cross-platform network because of its wide availability, low cost, and dependability.

Ethernet comes built into most Power Macintosh and Mac clone models. An Ethernet card can be added to models where it is not built-in, such as Performa models, some Motorola StarMax models, and older Macs.

The most common variant of Ethernet is 10BaseT, which uses an RJ-45 connector. The 10BaseT cable plugs directly into the RJ-45 port on the computer, without the need for a transceiver box. The 10BaseT Ethernet cable connects directly to a centrally located piece of hardware know as a hub. Every individual PC and Mac is connects directly to the Ethernet hub in a "star" configuration. For small Ethernet networks, you can buy inexpensive hubs, such as Asante's FriendlyNet 10TS (about $60). You can also use Farallon EtherWave products, which lets you daisy-chain Macs and PCs without the use of a hub.


The Printer port in old Macs can be used as a LocalTalk network interface port (the modem port can be used for LocalTalk instead of the printer port). LocalTalk is not common on Windows PCs, but you can add LocalTalk hardware to a PC (see MacWindows Solutions for products). LocalTalk is usually used for small networks or ad hoc networks, when you need to temporarily move files between machines.

LocalTalk is generally easier and less expensive to set up than Ethernet. LocalTalk uses ordinary telephone wire with standard RJ-11 telephone connectors, the same as you use to plug in a telephone and modem. Each connector plugs into a LocalTalk transceiver, which connects to the Mac printer port or a PC's LocalTalk interface card. (LocalTalk transceivers that connect to a PC's parallel port are also available.) You connect one computer to the next in a daisy chain, like the way railroad cars are connected on a train. (You can also configure LocalTalk using a hub, but this is not common since the advent of 10BaseT Ethernet.)

LocalTalk does have some limitations. For one, LocalTalk is slower than Ethernet. LocalTalk has a bandwidth of 230.4 kbits/second, while Ethernet has a bandwidth of 10 MB per second. In practice, Ethernet runs about 4-to-5 times faster than LocalTalk. Another limitation of LocalTalk is that it cannot run TCP/IP protocols directly. However, you can run TCP/IP on LocalTalk by "encapsulation" TCP/IP inside of AppleTalk using a MacIP server. (See below).

For these reasons, most people opt for Ethernet when creating a new cross-platform network. However, there are some situations where it would be less expensive to use LocalTalk. For instance, if you were adding a PC to a small Mac LocalTalk network, it would be less expensive to add a LocalTalk card to the Windows PC than to replace the LocalTalk cabling with Ethernet cabling. If you were adding PCs to a Mac LocalTalk network that had LocalTalk printers, upgrading to Ethernet would require a LocalTalk-to-Ethernet adapter for each printer.

Other Network Interface Hardware

Mac OS and Windows machines can also communicate over other types of network interface hardware with the addition of a network interface card. One such network interface is Fast Ethernet, also known as 100BaseT Ethernet, which has a bandwidth of 100 MB per second. Fast Ethernet cards can often operate on both 10BaseT and 100BaseT networks. These are described as 10/100BaseT network interface cards.

Macs can also participate on older types of network interfaces used in some Windows networks, such as Token Ring and ARCnet. However, there currently aren't any vendors selling ARCnet network interface cards for Macintosh.

Network Languages: Protocols

In addition to using the same network interface hardware, computers must be speaking the same language, or running the same protocol. You can run multiple protocols over the same wires at the same time, and computers can use multiple protocols for different network tasks.

This section will look at the similarities and differences of configuring protocols on Windows and Mac OS machines.


The most popular common network language is TCP/IP, the protocol used on the Internet and on corporate intranets. Mac OS, Windows 95, and Windows NT come with TCP/IP system software, so there is nothing that needs to be added at the protocol level. For Windows for Workgroups, you can add the Microsoft TCP-32 driver for Ethernet connections, or 3rd-party driver for dial up connections. For Windows 3.11, you can add other TCP/IP drivers. Macs and Windows machines can use standard Internet software to communicate, as well as a variety of other network applications using TCP/IP. Macs can use AppleTalk and TCP/IP at the same time, as you might if you were browsing the Web while printing a Web page to a network printer.

Windows and Macs can run TCP/IP over a variety different connection types, including Ethernet , Fast Ethernet , and dial-up connections over a modem. When using a dial-up connection, Macs and Windows machines use the point-to-point protocol, or PPP. PPP software comes with Mac OS, Windows NT, and Windows 95. For Windows 3.1, 3.11, and Windows for Workgroups, PPP is available as part of the Microsoft Internet Explorer browser. Another dial-up protocol, SLIP, can be used instead of PPP, but is not as common.

TCP/IP cannot run over LocalTalk connections. However, Macintoshes can "encapsulate" TCP/IP inside of AppleTalk packets, in which case LocalTalk will work (see below).

Configuring TCP/IP on Windows and Macintosh: Differences

When setting up TCP/IP connections, you enter the same information on Windows PCs and Macintoshes, though in different places. For both machines, there are three types of information needed:

The exact user interface for entering this information varies with different versions of Mac OS and Windows. In these examples, we'll use Mac OS 8 and Windows 95. You should always follow the directions of the ISP when configuring a TCP/IP connection. The following information is a general reference only.

Configuring the Type of TCP/IP Connection

In Mac OS 8, you can switch between Ethernet and a dial-up connection in the "Connect via" pop-up menu at the top of the TCP/IP control panel. Other network interface hardware, such as 100BaseT Fast Ethernet or Token Ring, will appear in the pop-up menu if these network cards are installed correctly.

A third choice for a TCP/IP connection, "AppleTalk (MacIP)" is for "encapsulating" TCP/IP through AppleTalk (see below for details.)

In Windows 95, you choose the protocol and the network interface together via the Network control panel (accessible from the Settings item in the Start button).


The screen shot above shows "TCP/IP -> Dial-up Adapter" selected, the setting for a modem connection. If there are no other adapters, this choice will just say "TCP/IP." The selection above the selection is for an Ethernet connection.

Please note that the Windows 95 Network control panel may give you choices, such as Ethernet, that are not present in the machine. On a Mac, you won't get the Ethernet choice if the Mac doesn't have an Ethernet port or network interface card.

ISP Info

A domain name server (DNS) is always required on Windows and Macs. In Mac OS 8, the IP address number of the domain name server (or host) is typed into the field in the lower left of the TCP/IP control panel.(See screen shot above.)You can list more than one host. On the right side, type in the domain name information of the host as required. Some of the fields may be left blank.

To enter this information in Windows 95, click on the Properties button of the Network control panel to bring up the TCP/IP Properties window. Click on the DNS tab of the TCP/IP Properties window. You type in the host address and domain name here.

The IP address, subnet mask, and router address are not always required, as the server you connect to can sometime supply this information. On Mac OS, if you select PPP sever in the TCP/IP control panel, the server will configure this info. If you select BootP server or DHCP server, the server will supply the IP address. Which option you select depends on your Internet server provider.

In Windows 95, select the IP Address tab of the TCP/IP Properties window. If your ISP directs you to select "Obtain an IP address automatically," you won't need to type in an IP address or subnet mask.

Configuring PPP

Dial-up connections to the Internet require additional information, including the telephone number of the ISP, your user name, and your password. In Mac OS 8, after selecting PPP in the TCP/IP control panel, you enter user name, password,and phone number in the PPP control panel (some earlier versions of Mac OS had a similar control panel called ConfigPPP).


To enter or change this information in Windows 95 click on the Start button, then Programs, Accessories, and Dial-Up Networking.

MacIP: Encapsulating TCP/IP Inside of AppleTalk.

To enable Macs to run TCP/IP over LocalTalk or over Apple Remote Access dial-up connections, you can "encapsulate" TCP/IP network packets inside of AppleTalk packets. Encapsulation uses a protocol called MacIP, which in past years was referred to as KIP (Kinetics Internet Protocol). MacIP encapsulation of TCP/IP requires the network to contain a computer running the MacIP server/gateway software. The MacIP server contains a list of IP addresses, which it automatically assigns to computers on the AppleTalk network. Users on the network select "AppleTalk (MacIP)" in the "Connect via:" pop-up menu of the TCP/IP control panel. The user (or network administrator) must also specify where on the network (in which AppleTalk zone) to look for the MacIP gateway.

You can find more information on MacIP in the Apple Technical Information Library.

Configuring Windows NT Server for BootP clients

With Microsoft's Service Pack 3, the DHCP Server of Windows NT Server gained the ability to support BootP clients. BootP is a method of obtaining an IP address automatically from a server. (Mac clients would choose BootP in the Configure popup of the TCP/IP control panel.)

BootP addresses currently must be reserved in advance by creating an IP address reservation. (See the Microsoft Readme file in Server Tips (NT and BootP) for more info.) To create an IP address reservation in Windows NT:

Cross-platform Intranet: DHCP Servers and Windows Laptops

1. Open the DHCP Manager tool found in Administration Tools (Common)

2. Double-click on the subnet that you want to create the reservation in

3. A window will pop up showing your current leases and reservations

4. Click the "Add Reservation" button (maybe it's just add)

5. Another window will appear

6. Enter the information for IP Address, Client Name, and Identifier

7. Click OK.

8. You might get a message stating that "The Unique Identifier you have chosen may not be correct. Use it anyway?". Tell it yes.

9. Exit DHCP Manager and happy BOOTP'ing!

(Thanks to Richard Birchall for these instructions.)


The AppleTalk protocol is easier to configure than TCP/IP because it is self-configuring. However, as with TCP/IP, you still need to choose the type of connection you want to run the protocol over. There is no such thing as an "AppleTalk cable," as Apple is a hardware-independent protocol that con run on Ethernet, LocalTalk, dial-up connections, or any other network interface hardware, such as Fast Ethernet or Token Ring. You select one of these types of connections in the AppleTalk control panel.

AppleTalk comes with Mac OS and can be run on Windows with the addition of software (see MacWindows Solutions for a list of products and descriptions). AppleTalk solutions for Windows also come with network services software that enables Windows PCs to participate in AppleTalk-based file sharing and printing. In addition, the Windows NT Server comes with AppleTalk for support of Macintosh file sharing clients.

Macs can use AppleTalk and TCP/IP at the same time, as you might if you were browsing the Web while printing a Web page to a network printer.

Other Protocols

In the past, local area network (LAN) systems for PCs using NETBEUI, or other protocols used gateway solutions for adding Macintoshes. With this type of solution, gateway software running on a PC connects an AppleTalk network of Macs to a Windows network running another protocol. These types of LAN systems are largely being replaced by TCP/IP-based intranets.

Novell Netware or IntraNetware systems sometimes use the IPX protocol. Novell's Netware Client for Macintosh makes use of the IPX via driver software called MacIPX.

NETBEUI, a common network protocol built into Windows, is not available for Macs OS. PC networking software, NETBIOS, isn't available to Macs directly, but is available as NETBIOS over TCP/IP (known as NBT) using Thursby Software's DAVE. (See MacWindows Solutions.)


While NetBEUI is a network protocol, NetBIOS is a set of network API's required for Windows networking connectivity (and defined in RFC's 1001/1002). References for Windows NT and MCSE training guides (those that don't make the same all-too-common mistake) go to great lengths to instill in the reader the distinction between NetBIOS and NetBEUI. A common misconception is that NetBEUI is required for Windows NT networking because it is some sort of extended version of NetBIOS, which is required by Windows NT and is integrated into the core of Windows NT. This is not the case. Here's an excerpt from Microsoft's Technet CD-ROM, NT Server 4.0 Resource Kit's Networking Guide:

"Network Basic Input/Output System (NetBIOS) defines a software interface and a naming convention, not a protocol. The NetBEUI protocol, introduced by IBM in 1985, provided a protocol for programs designed around the NetBIOS interface. However, NetBEUI is a small protocol with no networking layer and because of this, it is not a routable protocol suitable for medium-to-large intranets. NetBIOS over TCP/IP (NetBT) provides the NetBIOS programming interface over the TCP/IP protocol, extending the reach of NetBIOS client/server programs to the WAN and providing interoperability with various other operating systems.

"The Windows NT Workstation service, Server service, Browser, Messenger, and Netlogon services are all direct NetBT clients that use the TDI to communicate with NetBT. Windows NT also includes a NetBIOS emulator. The emulator takes standard NetBIOS requests from NetBIOS programs and translates them to equivalent TDI primitives."

Here's an excerpt from Chapter 13 of the same volume:

"The NetBEUI protocol was one of the earliest protocols available for use on networks composed of personal computers. In 1985, IBM introduced NetBEUI to provide a protocol that could be used with software programs designed around the Network Basic Input/Output System (NetBIOS) interface.

"NetBEUI was designed as a small, efficient protocol for use in department-sized local area networks (LANs) of 20 to 200 computers that do not need to be routed to other subnets. Today, NetBEUI is used almost exclusively on small, non-routed networks composed of computers running under a variety of operating systems that can include Microsoft Windows NT Server 3.5 and later, Windows NT Workstation version 3.5 and later, Microsoft LAN Manager, Windows for Workgroups, Windows 3.1, Windows NT version 3.1, and LAN Manager for UNIX as well as IBM PCLAN and LAN Server.

"Windows NT-based NetBEUI, also referred to as NBF because it uses NetBEUI Frame (NBF), implements the IBM NetBIOS Extended User Interface (NetBEUI) 3.0 specification. This protocol provides compatibility with existing LANs that use the NetBEUI protocol and is compatible with the NetBEUI protocol driver shipped with past Microsoft networking products."

Thanks to Jonathan Woodard, Encompass Group, Inc., for the information on NetBEUI.


Cross-Platform Network Services

See Cross-Platform Network Basics, Part 2.


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